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Purpose: To compare the biometric measurements obtained from the Pentacam AXL Wave, IOLMaster 700, and ANTERION and calculate the recommended intraocular lens power using the Barrett Formulae. Methods: This was a retrospective cross-sectional study of patients who underwent biometry using the Pentacam AXL Wave, IOLMaster 700, and ANTERION. Flat keratometry (K1), steep keratometry (K2), anterior chamber depth (ACD), and axial length (AL) from each device were measured and compared. These parameters were used to calculate the recommended IOL powers using the Barrett formula. Results: The study included 252 eyes of 153 patients. The IOLMaster had the highest acquisition rate among the two biometers. The Pentacam obtained the shortest mean AL, the IOLMaster measured the highest mean keratometry values, and the ANTERION measured the highest mean ACD. In terms of pairwise comparisons, keratometry and axial length were not significantly different between the Pentacam-IOLMaster and ANTERION-IOLMaster groups, while the rest of the pairwise comparisons were statistically significant. In nontoric and toric eyes, 35–45% of patients recommended the same sphere of IOL power. In another 30–40%, the Pentacam and ANTERION recommended an IOL power one step greater than that of the IOLMaster-derived data. 50% of the study population recommended the same toric-cylinder IOL power. Conclusions: The Pentacam AXL Wave, IOLMaster 700, and ANTERION can reliably provide data for IOL power calculations; however, these data are not interchangeable. In nontoric and toric eyes, 35–45% of cases recommended the same sphere IOL power, and in another 30–40%, the Pentacam and ANTERION recommended one-step higher IOL power than the IOLMaster-derived data. In targeting emmetropia, selecting the first plus IOL power is advisable when using the Pentacam and ANTERION to approximate the IOL power calculations recommended by the IOLMaster 700. [ABSTRACT FROM AUTHOR]

Purpose. To analyze changes of the corneal topography in the long-term period after hyperopic FS-LASIK in patients with low, moderate and high hyperopia.Patients and Methods. This retrospective non-randomized study included data of 174 patients (174 eyes). All patients were performed hyperopic FS-LASIK. All patients were divided into three groups. Group I included patients with low hyperopia (34 eyes), group II included patients with moderate hyperopia (97 eyes), group III included patients with high hyperopia (43 eyes). Before the surgery, the mean cycloplegic spherical equivalent in group I was +1.94 ± 0.61 D, in group II +3.8 ± 2.19 D, in group III +5.7 ± 0.9 D. The stability of corneal topography after surgery was analyzed: mean keratometry, Surface Asymmetry Index (SAI), Surface Regularity Index (SRI). The results were evaluated the day after the surgery, 1 month later, 6 months later, 1 year later and 3 years after the surgery.Results. There were no statistically significant changes in keratometry in groups I and II on the first day after surgery and 3 years later (p > 0.05). In group III, there was a statistically significant decrease in keratometry at 6 months after surgery by 1.35 ± 2.48. D (p = 0.003); however, keratometry remained stable for 3 years thereafter (p > 0.05). In groups I and II, SRI increased at all periods after surgery (p < 0.05), in group II there was an increase in SAI (p < 0.05), in group III, SRI and SAI increased at all periods after surgery (p < 0.05). Although the increase in the indices was statistically significant, it slightly exceeded the normal limits.Conclusions. After correction of low and moderate hyperopia by FS-LASIK, corneal topography remains stable for 3 years after surgery. Correction of high hyperopia is associated with gradual flattening of the cornea within six months after surgery, but then keratometry remains stable for 3 years. It is important to take it into account in clinical practice.

Abstract Purpose To compare the biometric measurements obtained from the Pentacam AXL Wave, IOLMaster 700, and ANTERION and calculate the recommended intraocular lens power using the Barrett Formulae. Methods This was a retrospective cross-sectional study of patients who underwent biometry using the Pentacam AXL Wave, IOLMaster 700, and ANTERION. Flat keratometry (K1), steep keratometry (K2), anterior chamber depth (ACD), and axial length (AL) from each device were measured and compared. These parameters were used to calculate the recommended IOL powers using the Barrett formula. Results The study included 252 eyes of 153 patients. The IOLMaster had the highest acquisition rate among the two biometers. The Pentacam obtained the shortest mean AL, the IOLMaster measured the highest mean keratometry values, and the ANTERION measured the highest mean ACD. In terms of pairwise comparisons, keratometry and axial length were not significantly different between the Pentacam-IOLMaster and ANTERION-IOLMaster groups, while the rest of the pairwise comparisons were statistically significant. In nontoric and toric eyes, 35–45% of patients recommended the same sphere of IOL power. In another 30–40%, the Pentacam and ANTERION recommended an IOL power one step greater than that of the IOLMaster-derived data. 50% of the study population recommended the same toric-cylinder IOL power. Conclusions The Pentacam AXL Wave, IOLMaster 700, and ANTERION can reliably provide data for IOL power calculations; however, these data are not interchangeable. In nontoric and toric eyes, 35–45% of cases recommended the same sphere IOL power, and in another 30–40%, the Pentacam and ANTERION recommended one-step higher IOL power than the IOLMaster-derived data. In targeting emmetropia, selecting the first plus IOL power is advisable when using the Pentacam and ANTERION to approximate the IOL power calculations recommended by the IOLMaster 700.

