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To investigate the associations between corneal curvature (CC) and other anterior segment biometrics in young myopic adults. In this retrospective multi-center study, 7893 young myopic adults were included. CC and other anterior segment biometrics were measured by Scheimpflug imaging (Pentacam). CC was defined as SimK at central 3 mm area, and other anterior segment biometrics included white-to-white corneal diameter (WTW), central corneal thickness (CCT), corneal volume (CV) at 3 mm, 5 mm, and 7 mm area, anterior corneal astigmatism (ACA), posterior corneal astigmatism (PCA), anterior corneal eccentricity (ACE) and asphericity (ACAP), posterior corneal eccentricity (PCE) and asphericity (PCAP), anterior chamber depth (ACD), and anterior chamber volume (ACV). Univariate regression analyses were used to assess the associations between CC and other anterior segment biometrics, and multivariate regression analyses were further performed to adjusted for age, gender and spherical equivalent. CC was higher in patients of female gender and higher myopia (all P < 0.05). Eyes in higher CC quartiles had lower WTW, thinner CCT, lower CV at 3 mm and 5 mm, lower ACD, and lower ACV (all P < 0.001), but had larger ACA, larger PCA, less PCE and less PCAP (all P < 0.001), compared to eyes in lower CC quartiles. The trends of CV at 7 mm, ACE and ACAP were inconsistent in different CC quartiles. After adjusting for age, gender and spherical equivalent with multivariate linear regression, CC was positively correlated to CV at 7 mm (β s  = 0.069), ACA (β s  = 0.194), PCA (β s  = 0.187), ACE (β s  = 0.072), PCAP (β s  = 0.087), and ACD (β s  = 0.027) (all P < 0.05), but was negatively correlated to WTW (β s  = - 0.432), CCT (β s  = - 0.087), CV-3 mm (β s  = - 0.066), ACAP (β s  = - 0.043), PCE (β s  = - 0.062), and ACV (β s  = - 0.188) (all P < 0.05). CC was associated with most of the other anterior segment biometrics in young myopic adults. These associations are important for better understanding of the interactions between different anterior segment structures in young myopic patients, and are also useful for the exploration of the pathogenesis of myopia., (© 2024. The Author(s).)

Purpose: Corneal scars after infectious keratitis lead to insufficient transparency and irregular astigmatism, affecting visual acuity; therefore, they should be accurately evaluated to estimate visual function. This study aimed to quantitatively evaluate corneal irregularity and scarring after infectious keratitis using anterior segment optical coherence tomography (AS-OCT)., Methods: This was an observational clinical study. We included patients who had corneal scarring after treatment of infectious keratitis between 2014 and 2021 at University of Tokyo Hospital. We retrospectively examined best spectacle-corrected visual acuity (BSCVA), average keratometric power, central corneal thickness (CCT), and four components of the Fourier harmonic analysis including spherical and asymmetry components, as well as regular astigmatism and higher-order irregularity. We included anterior and posterior corneal data and compared results with those of contralateral healthy eyes. Additionally, we quantitatively evaluated the densitometry of the cornea obtained using AS-OCT., Results: A total of 122 eyes of 61 patients were examined; male predominance was observed (n = 37), and the mean patient age was 55.3 ± 19.4 years. Comparisons with contralateral healthy eyes showed that BSCVA worsened (0.30 ± 0.83 and 0.93 ± 1.36 logMAR, respectively, P = 0.003), and CCT (531.1 ± 46.2 and 591.8 ± 132.4 μm, respectively, P < 0.001) and corneal densitometry (84.4 ± 11.8 and 111.9 ± 19.2 grayscale units, respectively, P < 0.001) increased significantly in affected eyes. The asymmetry component and higher-order irregularities that were not corrected with spectacles significantly increased (both P < 0.001), and there were no significant differences in the changes among the bacterial, fungal, herpetic, and acanthamoeba types of keratitis., Conclusion: Corneal scarring persisted after treatment for infectious keratitis, and the asymmetry and irregularities of corneal astigmatism increased as visual acuity deteriorated. AS-OCT with the Fourier harmonic analysis was useful for evaluating corneal topographic changes in patients with corneal scarring after keratitis., (© 2023. The Author(s).)

Objectives: To evaluate corneal topography in full-term and preterm children with or without retinopathy of prematurity (ROP)., Methods: We enrolled children aged from 2 years to 12 years between January 2019 and May 2021 in the following four groups: full-term (group 1), premature without ROP (group 2), untreated premature with ROP (group 3), and laser-treated and/or intravitreal injection (IVI) of anti-vascular endothelial growth factor (VEGF)-treated premature with ROP (group 4). Corneal topography was measured with the Galilei Placido-dual Scheimpflug analyzer G4 every half year, and was compared among the groups using generalized estimating equation models at approximately 7 years of age., Results: We included 77, 178, 45, and 131 participants in groups 1, 2, 3, and 4, respectively. The mean (standard deviation) number of visits per patient was 2.9 (1.4). Compared with full-term eyes, premature eyes demonstrated steeper anterior corneal curvature (p = 0.016 and p = 0.008 for the mean and steep K, respectively), higher anterior and posterior corneal astigmatism (p = 0.036 and p = 0.016, respectively), and thinner thinnest pachymetry (p < 0.001). The laser-treated ROP eyes displayed steeper anterior corneal curvature (p = 0.040 for steep K) and higher anterior corneal astigmatism (p = 0.005) than the IVI-treated eyes. Moreover, they exhibited high cone location and magnitude index (1.96) reaching the cut-off for detecting keratoconus (1.82)., Conclusions: The premature status led to greater corneal ectasia, and laser treatment for ROP caused further corneal steepness. Higher anterior corneal astigmatism was associated with laser treatment. The ROP pathology and IVI anti-VEGF treatment exerted a marginal effect on corneal topography., (© 2023. The Author(s), under exclusive licence to The Royal College of Ophthalmologists.)

Purpose: To find preoperative simple geometric parameters to predict the outcome of lamellar keratoscleroplasty in patients with corneal limbal dermoids., Methods: We retrospectively analyzed the data of 30 patients with limbal dermoids who underwent lamellar keratoscleroplasty and were followed up for more than 6 months. Seven geometric parameters were used to analyze the relationship with postoperative visual acuity, astigmatism, and scar formation and investigated for their influence on postoperative outcome. These seven parameters included the cornea-invaded area of dermoid, dermoid area, the cornea-invaded length of dermoid, the corneal limbus invaded length of dermoid, dermoid size, bed size, graft size. Furthermore, we divided patients with corneal limbal dermoids into amblyopia group and non-amblyopia group, and analyzed the clinical characteristics of the amblyopia group., Results: The mean age of the patients at surgery was 10.6 ± 5.83 years. The 7 geometric parameters, preoperative and postoperative astigmatism of the amblyopia group were higher than those of the non-amblyopia group (all P < 0.05). Among the geometric parameters analyzed, the r coefficients between the cornea-invaded length of dermoid and postoperative visual acuity and astigmatism were the highest (r = 0.854, r = 0.714). The r coefficient between the corneal limbus invaded length of dermoid and the postoperative scar was the highest (r = 0.375). The r coefficient between age and postoperative steroid-induced high intraocular pressure was the highest (r = - 0.416). In univariate regression analysis, the cornea-invaded length of dermoid was significantly correlated with postoperative visual acuity (β = 0.270, P < 0.001) and postoperative astigmatism (β = 1.362, P < 0.001). Among the geometric parameters analyzed, the cornea-invaded length of dermoid had best stratified patients in grouping with or without amblyopia (cutoff > 2.24)., Conclusion: The cornea-invaded length of dermoid was the most important related factor of postoperative visual acuity, astigmatism, and amblyopia. The corneal limbus invaded length of dermoid was the most important related factor of postoperative scar formation. The geometric parameters and astigmatism in patients with amblyopia were larger than those in patients without amblyopia., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Introduction: Scalp-Ear-Nipple syndrome is caused by pathogenic KCTD1 variants and characterised by a scalp defect, prominent ears, and rudimentary breasts. We describe here further clinical associations in the eye and kidney., Methods: Fifteen affected members from two unrelated families with p.(Ala30Glu) or p.(Pro31Leu) in KCTD1 were examined for ocular and renal abnormalities. The relevant proteins were studied in the eye and kidney, and the mutation consequences determined from mouse knockout models., Results: Five males and 10 females with a median age of 40 years (range 1-70) with pathogenic variants p.(Ala30Glu) (n = 12) or p.(Pro31Leu) (n = 3) in KCTD1 were studied. Of the 6 who underwent detailed ophthalmic examination, 5 (83%) had low myopic astigmatism, the mean spherical equivalent of 10 eyes was 2.38D, and one (17%) had hypermetropic astigmatism. One female had a divergent strabismus.Five individuals had renal cysts (5/15, 33%), with renal biopsy in one demonstrating a thinned glomerular basement membrane identical to that seen in Thin basement membrane nephropathy (AD Alport syndrome).In the eye, KCTD1 and its downstream targets, TFAP2, and the collagen IV α3 and α4 chains localised to the cornea and near the retinal amacrine cells. In the kidney, all these proteins except TFAP2 were expressed in the podocytes and distal tubules. TFAP2B and COL4A4 knockout mice also had kidney cysts, and COL4A3 and COL4A4 knockout mice had myopia., Conclusion: Individuals with a pathogenic KCTD1 variant may have low myopic astigmatism and represent a further rare genetic cause for a thinned glomerular basement membrane.

