Understanding structural changes in keratoconus: Anterior scleral and choroidal thickness analysis using swept source optical coherence tomography

Aims/Purpose: The study aims to investigate the anterior scleral thickness (AST) profile and choroidal thickness (CT) variations in keratoconus (KC) patients compared to healthy controls, with the objective of providing a comprehensive understanding of ocular structural changes in KC.

Methods: A cross‐sectional case‐control study was conducted, involving 46 eyes: 23 KC eyes and 23 age‐ and axial‐length‐matched healthy eyes. Anterior scleral thickness (AST) was evaluated at three scleral eccentricities (1, 3, and 6 mm from the scleral spur) across four scleral zones (nasal, temporal, superior, and inferior) using the anterior segment module of the Triton SS OCT (Topcon, Tokyo, Japan). Additionally, choroidal thickness profiles in KC patients were derived from SS‐OCT scans. Comparative analyses were conducted to assess thickness variations within and between groups.

Results: In KC eyes, AST exhibited significant variations across several meridians, particularly over the temporal and inferior meridians, in comparison to healthy eyes. Although AST profiles did not differ significantly between groups, differences in inferior‐superior thickness asymmetry were observed, particularly in subclinical KC eyes. Choroidal thickness in KC patients was notably greater compared to healthy controls and displayed a declining trend with age.

Conclusions: Keratoconus eyes manifest substantial anterior scleral thickness variations across eccentricities, indicating structural alterations in the paracentral sclera. While AST profiles did not reveal significant differences between KC and healthy eyes, observed asymmetry disparities in thickness imply vertical meridian scleral changes in KC, warranting further exploration. Additionally, the increased choroidal thickness in KC patients, coupled with its age‐related decrease, suggests potential implications for understanding KC pathogenesis.