Background: Keratoconus (KCN) is considered a bilateral corneal ectatic disorder characterized by cone-like steepening of the cornea and irregular stromal thinning, which can lead to decreased visual acuity. This study aimed to assess the prevalence and risk factors for the KCN development in Kosovo. Methods and Results: This retrospective study was conducted in the Department of Ophthalmology at the University Clinical Center of Kosovo. The study included 131 respondents, with a total of 262 eyes. Keratometry basis parameters, such as flat keratometry (K1), and steep keratometry (K2), and maximal corneal curvature (Kmax) were determined. Corneal pachymetry was applied to measure the thickness of the cornea. Staging of KCN was done according to the adapted Amsler-Krumeich staging classification system (AK) for anterior data and corneal thickness (CT). Of 262 examined eyes, 240 (91.6%) were KCN eyes, 2(0.8%) were suspect for KCN, and 20(7.6%) were normal. KCN Stage 1 on the AK classification was predominant (P

AIM: To evaluate the reliability of measurements of corneal changes with accommodation in healthy eyes using a Scheimpflug imaging-based system and how these measurements distribute in the normal population.METHODS: Prospective, non-randomized, comparative study including 27 healthy subjects(54 eyes), including emmetropia(13 eyes), myopia(17 eyes), hyperopia(4 eyes)and astigmatism(20 eyes)groups. In all cases, a complete eye examination was performed, including the analysis of corneal changes with different accommodative stimuli(+2.00, 0.00 and -3.00 D)using the Pentacam AXL system. The investigation was structured in 2 phases: repeatability analysis and characterization of accommodation-related corneal changes in healthy populations.RESULTS: In the repeatability analysis, the index of height asymmetry(IHA)showed the greatest variability with the three accommodative stimuli, being the results for the rest of parameters acceptable. The group of emmetropes showed significant differences with accommodative changes in the position of maximum keratometry(Kmax; P

AIM: To analyze ocular biometric parameters among candidates for cataract surgery.METHODS: This cross-sectional study was conducted on 4 607 cataract patients(4 607 eyes)in Farabi Eye Hospital, Tehran, Iran from January 2017 to September 2021. Axial length(AL), keratometry(Kf, Ks and Km), and anterior chamber depth(ACD)were assessed using IOLMaster 700. All eyes were categorized into three groups based on AL: short eyes(22 mm25 mm)and ACD as follows: low(3.00 mm3.60 mm).RESULTS: The mean age of patients was 60.3±14.1(range 8-95)years [2 243(48.69%)female and 2 364(51.31%)male]. The AL, ACD and mean keratometry ranges were 23.1 to 23.4 mm, 3.1 to 3.2 mm and 44.50 to 45.00 diopter(D), respectively. The mean amount of ACD in the long eyes group was significantly higher than the normal and short eyes group(P

Purpose: This retrospective study investigated the impact of corneal parameters on surgically induced astigmatism (SIA) in eyes with prior myopic correction undergoing cataract surgery. Setting: Department of Ophthalmology, San Marino Hospital, San Marino, Republic of San Marino. Design: This case–control study analyzed existing data retrospectively, without randomization or masking. Methods: Eighty eyes divided in group 1 (40 eyes previous underwent refractive surgery for myopia) and group 2 (40 myopic eyes) that underwent cataract surgery with intraocular lens (IOL) implantation were included. SIA was calculated using values from the IOL Master Zeiss 700 and mean pupil power (MPP) derived from the CSO Sirius Topographer (based on 3 mm pupil size) with vectorial analysis from doctor Hill software. Results: No significant difference in SIA was observed between eyes with prior myopic photorefractive keratectomy and the control group (p > 0.05). SIA calculations using the IOL Master and CSO Sirius Tomographer yielded similar results. There was no significant correlation between SIA and axial length, corneal curvature, peripheral corneal thickness, or anterior chamber depth (p > 0.05). However, an inverse correlation was found between SIA and horizontal corneal diameter (p < 0.05). Conclusions: Corneal parameters, such as axial length, corneal curvature, peripheral corneal thickness, and anterior chamber depth, showed no significant influence on SIA. The inverse correlation between SIA and horizontal corneal diameter in study group suggests potential influence of white-to-white distance on SIA. These findings highlight the importance of considering corneal parameters for optimizing surgical outcomes. [ABSTRACT FROM AUTHOR]

