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The postoperative result is determined not only by technique of a surgeon, the availability of modern innovative equipment, but also due to the accurate diagnostics and skilled interpretation of biometric, keratometric parameters; the use of modern formulas of IV, V generations to calculate the optical power of the intraocular lens (IOL), allowing to predict the correct position of the IOL, through the use of predictive variables that determine the postoperative lens position. The variety of modern research methods and continuous improvement of formulas for lens calculation allows us to get the closest results to emmetropia.

AIM:To evaluate the effect of keratometry on the calculation accuracy of intraocular lens(IOL)diopter in patients with normal axial cataract.METHODS:Totally 157 cases(157 eyes)with age related cataract were collected in Kaifeng Central Hospital from June 2020 to June 2021. Patients were divided into 3 groups according to keratometry: group A(53 eyes)(K46D). The IOL diopter was calculated by SRK/T, Hoffer Q, Holladay 2, Haigis, Kane and Barrett Ⅱ formulas respectively. Subjective optometry was performed after 1mo operation. The average refractive prediction error(RPE)and mean absolute error(MAE)were calculated, and their differences were compared and analyzed.RESULTS:There were significant difference between RPE of each formula and 0D in groups A and C(P0.01). There was no significant difference in RPE between group B and 0D(P>0.05). The ratio of Barrett Ⅱ formula in MAE≤0.5D in group A was significantly higher than SRK/T, Hoffer Q, Holladay 2 and Haigis formula(all P0.01). In group B, there was no significant difference among Barrett Ⅱ formula and the other formulas in the ratio of MAE≤0.5D and ≤1.0D(all P >0.01). In group C, the ratio of SRK/T and Hoff Q formula in MAE≤0.5D was lower than Barrett Ⅱ formula(all P0.01).CONCLUSION:If K46D before operation, the commonly used formulas will produce refractive error, but the accuracy of Kane and Barrett Ⅱ formulas are still higher than other formulas.

Background. The prevalence of corneal astigmatism in patients with cataract has not been well documented in both rural and urban areas of Indian population. Purpose. The aim of this study was to assess prevalence of corneal astigmatism before cataract surgery in adult age group population of rural Andhra Pradesh. Materials and methods. A Prospective, cross-sectional, and observational study was carried out from March 2019 to December 2019 in patients presenting for cataract surgery. Axial length, and intraocular lens power were measured, Keratometric values were measured with an auto refractokeratometer, and astigmatism was calculated. Data was analysed using SPSS software. Results. This study included 1000 eyes of 1000 patients with a mean age of 61.81 ± 8.94 years. The mean astigmatism was 0.80 ± 0.72 D and the mean keratometry was 44.12D ± 1.71 D. A total of less than 1D astigmatism is seen in 67.5% eyes, 23.3% eyes had astigmatism between 1.00 and 1.99 D, 4.6% eyes had 2-2.99D, and ≥3D in 0.8% eyes and no astigmatism in 3.8% eyes. Against the rule astigmatism was seen in 49.8% cases, with the rule astigmatism is found in 31.8% of eyes and oblique astigmatism in 14.9% of eyes. With the increasing age, the WTR percentage decreased while the ATR percentage increased. Conclusion. Our study showed that significant numbers of patients have preoperative corneal astigmatism, affecting the quality of vision after cataract surgery. Majority of patients have corneal astigmatism < 1.00D, which can be corrected by low-cost procedures like steep axis phaco, limbal relaxing incisions, and opposite clear corneal incisions, especially in developing countries like India, and less percentage of candidates require expensive toric IOLs.

AIM: To investigate the ocular development of patients who had unilateral congenital cataract (CC) combined with persistent fetal vasculature (PFV). METHODS: This cross-sectional, observational study included patients who had unilateral CC and PFV and those with isolated unilateral CC. Axial length (AL), keratometry, anterior chamber depth (ACD), lens thickness, and vitreous length were obtained. The ocular biometric parameters of the affected eyes of patients with CC and PFV were compared with the fellow eyes and with the affected eyes of patients with isolated CC. RESULTS: A total of 110 patients were included and divided into 4 groups: group 1 (18 patients with CC and PFV, 0.05). CONCLUSION: Compared with the fellow eyes, the ALs of the eyes with unilateral CC and PFV are shorter in patients younger than 24mo and longer in those older than 24mo; the keratometries of the eyes with unilateral CC and PFV are steeper in patients older than 24mo and similar with those younger than 24mo. These findings provide further understanding of ocular development in patients with both CC and PFV.

Abstract Background This study aimed to identify the features of ocular biometry in patients with EYS-related retinitis pigmentosa using IOLMaster 700. Methods We retrospectively reviewed the medical records of patients with retinitis pigmentosa. Patients with records of the following were included: (1) ocular biometry measurements using the IOLMaster 700 and (2) genetic diagnostic tests. Axial length, keratometry, anterior chamber depth, aqueous depth, lens thickness, central corneal thickness (CCT), and corneal diameter (white to white) measurements were extracted. Based on keratometry measurements, (1) standard keratometric astigmatism, (2) posterior corneal astigmatism, and (3) total corneal astigmatism were obtained. Demographics and biometric parameters were compared between patients with EYS-related retinitis pigmentosa and other patients with retinitis pigmentosa. Results A total of 86 eyes of 44 patients (23 females and 21 males; mean age: 47.7 years) with retinitis pigmentosa were included. Of these, 18 were identified as having EYS variants. CCT was significantly thinner (P

Purpose: To analyze the 5-year results of accelerated corneal collagen crosslinking (CXL) for progressive keratoconus and identify preoperative characteristics predictive of visual and topographic outcomes. Methods: A prospective interventional case series. Nineteen eyes of 19 patients receiving accelerated CXL with settings of 18 mW/cm2 for 5 min were included. Clinical and topographic parameters were assessed. Linear regression and logistic regression were used to compare the R2 and odds ratio (OR), respectively, between baseline characteristics and postoperative outcomes. Results: Corrected distance visual acuity (CDVA) remained stable from 0.28 ± 0.21 to 0.25 ± 0.18 logMAR (P = 0.486). The mean cylindrical refraction was stable (P = 0.119). The maximal keratometry (Kmax) decreased from 61.99 ± 10.37 to 59.25 ± 7.75 D (P < 0.001), flattening in the flattest and steepest meridians and mean keratometry were also observed (P ≤ 0.040). The mean anterior elevation at the apex reduced from 21.42 ± 16.69 to 18.53 ± 12.74 μm (P = 0.013) and changes in posterior elevation were non-significant (P = 0.629). Preoperative Kmax best predicted the postoperative change in Kmax (R2 = 0.55, P < 0.001) compared to the other baseline characteristics (P ≤ 0.028), whereas preoperative CDVA was the only significant predictor of postoperative change in CDVA (R2 = 0.41, P = 0.003). Accelerated CXL is less likely to fail in eyes with a steeper preoperative Kmax (OR = 0.74, P = 0.040) or greater posterior elevation at the apex (OR = 0.91, P = 0.042). Conclusion: Kmax significantly decreased following accelerated CXL. Eyes with worse preoperative CDVA and higher Kmax were more likely to have an improvement in visual acuity and corneal flattening.

