Corneal Indices in Different Corneal Thickness in Relation to Refractive Errors

Abdullah Gaafar, Amany Gaafar; Mohammed ALgohary, Sameh; Samy Abdalaziz, Mohammed

doi:10.21608/ejhm.2025.419500.1833

Corneal Indices in Different Corneal Thickness in Relation to Refractive Errors

Document Type : Original Article

Authors

¹ Ophthalmology ,faculty of medicine ,menofia university, Egypt

² Professor of Ophthalmology, Faculty of Medicine, Menoufia University, Menoufia, Egypt

10.21608/ejhm.2025.419500.1833

Abstract

Background: Accurate preoperative assessment of corneal parameters is essential in refractive surgery to minimize complications such as corneal ectasia and biomechanical instability. Central corneal thickness and curvature are key predictors for surgical planning, and emerging technologies like the Sirius Scheimpflug-Placido topography system offer comprehensive corneal evaluation
Objective: This study aimed to evaluate the variation of corneal tomographic indices across different corneal thickness profiles and their relationship to refractive errors using the Sirius imaging system.
Patients and Methods: This retrospective observational study included 60 eyes from 60 patients who presented for refractive surgery evaluation. Patients were stratified into three groups based on thinnest corneal thickness: Group 1 (≤ 509 µm), Group 2 (510–580 µm), and Group 3 (≥ 581 µm). Comprehensive ophthalmologic examinations and corneal tomography were performed using the Sirius system. Key parameters included keratometric readings, pachymetric indices, anterior chamber depth, and ectasia risk indices.
Results: Group 1 demonstrated significantly steeper anterior corneal curvature (K1, K2, and mean Sim-K) across the 3 mm, 5 mm, and 7 mm optical zones compared to Groups 2 and 3 (p < 0.05). No significant differences were found in posterior corneal curvature or corneal astigmatism across groups. The BCVf index was significantly higher in Group 3 than in Group 2 (p < 0.05), while other ectasia-related indices showed no significant variation. Refractive status did not significantly impact tomographic indices.
Conclusion: The Sirius topography system provides accurate and consistent measurements of corneal thickness and curvature. Thinner corneas are associated with steeper anterior curvature, while posterior surface parameters remain stable.

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