Background: To compare results from different corneal astigmatism measurement instruments; to reconstruct corneal astigmatism from the postimplantation spectacle refraction and toric intraocular lens (IOL) power; and to derive models for mapping measured corneal astigmatism to reconstructed corneal astigmatism. Methods: Retrospective single centre study involving 150 eyes treated with a toric IOL (Alcon SN6AT, DFT or TFNT). Measurements included IOLMaster 700 keratometry (IOLMK) and total keratometry (IOLMTK), Pentacam keratometry (PK) and total corneal refractive power in 3 and 4 mm zones (PTCRP3 and PTCRP4), and Aladdin keratometry (AK). Regression‐based models mapping the measured C0 and C45 components (Alpin's method) to reconstructed corneal astigmatism were derived. Results: Mean C0 components were 0.50/0.59/0.51 dioptres (D) for IOLMK/PK/AK; 0.2/0.26/0.31 D for IOLMTK/PTCRP3/PTCRP4; and 0.26 D for reconstructed corneal astigmatism. All corresponding C45 components ranged around 0. The prediction models had main diagonal elements lower than 1 with some crosstalk between C0 and C45 (nonzero off‐diagonal elements). Root‐mean‐squared residuals were 0.44/0.45/0.48/0.51/0.50/0.47 D for IOLMK/IOLMTK/PK/PTCRP3/PTCRP4/AK. Conclusions: Results from the different modalities are not consistent. On average IOLMTK/PTCRP3/PTCRP4 match reconstructed corneal astigmatism, whereas IOLMK/PK/AK show systematic C0 offsets of around 0.25 D. IOLMTK/PTCRP3/PTCRP4. Prediction models can reduce but not fully eliminate residual astigmatism after toric IOL implantation. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to estimate the corneal keratometric index in the eyes of cataract surgery patients who received zero-power intraocular lenses (IOLs). Methodology: This retrospective study analyzed postoperative equivalent spherical refraction and axial length, mean anterior curvature radius and aqueous humor refractive index to calculate the theoretical corneal keratometric index value (nk). Data was collected from 2 centers located in France and Germany. Results: Thirty-six eyes were analyzed. The results revealed a mean corneal keratometric index of 1.329 ± 0.005 for traditional axial length (AL) and 1.331 ± 0.005 for Cooke modified axial length (CMAL). Results ranged from minimum values of 1.318/1.320 to maximum values of 1.340/1.340. Conclusion: The corneal keratometric index is a crucial parameter for ophthalmic procedures and calculations, particularly for IOL power calculation. Notably, the estimated corneal keratometric index value of 1.329/1.331 in this study is lower than the commonly used 1.3375 index. These findings align with recent research demonstrating that the theoretical corneal keratometric index should be approximately 1.329 using traditional AL and 1.331 using CMAL, based on the ratio between the mean anterior and posterior corneal curvature radii (1.22). [ABSTRACT FROM AUTHOR]

Purpose: To determine change in biometric values of eye after fasting and to elucidate whether this change is significant enough to delay the refractive and cataract surgeries during fasting. Study Design: Cross sectional observational. Place and Duration of Study: Eye department, DHQ-UTH, Gujranwala, from April 2021 to May 2021. Methods: Thirty subjects of either gender between 20-40 years of age who participated in both phases were enrolled in this study. Phase 1 was conducted one week before Ramadan and 2nd phase in the last week of Ramadan. After routine ophthalmic examination, keratometric(K) values were obtained with Auto Ref-Keratometer (Canon), while Axial length (AL), Anterior chamber depth (ACD), and Intraocular lens power (IOLp)were obtained from Master-Vu A-scan (Sonomed, Model # MV4500). Data was analyzed using SPSS version 25. Results: Out of 30 participants, 66.6% were female and 33.3%were male with mean age of 29.8 years. Mean K1 increased to 43.03 D during fasting from non-fasting reading of 42.24 D, while Mean K2 increased to 43.87 D during fasting from non-fasting reading of 43.28 D with significant p-value (<0.05). Mean ACD was 3.15mm in non-fasting that also increased to 3.21D in fasting state. Mean AL in non-fasting state was 23.41mm that remains the same in fasting state as well. Mean IOLp in non-fasting state was 21.18D that reduced to 20.42D in fasting state with significant p-value. Conclusion: Fasting increased the keratometry and ACD values with no effect on AL but that reduced overall intraocular lens power [ABSTRACT FROM AUTHOR]

Determining the axial length (AL) of the eye is of significant interest in the management of myopia. However, the devices that allow this value to be obtained are either expensive, for example, optical biometers, or inconvenient for use in pediatric population, such is the case with ultrasound biometers. Therefore, this study aimed to develop a mathematical model for estimating the AL value based on easily obtainable variables, with the novel addition of body height to the analysis. A total of 170 eyes of 85 myopic volunteers (mean age of 10.8 ± 1.45 years, ranging from 7 to 14 years) were included in the analysis. Participants underwent anamnesis, keratometry by NVISION-K 5001, subjective refraction by an optometrist, AL measurement by the Topcon MYAH biometer, and body height measurement. Spearman's correlation test was employed to analyze the relationships between AL and keratometry, spherical equivalent, body height (Sperman's correlation, all r ≥ 0.267, all p < 0.001), and age (Spearman's correlation, p = 0.081). Subsequently, multiple regression analysis was conducted on the variables that demonstrated a previous correlation. The mathematical model obtained permits the estimation of AL based on average keratometry, spherical equivalent, and body height. This model is significant (p < 0.001) and explains 82.4% of AL variability. [ABSTRACT FROM AUTHOR]