Purpose: The purpose of this study was to determine whether astigmatism or corneal scarring is mediating the reduced visual acuity among patients with fungal keratitis randomized to corneal cross-linking (CXL)., Design: This was a prespecified exploratory outcome from an outcome-masked, 2 × 2 factorial design, randomized controlled clinical trial., Study Participants: Consecutive patients presented with moderate vision loss from a smear-positive fungal ulcer at Aravind Eye Hospital, Madurai, India., Intervention: Study eyes were randomized to one of 4 treatment combinations using an adaptive randomization protocol. The treatment arms included (1) topical natamycin 5% alone, (2) topical natamycin 5% plus CXL, (3) topical amphotericin B 0.15% alone, and (4) topical amphotericin 0.15% plus CXL. Best spectacle-corrected visual acuity (BSCVA), contact lens over-refraction, and scar size and depth as measured by a masked study ophthalmologist using a standardized protocol were recorded at 3 months. Pentacam Scheimpflug imaging was also obtained at 3 months., Main Outcome Measures: BSCVA and contact lens over-refraction, infiltrate and/or scar size and depth, total astigmatism of the front and back of the cornea, total lower-order and higher-order aberrations of the anterior and posterior cornea, and total densitometry of the anterior, central, and posterior stroma were recorded. We performed a mediation analysis looking at the proportion of the effect of CXL on BSCVA that was mediated through scar size, scar depth, astigmatism and density., Results: BSCVA at 3 months was available for 99 of 111 patients (89%) who had a mean of 0.82-LogMAR (SD 0.68). Three-month infiltrate and/or scar size ( P < 0.001), depth ( P < 0.001), and densitometry ( P = 0.001) were statistically significant predictors of 3-month BSCVA. Astigmatism seemed to mediate 23% of the effect of CXL on BSCVA, whereas scar size mediated 23%, scar depth 17%, and densitometry 7%., Conclusions: Corneal scarring and astigmatism are mediators of worse visual acuity after cross-linking in fungal keratitis. Corneal densitometry may be a helpful cornea-specific variable for clinicians and researchers in determining the effect of corneal scarring on visual acuity in specific patients and as an objective study outcome., Trial Registration: NCT02570321., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Corneal stability is essential for contact lenses and refractive surgery. It seems that paralyzing eye drops or expansion of the ciliary muscle affect the radius of curvature and the strength of the cornea, and this effect is to increase the strength of the cornea during muscle spasm and decrease it in the relaxed state of the muscle. On the other hand, different factors (such as contact lens wear, ocular surface disorders, trauma, dry eye, and immunosuppression) could alter the immune defense mechanisms of the outer eye and permit microorganisms to invade the cornea. Therefore, the present study compared Pilocarpine and tropicamide drop on corneal topography and their effect on IL-6 and TNF-α levels in tear. This prospective study was performed on sixty normal and healthy eyes of sixty volunteers with a mean age of 38.19 years and without any ocular pathology. Volunteers were divided into two groups of thirty. In the first group, corneal topography of both eyes was measured before and 30 minutes after instillation of topical tropicamide 1% in only one eye. The other eye was the control eye, and no drop was given. The same routine was performed in the second group, except that subject received one drop of Pilocarpine 2% in one eye. Statistical comparison between groups for the central corneal power, corneal radius, and corneal astigmatism was performed using paired t-test. IL-6 and TNF-α levels in tear were analyzed using two Luminex commercial assays with Bio-Plex 200TM System (Bio-Rad, Hercules, California, USA). In group 1, no significant changes were found in corneal radius, power, and astigmatism. However, in group 2 subjects who received pilocarpine eye drops, the mean corneal radius value decreased significantly by 0.05 mm. The mean corneal power increased by +0.32 D. There was no significant difference change in corneal astigmatism in both groups. Evaluation of IL-6 levels in tears showed a significant difference between the control and treatment groups (P = 0.041). But no significant difference was observed between the Pilocarpine and the Tropicamide groups (P = 0.761). Evaluation of TNF-α level in tears also showed no significant difference between these groups (P = 0.088). Pilocarpine induced ciliary muscle contraction, which may cause pressure on the corneal limbus and scleral spur, resulting in changes in corneal curvature. But tropicamide eye drop did not affect corneal radius and other corneal parameters, and corneal topography can be carried out after the installation of tropicamide eye drop.

Despite numerous investigations into ocular or corneal astigmatism, the dynamic nature of astigmatism remains poorly understood. To reveal potential associations between age and astigmatism, 264 Japanese participants who underwent systemic and ophthalmological examinations in Funagata Town (Yamagata Prefecture, Japan) were evaluated over a 10-year period. Astigmatism was evaluated with regard to the cylinder power, cylinder axis, and vector analyses. Whereas the refractive cylinders showed age-related increases in patients in their 40s to 60s, the corneal cylinders did not change over 10 years. Nevertheless, cylindrical axis of the cornea demonstrated a continuous shift toward against-the-rule (ATR) astigmatism. Vector analyses revealed that the astigmatic shift toward ATR progressed continually after patients reached their 40s, although the shift did not accelerate with age. These novel insights may pave the way for the development of potential strategies for vision correction, including refractive surgeries, and vision-quality maintenance in the elderly., Competing Interests: The authors have declared that no competing interests exist.

In this study, we aimed to evaluate the characteristics of astigmatism preoperatively and 1 month postoperatively in patients with age-related ptosis (AP) and contact lens-related ptosis (CLP), and investigate surgery-induced astigmatism (SIA) using the Jaffe vector analysis and the Cravy method. Consecutive patients who underwent blepharoptosis surgery between January 2019 and December 2019 were included. The patients were divided into AP and CLP groups. Computerized corneal topography was used to assess the magnitude and axis of corneal astigmatism. Astigmatism was classified as with-the-rule (WTR), against-the-rule (ATR), or oblique astigmatism (OA) pre- and postoperatively. SIA was calculated by vector analysis using the Cravy and Jaffe methods. The correlation between SIA and margin reflex distance (MRD) was calculated. One hundred and eight eyes from 58 patients (AP group: 85 eyes from 45 patients, CLP group: 23 eyes from 13 patients) were included. The AP group (73.8±7.6 years) was significantly older than the CLP group (47.7±6.6 years). The MRD increased significantly after treatment in both groups. The proportions of WTR, ATR, and OA were 52%, 22%, and 25%, and 86%, 9%, and 4% in the AP and CLP groups, respectively. A shift in astigmatism type was observed in 41% and 13% of patients in the AP and CLP groups, respectively. The average SIA measured using the Cravy method was 0.11±1.22 D in the AP group and -0.28±1.07 D in the CLP group (WTR astigmatism). The SIA calculated using the Jaffe method was 0.78±0.70 D in the AP group and 0.82±0.88 D in the CLP group. There was no significant correlation between SIA calculated using the Cravy and Jaffe methods and MRD. ATR was most common in age-related ptosis and WTR was most common in contact lens-related ptosis. Upper eyelid re-positioning may affect visual functions due to astigmatic changes in the short term postoperatively., Competing Interests: NO The authors have declared that no competing interests exist.

We investigated the relation between corneal regular and irregular astigmatism in normal human eyes. In 951 eyes of 951 patients, corneal irregular astigmatism, such as asymmetry and higher-order irregularity components, was calculated using the Fourier harmonic analysis of corneal topography data within the central 3-mm zone of the anterior corneal surface. The eyes were classified by the type of corneal regular astigmatism into four groups; minimum (< 0.75 diopters), with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism. The mean age was significantly different among the four groups (P < 0.001); patients with WTR astigmatism were the youngest, followed by those with minimum, oblique, and ATR astigmatism. Significant inter-group differences were found among the four groups in asymmetry (P = 0.005) and higher-order irregularity components (P < 0.001); the largest was in eyes with oblique astigmatism, followed by ATR, WTR, and minimum astigmatism. The stepwise multiple regression analysis revealed that corneal regular astigmatism pattern significantly influenced the amount of corneal irregular astigmatism after controlling for confounding factors (P < 0.001). Corneal irregular astigmatism, such as asymmetry and higher order irregularity components, was the largest in eyes with oblique astigmatism, followed by those with ATR, WTR, and minimum astigmatism, even after adjustment for age of subjects., (© 2021. The Author(s).)

The aim of the study is to explore the distribution patterns and internal correlations of the morphological parameters of the cornea in patients with age-related cataract. The Pentacam HR was used to measure anterior corneal astigmatism (ACA), posterior corneal astigmatism (PCA), total corneal astigmatism (TCA) and keratometric corneal astigmatism (KCA). With age, the proportion of with-the-rule (WTR) ACA decreased from 65.31% to 23.63%, while the against-the-rule (ATR) ACA increased from 26.53% to 56.20%. PCA exceeded 0.50 D in 9.14% of eyes, while 76.35% of them were ATR. The magnitude of ACA was positively correlated with PCA in the whole sample, with a more significant correlation in WTR eyes (s r  = 0.349, P < 0.001). The vector summation effect of PCA to ACA changed from compensation to augmentation with aging. In 57.53% of WTR eyes, KCA was overestimated by an average of 0.21 ± 0.17 D, while it was underestimated by 0.38 ± 0.27 D in 87.62% of ATR eyes. In conclusion, among age-related cataract patients, ACA and TCA gradually shifted from WTR to ATR with aging, while most PCA remained as ATR. Ignoring the age-related changes and real PCA might cause overestimation of WTR astigmatism and underestimation of ATR astigmatism.