Abstract Background This study aimed to evaluate the clinical outcomes and assess preoperative characteristics that may predict outcomes in keratoconus 1 year after accelerated transepithelial corneal cross-linking (ATE-CXL). Methods This prospective study included 93 eyes of 84 consecutive keratoconus patients with 1-year follow-up after ATE-CXL. Preoperative characteristics included corneal astigmatism, anterior chamber depth, anterior chamber volume, radius of curvature, posterior elevation, central corneal thickness (CCT), thinnest corneal thickness, steepest meridian keratometry, flattest meridian keratometry, and the maximum keratometry (Kmax). Data were obtained preoperatively and at 1, 3, 6, and 12 months postoperatively. The patient eyes were grouped into 3 subgroups according to CCT and Kmax values to observe the changes of keratoconus progression. Results All patients were successfully operated without complications at any follow-up time point. Mean changes of Kmax from baseline at 6 and 12 months were − 0.60 ± 2.21 D (P = 0.011) and − 0.36 ± 1.58 D (P = 0.030), respectively. Eyes with a thinner CCT and higher Kmax values exhibited a tendency for topographic flattening of ≥1.0 D (P = 0.003; P = 0.003). In the subgroup comparison, the Kmax values decreased significantly at 6 and 12 months after ATE-CXL in the group with CCT ≤ 450 μm (P = 0.018 and P = 0.045); the Kmax values of the group with Kmax > 65.0 D decreased significantly at 6 months postoperatively (P = 0.025). Conclusion ATE-CXL is a safe and effective treatment for keratoconus patients. Patients with thinner CCT and higher Kmax values are more likely to benefit from ATE-CXL.

This study aims to evaluate the existing mathematical approach for the theoretical estimation of axial length (AL) in a cross-sectional study, developing a new mathematical model and testing it in a longitudinal sample. Many professionals do not have a device to measure the AL due to clinic space and cost of equipment. However, this parameter plays an important role in the assessment of myopia progression to monitor treatment effects with myopia control strategies. First, a cross-sectional study based on the mathematical equation proposed by Morgan was performed. The AL was estimated based on the mean values of keratometry and spherical equivalent in 1783 subjects (52% female), aged 14.6 ± 4.6 years (6 to 25 years), of whom 738 were myopic, 770 emmetropic and 275 hyperopic. On average, the AL estimated with the Morgan formula was 0.25 ± 0.48 mm larger than the real AL value (95% limits of agreement: +0.70 to −1.20 mm). The study by gender, ametropia, type of astigmatism and age showed statistically significant differences between the real AL and predicted AL_Morgan (r > 0.750, spearman). Based on the previous sample, a multiple linear regression was applied, and a new mathematical model was proposed. The model was tested on a longitudinal sample of 152 subjects whose mean age was 13.3 ± 3.1 years (9 to 24 years) and of whom 96 were female (64%). The sample consisted of 46 myopes, 82 emmetropes and 24 hyperopes. The longitudinal study of the differences in axial length at one year between the models showed no statistically significant differences and that the mathematical equations are valid for estimating differences in axial increment for ages between 9 and 24 years, despite errors in the predicted value for axial length. [ABSTRACT FROM AUTHOR]

Purpose: Hyperopic surprises tend to occur in axial myopic eyes and other factors including corneal curvature have rarely been analyzed in cataract surgery, especially in eyes with long axial length (≥ 26.0 mm). Thus, the purpose of our study was to evaluate the influence of keratometry on four different formulas (SRK/T, Barrett Universal II, Haigis and Olsen) in intraocular lens (IOL) power calculation for long eyes. Methods: Retrospective case series. A total of 180 eyes with axial length (AL) ≥ 26.0 mm were divided into 3 keratometry (K) groups: K ≤ 42.0 D (Flat), K ≥ 46.0 D (Steep), 42.0 < K < 46.0 D (Average), and all the eyes were underwent phacoemulsification cataract surgery with Rayner (Hove, UK) 920H IOL implantation. Prediction errors (PE) were compared between different formulas to assess the accuracy of different formulas. Multiple regression analysis was performed to investigate factors associated with the PE. Results: The mean absolute error was higher for all evaluated formulas in Steep group (ranging from 0.66 D to 1.02 D) than the Flat (0.34 D to 0.67 D) and Average groups (0.40 D to 0.74D). The median absolute errors predicted by Olsen formula were significantly lower than that predicted by Haigis formula (0.42 D versus 0.85 D in Steep and 0.29 D versus 0.69 D in Average) in Steep and Average groups (P = 0.012, P < 0.001, respectively). And the Olsen formula demonstrated equal accuracy to the Barrett II formula in Flat and Average groups. The predictability of the SRK/T formula was affected by the AL and K, while the predictability of Olsen and Haigis formulas was affected by the AL only. Conclusions: Steep cornea has more influence on the accuracy of IOL power calculation than the other corneal shape in long eyes. Overall, both the Olsen and Barrett Universal II formulas are recommended in long eyes with unusual keratometry. [ABSTRACT FROM AUTHOR]

Purpose: To describe the cataract surgery outcomes in 34 adult patients with Down's syndrome in our center between 1996 and 2019. Setting: Clinical practice, tertiary hospital in Madrid, Spain. Design: Retrospective, descriptive study in which 34 patients with Down's syndrome who underwent cataract surgery in our center between 1996 and 2019 were included. Methods: Socio-demographic and clinical data such as the type of cataract, the keratometry and biometry, the type of surgery, the IOL material, and the complications before and after surgery were recovered. Results: Fifty-four eyes of 34 patients (23 female, 11 male, mean age 49 ± 8 years) underwent cataract surgery with general anesthesia. Immediately sequential, bilateral cataract surgery was performed in 18 patients (90% of bilateral cases). White cataract was found in 11 eyes (20.4%). Phacoemulsification technique was used in 51 eyes, extracapsular technique in 2 eyes (3.7%), and intracapsular technique in 1 eye (1.85%) (the only aphakic eye after surgery). The mean Km was 48.73 ± 4D, and the mean axial length was 25.2 ± 2.5 mm. The most frequent ocular comorbidity was myopia (27 eyes, 50%) followed by strabismus (11 eyes, 20.4%) and keratoconus (10 eyes, 18.5%). Posterior capsular rupture as a complication during surgery was found in 3 eyes (5.5%). The mean preoperative visual acuity was 0.8 ± 0.2 logMAR, and the mean postoperative visual acuity was 0.5 ± 0.18 logMAR. Conclusions: Phacoemulsification technique can be performed in adults with Down's syndrome with an acceptable rate of complications. The lack of patient cooperation, the ocular comorbidities and the challenging biometric estimation must be considered in surgical planning. It seems reasonable to perform immediately sequential, bilateral cataract surgery when possible, in order to reduce the exposure to general anesthesia. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the corneal topography and tomography of cats using a dual Scheimpflug and Placido disc device. Animal studied: Sixteen mixed‐breed cats (32 eyes). Procedure(s): Cats were sedated using meperidine (4.3 mg/kg/IM) and xylazine (0.5 mg/kg/IM), and evaluated using the software Galilei™. Values assessed included anterior and posterior corneal curvature, total corneal power, and corneal thickness. Results: Ten males and six females aged between 18 and 48 months were evaluated. The simulated keratometry (SimK) was 38.37 ± 0.83D, mean posterior keratometry −4.89 ± 0.34D, and mean total corneal power 38.04 ± 0.94D. The mean central corneal thickness (CCT) was 617.34 ± 53.38 μm with a mean thinnest point of 583.74 ± 60.60 μm. Conclusion: The Galilei™ examination was feasible in cats, enabling a detailed study of the cornea. To the best of our knowledge, this is the first study evaluating the corneal topography and tomography of cats using a device that integrates data from a dual Scheimpflug and Placido disc system. [ABSTRACT FROM AUTHOR]

We report the phenotype of a 15-year-old female patient with anterior segment dysgenesis (ASD) caused by a novel heterozygous loss-of-function FOXC1 variant. The proband underwent an ophthalmic examination as well as a molecular genetic investigation comprising exome sequencing, a single nucleotide polymorphism array to access copy number and Sanger sequencing to exclude non-coding causal variants. There was bilateral mild iris hypoplasia with pupil deformation and iridocorneal adhesions. In addition to these features of ASD, the corneas were flat, with mean keratometry readings of 38.8 diopters in the right eye and 39.5 diopters in the left eye. There was a snail track lesion of the left cornea at the level of the Descemet membrane. The central corneal endothelial cell density was reduced bilaterally at 1964 and 1373 cells/mm2 in the right and left eyes, respectively. Molecular genetic analysis revealed that the proband was a carrier of a novel heterozygous frameshifting variant in FOXC1, c.605del p.(Pro202Argfs*113). Neither parent had this change, suggesting a de novo origin which was supported by paternity testing. We found no possibly pathogenic variants in the other genes associated with posterior corneal dystrophies or ASD. Further studies are warranted to verify whether there is a true association between snail track lesions, corneal flattening, and pathogenic variants in FOXC1. [ABSTRACT FROM AUTHOR]

