The Impact of Alterations in Corneal Curvature on the Measurement of the Optic Nerve Head Size in Non-Glaucomatous Keratoconus Patients Publisher Pubmed



Atighehchian M ; Vahedian Z ; Zareighanavati M ; Jafari R ; Ghassemi H
Source: International Ophthalmology Published:2026

Abstract

Purpose: To examine the impact of corneal curvature on the optic nerve head (ONH) area size measured by optical coherence tomography in non-glaucomatous keratoconus (KC) patients. Methods: This study was conducted at Farabi Eye Hospital between 2022 and 2024. Patients with a confirmed diagnosis of KC, based on clinical examinations and corneal topography, were included. Heidelberg spectral-domain optical coherence tomography (SD-OCT) was used to examine the Bruch’s Membrane Opening (BMO) area size, in order to determine the size of the optic nerve head (ONH) area. This was performed twice: once using a default corneal curvature of 7.7 mm and once using the patient’s anterior corneal radius of curvature obtained from the Pentacam. The changes in the ONH area size were then compared and analyzed. Results: In this study, we evaluated a total of 102 eyes from 51 patients diagnosed with KC. The average area of the BMO, measured using corneal curvature based on Pentacam, was 1.822 ± 0.457 mm2. In contrast, the BMO size measured using a standard corneal curvature (SCC) value of 7.7 mm was 1.955 ± 0. 497mm2. The mean difference between the BMO area measurements obtained with Pentacam-based corneal curvature (PCC) and the SCC value of 7.7 mm was − 0.133 ± 0.221 mm2(95% CI − 0.175 to 0.091, p < 0.001). The 95% limits of agreement (LoA) for the differences between these measurements ranged from − 0.56 to 0.30 mm2. Conclusion: The study emphasizes the importance of corneal curvature measurements in determining the size of the ONH area in individuals diagnosed with KC. It suggests that changes in corneal curvature size directly affect the size of the BMO area. This information is crucial for accurately calculating the actual size of the ONH, especially in non-glaucomatous KC patients. © The Author(s), under exclusive licence to Springer Nature B.V. 2025.