This study was aimed to determine the effect of the amount of astigmatism on distance visual acuity, and to provide a prediction formula of visual acuity according to astigmatism, in a presbyopic population. We comprised 318 eyes of 318 consecutive patients (158 phakic and 160 pseudophakic subjects) without any eye diseases, except for refractive errors with astigmatism of 3 diopter or less. We assessed the relationship of the spherical equivalent visual acuity (SEVA) with astigmatism, and also provided a regression formula of visual acuity according to astigmatism in such subjects. We found a significant correlation between the SEVA and the amount of astigmatism (r = 0.715, p < 0.001) in the entire study population. We obtained similar results, not only in phakic eyes (r = 0.718, p < 0.001), but also in pseudophakic eyes (r = 0.717, p < 0.001). The regression formula was expressed as follows: y = 0.017x 2  + 0.125x - 0.116 (R 2  = 0.544), where y = logMAR SEVA, and x = astigmatism. We also found no significant differences in the SEVA for matched comparison among the with-the-rule (WTR), against-the-rule (ATR), and oblique (OBL) astigmatism subgroups (p = 0.922). These regression formulas may be clinically beneficial not only for estimating the visual prognosis after astigmatic correction, but also for determining the surgical indication of astigmatic correction.

The progressive addition lens (PAL) is a spectacle lens design with progressive refractive power changes across the lens surface to provide sharp vision at different viewing distances for patients with reduced accommodative strength. It has gained in popularity not just for presbyopic patients, but also patients with occupational (office, driving, or digital device) and therapeutic (e.g., myopia control) needs. However, despite the increasing prevalence of astigmatism in adults > 40 years old who rely on PAL correction, no metric is available to reflect the optical variation in PALs with astigmatic prescriptions. Based on recent studies, four novel optical metrics sensitive to variation of refractive power across the lens surface of PALs have been developed. These metrics were used to compare the optical performance of PALs of various prescriptions, designs, and manufacturers. For each lens, the refractive power profile was first measured with a Moire-deflectometry-based instrument.The data was then exported and analyzed using a two-dimensional error map for each of the four metrics. The results revealed significant impacts of astigmatic prescription, providing evidence for the usefulness of these metrics in quantifying the optical performance of PALs for patients with astigmatic prescriptions.

Background: Classic homocystinuria (HCU), or cystathionine beta-synthase (CBS) deficiency, is a rare inborn error of methionine metabolism. Main clinical features may include skeletal and vascular manifestations, developmental delay, intellectual disability and eye disorders., Material and Methods: This is an observational and retrospective study aiming at describing eye abnormalities presented by a cohort of late-diagnosed HCU patients. Data regarding ophthalmological evaluation included visual acuity, refraction, biomicroscopy, Perkins tonometry, fundus examination, retinography, biometry, ocular ultrasound, optical coherence tomography, anterior segment photography and topography., Results: Ten patients with HCU (20 eyes) were included. The most frequent findings were ectopia lentis (n = 20) and myopia (n = 9). Biometry, ultrasound, OCT and topography findings were available for four patients. One patient had keratoconus; one had abnormal retinal pigmentation; and two had lens surgery scars with irregular astigmatism., Conclusions: Eye abnormalities are very frequent in late-diagnosed HCU patients. The presence of ectopia lentis should always raise the diagnostic hypothesis of HCU.

To determine the distribution of ocular residual astigmatism (ORA) in astigmatic eyes and the influence on the anterior corneal (ACA) and refractive astigmatism (RA). A total of 165 children met the inclusion criteria. Right eyes' data were analyzed. Using Thibos vector analysis to calculate ORA. Spearman correlation analysis was used to obtain the correlation between the magnitude of ORA, ACA and RA. The median magnitude of ORA in astigmatic eyes was 0.57 D, with interquartile range was 0.42 D. And they were main against-the-rule (57.6-75.8%) and oblique astigmatism (13.9-34.5%) ORA. The ORA in 140 eyes (84.8%) acted as an offset to ACA, meanwhile, 25 eyes (15.2%) superimposed it. About 98% (97.9-98.4%) against-the-rule and 75% (73.9-82.5%) oblique ORA counteracted ACA, nevertheless, all with-the-rule ORA had a superimposed effect on ACA. For with-the-rule ACA, about 86% (85.4-85.9%) ORA worked to offset it. There was statistically correlations between ORA and ACA (r = 0.17, P = 0.03), ORA and RA (r = - 0.27, P = 0.001). The magnitude of ocular residual astigmatism was relatively small in children's astigmatic eyes. Both against-the-rule and oblique ORA can counteract with-the-rule ACA.

Objective: To investigate the effects of orthokeratology on biological parameters and visual quality of adolescents with low-grade corneal astigmatism myopia., Patients and Methods: In this study, a total of 41 myopic adolescents were prescribed with orthokeratology glasses in our hospital from February 2018 to March 2019 and voluntarily cooperated with relevant examinations before and after wearing orthokeratology lenses. Patients' uncorrected distant visual acuity (UCVA-D), uncorrected near visual acuity (UCVA-N) and naked eye near stereoacuity before wearing glasses, 1 month, and 3 months after wearing glasses were observed. The corneal astigmatism of patients was observed. The corneal endothelial cell density was observed. The dynamic adjustment function (NP, AF, NRA, PRA) values of patients were observed. The comparison of biological indexes in different time periods was observed. The changes of corneal curvature before wearing orthokeratology lens, 1 month and 3 months after wearing orthokeratology lens were observed., Results: There were significant changes of patients 1 month after wearing orthokeratology lenses (p < 0.05), while there was no significant difference between 3 months after wearing the orthokeratology lenses and 1 month after wearing the orthokeratology lenses (p < 0.05). Patients' NCAV-D and UCVA-N were recorded by a conversion method of 5 points. There were differences in the NCVA-D, NCVA-N, naked eye near stereoacuity before, 1 month, and 3 months after wearing glasses (p < 0.05). By observing patients' biological indicators and dynamic adjustment, it was found that there were statistically significant differences in NP, AF, BRA and PRA before wearing the glasses, 1 month and 3 months after wearing the glasses (p < 0.05)., Conclusions: The use of orthokeratology can greatly correct myopia patients' vision, improve their stereoscopic vision, control the progression of myopia, and improve their eye regulation, which is of high safety and great short-term effect.

This study examined the factors affecting corneal curvature change after lateral rectus recession and medial rectus resection surgery in patients with intermittent exotropia. This was a retrospective cross-sectional study in intermittent exotropia patients who underwent rectus resection surgery. The study involved 41 male and 42 female patients (mean age: 9.55 ± 5.03 years, range: 3-28 years). Corneal astigmatism analysis was performed using the Galilei G4 Dual Scheimpflug Analyzer. The values of simulated and ray tracing corneal keratometry (K) of astigmatism, including axis changes, were determined preoperatively and at 1 week and 3 months postoperatively. The factors found to affect corneal curvature change were sex, extent of surgery, and axial length. Simulated and ray tracing changes were significant preoperatively and at 1 week and 3 months after rectus resection surgery (p < 0.05); however, there were no differences in astigmatism (D) at any time. The spherical equivalent had a myopic change after rectus resection surgery with cycloplegic refraction, and in ray tracing mode, flat K was decreased at 1 week from baseline and increased 3 months later. Steep, mean K, and axis increased continuously from baseline to 1 week and 3 months. Astigmatism, in contrast, was increased at 1 week, but decreased at 3 months, with no return to baseline. Univariable linear regression analyses showed that the extent of surgery had an effect on flat K change and that sex had an effect on steep K and axis. Additionally, axial length affected steep K and astigmatism, while age had no effect on any variable. Ray tracing values were significantly different from simulated values. In ray tracing mode, rectus resection surgery may result in astigmatism shifted toward with-the-rule, and myopic changes may be caused by differences in thickness and flexibility of the sclera. Notably, age did not affect any variable., Competing Interests: The authors have declared that no competing interests exist.

Purpose: The objective of this study is to evaluate the preoperative and short- and long-term postoperative results in terms of visual acuity, refractive error, and corneal wavefront aberrations in patients with myopia and myopic astigmatism undergoing small incision lenticule extraction (SMILE)., Methods: Seventy-nine eyes of 52 myopes with or without astigmatism (41 right and 38 left) were enrolled in this retrospective study. The measurements included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SE) and wavefront aberrations. All the measurements before and after SMILE surgery were systematically recorded., Results: Mean preoperative UDVA was 1.19±0.24 logMAR and improved to 0.06±0.17 logMAR at the 3-year postoperative follow-up. At the conclusion of the 3-year follow-up, UDVA was better than or equal to 20/20 and 20/25 in 73% and 84% of eyes, respectively. At 1 month postoperatively, CDVA was 0.05±0.23 logMAR and significantly lower than the preoperative CDVA, 0.02±0.04 log MAR (P>0.05). However, at 1 year and 3 years after surgery, CDVA showed a significant increase compared to preoperative CDVA. At the conclusion of the 3-year follow-up, SE was -0.47 D, and 69.6% and 83.5% of the eyes were within±0.50 D and±1.00 D, respectively, of the intended correction. HOA's, coma, and spherical aberration increased significantly. No significant change in trefoil was detected., Conclusion: This study showed that SMILE produces a stable, safe outcome for surgical treatment of myopia and myopic astigmatism., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Purpose: Visual rehabilitation following penetrating keratoplasty is the primary indication for approximately 15% of all scleral lens fittings. Since corneal biomechanics are altered following penetrating keratoplasty, the aim of this study was to quantify changes in anterior corneal optics following short-term scleral lens wear in eyes with corneal grafts., Methods: Scheimpflug images were obtained before and after a period of scleral lens wear (mean 6.3 ± 1.4 h), from eyes that had previously undergone penetrating keratoplasty (10 eyes of nine participants, mean age 31 ± 9 years). Corneal power and thickness data were examined over the central 6 mm, including regional analyses of the central (0-3 mm) and the mid-peripheral cornea (3-6 mm annulus) using customised software to deterime corneal power vectors M (best fit sphere), J 0 (90/180 astigmatism) and J 45 (45/135 astigmatism). Anterior corneal aberrations were extracted using corneal elevation data., Results: Corneal power vector J 45 increased following lens wear (by 0.22 ± 0.05 D, p = 0.003) across the central 6 mm, while M displayed regional variations following lens wear indicating larger changes further from the corneal centre (p = 0.004). The change in corneal power vector M was also correlated with the magnitude of central corneal swelling (r = 0.65, p = 0.04). The anterior corneal aberration terms of oblique astigmatism, hoirzontal coma, and spherical aberration also varied following lens wear (all p ≤ 0.01). The mean change in the corneal spherocylinder derived from the elevation data following lens wear was +0.14/-0.54 × 44 for a 6 mm corneal diameter., Conclusions: Clinically significant alterations in anterior corneal topography and higher order aberrations were observed following short-term scleral lens wear in eyes that had undergone penetrating keratoplasty. Spherocylindrical changes were approximately double the magnitude and more oblique in orientation compared to previous reports of healthy eyes. Changes in corneal power vector M may be related to epithelial corneal oedema., (© 2020 The Authors Ophthalmic & Physiological Optics © 2020 The College of Optometrists.)