Surgically induced astigmatism (SIA) has been widely discussed in the literature as the change in corneal astigmatism resulting from corneal incision. The purpose of this study was to investigate the change in corneal refractive power preoperative to postoperative using a vector analysis of keratometry, total keratometry, and corneal back surface data from a modern optical biometer. The analysis was based on a dataset of 122 eyes of 122 patients with preoperative and one month postoperative measurements performed with the IOLMaster 700 biometer from 1 clinical center and a standardized surgical technique involving a corneal 2.5 mm 45°-incision made from the superior direction. Keratometry, total keratometry and corneal back surface data were processed in three vector components (spherical equivalent power SEQ and astigmatism considered in 0°/90° (C0°) and in 45°/135° (C45°) meridian), and the changes in corneal power vectors were analyzed, comparing preoperative to postoperative values. The mean corneal power of total keratometry reduced slightly after cataract surgery (−0.05 dpt), resulting mostly from a decrease in back surface power (−0.04 dpt). The astigmatism vector component C0° of total keratometry reduced by −0.28 dpt, mostly due to a decrease at the corneal front surface (−0.26 dpt). With the corneal incision at 12 o'clock position, this flattening in the 90° meridian refers to a SIA of around ¼ dpt. The change in C0° and the C45° astigmatic vector components for both keratometry and total keratometry show a large variation ranging between 0.24 and 0.33 dpt (standard deviations), indicating a poor predictability of the change in astigmatism due to cataract surgery. Cataract surgery locally flattens the cornea in the incision meridian. This flattening shows a large individual variation and therefore a poor predictability. Our study indicates that SIA in modern cataract surgery with standardized corneal incision is in a range of 1/4 dpt. [ABSTRACT FROM AUTHOR]

Introduction: Diabetes today is a global health issue, posing a risk to several organ systems. Besides complications like cataracts, diabetic retinopathy (DR), glaucoma and refractive errors, anatomical parameters like central corneal thickness (CCT), which is a crucial indicator of corneal endothelium function and keratometry parameters, have also been noticed to be altered in diabetes. Variations in these parameters may affect the accuracy of applanation tonometry in measuring intraocular pressure. This study aims to investigate variations in CCT and keratometry across different stages of DR, as prior research has yielded inconsistent results. The study also intends to explore the relationship between glycosylated hemoglobin (HbA1C) levels and changes in keratometry and CCT., Materials and Methods: This observational cross-sectional study was conducted from July 2022 to June 2024. A total of 204 subjects, aged 35-70 years, were included in the study. All participants were evaluated for DR, and those showing fundus findings were graded into five classes based on the Early Treatment Diabetic Retinopathy Study (ETDRS) classification. CCT, keratometry parameters (K1 and K2) and HbA1C levels were measured for all participants. The clinical parameters were correlated across different grades of diabetes mellitus and compared using Statistical Package for the Social Sciences (IBM SPSS Statistics for Windows, IBM Corp., Version 23.0, Armonk, NY) software., Results: The patient population consisted of 130 males (63.7%) and 74 females (36.3%). It was found that there was a trend indicating that the presence of DR increased with age, which was statistically significant (p=0.036). However, the differences in the mean duration of diabetes across DR groups were not statistically significant. Findings suggested that individuals with DR generally possess a higher CCT compared to the control group, particularly in the earlier stages of the disease, i.e. no DR and mild non-proliferative diabetic retinopathy (NPDR). However, as the severity of DR increases, the CCT tends to decrease slightly in moderate NPDR, severe NPDR, and proliferative diabetic retinopathy (PDR) stages. The study notes that the variations in CCT across these groups were not statistically significant (p-value of 0.29). The study also found that changes in corneal curvature, as indicated by keratometry values, were more pronounced in the proliferative stage of DR, with a statistically significant increase in k2 values of the left eye (p-value = 0.025). The study concluded that there was no statistically significant relationship between CCT and keratometry values of both eyes with HbA1c levels., Conclusion: While there were some clear patterns, especially concerning age, most variations in ocular parameters were not statistically significant, suggesting that other factors might need an in-depth study in the development of DR and its correlation with ocular parameters. Similarly, while HbA1c has often been stated to be a prognostic factor in diabetes mellitus, significant correlations were neither noted with ocular parameters like CCT and keratometry, nor the stage of retinopathy., Competing Interests: Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Institute Ethics Committee, Ophthalmology, Kalinga Institute of Medical Sciences (KIMS), Bhubaneswar issued approval KIIT/KIMS/IEC/955/2022. This observational cross-sectional study was carried out in the Ophthalmology Department at Pradyumna Bal Memorial Hospital, KIMS in Bhubaneswar from July 2022 to June 2024, following the approval. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Yousuf et al.)

Purpose: To systematically compare the effectiveness of conventional corneal collagen cross-linking (CCXL) protocols and accelerated corneal collagen cross-linking (ACXL) protocols in cases with progressive keratoconus., Methods: The Cochrane library, EMBASE, MEDLINE, PubMed, and Web of Science databases were searched for randomized controlled trials (RCTs). Outcomes were clinical results and changes in corneal properties. Standardized mean differences (SMD) and 95% confidence interval (CI) were used to estimate the clinical consequences. All outcomes were distributed by different follow-up durations (6 months, 12 months, and > 12 months). We also compared maximum keratometry (Kmax) and best spectacle-corrected visual acuity (BCVA) in subgroups, which were categorized by the discrepant impregnation time period of riboflavin., Results: We included 14 RCTs that met the eligibility criteria in this meta-analysis. At the last follow-up, CCXL was superior in postoperative change in demarcation line (SMD: -1.573; 95% CI: -2.897 to -0.248) and in Kmax (SMD:0.302; 95% CI: 0.071 to 0.533), whereas ACXL provided a significantly lower reduction in central corneal thickness (SMD: 0.498; 95% CI: 0.125 to 0.871). No differences in the changes in uncorrected visual acuity, BCVA, manifest refraction spherical equivalent, corneal biomechanical properties, and the endothelial cell density were found among both groups., Conclusion: CCXL was superior to ACXL in greater corneal flattening and deeper demarcation line, while ACXL seemed to cause less reduction in CCT and allow for earlier UDVA stability. To clearly define the comparative safety and clinical consequences of the different regimens of CXL, more RCTs are required., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objective: To compare the accuracy of Kane, Barrett Universal II, Haigis, and SRK-T formulas in eyes with average keratometry greater than 46 diopters (D)., Methods: A retrospective analysis was conducted on 101 eyes of 101 patients with average keratometry greater than 46 D. The absolute prediction error (EA) was obtained for each patient one month after surgery. The mean absolute prediction error (MEA), median absolute prediction error (MedEA) and the percentage of patients with absolute refractive error less than 0.25 D, 0.50 D, and 1.00 D were calculated for each formula analyzed., Results: The Kane formula achieved the lowest MEA (0.53 ± 0.43) and the lowest MedEA (0.41), followed by Barrett Universal II (MEA: 0.56 ± 0.42, MedEA: 0.49), SRK-T (MEA: 0.59 ± 0.44, MedEA: 0.54), and Haigis (MEA: 0.77 ± 0.47, MedEA: 0.69), showing a significant difference in the results. It was also observed that the Kane formula was the most accurate, with the highest percentage of patients, with EA less than 0.25 D, 0.50 D, and 1.00 D (30.7%, 54.4%, and 86.1%, respectively), while the Haigis formula was the least accurate (12.9%, 33.7%, and 69.3%, respectively)., Conclusion: In eyes with corneas having average keratometry greater than 46 D, the Kane formula proves to be a useful tool in intraocular lens (IOL) power calculation and demonstrates higher precision compared to the Barrett Universal II, SRK-T, and Haigis formulas., (Copyright © 2024 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.)