Cataract surgery is one of the most successful surgical procedures, mainly due to the recent developments in surgical instruments and intraocular lens (IOL) measurements. Understanding the nature of axial length (AL) and keratometry readings (K) in patients with cataracts has significant implications for accurate postoperative IOL size selection. This study aimed to measure AL and K in patients undergoing cataract surgery in Saudi Arabia. This retrospective study included patients who underwent cataract surgery in Madinah, Saudi Arabia. The medical records of adult patients between May 2022 and May 2023 were reviewed, and those with a history of retinal detachment, refractive surgery, or trauma were excluded. The AL and K readings were obtained from the patient’s IOL master results. A total of 691 eyes from 451 patients were included in the analysis. The mean age was 64.54 years old. Most of the patients were women (55%). The mean AL, K1, and K2 values were 23.27, 43.42, and 44.69, respectively. Linear regression analysis was used to measure the relationship between AL and K, revealing an inverse relationship in our findings. As AL increased by one unit, the mean K was estimated to decrease by 0.548, with a 95% confidence interval. Our results demonstrated an inverse relationship between AL and K, implying that when AL increases, K decreases, or the corneal curvature becomes flat. Further studies are needed to investigate the biomechanical mechanisms underlying this relationship. [ABSTRACT FROM AUTHOR]

Cataracts are characterized by the crystalline lens of the eye becoming cloudy, and dry eye disease (DED) is a multifactorial disease in which the homeostasis of the tear film is lost. As the prevalence of both diseases increases with age, there is a high prevalence of DED among patients who are candidates for cataract surgery. In recent years, cataract surgery has evolved from vision restoration surgery to refractive surgery. To achieve good surgical outcomes, it is necessary to minimize postoperative refractive error in intraocular lens (IOL) power calculation, which requires accurate preoperative keratometry measurements. A stable tear film is important for the accuracy and reproducibility of keratometry measurements, and DED may have a deleterious effect. In this study, original articles that focused primarily on findings related to this topic were evaluated. A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Although appropriate DED diagnoses were not presented in the articles evaluated in this review, it was confirmed that the clinical signs of DED, particularly the shortening of the tear film break-up time (TBUT), negatively impact IOL power calculations. Improvement in these clinical signs might mitigate the negative effects on these calculations. [ABSTRACT FROM AUTHOR]

AIM:To compare the differences of ocular biometric parameters of age-related cataract between Tibetan and Han ethnic groups, and to analyze the distribution characteristics of ocular biometric parameters in Tibetan cataract patients.METHODS:Retrospective cohort study. A total of 661 patients(1 030 eyes)with age-related cataract confirmed in the hospital between January 2019 and December 2020 were enrolled. The parameters of axial length, anterior chamber depth, keratometry, corneal astigmatism and astigmatic axis were measured by IOL Master 500 in 483 cases(739 eyes)of Tibetan age-related cataract patients and 178 cases(291 eyes)of Han patients.RESULTS:The axial length, anterior chamber depth and corneal astigmatism of the Tibetan patients with age-related cataract were 23.33(22.81, 23.86)mm, 3.04(2.79, 3.30)mm and 0.73(0.47, 1.07)D. The mean keratometry was 43.89±1.35 D. The results indicated that Tibetan cataract patients had shorter axial lengths and smaller keratometry compared to Han patients(all P

Abstract Background The precision of anterior segment biometric measurements in eyes has become increasingly important in refractive surgery. The purpose of this study is to assess the repeatability of the automatic measurements provided by a new spectral-domain optical coherence tomograph (SD-OCT)/Placido topographer (MS-39, CSO) and its agreement with a swept-source OCT (SS-OCT) biometer (CASIA SS-1000, Tomey) in patients with myopia. Methods The right eye of 235 subjects was scanned 3 times with both devices. The evaluated parameters included central corneal radius of the steep meridian, central corneal radius of the flat meridian, mean central corneal radius, thinnest corneal thickness, central corneal thickness, anterior chamber depth, corneal volume and diameter. The intraobserver repeatability of the MS-39 measurements was calculated using intraclass correlation coefficient (ICC), within subject standard deviation, coefficient of repeatability, coefficient of variation and repeated-measures analysis of variance of the 3 repeated measurements. The agreement between the two devices was evaluated by 95% limits of agreement (LoA). Results The majority of the parameters acquired from MS-39 showed high repeatability. The repeatability of corneal diameter was slightly lower than the other measurements, although the ICC remained high. Agreement with the CASIA SS-1000 was good, indicated by the Bland-Altman plots with narrow 95% LoA values for all parameters assessed. Conclusions The high repeatability of automatic measurements by the new device supports its clinical application in eyes with myopia, and the good agreement between the two devices indicates they could be used interchangeably for the parameters evaluated.