Purpose: Astigmatism is a refractive error due to meridional differences in refractive powers of lens or cornea. The resulting failure to focus image points in a single plane causes blurred vision at all distances. In this study, using an animal model of lens-induced astigmatism, we tested the hypothesis that induced astigmatism is due to processing of astigmatic retinal image information by the brain, which causes distorted growth in the anterior segment via centrifugal neural projections., Methods: To induce astigmatism, +4.00DS/-8.00DC crossed-cylinder-lens goggles were affixed over the right eyes of 7-day-old chicks (P7), with the -8.00DC axis oriented vertically (at 90°) or horizontally (180°) (n = 12 each); the left eyes were without goggles (non-goggled). For all experiments, refractive errors of both eyes were measured by streak retinoscopy, before and after 1 week of lens wear. To test whether neuronal pathways between retina and brain are required, axonal conduction within the eye was blocked by intravitreal injections of tetrodotoxin (TTX; 7 μL of 10 - 4 M) in phosphate-buffered saline (PBS), or of PBS alone (7 μL); fellow open eyes received PBS alone. Pupillary light reflex (PLR) and optokinetic response (OKR) were measured, to assess the efficacy and duration of TTX action. To test whether retinal circuitry is required, groups of chicks (n = 12 each) were treated at P7 by intravitreal injection of 20 μL of mixed excitotoxins (2 μmol N-methyl-D-aspartate, 0.2 μmol quisqualic acid, 0.2 μmol kainic acid; in water) into goggled or non-goggled eyes, to compromise retinal circuitry needed for emmetropization., Results: Crossed-cylinder goggles reliably induced refractive astigmatism. Maximum astigmatic error was induced when the cylindrical axis was oriented at 90° (vertically). TTX effectively blocked nerve conduction within the eye for 48 h after injection. Goggled eyes developed astigmatism after treatment with TTX or PBS, but not after excitotoxins., Conclusion: Our hypothesis was rejected. In this model, the compensatory astigmatism induced by crossed-cylinder lenses is intrinsic to the eye, and mediated by visual processing in the retina., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Purpose: To investigate corneal tomography changes and refractive outcomes after Descemetorhexis without endothelial keratoplasty (DWEK)., Methods: Retrospective chart review of 25 eyes from 16 patients with Fuchs corneal endothelial dystrophy that underwent successful DWEK combined with cataract surgery., Results: There was no significant change in anterior corneal curvature on tomography maps. However, all tomography maps demonstrated an increase in central posterior float and all but one demonstrated a decrease in pachymetry after DWEK. Only 7 of 25 eyes had increased irregular astigmatism on tomography after DWEK, of which 57% had preexisting irregular astigmatism before the procedure. The mean difference between the targeted and outcome refraction was +0.65 diopters (D) at the time of corneal clearance, but this improved to +0.38 D 1 month after corneal clearance. Postoperative refraction was within 1 D of target refraction for 92% of cases (23 eyes) but within 0.5 D of target refraction for only 48% of cases (12 eyes). The differences between expected and actual refractive outcomes were correlated with change in posterior corneal curvature and pachymetry., Conclusions: DWEK induces an increased central posterior float localized to the site of Descemet membrane stripping, confirming the need for centralized stripping. Irregular astigmatism can occur after DWEK but is typically minimal and occurs more commonly in the setting of preoperative irregular astigmatism. DWEK induces about a 0.5 D hyperopic shift, which should be considered when determining intraocular lens power with simultaneous surgery.

Purpose: To assess the prediction accuracy of four variations of total corneal refractive power (TCRP) by the ray tracing method in determining corneal power in eyes after myopic small incision lenticule extraction (SMILE)., Methods: Forty eyes of forty patients who had undergone myopic SMILE were enrolled in this prospective study. Manifest refraction and Pentacam HR were performed preoperatively and three months or more postoperatively. Mean keratometry (Km), true net power (TNP), equivalent keratometry readings (EKR) and 4 subtypes of TCRP (pupil centered or apex centered within a ring or a zone)-TCRPpupil,ring, TCRPpupil,zone, TCRPapex,ring and TCRPapex,zone-were recorded and compared to the theoretical postoperative keratometry value using the clinical history method (CHM)., Results: The only keratometric values that showed no statistically significant differences from the CHM were 4.0 mm and 4.5 mm EKR, 6.0 mm TCRPpupil,zone and TCRPapex,zone. Pearson's correlation test revealed that 4.0 mm TCRPpupil,zone exhibited the highest correlation coefficient (r = 0.974) followed by TCRPapex,zone 4.0 mm (0.972) and EKR 4.5 mm (0.970). The 95% limits of agreement (LOA) of the 4.0 mm EKR and CHM, the 4.5 mm EKR and CHM, the 6.0 mm TCRPpupil,zone and CHM, the 6.0 mm TCRPapex,zone and CHM were (-1.27 to 1.22 D), (-1.04 to 0.98 D), (-1.39 to 1.08 D) and (-1.38 to 0.96 D), respectively, while the modified 4.0 mm TCRPpupil,zone (TCRPpuil,zone + 0.70 D) and TCRPapex,zone (TCRPapex,zone+0.70 D) yielded the narrowest 95% LOA of (-0.96 to 0.95 D) and (-0.96D, 1.05 D)., Conclusions: Total corneal refractive power using the ray tracing method could predict corrected corneal power derived from the CHM in eyes following SMILE surgery after simple modification., Competing Interests: The authors have declared that no competing interests exist.

Purpose: To investigate chronological changes in patients with very asymmetric keratoconus (KC) by Scheimpflug-based corneal tomographic evaluation., Methods: We retrospectively reviewed the clinical records of 382 patients with KC attending a university hospital. Patients who were diagnosed with KC in one eye and forme fruste keratoconus in the other eye at the last visit and followed up with Scheimpflug-based tomographic corneal imaging were included. The anterior radius of curvature (ARC) and posterior radius of curvature (PRC) obtained at a 3.0-mm optical zone and the thinnest pachymetry reading of corneal thickness (Tmin), were used to investigate the chronological changes in tomographic parameters., Results: Twenty-six patients aged 16 to 66 years met the inclusion criteria. The mean observation period was 6 years and 4 months. There was a significant increase in annual change in PRC with a longer follow-up period after initial examination (P = 0.011). Moreover, a greater increase in annual change in ARC was observed in patients in whom the initial examination was performed at a younger age than in those in whom it was performed at an older age (P < 0.001)., Conclusions: On the basis of tomographic evaluation, even if the measured values are almost stable and within normal limits, a long-term clinical follow-up is warranted in forme fruste keratoconus eyes. Younger patients with very asymmetric keratoconus should be monitored carefully.

Objective: To introduce a new approach to simulatethe fitting process of rigid gas-permeable (RGP) contact lenses using 3D printing technology., Methods: A hemispherical or parabolic 3D model was created using 3D Builder or Tinkercad software. The horizontal and vertical diameters and the hemispherical or ellipsoid height were adjusted to simulate different morphologies of the corneal anterior surface. After exporting the file in stereo lithography (STL) format, a solid model was printed using a 3D printer and was used to simulate RGP contact lens fitting., Results: Limited by the precision of the entry-level 3D printer which was used in this study, the print-outs of the corneal models were crude, but the models were tested for their ability to simulate common corneal morphologies with no corneal astigmatism and different axial corneal astigmatism. Compared with some built-in simulation programs for corneal topography, the solid models generated by 3D printing could well simulate the positioning of the lens under the influence of gravity and the eyelid, as well as lens eccentricity or the bubbles under lenses caused by an improper wearing method., Conclusion: 3D printing technology can be well applied in the simulation of RGP contact lens fitting, which may become a new teaching method in optometry., (Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

BACKGROUND The aim of this study was to present ophthalmological findings regarding Alport syndrome and report refractometry data and to present possible early signs of the syndrome. MATERIAL AND METHODS Seven patients suffering from Alport syndrome were referred to the Department of Ophthalmology at the University of Debrecen between January 1st, 2014, and December 31st, 2015. All patients underwent slit lamp evaluation and dilated fundus biomicroscopy, with special attention paid to lenticonus and retinal changes. IOL Master, Pentacam HR, and ultrasound biomicroscopy were performed to assess keratometry, corneal thickness, anterior chamber depth, lens size, and axial length data. RESULTS One patient out of seven had ocular symptoms. Posterior polymorphous corneal dystrophy (PPMD) and dot-and-fleck retinopathy were seen. Meanwhile, although keratoconus was not proven, remarkable astigmatism with high myopia was detected. The other six patients were found to have a significantly smaller lens diameter (an average of 7.82±0.66 mm, p=0.035) compared to normal controls (an average of 8.65±0.46 mm). Lenses also tended to be thicker in Alport patients (3.48±0.19 mm) compared to controls (3.4±0.2 mm), although the difference was not significant (p=0.394). The power of the lens also showed a significant difference (p=0.026), with Alport patients having lower lens power. CONCLUSIONS Alport syndrome patients without classical ophthalmological findings have smaller crystalline lens diameter and lower lens power. These signs may support the diagnosis of Alport syndrome. Ophthalmologists should not only seek for the known classic signs, but also the parameters of the crystalline lens, especially if genetic testing is not available.