Shavini Athukorala,1 Neal Kansara,2 Erik Lehman,3 Seth M Pantanelli1 1Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, USA; 2Department of Ophthalmology, Baylor College of Medicine, Houston, TX, USA; 3Department of Public Health Sciences, Penn State College of Medicine, Hershey, PA, USACorrespondence: Seth M PantanelliDepartment of Ophthalmology, Penn State College of Medicine, 500 University Drive, HU19, Hershey, PA, 17033-0850, USATel +1 717-531-5690Fax +1 717-531-5009Email spantanelli@pennstatehealth.psu.eduPurpose: To investigate the relationship between measured anterior, posterior, and total keratometric astigmatism and post-operative refractive astigmatism (RA) after cataract surgery.Patients and Methods: This was a retrospective analysis of eyes that consecutively underwent pre-operative measurements of keratometric astigmatism with a swept-source optical coherence tomography (SS-OCT)-based optical biometer and dual-Scheimpflug/Placido disc corneal topographer, cataract surgery with implantation of a monofocal intraocular lens, and post-operative manifest refraction. The difference between post-operative refractive astigmatism and keratometric astigmatism measured using four different ways [Keratometry (K), Simulated Keratometry (SimK), Total Keratometry (TK), and Total Corneal Power (TCP)] was calculated.Results: For all 118 eyes, a smaller mean vector difference between post-operative refractive astigmatism and measured keratometric astigmatism was realized with TK (0.08 @ 151) vs TCP2 (0.30 @ 174; p < 0.0006), as well as with K (0.26 @ 173) vs SimK (0.52 @ 177; p = 0.036). The mean vector difference between post-operative refractive astigmatism and TK astigmatism was 0.31 @ 097, 0.21 @ 163, and 0.69 @ 179 in eyes with against-the rule (ATR), oblique, and with-the-rule (WTR) anterior corneal astigmatism, respectively (p < 0.0006). On the other hand, posterior corneal astigmatism did not significantly change with the orientation of anterior corneal astigmatism [0.10 @ 180 for ATR, 0.22 @ 180 for oblique, and 0.28 @ 180 for WTR (p = 0.58)].Conclusion: Compared with the other measures of corneal astigmatism, total keratometric astigmatism from the SS-OCT device most closely correlated with post-operative RA. The difference between anterior corneal astigmatism and refractive astigmatism is not completely explained by the contribution from the posterior cornea. Other contributors, such as lens tilt or neuro-adaptation, may be at play.Keywords: astigmatism, biometry, keratometry

Intraocular lens (IOL) power calculation after corneal refractive surgery (CRS) becomes an expanding challenge for ophthalmologists as more and more cataract surgeries after CRS are required. These patients typically also have high expectations as to visual performance. Conventional IOL power calculation schemes frequently provide inaccurate results in these cases. This review aims to summarize and recommend currently available IOL power calculation methods for eyes with the most common CRS methods: radial keratotomy (RK), photorefractive keratectomy (PRK), laser in situ keratomileusis (LASIK), and small incision lenticule extraction (SMILE). To this end, biometry measuring methods and IOL formulas will be explained and combinations of both are proposed. In synopsis, it is evident that the latest generation of vergence formulas exhibit favorable IOL power prediction accuracy in post-CRS eyes, even though the predictive precision of methods in eyes without CRS is not attained. Ray tracing computation, intraoperative aberrometry, and machine learning–based formulas hold potential to further improve refractive outcomes in post-CRS eyes. [ABSTRACT FROM AUTHOR]

Background: This study analyzed regional corneal thickness remodeling, biomechanical properties, and visual outcomes after femtosecond laser-assisted in situ keratomileusis combined with intraoperative accelerated corneal collagen crosslinking (LASIK Xtra) for myopia.Methods: This retrospective study analyzed 21 consecutive patients (18 women, three men; 42 eyes) who were treated with LASIK Xtra. All treatments were performed with ultraviolet-A (energy, 2.7 J/cm2; irradiance, 30 mW/cm2), using continuous (90 s) illumination. Postoperative values of corneal biometrics and visual outcomes were compared with preoperative values. Corneal thickness changes were evaluated using anterior segment optical coherence tomography. All patients were followed up for 12-month postoperatively. Preoperative and postoperative data were compared statistically using the paired t-test for normally distributed parameters and the Wilcoxon rank-sum test and Friedman analysis of variance with Bonferroni correction for non-normally distributed data.Results: Uncorrected distance visual acuity (UDVA) significantly improved at 6-month after surgery (P < 0.001). The central and inner regional corneal epithelial thickness significantly increased after LASIK Xtra (P < 0.05 for all), while the peripheral corneal epithelial thickness remained stable at 12-month after surgery. There was also a statistically significant decreased in the stromal thickness at most locations (P < 0.05 for all), except in the outer superior and outer superior-temporal regions.Conclusions: LASIK Xtra provided improvement in UDVA, corneal curvature, and corneal biomechanical stability. Because the results of this retrospective study results depended on the cohort members' past information, it was inferred and confirmed that regular corneal thickness remodeling occurred after treatment. [ABSTRACT FROM AUTHOR]

Purpose: To analyze the 5-year results of accelerated corneal collagen crosslinking (CXL) for progressive keratoconus and identify preoperative characteristics predictive of visual and topographic outcomes.Methods: A prospective interventional case series. Nineteen eyes of 19 patients receiving accelerated CXL with settings of 18 mW/cm2 for 5 min were included. Clinical and topographic parameters were assessed. Linear regression and logistic regression were used to compare the R2 and odds ratio (OR), respectively, between baseline characteristics and postoperative outcomes.Results: Corrected distance visual acuity (CDVA) remained stable from 0.28 ± 0.21 to 0.25 ± 0.18 logMAR (P = 0.486). The mean cylindrical refraction was stable (P = 0.119). The maximal keratometry (Kmax) decreased from 61.99 ± 10.37 to 59.25 ± 7.75 D (P < 0.001), flattening in the flattest and steepest meridians and mean keratometry were also observed (P ≤ 0.040). The mean anterior elevation at the apex reduced from 21.42 ± 16.69 to 18.53 ± 12.74 μm (P = 0.013) and changes in posterior elevation were non-significant (P = 0.629). Preoperative Kmax best predicted the postoperative change in Kmax (R2 = 0.55, P < 0.001) compared to the other baseline characteristics (P ≤ 0.028), whereas preoperative CDVA was the only significant predictor of postoperative change in CDVA (R2 = 0.41, P = 0.003). Accelerated CXL is less likely to fail in eyes with a steeper preoperative Kmax (OR = 0.74, P = 0.040) or greater posterior elevation at the apex (OR = 0.91, P = 0.042).Conclusion: Kmax significantly decreased following accelerated CXL. Eyes with worse preoperative CDVA and higher Kmax were more likely to have an improvement in visual acuity and corneal flattening. [ABSTRACT FROM AUTHOR]

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Introduction: Cataract is a common cause of vision loss and blindness in humans. After surgical management of cataract, all efforts should be focused on reducing postoperative astigmatism thus providing an excellent vision to patients.Aim: To determine the relationship between corneal incision and refraction changes before and after phacoemulsification surgery in 300 patients undergoing cataract surgery in Khatam hospital in Mashhad, Iran from January 2017 to April 2018.Materials and methods: Three hundred patients (144 women and 156 men) with cataract undergoing phacoemulsification surgery were recruited in this cross-sectional study. Refraction, keratometry and visual acuity measurement were performed before surgery. Then, a steep-based incision in the cornea was made without stitches. A 3.2 mm corneal incision was made at two supratemporal and temporal sites. The patients were followed-up for one and six months, and one year after surgery monitoring their vision and refraction, and performing keratometric measurements.Results: The mean age of the patients was 65.7±9.54 years (age range, 42–84 years). No major complications were observed. The greatest mean of changes in corneal power was in the supratemporal incision (1.28±0.6). Keratometry had a significant relation with the incision (p