Abstract Aim To investigate the correlation of angles α and κ with the refractive and biological parameters in children. Methods This case-series study included 438 eyes of 219 children (males/females = 105/114, age: 3–15 years). Ocular biometric parameters, including axial length, corneal radius of curvature (CR), white-to-white distance (WTW), angle κ and angle α, were measured using IOL Master 700; auto-refraction were assessed under cycloplegia. The eyes were assigned to different groups based on CR, WTW, and gender to compare the angles α and κ, and analyze the correlations between the differences of biological parameters on angles α and κ. Results The means of axial length, CR, WTW, angle α, and angle κ were 23.24 ± 1.14 mm, 7.79 ± 0.27 mm, 11.68 ± 0.41 mm, 0.45 ± 0.25 mm, and 0.27 ± 0.22 mm, respectively. Angle α was correlated with CR and WTW (fixed effect coefficient [FEC] = 0.237, p = 0.015; FEC = -0.109, p = 0.003; respectively), and angle κ also correlated with CR and WTW (FEC = 0.271, p = 0.003; FEC = -0.147, p

Background: This study aimed to compare keratometry and anterior chamber depth (ACD) changes after XEN implantation in primary open-angle glaucoma (POAG) cases over a 3-month follow-up period. Methods: Twenty patients with POAG who underwent XEN63 implantation, either standalone or combined with cataract surgery, were included. Preoperative data, including best-corrected visual acuity (BCVA), refraction, gonioscopy, ophthalmoscopy, intraocular pressure (IOP) evaluation, and axial length, were collected. Corneal topography and ACD measurements were assessed preoperatively and at postoperative days 1, 7, 15, 30, 60, and 90. Each patient's eye that underwent XEN surgery was included in the study group, with the fellow eye serving as a control. Results: In the study group, there was a significant decrease in IOP after XEN stent implantation at all investigated time intervals (p < 0.05). However, changes in mean ACD did not show statistically significant differences at any follow-up examination in both the study and control groups. Additionally, keratometry readings revealed no significant changes in total astigmatism or steep keratometry values in either group. Conclusions: XEN implantation in POAG cases resulted in a significant decrease in IOP over the 3-month follow-up period. However, there were no significant changes observed in mean ACD or keratometry readings, indicating stability in these parameters post-XEN implantation. These findings suggest that XEN implantation may be an effective option for IOP reduction without affecting corneal curvature or ACD in POAG patients. [ABSTRACT FROM AUTHOR]

To evaluate prediction accuracy of pre- and post-DMEK keratometry (K) and total keratometry (TK) values for IOL power calculations in Fuchs endothelial corneal dystrophy (FECD) eyes undergoing DMEK with cataract surgery (triple DMEK). Retrospective cross-sectional multicenter study of 55 FECD eyes (44 patients) that underwent triple DMEK between 2019 and 2022 between two centers in USA and Europe. Swept-source optical coherence tomography biometry (IOLMaster 700) was used for pre- and post-DMEK measurements. K and TK values were used for power calculations with ten formulae (Barrett Universal II (BUII), Castrop, Cooke K6, EVO 2.0, Haigis, Hoffer Q, Hoffer QST, Holladay I, Kane, and SRK/T). Mean error, mean absolute error (MAE), standard deviation, and percentage of eyes within ±0.50/±1.00 diopters (D) were calculated. Studied formulae were additionally adjusted using a method published previously (IOLup1D Method), which increases the IOL power by 1D. While both eyes from the same patient were considered for descriptive statistics, we restricted to one eye per individual (44 eyes for statistical comparisons. MAEs for all formulae were lower for post-DMEK K and TK than pre-DMEK K and TK by an average of 0.24 and 0.47 D, respectively. The lowest MAE was 0.49 D for Kane using post-DMEK TK, and the highest MAE was 1.05 D for BUII using pre-DMEK TK. Most IOLup1D formulae had lower MAEs than pre-DMEK K and TK formulae. The IOLup1D Method should be used instead of pre-DMEK K and TK values for triple DMEK in FECD eyes. Using post-DMEK TK values for cataract surgery after DMEK provides better refractive accuracy than any of the three studied methods used for triple DMEK procedures. [ABSTRACT FROM AUTHOR]