This study was aimed to investigate the early clinical outcomes of small-incision lenticule extraction (SMILE) to correct both myopia and myopic astigmatism at major clinical centers in Japan. This case series consisted of two hundred fifty-two eyes of 130 consecutive patients who underwent SMILE surgery (29.5 ± 6.3 years, mean age ± standard deviation), with spherical equivalents of -4.33 ± 1.61 D. We determined the safety, efficacy, predictability, stability, and adverse events of this procedure. Corrected distance visual acuity significantly improved, from -0.18 ± 0.04 preoperatively to -0.19 ± 0.07 logMAR postoperatively (paired t-test, p < 0.001). Uncorrected distance visual acuity also significantly improved, from 1.05 ± 0.26 preoperatively to -0.15 ± 0.11 logMAR postoperatively (p < 0.001). 88% and 98% of eyes were within ± 0.5 and 1.0 D of the targeted correction, respectively. Changes in manifest spherical equivalent from 1 week postoperatively were 0.02 ± 0.35 D (p = 0.127). No vision-threatening complications were observed in any of the cases. SMILE performed well in the correction of myopic refractive errors, and we experienced no severe complications in this series, indicating its feasibility as a surgical option for the treatment of these eyes.

In this paper, an analytical closed-form formula for the design of freeform lenses free of spherical aberration and astigmatism is presented. Given the equation of the freeform input surface, the formula gives the equation of the second surface to correct the spherical aberration. The derivation is based on the formal application of the variational Fermat principle under the standard geometrical optics approximation.

Purpose: To determine the association between anterior corneal curvature and optical zone centration as well as its impact on aberration profiles in small-incision lenticule extraction (SMILE) and laser in situ keratomileusis (LASIK)., Methods: Seventy-eight eyes of 78 patients treated with SMILE (45 eyes) and LASIK (33 eyes) were included. The centration of the optical zone was evaluated on the instantaneous curvature difference map between the preoperative and 3-month postoperative scans using a superimposed set of concentric circles. The correlation between optical zone decentration and anterior keratometry values was evaluated. The effect of optical zone decentration on vector components of astigmatic correction and induction of higher-order aberrations (HOA) was assessed., Results: The mean decentration distance was 0.21 ± 0.11 mm for SMILE and 0.20 ± 0.09 mm for LASIK (p = 0.808). There was a significant correlation between anterior keratometric astigmatism and decentration distance (r = 0.653, p < 0.001) for SMILE but not for LASIK (r = - 0.264, p = 0.138). Astigmatic correction was performed in 67 eyes. Optical zone decentration and the vector components of astigmatic correction were not correlated (p ≥ 0.420). Significant correlation was demonstrated between the decentration distance and the induced total coma (SMILE: r = 0.384, p = 0.009; LASIK: r = 0.553, p = 0.001) as well as the induced total HOA (SMILE: r = 0.498, p = 0.001; LASIK: r = 0.555, p = 0.001)., Conclusion: Anterior cornea astigmatism affected the treatment centration in SMILE but not LASIK. Subclinical decentration was associated with the induction of total coma and total HOA, but it did not affect the lower-order astigmatic correction.

Previous studies have suggested that naturally occurring genetic variation contributes to the risk of astigmatism. The purpose of this investigation was to identify genetic markers associated with corneal and refractive astigmatism in a large-scale European ancestry cohort (UK Biobank) who underwent keratometry and autorefraction at an assessment centre. Genome-wide association studies for corneal and refractive astigmatism were performed in individuals of European ancestry (N = 86,335 and 88,005 respectively), with the mean corneal astigmatism or refractive astigmatism in fellow eyes analysed as a quantitative trait (dependent variable). Genetic correlation between the two traits was calculated using LD Score regression. Gene-based and gene-set tests were carried out using MAGMA. Single marker-based association tests for corneal astigmatism identified four genome-wide significant loci (P < 5 × 10 -8 ) near the genes ZC3H11B (1q41), LINC00340 (6p22.3), HERC2/OCA2 (15q13.1) and NPLOC4/TSPAN10 (17q25.3). Three of these loci also demonstrated genome-wide significant association with refractive astigmatism: LINC00340, HERC2/OCA2 and NPLOC4/TSPAN10. The genetic correlation between corneal and refractive astigmatism was 0.85 (standard error = 0.068, P = 1.37 × 10 -35 ). Here, we have undertaken the largest genome-wide association studies for corneal and refractive astigmatism to date and identified four novel loci for corneal astigmatism, two of which were also novel loci for refractive astigmatism. These loci have previously demonstrated association with axial length (ZC3H11B), myopia (NPLOC4), spherical equivalent refractive error (LINC00340) and eye colour (HERC2). The shared role of these novel candidate genes for astigmatism lends further support to the shared genetic susceptibility of myopia and astigmatism.

Purpose: To compare the effect of 3 common suturing techniques on eyes that received femtosecond laser-enabled penetrating keratoplasty (FLEK) with a zig-zag configuration at the Gavin Herbert Eye Institute, University of California- Irvine, California., Methods: This is a retrospective chart review of a series of 319 eyes of 286 patients who underwent FLEK with a zig-zag configuration. One hundred fifty-seven eyes had running sutures, 136 eyes had simple interrupted sutures, and 26 eyes had combined sutures (single running and simple interrupted). The main outcome measures were uncorrected distance visual acuity, best spectacle-corrected visual acuity (BSCVA), and topographic astigmatism (TCyl). These parameters were recorded for the first year of follow-up regardless of suture removal status and also after full suture removal., Results: At 3 months, the BSCVA of the running, interrupted, and combined suture groups was 0.22 (±0.2), 0.41 (±0.3), and 0.29 (±0.1), respectively (P < 0.01). The mean TCyl of the running, interrupted, and combined groups at 3 months was 3.95 (±2.7), 6.41 (±4.4), and 5.44 (±3.3) D, respectively (P < 0.01) All sutures were removed in 190 of 319 eyes, and at the last recorded visit, the mean BSCVA was 0.18 (±0.2), 0.34 (±0.2), and 0.19 (±0.2) logarithm of the minimum angle of resolution in the running, interrupted, and combined groups, respectively (P < 0.01) and mean TCyl was 4.51 (±2.8), 5.62 (±3.7), and 4.57 (±2.9) D, respectively (P = 0.11)., Conclusions: Better visual acuity after full suture removal was observed in the running suture group; however, the subgroups of patients with keratoconus were similar after all sutures were removed.

Purpose: To investigate the essential role of ultraviolet (UV) radiation in the decrease of corneal endothelial cell density (ECD) caused by pterygium., Methods: In this retrospective controlled study, 76 consecutive patients with unilateral primary pterygium were enrolled from January 2016 to August 2016. The Central corneal ECD was measured in both eyes. Divide the subjects into two subgroups according to the UV exposure time, and the difference of corneal ECD between both eyes was analyzed using independent samples t-test. The relationship between the percentage of difference of corneal ECD and the disease duration, the percentage of pterygium to the cornea and the astigmatism value were analyzed., Results: For subjects with longer UV exposure, the average of ECD in pterygium group and control group were, respectively, 2264.83 ± 349.78 cells/mm 2 and 2477.16 ± 300.36 cells/mm 2 (P = 0.004). For subjects with short UV exposure, the average of ECD in pterygium group and control group were, respectively, 2596.46 ± 373.24 cells/mm 2 and 2690.66 ± 321.34 cells/mm 2 (P = 0.262). The decrease of corneal ECD was positively correlated with the period of the disease (P = 0.035). There was no statistical correlation between a decrease in the corneal ECD and the percentage of pterygium to cornea (R = -0.055, P = 0.635) and the astigmatism value in the pterygium eye (R = -0.135, P = 0.246)., Conclusions: UV radiation exposure played a significant role in the effect of pterygium decreasing the corneal ECD.

Purpose: The goal of our retrospective, single-center study of a case series was to compare the total, corneal, and internal astigmatism, and the visual acuity at one year after combined or stand-alone surgery consisting of iris fixation of an iris-claw intraocular lens (ARTISAN aphakia) in aphakic patients, according to whether the lens was fixated to the anterior (n=21) or posterior (n=51) surface of the iris., Results: We did not find a significant difference between these two types of fixation for any of the studied variables. The surgically induced astigmatism was 1.67 D at 176° in group A versus 1.19 D at 11° in group P., Conclusion: Although this surgery creates additional corneal astigmatism, it has not been proven that it differs depending on the type of fixation of the iris-claw. If we adhere to the notion that the posterior fixated iris-claw decreases the risk of endothelial decompensation in case the implant becomes disenclavated, then reverse iris fixation of the iris-claw makes sense., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Purpose: To evaluate the corneal topographic changes and postvitrectomy astigmatism after 27-gauge (g) microincision vitrectomy surgery (MIVS) by using Pentacam HR-Scheimpflug imaging system., Methods: This prospective descriptive study included 30 eyes of 30 patients who underwent 27-g MIVS. All eyes underwent a Pentacam HR examination preoperatively and on the first week, first month and third month postoperatively. The power of the corneal astigmatism, mean keratometry (K m ), K 1 and K 2 values and corneal asphericity (Q value) values for the both front and back surfaces of the cornea, index of surface variance (ISV), index of vertical asymmetry (IVA), index of height asymmetry (IHA), index of height decentration (IHD) and higher-order aberrations including coma, trefoil, spherical aberration, higher-order root-mean-square and total RMS were recorded. Additionally, the mean induced astigmatism was estimated by vector analysis., Results: No statistically significant changes were observed in the mean power of corneal astigmatism, mean keratometry, K 1 and K 2 values, corneal asphericity values, ISV, IVA, IHA, IHD and higher-order aberrations on the first week, first month and third month after the operation. The mean surgically induced astigmatism was calculated as 0.23 ± 0.11 D on the first week, 0.19 ± 0.10 D on the first month and 0.19 ± 0.08 D on the third month postoperatively., Conclusion: Minor corneal surface and induced astigmatic changes are expected to result in rapid visual rehabilitation after pars plana vitrectomy with the 27-g MIVS system.