AIM: To study the efficacy and safety of accelerated collagen cross-linking in keratoconus.METHODS: Medical records of keratoconic corneas underwent accelerated collagen cross-linking at King Chulalongkorn Memorial Hospital, Thailand between April 2015 and August 2018 were reviewed. Preoperative and postoperative data at 1a of visual acuity, auto-refraction, corneal topography, higher-order aberrations(HOA), topometric indices and corneal densitometry were evaluated. Age of 24 and 30 years old, maximum keratometry value(Kmax)of 55 D, and baseline best corrected visual acuity(BCVA)of 20/40(or 0.3 in LogMAR unit)were used as cut-off values to highlight the cross-linking effects. The effect of age, preoperative Kmax and BCVA were analyzed. The association between the change of corneal densitometry and other factors including preoperative Kmax, Kmean, manifest refraction spherical equivalent(MRSE), visual acuity, thinnest pachymetry, the change in Kmax, and the change of those parameters were also analyzed. P

Abstract Purpose: To compare the outcomes of accelerated versus standard corneal cross-linking for the treatment of progressive keratoconus. Methods: In this retrospective comparative study, 63 eyes of 40 patients with progressive keratoconus were divided into two groups; 27 eyes in group one were treated with an accelerated protocol (10 mW/cm 2 , 9 min) and 36 eyes in group two were treated with the standard method (3 mW/cm 2 , 30 min). Visual acuity, refraction, corneal topography, corneal tomography, and anterior and posterior corneal higher-order aberrations (HOAs) were assessed preoperatively and 18–30 months postoperatively. Results: The LogMAR uncorrected and corrected distance visual acuity values were improved in both groups postoperatively. However, the improvement was significantly higher in group one (P < 0.05, all). The flattening in the anterior keratometry readings, flat K, steep K, and average K were significantly higher in group two (P < 0.001, all). The maximum anterior keratometry (AKf) values significantly decreased in both groups, whereas the maximum posterior keratometry (AKb) values increased. The reduction in the minimum corneal thickness (ThKmin) was significantly greater (36.49um) in group two, compared to 10.85um in group one. There was a significant increase in the posterior average keratometry, and a significant decrease in the posterior astigmatism, along 3 mm meridian in S-CXL (P = 0.03, P = 0.008, respectively), while the corresponding values showed no statistical significance in group one (P > 0.05). The anterior corneal trefoil was significantly reduced in group one (P = 0.002), whereas anterior total HOAs and coma were significantly improved in group two (P < 0.0014, all). The posterior corneal spherical aberration decreased significantly in group one (P = 0.02), while group two revealed significant reduction in the posterior trefoil values (P = 0.011). The change in the anterior maximum keratometry was significantly and positively correlated to the preoperative maximum keratometry in group two (P = 0.53, P = 0.003). Conclusion: An accelerated cross-linking protocol using 10 mW/cm 2 for 9 min showed more visual improvement and less pachymetric reduction when compared to the standard protocol, however, anterior corneal flattening, posterior corneal steepening, and the change in the posterior astigmatism were significantly higher in the standard protocol; while corneal HOAs were improved in both protocols.

Purpose: Corneal hysteresis (CH) and corneal resistance factor was found to be less for patient wearing toric contact lens as compared to soft spherical CH was calculated as the difference in air pressures between force-in applanation (P1) and force-out applanation (P2), or (P1–P2). Materials and Methods: This was the prospective study, 40 eyes of 22 patients with mean age of 22.09 ± 4.05 years. Eleven eyes were fitted with soft toric contact lens and 29 eyes were fitted with soft spherical contact lens. Dry eye, keratoconic or any systemic pathology were excluded. Soft toric and soft spherical contact lenses (Comfilcon A, Coopervision, and Southampton, UK) were fitted. The Ocular response Analyzer (Reichert Ophthalmic Instruments, Depew, New York, USA) was used to measure CH before and after 3 months using soft toric and soft spherical contact lenses. Descriptive statistics were used to analyze the demographic data. Paired t-test was employed for analyzing the difference between the base line value of CH with soft toric and soft spherical contact lens wearers after 3 months. Independent t-test was used to find the association between CH and gender. Results: CH was found to be lesser after 3 months of soft toric contact lens wear, as compared with soft spherical contact lenses. Mean increase of CH was found to range from 10.44 ± 0.96to 10.80 ± 0.96 mmHg (P = 0.000). Conclusion: In this study, there was a decrease in CH after using soft toric contact lenses and increase after using soft spherical contact lenses for 3 months. The increased CH with soft spherical contact lens was reversible in nature. However, CH may differ between lens type and modality of wear which can lead to long-term changes in the corneal biomechanical properties.

Duangratn Niruthisard,1 Wasee Tulvatana,1 Vannarut Satitpitakul2 1Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, Thailand; 2Center of Excellence for Cornea and Stem Cell Transplantation, Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, ThailandCorrespondence: Vannarut SatitpitakulCenter of Excellence for Cornea and Stem Cell Transplantation, Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, ThailandTel +66 894959022Email Vannarut.s@chula.ac.thPurpose: To determine the percentage of eyes with corneal astigmatic power stability and mean corneal keratometric power at 6-month post-pterygium excision, and to identify the time, and the associated factors, required to achieve stability.Methods: This prospective observational study enrolled patients undergoing pterygium excision. Patients were evaluated for baseline characteristics and keratometric data before and every month after pterygium excision for six months using IOL Master 500® (Carl Zeiss, Meditec). Clinically stable corneal astigmatic power and keratometric power were, respectively, defined as changes in these parameters of less than 0.25 and 0.27 diopters after two consecutive visits. Time to corneal astigmatic and keratometric power stability, as well as factors associated with the stability, were analyzed.Results: Forty percent and 73.3% of eyes, respectively, demonstrated corneal astigmatic and corneal keratometric stability at six months post-operation. Within three months of reaching initial stability, the corneal astigmatic power and the mean keratometric power showed instability in 46.7% and 27.3% of patients, respectively. No patients with keratometric stability for more than three months became unstable during the study period. The extension of pterygium exceeding 3.0 mm was associated with a delay in time to corneal astigmatic stability (HRadjusted 0.41; 95% CI 0.19– 0.89; P= 0.02).Conclusion: According to the clinical relevance, 40% and 73% of patients, respectively, presented corneal astigmatic and keratometric stability within six months post-operation. Patients with a pterygium extension of more than 3 mm required a longer time for corneal astigmatic stability. It is recommended that keratometric stability be achieved for at least three months before commencing with additional procedures.Keywords: pterygium, corneal curvature, keratometry, astigmatism

To determine the changes in keratometry measurements and refraction in patients having the thermo-mechanical periorbital skin treatment, Tixel®, to treat dry eye disease (DED). A multi-centre, prospective, non-masked study was conducted. DED patients were recruited in 3 international centres and were evaluated in 5 visits separated by an interval of 2 weeks except for the last visit which took place after 18 weeks from visit 1. The same clinical examination was performed at all visits: OSDI questionnaire, tear stability, keratometry, best corrected visual acuity and refraction. Tixel® treatment was applied at the first 3 visits. 89 participants (24 males/65 females; mean age: 55.0 ± 14.2 years) were included: 20 presented moderate DED symptoms and 69 severe DED symptoms. Significant differences were found for the spherocylindrical refraction (vector analysis) between visit 1 and visits 2 and 3. Following cumulative analysis, 11.86 % and 16.94 % of participants had more than 0.5 dioptre (D) change in mean keratometry and keratometric astigmatism, respectively, at 3 months post-treatment. A total of 5.40 % had a sphere and cylinder change greater than 0.50D and 16.21 % had the axis changed more than 10 degrees (vector analysis). These changes were particularly significant in patients with severe DED symptoms. Keratometry readings and refraction can change following thermo-mechanical skin treatment for DED, especially in those patients with severe DED symptoms. This should be considered as potential errors in intraocular lens calculations may be induced. [ABSTRACT FROM AUTHOR]