Background: The precision of anterior segment biometric measurements in eyes has become increasingly important in refractive surgery. The purpose of this study is to assess the repeatability of the automatic measurements provided by a new spectral-domain optical coherence tomograph (SD-OCT)/Placido topographer (MS-39, CSO) and its agreement with a swept-source OCT (SS-OCT) biometer (CASIA SS-1000, Tomey) in patients with myopia. Methods: The right eye of 235 subjects was scanned 3 times with both devices. The evaluated parameters included central corneal radius of the steep meridian, central corneal radius of the flat meridian, mean central corneal radius, thinnest corneal thickness, central corneal thickness, anterior chamber depth, corneal volume and diameter. The intraobserver repeatability of the MS-39 measurements was calculated using intraclass correlation coefficient (ICC), within subject standard deviation, coefficient of repeatability, coefficient of variation and repeated-measures analysis of variance of the 3 repeated measurements. The agreement between the two devices was evaluated by 95% limits of agreement (LoA). Results: The majority of the parameters acquired from MS-39 showed high repeatability. The repeatability of corneal diameter was slightly lower than the other measurements, although the ICC remained high. Agreement with the CASIA SS-1000 was good, indicated by the Bland-Altman plots with narrow 95% LoA values for all parameters assessed. Conclusions: The high repeatability of automatic measurements by the new device supports its clinical application in eyes with myopia, and the good agreement between the two devices indicates they could be used interchangeably for the parameters evaluated. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to evaluate the impact of clear corneal incisions on astigmatism in patients undergoing cataract surgery. The values of corneal astigmatism before and after surgery were compared, and the difference was analyzed. Methods: A total of 50 patients (50 eyes) with regular astigmatism who underwent phacoemulsification due to cataracts were included in this study. The patient's pre-operative corneal astigmatism, keratometry values, and steep axis were calculated. The operation was performed by the same surgeon, and the phacoemulsification clear corneal incision was keratometrically placed on the steep axis. The results of the pre- and post-operative examinations of patients who underwent cataract surgery were retrospectively analyzed at the 1st month of astigmatism. The values of corneal astigmatism before and after surgery were compared, and the difference was examined. Results: The mean age of the patients was 67.9±6.7 years. Of them, 26 (52%) were women and 24 were men (48%). After surgery, the patient's best-corrected visual acuity was 20/20. Furthermore, their mean keratometric steep axis was 108.6°±34.9°. It was observed that the patients' pre- and post-operative corneal astigmatism were 1.24±0.7 diopter (D) and 0.83±0.58 D, respectively. When the values were compared, a difference of 0.41±0.25 D was observed, which was statistically significant (p<0.001). The mean pre-operative flat keratometry was 42.98±0.78 D, and the mean pre-operative steep keratometry was 44.24±0.78 D. On the other hand, the mean post-operative flat keratometry was 42.99±0.79 D, and the mean post-operative steep keratometry was 43.84±0.74 D. Conclusion: Clear corneal incision during cataract surgery flattens the cornea in the meridian of the incision, which potentially lessens pre-existing astigmatism. This method can reduce glass dependence among patients in secondary hospitals with no available toric intraocular lenses. [ABSTRACT FROM AUTHOR]

Aim: To investigate the correlation of angles α and κ with the refractive and biological parameters in children. Methods: This case-series study included 438 eyes of 219 children (males/females = 105/114, age: 3–15 years). Ocular biometric parameters, including axial length, corneal radius of curvature (CR), white-to-white distance (WTW), angle κ and angle α, were measured using IOL Master 700; auto-refraction were assessed under cycloplegia. The eyes were assigned to different groups based on CR, WTW, and gender to compare the angles α and κ, and analyze the correlations between the differences of biological parameters on angles α and κ. Results: The means of axial length, CR, WTW, angle α, and angle κ were 23.24 ± 1.14 mm, 7.79 ± 0.27 mm, 11.68 ± 0.41 mm, 0.45 ± 0.25 mm, and 0.27 ± 0.22 mm, respectively. Angle α was correlated with CR and WTW (fixed effect coefficient [FEC] = 0.237, p = 0.015; FEC = -0.109, p = 0.003; respectively), and angle κ also correlated with CR and WTW (FEC = 0.271, p = 0.003; FEC = -0.147, p < 0.001, respectively). Comparing subgroups, the large CR and small WTW group had larger angles α (0.49 ± 0.27 vs. 0.41 ± 0.21, p < 0.001; 0.46 ± 0.27 vs. 0.44 ± 0.21, p < 0.05, respectively) and κ (0.29 ± 0.25 vs. 0.24 ± 0.15, p < 0.01; 0.29 ± 0.25 vs. 0.26 ± 0.19, p < 0.05, respectively). The differences in interocular angles α and κ showed correlation with interocular WTW (r = − 0.255, p < 0.001; r = − 0.385, p < 0.001). Eyes with smaller WTW tended to have larger angle κ (0.28 ± 0.27 vs. 0.25 ± 0.15, p < 0.05). Conclusion: The size of angle α/κ may be correlated to CR and WTW, and a larger WTW eye may suggest a smaller angle κ compared with the fellow eye. [ABSTRACT FROM AUTHOR]

Purpose: To assess the feasibility and reliability of biometric measurements taken with the Eyestar 900 device in keratoconus eyes in comparison with those taken with the Pentacam HR and IOLMaster 700. Methods: Seventy-five eyes of 75 patients with keratoconus were included. The central corneal thickness (CCT), thinnest point of corneal thickness (TCT), axial length (AL), flat (K1) and steep (K2) anterior and posterior (Kp1, Kp2) keratometry, maximal keratometry (KMax) and anterior chamber depth (ACD) were compared between the Eyestar 900, Pentacam HR and IOLMaster 700. Reliability parameters such as the coefficient of variation (CoV) and intraclass correlation coefficient (ICC) were calculated. Pearson's r was determined to assess the correlation between devices. Results: A high repeatability (CoV < 1%) and intraclass correlation (ICC > 0.9) was found for all devices, led by AL, TCT, K1 and K2 (CoV 0.01–0.36%; ICC 0.994–1.00). The largest correlation between devices was found for AL (Eyestar vs. IOLMaster, r = 1.0), K1 (Eyestar vs. IOLMaster, r = 0.997) and ACD (Eyestar vs. IOLMaster, r = 0.995; Pentacam vs. IOLMaster, r = 0.987; Eyestar vs. Pentacam, r = 0.983), but there were significant differences in measured values between devices (p < 0.001), whereas the correlation was only slightly lower (r = 0.947 to 0.994) for KMax, CCT, TCT, K2, Kp1 and Kp2. Conclusion: Keratometric and axial length measurements with the Eyestar 900 were feasible and revealed a high repeatability and a good correlation to the other devices in eyes with keratoconus. [ABSTRACT FROM AUTHOR]