Purpose: To study the Scheimpflug's imaging and corneal biomechanics in primary pterygium., Methods: A prospective observational study of 55 patients with unilateral primary nasal pterygium was done. The normal fellow eyes of patients with pterygium were taken as controls. Clinical parameters noted included visual acuity, values of corneal curvature by doing Scheimpflug imaging, wavefront aberrations in terms of higher and lower-order aberrations and corneal hysteresis (CH) as well as corneal resistance factor (CRF) values by using ocular response analyzer., Results: Of the total 55 patients, mean age was 43.0 + 11.4 years (range: 20-72 years). Mean LogMar uncorrected visual acuity in pterygium eyes and control eyes was 0.21 + 0.20 and 0.12 + 0.15, respectively (p = 0.016). On Scheimpflug imaging the mean anterior corneal curvature values (Ka1/Ka2 D) were 41.09 + 3.38/44.33 + 2.29 in pterygium eyes, 43.13 + 1.79/43.98 + 2.17 in control eyes (p < 0.0005) and mean posterior corneal curvature (Kp1/Kp2 D) values were 6.14 + 0.39/6.53 + 0.43 in pterygium eyes and 6.13 + 0.28/6.46 + 0.47 in control eyes (p > 0.05). Analysis of corneal aberrations showed significantly higher corneal wavefront aberrations in pterygium eyes. Highest correlation of corneal astigmatism was noted with corneal area encroached by pterygium (ρ = 0.540 for LOA and 0.553 for HOA) and distance from pupillary center (ρ = 0.531 for LOA and 0.564 for HOA). Corneal biomechanical parameters including CH and CRF were found to be lower in the pterygium eyes, though not statistically significant (p value 0.60 and 0.59, respectively)., Conclusion: Pterygium leads to deterioration of visual performance not only by causing refractive and topographic changes but also by causing a significant increase in corneal wavefront aberrations.

Marfan syndrome (MFS) is associated with abnormalities of corneal biometric characteristics. We conducted a retrospective case-control study including 55 eyes of the MFS patients with lens subluxation and 53 normal eyes of the control subjects to evaluate the corneal curvature, astigmatism and aberrations using a rotating Scheimpflug camera (Pentacam HR). Compared with the control group, the anterior, posterior, and total corneal curvature were flatter in the MFS group. The anterior and total corneal astigmatism were higher in the MFS patients, whereas the posterior corneal astigmatism was not significantly different between the two groups. Regarding the total corneal aberrations, the root mean square (RMS) aberrations, RMS higher-order aberrations and RMS lower-order aberrations increased, whereas the spherical aberration decreased in the MFS patients. Corneal parameters had potential diagnostic values for MFS patients with lens subluxation and the more reasonable cutoffs were the values of corneal curvature <41.35 D, corneal astigmatism >0.85 D and spherical aberration <0.188 μm. Corneal biometric characteristics of MFS patients with lens subluxation include decreased corneal curvature, higher corneal astigmatism, larger corneal aberrations, and lower spherical aberration. Corneal curvature, corneal astigmatism, and spherical aberration are better diagnostic tools for suspicious MFS.

Purpose: We assessed the impact of sequential double running suture removal on corneal curvature after penetrating keratoplasty (PK), comparing mechanical and nonmechanical excimer laser trephination., Methods: PK was performed in 134 patients (mean age 51 ± 18 yrs) using either the excimer laser [excimer, n = 60 (37 keratoconus and 23 Fuchs dystrophy)] or motor trephination [control, n = 74 (44 keratoconus and 30 Fuchs dystrophy)] and a double running cross-stitch suture. Refractometry, Zeiss keratometry, and Tomey corneal topography were performed before removal of the first suture (15.2 ± 4.2 mo) and immediately before and at least 6 weeks after removal of the second suture (21.4 ± 5.6 mo)., Results: Keratometry before removal of the first (-1.7 ± 2.3 D vs. -3.1 ± 2.8 D) and second (-2.3 ± 2.6 D vs. -3.8 ± 2.8 D) sutures showed that the change in the corneal base curve was significantly smaller in the excimer group than the control group (P < 0.004). After complete suture removal, astigmatism decreased in 52% and 11%, remained stable (±0.5 D) in 27% and 9%, and increased in 21% and 80% of eyes in the excimer and control groups, respectively, resulting in significantly lower astigmatism in the excimer (3.1 ± 2.1 D) group compared with the control group (6.2 ± 2.9 D) with "all-sutures-out" (P < 0.0001). The change in vector-corrected astigmatism (Jaffe) was significantly smaller in the excimer group (4.3 ± 3.5 D) than in the control group (6.9 ± 4.5 D; P < 0.001)., Conclusions: In conclusion, less change in astigmatism and the base curve after sequential removal of a double running suture indicates better alignment of the graft in the recipient bed after excimer laser trephination. After double running suture removal, astigmatism decreases or remains unchanged in 79% of patients after excimer laser keratoplasty and increases in 80% of patients after conventional motor trephination.

Purpose: To identify genes and genetic markers associated with corneal astigmatism., Methods: A meta-analysis of genome-wide association studies (GWASs) of corneal astigmatism undertaken for 14 European ancestry (n=22,250) and 8 Asian ancestry (n=9,120) cohorts was performed by the Consortium for Refractive Error and Myopia. Cases were defined as having >0.75 diopters of corneal astigmatism. Subsequent gene-based and gene-set analyses of the meta-analyzed results of European ancestry cohorts were performed using VEGAS2 and MAGMA software. Additionally, estimates of single nucleotide polymorphism (SNP)-based heritability for corneal and refractive astigmatism and the spherical equivalent were calculated for Europeans using LD score regression., Results: The meta-analysis of all cohorts identified a genome-wide significant locus near the platelet-derived growth factor receptor alpha ( PDGFRA ) gene: top SNP: rs7673984, odds ratio=1.12 (95% CI:1.08-1.16), p=5.55×10 -9 . No other genome-wide significant loci were identified in the combined analysis or European/Asian ancestry-specific analyses. Gene-based analysis identified three novel candidate genes for corneal astigmatism in Europeans-claudin-7 ( CLDN7 ), acid phosphatase 2, lysosomal ( ACP2 ), and TNF alpha-induced protein 8 like 3 ( TNFAIP8L3 )., Conclusions: In addition to replicating a previously identified genome-wide significant locus for corneal astigmatism near the PDGFRA gene, gene-based analysis identified three novel candidate genes, CLDN7 , ACP2 , and TNFAIP8L3 , that warrant further investigation to understand their role in the pathogenesis of corneal astigmatism. The much lower number of genetic variants and genes demonstrating an association with corneal astigmatism compared to published spherical equivalent GWAS analyses suggest a greater influence of rare genetic variants, non-additive genetic effects, or environmental factors in the development of astigmatism.

Purpose: To compare the anterior segment parameters in patients with Turner syndrome (TS) as measured by the Pentacam HR-Scheimpflug imaging system with those of healthy control subjects., Methods: This cross-sectional prospective study included 35 patients with TS and 30 age-matched controls. Corneal topographic analysis was performed using the Pentacam HR-Scheimpflug imaging system (Oculus, Wetzlar, Germany). The power of the corneal astigmatism, mean keratometry (Km) values for the both front and back surfaces of the cornea, maximum keratometry (Kmax), central corneal thickness (CCT), corneal volume (CoV), white-to-white diameter (WTW), chamber volume (CaV), angle and anterior chamber depth (ACD) values were recorded., Results: The mean age of TS subjects was 17.2 ± 6.1 years; of controls, 16.4 ± 5.7 years. All participants were female. There was a significant difference in the mean values of WTW (11.3 ± 0.5 mm vs 12.0 ± 0.4 mm [P < 0.001]), CaV (148.4 ± 33.5 mm 3 vs 191.9 ± 27.6 mm 3 [P < 0.001]), and ACD (2.8 ± 0.3 mm vs 3.1 ± 0.2 mm [P < 0.001]) between TS versus group and the control group. The mean values of the power of the corneal astigmatism, Km values for the both front and back of the corneal surface, Kmax, CCT, CoV, and angle values were similar between groups (P > 0.05 for each one)., Conclusions: There was a reduction in CaV, ACD, and WTW measurements in TS patients compared with controls., (Copyright © 2017 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.)