Objectives: To find out the prevalence and severity of keratoconus in spring catarrh patients. Study Design: Descriptive and Perspective study. Setting: OPD K.D.A Teaching Hospital Kohat. Period: March 2017 to October 2019. Material & Methods: All patients suffering from spring catarrh were included in the study after consent. Proper proforma was designed for record. Detail history was taken and for diagnosis all the patients were properly examined with slit lamp. Visual acuity was checked. Radioscopy for irregular scissor reflex and fundoscopy for oil droplet sign for keratoconus was carried out. Keratometry was done to determine the astigmatism and severity of keratoconus Grading of keratoconus was done by the highest axis of corneal power on keratometry as mild (< 48 D), moderate (48-54 D) and severe (> 54 D). Suspected cases were advised corneal topography. Total 480 patients were included in the study. Out of these 480 patients 295 (61.45%) were male and 185 (38.54%) female. The age range of patients was 9 to 37 years. Results: Out of 480 patients, 47(9.79%) patients had keratoconus in which 36(76.59%) were male and 11(23.40%) were female. Out of 47 patients 19 (40.42%) had mild, 22(46.80%) had moderate and 6(12.76%) patients had severe keratoconus. Conclusion: Keratoconus has strong association with spring catarrh. [ABSTRACT FROM AUTHOR]

Purpose: To compare the prediction accuracy of algorithmic intraocular lens (IOL) power calculation formula selection method using conventional formulas (Haigis, Hoffer Q, Holladay 1, SRK/T and/or Barrett Universal II) based on keratometry (K), anterior chamber depth (ACD) and axial length (AL). Methods: A total of 1653 patients (1653 eyes) implanted with Tecnis ZCB00 IOL during cataract surgery were enrolled in this study. Intraocular lens (IOL) power calculation formulas with a small absolute value in the sum of the area under the curve measured by K, ACD and AL subgroup were selected to calculate IOL power in the relevant biometry subgroup. The median absolute error (MedAE) calculated by the Haigis, Hoffer Q, Holladay 1, SRK/T and Barrett Universal II formulas individually was compared to that calculated by the algorithmic selection method using four formulas, Haigis, Hoffer Q, Holladay 1 and SRK/T, or five formulas when Barrett is included. Results: The MedAE was 0.27 D in the Haigis, 0.30 D in the Hoffer Q, 0.27 D in the Holladay 1, 0.29 D in the SRK/T and 0.26 D in the Barrett Universal II formulas. The MedAEs determined by the algorithmic selection method using four (019 D) and five (0.21 D) formulas were significantly lower than those by the conventional IOL power calculation formulas. Conclusions: The IOL power calculation formula selection method by biometry subgroup combined with biometric parameters K, ACD and AL may offer a more superior postoperative refractive error prediction in cataract surgery. [ABSTRACT FROM AUTHOR]

In this paper we present a technique to measure the radius of curvature of a test sphere based on the relation between acquired images of a circular cosine fringe pattern and size of virtual image formed on the calibration test surface. Radius of curvature is calculated with the exact equation proposed, using the parameters of the optical setup. Fringe pattern evaluation was performed by locating extrema indices. The mathematical formulation as well as the experimental setup and results are presented. After applying a linear fit algorithm to the data as a method of compensation, obtained results show an error within the tolerance established by the ISO 10343 specifications. [ABSTRACT FROM AUTHOR]

PURPOSE: The purpose of the study is to evaluate the comparability of corneal power measurements, anterior chamber depth (ACD), and white‑to‑white (WTW) distance between a high‑resolution Scheimpflug‑based tomography (Pentacam HR; Oculus GmbH, Wetzlar, Germany) and a swept‑source optical biometry (IOL Master 700; Carl Zeiss Meditec AG, Jena, Germany) in patients having undergone a myopic refractive surgery. METHODS: This prospective, interinstrument reliability analysis included 31 individuals with a previous myopic laser refractive correction. Standard keratometry and total keratometry (TK) of the flattest and steepest axis of the IOL Master 700 were compared with standard keratometry (simulated keratometry [SimK]), true net power (TNP), equivalent keratometer readings (EKR), and total corneal refractive power of the Pentacam. The Bland–Altman analysis evaluated the agreement between the measurements of both devices. A paired t‑test was performed to compare the mean values of the variables obtained by the two devices. RESULTS: Mean age of the participants was 31.87 ± 13.17 years. Ten patients (32.3%) had undergone laser in situ keratomileusis surgery, and 21 (67.7%) had undergone photorefractive keratectomy surgery. The two devices generated statistically significant differences in almost all the comparisons between their corneal keratometry values, ACD, and WTW. The two devices agreed in some of the flat axis values and more specifically on SimK1 and K1, EKR K1 along 1 mm‑zone and K1, as well as on the comparison between the EKR keratometry values along 1, 2, and 3 mm‑zone with their corresponding TKs. CONCLUSION: IOL Master 700 and Pentacam HR do not show good concordance and cannot be used interchangeably when measuring keratometry values in postrefractive eyes, rendering the IOL power calculation in postrefractive eyes really challenging. [ABSTRACT FROM AUTHOR]

Background: Cataract surgery in keratoconic patients is challenging because of the corneal distortion, which can lead to inaccurate keratometry readings. This study is a comparison of the accuracy of keratometry readings by two types of devices in a tertiary hospital. Purpose: To evaluate the comparability of corneal power measurements, anterior chamber depth (ACD), and white-to-white (WTW) distance between Scheimpflug-based tomography (Pentacam AXL; OCULUS GmbH, Wetzlar, Germany) and swept-source optical biometry (IOLMaster 700; Carl Zeiss Meditec AG, Jena, Germany) in patients with keratoconus. Methods: This pilot, prospective, interinstrument reliability study included 30 keratoconic eyes of 15 individuals who had not undergone any kind of corneal surgery. Standard K and total refractive power (TK®) of the flattest and steepest axes of the IOLMaster 700 were compared with the standard keratometry (SimK), true net power (TNP), equivalent keratometer readings (EKR), and total corneal refractive power (TCRP) of the Pentacam. The Bland–Altman analysis was used to evaluate the agreement between the measurements of both devices. The paired-samples t -test and the Wilcoxon signed-rank test were performed to compare the mean values of the variables obtained with the devices. Results: The K1 value of the IOLMaster 700 was significantly higher from EKR K1 along the 3-mm (mean difference: 0.79 diopters, p = 0.01), 4-mm (mean difference: 1.01 D, p = 0.01), and 4.5-mm zones (mean difference: 1.20 D, p = 0.01) and TNP K1 along the 3-mm (mean difference: 0.88 D, p < 0.001) and 4-mm zones (mean difference: 0.97 D, p < 0.001). The TK1 value was significantly higher from EKR K1 along the 2-mm (mean difference: 0.42 D, p = 0.04), 3-mm (mean difference: 0.83 D, p = 0.003), 4-mm (mean difference: 1.05 D, p = 0.004), and 4.5-mm zones (mean difference: 1.24 D, p = 0.005) and TNP K1 along the 3-mm (mean difference: 0.92 D, p < 0.001) and 4-mm zones (mean difference: 1.01 D, p < 0.001). The K2 value of the IOLMaster 700 was significantly higher from TK2 (mean difference: 0.11 D, p = 0.04) and all the corresponding variables of the Pentacam device. The TK2 value was significantly higher from all the corresponding variables of the Pentacam device. The Pentacam also yielded significantly lower values for the WTW distance (mean difference: 0.31 mm, p < 0.001) and no significant difference in terms of ACD values (p = 0.9). Conclusion: The IOLMaster measured significantly greater keratometry readings in the steep axis for all the variables studied. The keratometry and WTW measurements of the investigated devices cannot be used interchangeably in keratoconus. [ABSTRACT FROM AUTHOR]