Abstract Background Several studies have previously reported the normal values of corneal volume (CV) in various populations, whereas little is known about the CV distribution in healthy young Chinese adults. Our study aimed to investigate the distribution of CV and its relationships with other ocular biometric parameters among healthy young Chinese adults. Methods A total of 1645 eyes from 1645 students at Dali University in Yunnan Province, China, were analyzed. Pentacam was used to measure CV. Central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were evaluated by Corvis-ST. Other biometrical parameters, including axial length (AL), keratometry, and white-to-white (WTW) distance, were measured using IOL Master. Results The mean age of the study population was 19.01 ± 0.92 years, and 68.81% of them were women. The CV was normally distributed in the whole sample, with a mean value of 61.23 ± 3.22 mm3. CV and CCT were significantly smaller in the Yi ethnic group than in the Han ethnic group (p

Background: Various demographic and ocular factors influence central corneal thickness (CCT). Studies on the relationships between these parameters have shown conflicting results. We aim to investigate the correlation of CCT with different types of refractive error, axial length (AL), and corneal curvature. Materials and Methods: An observational study was undertaken in the Department of Ophthalmology, recruiting patients from 18 to 40 years of age with myopia (−0.5 D to −6 D) or hypermetropia (≤ +3 D) or emmetropia (−0.25 D to +0.25 D). All participants underwent comprehensive ophthalmic examination, including refraction, slit lamp examination and fundoscopy, followed by CCT, corneal curvature, and AL measurement. Result: A total of 1224 eyes of 612 patients (260 males and 352 females) were enrolled in the study. Out of them, 31.5% (n = 386) had emmetropia, 28.6% (n = 350) had hypermetropia, and 39.9% (n = 488) had myopia. The mean (±standard deviation [SD]) keratometry (K), CCT and AL were found to be 44.08 (±1.55) D, 528.46 (±29.78) μm, and 22.75 (±1.21) mm, respectively. With increasing age, CCT was found to be decreased (P < 0.001). Compared to myopia, a significantly higher CCT was noted in hypermetropia (P < 0.001). There was a negative correlation between CCT and corneal curvature among the entire study population, irrespective of their refractive status (P < 0.001). This correlation was more significant among emmetropes and hypermetropes as compared to myopes. However, we found no correlation between CCT and AL in any groups. Conclusion: CCT is found to be thicker in hypermetropia and thinner in myopia as compared to emmetropia. With increasing age, the cornea tends to become steeper and thinner.

Purpose: To assess the corneal parameters in rheumatoid arthritis (RA) patients. Methods: We enrolled 64 patients with RA (32 receiving biologic and 32 receiving conventional drugs) and 32 healthy subjects. Keratometric values (anterior flat [K1], steep [K2], and mean keratometry [Km]), corneal thickness from the pupil center (CCT), apex (ACT), and the thinnest point (TCT), and corneal volume (CV) were measured and compared between the groups. Results: K1, K2, and Km values were significantly higher in the RA group (P = 0.013, P = 0.048, P = 0.027, respectively). The means of CCT, ACT, TCT, and CV were significantly lower in RA patients (P < 0.001, P < 0.001, P < 0.001, P = 0.011, respectively). When we divided RA patients into two groups according to the treatment and compared them to controls, the differences in K1, CCT, ACT, TCT and CV were significant (P = 0.030, P = 0.005, P = 0.001, P = 0.001, P = 0.034, respectively). K1 and CV values of RA-biologic group were similar to the control group (P = 0.205 and P = 0.127, respectively). Conclusion: Biologic agents contribute to the improvement of K1 and CV values in patients with RA.

Background Keratoconus (KC) is an ectatic corneal disorder characterized by progressive corneal thinning with myopic astigmatism. Intrastromal corneal ring segments (ICRS) have been broadly selected as a surgical intervention for KC correction to delay the need of keratoplasty. The purpose of this study was to evaluate the corneal densitometry changes in the various annuluses and depths in KC corneas after intrastromal corneal ring segment (ICRS) implantation and to correlate those changes with the other optical and refractive outcomes. Methodology This was a prospective interventional study included 56 eyes of 40 patients with KC who underwent femtosecond laser-assisted Keraring ICRS implantation. The uncorrected and best-corrected visual acuities (UCVA and BCVA), refraction, keratometry, Q-value, thinnest corneal location thickness (TCLT), and corneal densitometry in all the annular zones were assessed preoperatively and 90 days after surgery. Results Following the ICRS implantation after 3 months, when compared to preoperatively, the UCVA, BCVA, improved significantly from 0.21±0.12 and 0.44±0.15 to 0.27±0.12 and 0.58±0.15 (P