Purpose: To detect corneal inflammation and apoptosis induced after small incision lenticule extraction (SMILE) at different refractive corrections for moderate to high values of myopia., Methods: Fifty patients (50 eyes) suffering from medium to high myopia (spherical equivalent refraction from -3.75 to -10.00 diopters (D) with refractive astigmatism under -0.75 D) underwent SMILE in order to correct myopic error. In vivo evaluation was done by corneal confocal microscopy (IVCM) and ex vivo by immunohistochemistry. After surgery, all corneal lenticules were checked for regularity, entirety, and fixed in formalin for immunohistochemistry evaluation of apoptosis (TUNEL) and inflammation (CD11b) levels. Postoperative assessments took place during the first week and the first and third months after surgery. Patients returned for IVCM examination for analysis of the corneal stromal femtosecond laser treatment interfaces reflectivity., Results: No correlation was observed between treated myopic refractive error and number of CD11b + and TUNEL + cell in all analyzed extracted lenticules. IVCM at 1 week and 1 month of follow-up showed numerous reflective particles at the laser treatment interface with a moderate light scattering. In semi-quantitative analysis of reflectivity intensity at the laser interfaces, a statistical difference was evident only between 1 week and 1 month (p = 0.0213)., Conclusions: SMILE, as an innovative all-femto surgical procedure, results in a reduced tissue inflammation and apoptosis levels with a minimum tissue response, in terms of interface reflectivity, and there are no statistically significant differences among variable treated refractive error range.

Purpose: To describe clinical features in children diagnosed with posterior polymorphous corneal dystrophy (PPCD) in their first or second decade of life., Methods: A retrospective study was performed with the medical records of seven unrelated Korean pediatric patients who were diagnosed with PPCD and were followed up for a minimum of 3 years. Thorough ocular examinations were performed, including best-corrected visual acuity, intraocular pressure, refractive and keratometric measurements, slit-lamp biomicroscopy, and specular microscopy at all visits., Results: Slit-lamp examinations revealed vesicular lesions in one patient and horizontally parallel band-like endothelial lesions in six patients. Unilateral corneal involvement was displayed in 4 patients, yielding 10 eyes with deep corneal features characteristic of PPCD. Other corneal, iris, or fundus pathologic findings were not detected in all cases. Among four children who were examined in their visual development (approximately under 8 years of age), two cases demonstrated unilateral amblyopia at initial examination and exhibited improved visual acuity after refractive correction and occlusion therapy. Astigmatism more than 1.5D, which is generally considered amblyogenic, was found in 8 among 10 PPCD-affected eyes. A final visual acuity of more than 20/32 was achieved with appropriate refractive correction in all PPCD-affected eyes. There was a negative correlation between the corneal astigmatism and the mean endothelial cell density (ECD) (r = -0.655, P = .011). Initial specular microscopic examinations revealed reduced ECD (1733.0 ± 543.9 cells/mm) composed of enlarged cells (average cell area, 624.8 ± 182.1 μm/cell) in PPCD-affected eyes, compared with those in PPCD-unaffected eyes from our study subjects (P < .001 and P = .005, respectively). A statistically significant percent loss in ECD from initial to 3 years was noted in the PPCD-affected eyes (P = .03)., Conclusions: The awareness and treatment of refractive error are important, especially in children with early-onset PPCD during the reversible period of amblyopia. Long-term monitoring of corneal endothelium is required in pediatric patients with early-onset PPCD based on a significant endothelial loss over 3 years in PPCD-affected eyes.

Purpose: The human eye has typically more optical aberrations than conventional artificial optical systems. While the lower order modes (defocus and astigmatism) are well studied, our purpose is to explore the influence of genes versus the environment on the higher order aberrations of the optical components of the eye., Methods: We have performed a classical twin study in a sample from the Region of Murcia (Spain). Optical aberrations using a Hartmann-Shack sensor (AOnEye Voptica SL, Murcia, Spain) and corneal aberrations (using corneal topography data) were measured in 138 eyes corresponding to 69 twins; 36 monozygotic (MZ) and 33 dizygotic (DZ) pairs (age 55 years, SD 7 years). Intraclass correlation coefficients (ICCs) were used to estimate how strongly aberrations of twins resemble each other, and genetic models were fitted to quantify heritability in the selected phenotypes., Results: Genes had a significant influence in the variance of most of the higher order aberration terms (heritability from 40% to 70%). This genetic influence was observed similarly in both cornea and complete eye aberrations. Additionally, the compensation factor of spherical aberration in the eye (i.e., how much corneal spherical aberration was compensated by internal spherical aberration) was found under genetic influence (heritability of 68%)., Conclusions: There is a significant genetic contribution to the variance of aberrations of the eye, not only at macroscopic levels, as in myopia or astigmatism, but also at microscopic levels, where a few micrometers changes in surface topography can produce a large difference in the value of the optical aberrations.

Objective: To study the compensation mechanism of aberrations between anterior and posterior corneal surface, and to investigate the correlations between corneal aberrations and K values, intraocular pressure and central corneal thickness. Methods: One hundred and sixty-one subjects (300 eyes) with myopia and myopic astigmatism were recruited randomly. Corneal aberrations (anterior, posterior and total) in three different optical zones (2 mm, 4 mm, and 6 mm) centered on the corneal vertex were assessed with a corneal topographer (Sirius). We also calculated compensation factors (CFs) as a measure of the relative efficiency of the aberration compensation mechanism. Astigmatism was divided into corneal astigmatism and non-corneal astigmatism. Mann-Whitney U test was utilized for the comparison of different aberrations and CFs between the two astigmatism groups. Spearman correlation was applied to analyze the correlations between corneal aberrations and K values, intraocular pressure and central corneal thickness. Results: As the order of the aberrations elevated from the second to the seventh, the RMS values decreased significantly. The larger the optical zone, the greater the values of aberrations and the lower the percentage of the compensation mechanism among all the Zernike terms. At the same time, as the order of the aberrations increased, the predominance of the compensation mechanism was increasingly obvious. Slight compensation of spherical aberration (Z 4 0 ) was observed in the peripheral. In the center of the analyzing zones (2 mm), compensation mechanism represented in coma (Z 3 ±1 ), and it disappeared in the peripheral. We detected slight compensation of the corneal astigmatism (Z 2 ±2 ) in the surrounding zone, although the compensation factors were closed to zero in diverse optical zones. Superposition was found in trefoil (Z 3 ±3 ) straightly. Nevertheless, a tendency towards compensation was discovered with the enlargement of the optical zones. And the secondary spherical aberration (Z 6 0 ) behaved compensation continuously. However, similar compensation was discovered between the right eye and left eye in different analyzing optical zones. There were significant correlations between the flattest K values and Z 2 ±2 , Z 3 ±3 and Z 4 0 in the anterior, posterior and total cornea. It was similar with the steepest K values. When the optical zone expanded to 6 mm, Z 3 ±1 and Z 4 0 significantly decreased with intraocular pressure ( r coma =-0.188, P< 0.05. r spherical =-0.147, P< 0.05). No correlation was found between various aberrations and central corneal thickness ( P> 0.05). Conclusions: Compensation dominated in the corneal center, while the percentage decreased gradually as the optical zone extended. Slight compensation in astigmatism and spherical aberration between the anterior and posterior cornea may be benificial to the scotopic visual quality. Corneal aberrations were significantly related to K values and intraocular pressure. (Chin J Ophthalmol, 2016, 52: 840-849) .

Purpose: The purpose was to determine the effect of the corneal tunnel length in the 2.75 mm wide clear corneal incision, created during phacoemulsification on surgically induced astigmatism, central corneal thickness and corneal endothelial cell loss., Material and Methods: The study comprised 27 eyes (27 patients) who underwent phacoemulsification through 2.75 mm temporal clear corneal incision. Patients were examined preoperatively, 1 day, 7 days and 1 month postoperatively. Exclusion criteria were: previous intraocular surgery, corneal disorders and previous ocular trauma. Best corrected distance visual acuity, keratometry, slit-lamp examination, anterior segment optical coherence tomography and corneal endothelial cell density measurement were performed. Surgically induced astigmatism was calculated with vector method. Statistical analysis was done using non-parametric tests: Wilcoxon test, Mann-Whitney U test and Spearmann correlation coefficient., Results: Mean best-corrected distance visual acuity was 0.30±0.24 preoperatively and 0.94 ± 0.18 postoperatively (p<0.05). Mean corneal incision length 1 day postoperatively was 1.84±0.36 mm. Surgically induced astigmatism was 0.51 ± 0.41 D one month postoperatively. Clear corneal incision length and surgically induced astigmatism were positively correlated (p<0.05). Mean central corneal thickness was 0.51 ± 0.05mm preoperatively, 0.56± 0.09 mm one day and 0.51 ±0.05 mm one month postoperatively (p <0.05). Clear corneal incision length and central corneal thickness 30 days postoperatively were not corrdlated (p=0.27). Mean corneal endothelial cell density was 2483?417 cells/mm² preoperatively and 2325 ± 410 cells/mm² postoperatively. The difference was significant (p<0.05). Clear corneal incision length and corneal endothelial cell loss were not correlated (p>0.05)., Conclusions: The results suggest that the length of the 2.75 mm clear corneal incision influences the surgically induced astigmatism, but it doesn't influence the central corneal thickness and corneal endothelial cell loss. Shorter clear corneal incisions induce smaller surgically induced astigmatism in comparison with longer incisions of the same width and localization. Unequivocal confirmation.of the influence of clear corneal incision length on surgically induced astigmatism requires further investigation on a larger group of patients. Using laser techniques could help, as it would enable to examine patients in groups with different predefined clear corneal incision lengths.