Background: Corneal transplantation surgery is associated with an increased risk of intraocular pressure (IOP) elevation. Increased IOP may cause irreversible vision loss and graft failure.Purpose: We aimed to evaluate early IOP changes following different keratoplasty techniques and to investigate the relationship between corneal thickness (CT), keratometry values, anterior chamber depth (ACD), and IOP changes. Methods: We included patients who underwent penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), and Descemet membrane endothelial keratoplasty (DMEK) in this observational study. ACD, CT, and keratometry measurements were repeated postoperatively at hour 24, week 1, and month 1. IOP measurements were repeated at postoperative hours 6 and 24, week 1, and month 1 by Tono-Pen XL. Results: In total, 22 patients underwent PK, 12 patients underwent DALK, and 19 patients underwent DMEK. The difference between the IOP preoperatively and postoperatively hour 6, and between the IOP preoperatively and postoperatively hour 24 was statistically significant in the three types of surgery (p < 0.05 for each). The difference between preoperative and postoperative week 1 IOP was statistically significant only in the PK group (p = 0.023). When the IOP was compared between the three types of surgeries, the IOP at postoperative week 1 in the PK group was significantly higher than the DALK and DMEK groups (p = 0.021). There was no correlation between ACD, CT, K values, and IOP in any group. Conclusion: IOP may increase in all types of keratoplasty during the first hours after surgery, but PK has a risk of high IOP longer in the early postoperative period. PK patients should be followed more carefully during postoperative week 1 to check for an increase in IOP. [ABSTRACT FROM AUTHOR]

We present four operated cataract cases with extreme axial lengths where the biometric formulas used for intraocular lens dioptre calculation have made surprising or unusual predictions. The four operated cases were part of a study on 1192 eyes that compared the accuracy of five biometric formulas. Case 2 and 3 had an unexpected increase in both keratometric and refractive cylinder, compared to the preoperative cylinder. Case 1 with short axial length showed unexpectedly poor results for Hoffer Q formula and Case 4 showed good results for all five formulas, even Hoffer Q that is not recommended for long axial lengths. Refraction prediction errors altered by test-to-test variations in keratometry or surgically induced astigmatism, as well as other erroneous measured variables, could influence the results of studies analysing accuracy of biometric formulas, if the number of cases is great enough, and should not be ignored. [ABSTRACT FROM AUTHOR]

Background: This is a prospective study which aims: To compare the preoperative and postoperative corneal astigmatism in patients undergoing pterygium excision by conjunctival autograft technique using autologous blood. To determine the correlation of pterygium length with preoperative and postoperative corneal astigmatism and thus ascertain an early indication for pterygium surgery. Materials and methods: 75 patients with primary pterygia were evaluated after dividing them into three groups based on length, Grade A - < 2mm, Grade B - 2 – 4mm and Grade C - > 4mm. Preoperative and postoperative corneal astigmatism were compared between the three groups using autorefraction and keratometer readings. Postoperative astigmatism was recorded on three visits – day 7, day 28 and third month. Statistical analysis: Statistical Package for Social Sciences (SPSS) version 19.0 for windows was used. Spearman's rank order (χ) was calculated to observe correlation of pterygium length with the preoperative and postoperative corneal astigmatism. A p-value < 0.05 was considered statistically significant. Results: The mean length of the pterygium was 2.77 ± 0.12mm. Majority had with – the – rule astigmatism (64%). Postoperatively mean uncorrected visual acuity (UCVA) increased significantly from 0.533 ± 0.03 to 0.78 ± 0.03 (P < 0.0001). Preoperative mean keratometric astigmatism of 2.55 ± 0.36D significantly decreased to 1.213 ± 0.20D postoperatively (r = 0.89, P < 0.0001). A positive correlation between the length of pterygium and both preoperative (χ = 0.68, P < 0.001) and postoperative (χ = 0.53, P < 0.001) corneal astigmatism was observed. Conclusion: The increase in the length of pterygium significantly correlated with the degree of preoperative corneal astigmatism. The evidence of significant improvement in visual acuity and decrease in pterygium induced corneal astigmatism was observed three months postoperatively by conjunctival autograft technique with autologous blood. Hence, pterygium induced corneal astigmatism of length > 2mm is an early indication for surgical intervention.

Background: To compare the keratometric data of unilateral cataractous paediatric eyes with their corresponding non-cataractous fellow eyes. Methods: In this clinic-based observational study eyes of 354 consecutive children who presented with unilateral or bilateral cataract were analysed. Other data collected included age at the time of surgery, gender, keratometry, axial length (AL) and laterality of cataract. Keratometric values were obtained under general anaesthesia using a handheld Nidek Auto Keratometer. AL was measured with an ultrasound A-scan using either the immersion or the contact technique (Ocuscan, Alcon). Results: The average K value in the cataractous eyes was 44.97 ± 2.53 D (range: 37.38–55.13 D). The K values in different age groups were significantly different (P < 0.001). Irrespective of age, there was a significant difference between the K values of unilateral (n = 34 eyes: K = 44.16 ± 2.02) and bilateral cataracts (n = 320 eyes: K = 45.07 ± 2.56) (P < 0.05). In the age groups of 6–18 and 18–60 months, there was significant difference in K values of males and females (P < 0.02, P < 0.008). There was no significant difference in K values of unilateral cataractous eyes and their fellow eyes (P = 0.096). Age and AL demonstrated a significant linear relationship with K values: K =46.29− (0.6 1 log of age in months) (R2 = 0.09, P < 0.001) and K = 53.78− (0.451 AL) (R2 = 0.17, P < 0.001). Conclusions: The keratometric values of young children were steeper than those of older children. There was no significant difference in K values of the unilateral cataractous eyes as compared to the fellow eyes.

OBJECTIVE: This study aims to compare the long-term outcomes of standard corneal collagen crosslinking with accelerated corneal collagen crosslinking (CXL) for progressive keratoconus. PATIENTS AND METHODS: This prospective, comparative study included 79 eyes with progressive keratoconus, which were randomly assigned: 42 eyes received a standard CXL procedure, and 37 eyes were treated with the accelerated CXL protocol. We evaluated the following parameters, before the procedure and 1 month, 6 months, 12 months and 24 months postoperatively: best corrected visual acuity (BCVA), manifest refraction spherical equivalent (MRSE), cylindrical values, corneal dioptric powers on the steepest meridian (Kmax), central corneal thickness (CCT); demarcation line depth (DLD) preoperatively and 1 month after the CXL procedure. RESULTS: The BCVA, MRSE, cylindrical values, Kmax, CCT improved significantly, after both the accelerated and the standard CXL procedure. Throughout the 24-months follow-up, BCVA improvement was achieved sooner in the accelerated group (after 1 month, vs. after 3 months). However, there were no statistically significant differences between the two groups in these aspects. The DLD-to-CCT was significantly greater in the standard group (66% vs. 62%, p = 0.02). CONCLUSIONS: Standard and accelerated CXL are effective in stabilizing keratoconus progression in the long term. In clinical practice, the accelerated protocol has the added benefit of a faster visual recovery, in addition to the known reduced treatment time and increased comfort. [ABSTRACT FROM AUTHOR]