Background: Several studies have previously reported the normal values of corneal volume (CV) in various populations, whereas little is known about the CV distribution in healthy young Chinese adults. Our study aimed to investigate the distribution of CV and its relationships with other ocular biometric parameters among healthy young Chinese adults. Methods: A total of 1645 eyes from 1645 students at Dali University in Yunnan Province, China, were analyzed. Pentacam was used to measure CV. Central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were evaluated by Corvis-ST. Other biometrical parameters, including axial length (AL), keratometry, and white-to-white (WTW) distance, were measured using IOL Master. Results: The mean age of the study population was 19.01 ± 0.92 years, and 68.81% of them were women. The CV was normally distributed in the whole sample, with a mean value of 61.23 ± 3.22 mm3. CV and CCT were significantly smaller in the Yi ethnic group than in the Han ethnic group (p < 0.01). CCT (coefficient: 0.085; p < 0.001) and keratometry (coefficient: 0.422; p < 0.001) were positively correlated with CV, while AL (coefficient: -0.204; p < 0.001), WTW distance (coefficient: -0.236; p < 0.001) and bIOP (coefficient: -0.06; p < 0.001) were inversely associated with CV. Conclusions: Our study provides an age-specific distribution of CV among healthy young Chinese adults. CCT, keratometry, AL, WTW distance and bIOP were important factors associated with CV. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of vectored thermal pulsation therapy (VTPT) on the repeatability of biometry readings of two different optical biometers in patients with meibomian gland dysfunction (MGD). Methods: Patients affected by MGD were included in this prospective, randomized, controlled, investigator‐masked study. One eye was randomized to VTPT (LipiFlow®, Johnson & Johnson), and the contralateral eye served as a control. Three visits were scheduled at baseline, 2 weeks and 3 months after the treatment. The main outcome parameter of the study was the repeatability of three calculations of emmetropic intraocular lens power (EIOLP) at the 3 months visit as compared to baseline using an optical biometer (IOLMaster® 700, Carl Zeiss Meditec AG). Repeatability of different keratometry values obtained by the optical biometer and a Placido‐disc topographer (MS‐39®, CSO) served as secondary outcome parameters. Results: Twenty‐nine patients were included in the final analysis. While tear film parameters improved in the study eyes, there were no significant differences regarding the repeatability of three EIOLP measurements between baseline and 3‐months‐visit in both eyes (p > 0.05) and keratometry measurements in both the optical biometer and the Placido‐disc topographer. Remarkably, throughout all study visits, there were some outliers regarding the repeatability of measurements. Conclusion: While both devices showed high repeatability regarding EIOLP and keratometry, future studies are needed to detect high‐risk patients for poor repeatability. [ABSTRACT FROM AUTHOR]

This study aims to compare changes of corneal topography (Galilei G4) before and after the instillation of artificial tears in patients with dry eye disease (DED). Corneal topography was performed in patients 1 min before and after artificial tear instillation. Two types of artificial tears were used: 1% polysorbate 80 (PSB) and 0.5% carboxymethylcellulose (CMC). Of 135 patients, PSB and CMC were instilled in 101 and 34 eyes, respectively. The average value of Sim K increased significantly after instillation (44.07 ± 2.26 diopter (D)) compared to before (43.90 ± 2.02 D, p = 0.006) the instillation of artificial tears. Mean Sim K astigmatism was statistically increased after PSB instillation (1.48 ± 2.17 D) compared to before instillation (1.31 ± 2.10 D, p = 0.049). An axis change of astigmatism 10° or more after artificial tear instillation was found in 51.9% of patients, and 30° or more in 20.0% of patients. Increased Sim K value and significant changes in the astigmatic axis in the corneal topography were observed after instillation of artificial tears in DED patients. PSB instillation had a greater effect on corneal keratometry values than CMC instillation. [ABSTRACT FROM AUTHOR]

Purpose: To assess the corneal parameters in rheumatoid arthritis (RA) patients. Methods: We enrolled 64 patients with RA (32 receiving biologic and 32 receiving conventional drugs) and 32 healthy subjects. Keratometric values (anterior flat [K1], steep [K2], and mean keratometry [Km]), corneal thickness from the pupil center (CCT), apex (ACT), and the thinnest point (TCT), and corneal volume (CV) were measured and compared between the groups. Results: K1, K2, and Km values were significantly higher in the RA group (P = 0.013, P = 0.048, P = 0.027, respectively). The means of CCT, ACT, TCT, and CV were significantly lower in RA patients (P < 0.001, P < 0.001, P < 0.001, P = 0.011, respectively). When we divided RA patients into two groups according to the treatment and compared them to controls, the differences in K1, CCT, ACT, TCT and CV were significant (P = 0.030, P = 0.005, P = 0.001, P = 0.001, P = 0.034, respectively). K1 and CV values of RA-biologic group were similar to the control group (P = 0.205 and P = 0.127, respectively). Conclusion: Biologic agents contribute to the improvement of K1 and CV values in patients with RA. [ABSTRACT FROM AUTHOR]