Purpose: Scheimpflug imaging allows quantitative analysis of the width of the anterior chamber angle. We report the population-based distribution of the anterior chamber angle width using this noncontact imaging technique and investigate associated factors., Methods: A population-based cross-sectional study was carried out in Germany. A comprehensive ophthalmologic examination including refraction, biometry, and Scheimpflug imaging was performed. Automated measurement of the anterior chamber angle was performed in each anterior chamber quadrant. Exclusion criteria were previous ocular surgery or inadequate image quality. Association analyses were carried out to determine independently associated systemic and ocular factors for anterior chamber angle width using a generalized estimating equation model., Results: A total of 3014 subjects (48% female) with a mean age of 58.6 ± 10.4 years were included in this study. The mean anterior chamber angle width was 32.6° ± 5.5°. Statistical analysis revealed an independent association between a smaller anterior chamber angle and female sex, higher age, and more hyperopic refraction. When including biometric parameters, shallow anterior chamber depth, shorter axial length, higher central corneal thickness, and lower corneal power were independently associated with a narrower mean anterior chamber angle width., Conclusions: These parameters are considered risk factors for angle-closure glaucoma.

Purpose: Transient changes in corneal topography associated with soft and conventional or reverse geometry rigid contact lens wear have been well documented; however, only a few studies have examined the influence of scleral contact lens wear upon the cornea. Therefore, in this study, we examined the influence of modern miniscleral contact lenses, which land entirely on the sclera and overlying tissues, upon anterior corneal curvature and optics., Methods: Anterior corneal topography and elevation data were acquired using Scheimpflug imaging (www.pentacam.com) immediately prior to and following 8 h of miniscleral contact lens wear in 15 young healthy adults (mean age 22 ± 3 years, eight East Asian, seven Caucasian) with normal corneae. Corneal diurnal variations were accounted for using data collected on a dedicated measurement day without contact lens wear. Corneal clearance was quantified using an optical coherence tomographer (RS-3000, www.nidek.com) following lens insertion and after 8 h of lens wear., Results: Although corneal clearance was maintained throughout the 8-h lens wear period, significant corneal flattening (up to 0.08 ± 0.04 mm) was observed, primarily in the superior mid-peripheral cornea, which resulted in a slight increase in against-the-rule corneal astigmatism (mean +0.02/-0.15 × 94 for an 8 mm diameter). Higher order aberration terms of horizontal coma, vertical coma and spherical aberration all underwent significant changes for an 8 mm corneal diameter (p ≤ 0.01), which typically resulted in a decrease in RMS error values (mean change in total higher order RMS -0.035 ± 0.046 μm for an 8 mm diameter). There was no association between the magnitude of change in central or mid-peripheral corneal clearance during lens wear and the observed changes in corneal curvature (p > 0.05). However, East Asian participants displayed a significantly greater reduction in corneal clearance (p = 0.04) and greater superior-nasal corneal flattening compared to Caucasians (p = 0.048)., Conclusions: Miniscleral contact lenses that vault the cornea induce significant changes in anterior corneal surface topography and higher order aberrations following 8 h of lens wear. The region of greatest corneal flattening was observed in the superior-nasal mid-periphery, more so in East Asian participants. Practitioners should be aware that corneal measurements obtained following miniscleral lens removal may mask underlying corneal steepening., (© 2015 The Authors Ophthalmic & Physiological Optics © 2015 The College of Optometrists.)

The prevalence and the distribution characteristics of corneal astigmatism (CA) and anterior segment biometry before surgery in Chinese congenital cataract (CC) patients are not completely understood. This study involved 400 CC patients from the Zhongshan Ophthalmic Center enrolled from February 2011 to August 2015. Data on CA, keratometry, central corneal thickness (CCT) and anterior chamber depth (ACD) were measured by the Pentacam Scheimpflug System. The mean age of patients was 54.27 months, and the ratio of boys to girls was 1.53:1. The mean CA was 2.03 diopters (D), and 39.25% of subjects had CA values ≥2 D. The most frequent (71.8%) diagnosis was with-the-rule astigmatism. Oblique astigmatism was present in 16.2% of cases, and 12% of cases had against-the-rule astigmatism. The mean keratometry measurement of cataractous eyes in bilateral patients was significantly larger than that in unilateral patients. Girls had a larger mean keratometry but a thinner CCT than did boys. The CA, CCT, and ACD of cataractous eyes were significantly larger than those of non-cataractous eyes in unilateral patients. The CA, mean keratometry, CCT, and ACD in CC patients varied with age, gender, and laterality. Fully understanding these characteristics may help inform guidelines and treatment decisions in CC patients.

Purpose: Refraction in the peripheral visual field is believed to play an important role in the development of myopia. The purpose of this study was to investigate the differences in peripheral refraction among anisomyopia, isomyopia, and isoemmetropia for schoolchildren., Methods: Thirty-eight anisomyopic children were recruited and divided into two groups: (1) both eyes were myopic (anisomyopic group, AM group) and (2) one eye was myopic and the contralateral eye was emmetropic (emmetropic anisomyopic group, EAM group). As controls, 45 isomyopic and isoemmetropic children were also recruited with age and central spherical equivalent (SE) matched to those of the AM and EAM groups. The controls were divided into three groups: (1) intermediate myopia group (SE matched to the more myopic eye of AM group), (2) low myopia group (SE matched to the less myopic eye of AM group and the more myopic eye of EAM group), and (3) emmetropia group (SE matched to the less myopic eye of EAM group). Peripheral refraction at 7 points across the central ±30° on the horizontal visual field with a 10° interval was measured with an autorefractor. Axial length (AL), corneal curvature (CC), and anterior chamber depth (ACD) were also determined by using the Zeiss IOL-Master., Results: The relative peripheral spherical equivalent [RPR(M)] and relative peripheral spherical value [RPR(S)] of the more myopic eye was shifted more hyperopically than the contralateral eye in both the AM and the EAM groups (both p<0.0001). The RPR(M, S) of the less myopic eyes in the AM and EAM groups showed a relatively flat trend across the visual field and were not significantly different from the emmetropia group. The RPR(M, S) of less myopic eyes in the AM group were shifted less hyperopically than in the isomyopic low myopia group and the more myopic eye of the EAM group [RPR(M), p = 0.007; RPR(S), p = 0.001], although the central SEs of the three groups were not significantly different from each other. However, RPR(M, S) of the more myopic eyes were not different from the corresponding isomyopic groups. There was also no significant difference in the relative peripheral astigmatism [RPR(J0, J45)] between the more and the less myopic eyes in either the AM or the EAM group., Conclusion: Refraction of anisomyopia differs between the two eyes not only at the central visual field but also at the off-axis periphery. The relative peripheral refraction of the more myopic eye of anisomyopia was shifted hyperopically, as occurs in isomyopia with similar central subjective SE values. Less myopic eyes were much less hyperopically shifted in relative peripheral refraction than the corresponding isomyopic eyes, but are comparable to emmetropic eyes. This emmetropia-like relative peripheral refraction in less myopic eyes might be a factor responsible for slowing down the progression of myopia.

Purpose: To investigate the correlation of major components of ocular astigmatism in myopic patients in an academic hospital., Methods: This cross-sectional study was conducted on 376 eyes of 188 patients who were referred to Farabi Eye Hospital for refractive surgery. Preoperative examinations including refraction and corneal topography were performed for all candidates to measure refractive and corneal astigmatism. Ocular residual astigmatism was calculated using vector analysis. Pearson's correlation and ANOVA analysis were used to evaluate the strength of the association between different types of astigmatism. Both eyes were defined as cluster and the Generalized Estimating Equations (GEE) analysis were performed., Results: Mean age of 119 women (63.3%) and 69 men (36.7%) was 27.8 ± 5.7 years. Mean refractive error based on spherical equivalent was -3.59 ± 1.95D (range, -0.54 to -10.22D). Mean refractive and corneal astigmatism was 1.97 ± 1.3D and 1.85 ± 1.01D, respectively. Mean amount of ORA was 0.65 ± 0.36D.There was a significant correlation between ORA and refractive astigmatism(r=0.23, p<0.001), corneal and refractive astigmatism (r=0.91, p<0.001) and a weak correlation between ORA and corneal astigmatism (r=0.13, p=0.014). There was a significant correlation between J0 and J45 values of ORA and corneal astigmatism (p<0.001)., Conclusion: There is a significant correlation between ORA and refractive astigmatism, refractive and corneal astigmatism and a weak correlation between ORA and corneal astigmatism in refractive surgery candidates. Identifying the type of astigmatism and preoperative measurement of ocular residual astigmatism is highly recommended prior to any refractive surgery, especially in cases with significant astigmatism., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The aim of this study is to describe factors that influence the measured intraocular pressure (IOP) change and to develop a predictive model after myopic laser in situ keratomileusis (LASIK) with a femtosecond (FS) laser or a microkeratome (MK). We retrospectively reviewed preoperative, intraoperative, and 12-month postoperative medical records in 2485 eyes of 1309 patients who underwent LASIK with an FS laser or an MK for myopia and myopic astigmatism. Data were extracted, such as preoperative age, sex, IOP, manifest spherical equivalent (MSE), central corneal keratometry (CCK), central corneal thickness (CCT), and intended flap thickness and postoperative IOP (postIOP) at 1, 6 and 12 months. Linear mixed model (LMM) and multivariate linear regression (MLR) method were used for data analysis. In both models, the preoperative CCT and ablation depth had significant effects on predicting IOP changes in the FS and MK groups. The intended flap thickness was a significant predictor only in the FS laser group (P < .0001 in both models). In the FS group, LMM and MLR could respectively explain 47.00% and 18.91% of the variation of postoperative IOP underestimation (R2 = 0.47 and R(2) = 0.1891). In the MK group, LMM and MLR could explain 37.79% and 19.13% of the variation of IOP underestimation (R(2) = 0.3779 and 0.1913 respectively). The best-fit model for prediction of IOP changes was the LMM in LASIK with an FS laser.