Purpose: To report the prevalence of keratoconus (KCN) in patients presenting for refractive surgery in western India. METHODS: A cross-sectional, observational, retrospective study performed at a tertiary eye care center. A total of 2902 cases, aged 18–40 years who presented in the refractive surgery department between January 2014 and December 2018 were included. Records of all the included cases were reviewed. Patients showing KCN pattern on topography were noted and divided into KCN and KCN suspects. Annual and overall 5-year prevalence were calculated at 95% confidence interval (CI). Demographic details of KCN and non-KCN participants were compared. RESULTS: Of the 2902 cases, 25 (0.86%) had clinical KCN and 22 (0.76%) were KCN suspects. The combined 5-year prevalence of all these 47 KCN cases was 1.61% (95% CI: 1.15%-2.07%), with an annual prevalence range of 0.97%–2.43%. The mean age of non-KCN cases was 24.60 ± 4.91 years and KCN cases was 24.62 ± 5.37 years ( P = 0.98). Among the KCN cases, there were more females (30; 63.83%), and the gender ratio was significantly different than non-KCN cases ( P = 0.004). CONCLUSION: The prevalence of KCN in refractive surgery cases was 1.61% which is higher than those found in the western population and lower than those found in the Middle East (Saudi Arabia and Iran). Furthermore, topographic examination performed during the routine screening of patients for refractive surgery can be a useful tool to diagnose new cases of KCN in asymptomatic patients.

SIGNIFICANCE:The article highlights various topographic patterns and their prevalence in a large spectrum of ectatic corneal diseases (ECDs). Knowledge of these patterns can help clinicians for quicker diagnosis and selection of appropriate contact lens design.PURPOSE: This study aimed to determine various corneal topography patterns and their prevalence in patients with ECDs who visited a tertiary eye hospital in western India.METHODS: Keratoconus, pellucid marginal degeneration, keratoglobus, and post-refractive surgery progressive corneal ectasia are considered under ECDs. This cross-sectional retrospective study reviewed records of 632 consecutive patients with clinical ECDs at their first presentation. The right eye was considered for pattern analysis. In cases with suspected or forme fruste ectasia in the right eye, the fellow eye was considered. A sagittal map with standard scale of Atlas 9000 topographer (Carl Zeiss Meditec AG, Jena, Germany) was used for pattern analysis. They were classified into 18 categories and grouped under five groups. The prevalence of these patterns was calculated and assessed with 95% confidence interval (CI). RESULTS:The mean ± SD age of patients was 23.6 ± 8.2 years. The highest prevalence was of asymmetric patterns (39.6% [95% CI, 35.7 to 43.5%]; asymmetric bowtie [AB] with steepest radial axis index [SRAX], 18.8%; AB with inferior steep, 16.0%; AB with superior steep [SS], 3.2%; symmetric bowtie with SRAX, 1.6%) and of central or paracentral patterns (28.6% [95% CI, 25.1 to 32.3%]; inferior steep, 12.2%; heart, 7.4%; oval, 4.1%; symmetric bowtie, 2.4%; round, 1.6%; irregular, 0.9%) followed by advanced patterns (17.3% [95% CI, 14.4 to 20.4%; nonmeasurable, 5.4%; globus, 4.9%; indiscriminate, 7.0%). The peripheral patterns were 11.7% (95% CI, 9.3 to 14.4%) (claw, 6.3%; junctional, 3.2%; butterfly, 1.9%; SS, 0.3%). Rare patterns were 2.8% (95% CI, 1.7 to 4.5%) (superior [junctional, claw, and heart], AB with SS with SRAX, and AB with SRAX located temporally).CONCLUSIONS: Asymmetric and central or paracentral are the most common patterns in our study. The higher prevalence of advanced patterns indicates the need for earlier diagnosis of ECDs in our population. The peripheral patterns also have significant prevalence.

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Introduction: Laser-assisted in situ Keratomileusis (LASIK) is the most commonly performed refractive surgical procedure. The amount of tissue ablated in LASIK affects the safety and long-term outcome. The objective of this study was to compare the percent tissue altered (PTA) in topography guided (TG) and wavefront optimized (WFO) LASIK using Zeiss MEL 80 excimer laser. Materials and methods: This retrospective observational study was conducted at a tertiary eye center. Patients with moderate myopia who underwent LASIK between June 2016 and January 2019 were divided into two groups (Group I: TG LASIK, 69 eyes; Group II: WFO LASIK, 70 eyes). The groups were compared for preoperative parameters [spherical equivalent (SE), keratometry and pachymetry], intraoperative parameters [ablation depth (AD), PTA and residual stromal bed thickness (RSBT)] and postoperative parameters (vision, SE). Results: Among preoperative parameters, SE and keratometry were similar while thinnest pachymetry was significantly less in group I. Among the intraoperative parameters, PTA (P < 0.01) and AD (P < 0.01) were significantly less in group I while RSBT (P = 0.54) was not significantly different. Postoperatively at 6 months, 92.75% (64) eyes in group I and 90% (63) eyes in group II had visual acuity of 6/6 or better (P = 0.57). 98.55% (68) and 97.14% (68) eyes in group I and group II respectively had SE refraction within ± 0.5 dioptres. Conclusion: TG LASIK induces less tissue alteration for given refractive error with similar visual outcome as compared to WFO LASIK which makes TG apparently safer and is the preferred technique for borderline thin corneas.

SIGNIFICANCE:The endothelial changes in keratoconus are of interest because these can affect the surgical plan in management. Previously, many studies have evaluated the endothelium in eyes with keratoconus, but there is no common consensus on change in endothelial cell density (ECD) with studies showing variable results.PURPOSE: This study aimed to compare and correlate endothelial cell parameters in different stages of keratoconus using specular microscope.METHODS: This cross-sectional, cohort, comparative study included 162 eyes of 96 patients with keratoconus in one or both eyes. Corneal endothelial cell parameters were assessed with SP-1P specular microscope (Topcon Co., Tokyo, Japan). Corneal topography and thickness data were obtained from Sirius tomographer (Costruzione Strumenti Oftalmici, Florence, Italy). Eyes were divided into keratoconus stage 0 to 4 according to ABCD classification. Comparison and correlation of endothelial cell parameters in different stages were done.