Copyright of Der Ophthalmologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: This study aimed to evaluate the clinical outcomes and assess preoperative characteristics that may predict outcomes in keratoconus 1 year after accelerated transepithelial corneal cross-linking (ATE-CXL).Methods: This prospective study included 93 eyes of 84 consecutive keratoconus patients with 1-year follow-up after ATE-CXL. Preoperative characteristics included corneal astigmatism, anterior chamber depth, anterior chamber volume, radius of curvature, posterior elevation, central corneal thickness (CCT), thinnest corneal thickness, steepest meridian keratometry, flattest meridian keratometry, and the maximum keratometry (Kmax). Data were obtained preoperatively and at 1, 3, 6, and 12 months postoperatively. The patient eyes were grouped into 3 subgroups according to CCT and Kmax values to observe the changes of keratoconus progression.Results: All patients were successfully operated without complications at any follow-up time point. Mean changes of Kmax from baseline at 6 and 12 months were - 0.60 ± 2.21 D (P = 0.011) and - 0.36 ± 1.58 D (P = 0.030), respectively. Eyes with a thinner CCT and higher Kmax values exhibited a tendency for topographic flattening of ≥1.0 D (P = 0.003; P = 0.003). In the subgroup comparison, the Kmax values decreased significantly at 6 and 12 months after ATE-CXL in the group with CCT ≤ 450 μm (P = 0.018 and P = 0.045); the Kmax values of the group with Kmax > 65.0 D decreased significantly at 6 months postoperatively (P = 0.025).Conclusion: ATE-CXL is a safe and effective treatment for keratoconus patients. Patients with thinner CCT and higher Kmax values are more likely to benefit from ATE-CXL. [ABSTRACT FROM AUTHOR]

Background. The prevalence of corneal astigmatism in patients with cataract has not been well documented in both rural and urban areas of Indian population. Purpose. The aim of this study was to assess prevalence of corneal astigmatism before cataract surgery in adult age group population of rural Andhra Pradesh. Materials and methods. A Prospective, cross-sectional, and observational study was carried out from March 2019 to December 2019 in patients presenting for cataract surgery. Axial length, and intraocular lens power were measured, Keratometric values were measured with an auto refractokeratometer, and astigmatism was calculated. Data was analysed using SPSS software. Results. This study included 1000 eyes of 1000 patients with a mean age of 61.81 ± 8.94 years. The mean astigmatism was 0.80 ± 0.72 D and the mean keratometry was 44.12D ± 1.71 D. A total of less than 1D astigmatism is seen in 67.5% eyes, 23.3% eyes had astigmatism between 1.00 and 1.99 D, 4.6% eyes had 2-2.99D, and ≥3D in 0.8% eyes and no astigmatism in 3.8% eyes. Against the rule astigmatism was seen in 49.8% cases, with the rule astigmatism is found in 31.8% of eyes and oblique astigmatism in 14.9% of eyes. With the increasing age, the WTR percentage decreased while the ATR percentage increased. Conclusion. Our study showed that significant numbers of patients have preoperative corneal astigmatism, affecting the quality of vision after cataract surgery. Majority of patients have corneal astigmatism < 1.00D, which can be corrected by low-cost procedures like steep axis phaco, limbal relaxing incisions, and opposite clear corneal incisions, especially in developing countries like India, and less percentage of candidates require expensive toric IOLs. [ABSTRACT FROM AUTHOR]

To compare the inter-device agreement of anterior chamber depth (ACD), central corneal thickness (CCT), flat keratometry (K1), steep keratometry (K2), corneal astigmatism (ΔK), and white-to-white (WTW) measurements. This is a retrospective study with 73 myopic patients (142 eyes). We extracted and compared anterior segment measurements (ACD, CCT, K1, K2, ΔK, and WTW) of four devices (OPD-Scan III, Pentacam HR, Lenstar LS 900, and Galilei G4), and performed pairwise agreement comparisons between them. Agreement analyses revealed that the most agreement occurred: in Pentacam HR and Galilei G4 for ACD measurements, in Pentacam HR and Lenstar LS 900 for CCT measurements, in OPD-Scan III and Galilei G4 for WTW measurements, in OPD-Scan III and Pentacam HR for K1 and K2 measurements, and OPD-Scan III and Galilei G4 for ΔK measurements. OPD-Scan III is interchangeable with both Galilei G4 and Lenstar LS 900 for WTW measurements. OPD-Scan III and the Pentacam-HR are interchangeable in K1, K2, and ΔK measurements. OPD-Scan III and Lenstar LS 900, and OPD-Scan III and Galilei G4 are interchangeable in K1 and ΔK measurements, respectively. [ABSTRACT FROM AUTHOR]

To compare anterior chamber depth (ACD), keratometry (K1, K2), central corneal thickness (CCT), and axial length (AL) measured by four different devices. 150 eyes qualified for cataract surgery were included in the study. Four devices: IOL Master 500, OCT CASIA2, Dual Scheimpflug Analyzer Galilei G6, and Quantel Compact Touch ultrasound biometer, were compared. The agreement of measurements between the devices was evaluated by the Bland-Altman method. ACD was significantly different for Ultrasound and IOL Master 3 ± 0.33 3.12 ± 0.42 respectively Interclass correlation ecoefficiency (ICC):0.69 (95% confidence interval (CI): 0.62; 0.76) p < 0.001. A significant difference was observed between Casia and IOL while measuring K1, 43.5 ± 1.7 vs. 43.61 ± 1.56 ICC:0.84 (95%CI: 0.79; 0.87) and ACD parameters 2.65 ± 0.45 vs. 3.12 ± 0.42 ICC 0.68 (95%: 0.6; 0.75) and K2 42.51 ± 1.62 vs. 44.57 ± 1.59 ICC; 0.83 (95%CI:0.78; 0.87) p < 0.001. Similarly, measurements obtained by Casia, and Galilei were also different K1 43.5 ± 1.7 ICC:0.7 (95%CI:0.62; 0.76), CCT 546.35 ± 34.75 vs. 566.73 ± 37.92 ICC:0.88 (95%CI:0.84; 0.9) p < 0.001. Differences between Galilei and IOL master were not significant p values from 0.175 to 0.999 ICC 0.8 (95%CI:0.75; 0.85) to ICC 0.94 (95%CI:0.92; 0.95). The measurements obtained from Casia, and Ultrasound were significantly different and not interchangeable except for IOL master and Galilei. [ABSTRACT FROM AUTHOR]

Purpose: to assess effect of eye drops instillation on the refractive power of the cornea and potential intraocular lens (IOL) power calculation errors appearing related within.Patients and methods. There were 478 patients divided in 3 groups: 1st — patients without glaucoma and topical treatment (n = 325); 2nd — individuals with primary open angle glaucoma (POAG) on treatment (n = 122); 3rd — patients with POAG and previous trabeculectomy (TE) without using eye drops (n = 31). For each patient keratometry was performed by IOL-Master 500. Mean preoperative keratometry and corneal astigmatism were compared within IOL calculation error received by Barrett Universal II formula 1 month after phacoemulsification (PE).Results. Mean keratometry was significantly (p < 0.001) less (0.6 D) at the 1st group (44.00 ± 1.96 D) versus 2nd group (44.6 ± 1.76 D). Cancellation of topical eye drops due to TE leads to insignificant decline of corneal curvature (from 44.6 ± 1.76 D to 44.1 ± 1.59 D). There was no any difference in corneal astigmatism level between study groups (0.92 ± 2.23 D, 0.8 ± 0.59 D and 0.86 ± 0.50 D for groups respectively) as like as no distinction in IOL calculation error in these groups (–0.08 ± 0.57 D, –0.06 ± 0.6 D and 0.003 ± 0.61 D). However, men have more flatter cornea (43.6 ± 1.98 D) than women (44.4 ± 1.80 D) (p < 0.001). Mean keratometry at the age group 60–74 years was less (43.7 ± 2.3 D) than at 75–90 years (44.4 ± 1.54) (p = 0.002).Conclusion. Patients with coexistent cataract and glaucoma on treatment require special attention in IOL calculation. To avoid keratometric errors it is recommended to prescribe lubricants and change hypotensive eye drops to preservative-free analogs to form a stable tear film.