Topographic analysis of choroidal thickness in pachychoroid disease using ultra-widefield swept-source optical coherence tomography

Abstract

Purpose To characterise regional and topographic choroidal thickness (CT) profiles using ultra-widefield swept-source optical coherence tomography (UWF SS-OCT) and to compare topographic CT between normal eyes and eyes with pachychoroid disease. Methods All participants underwent UWF SS-OCT using an approximately 26 mm × 21 mm field of view with fixation centred on the fovea. CT was quantified within concentric rings centred on the optic nerve head and stratified by sector. Linear mixed-effects models were performed separately for each sector, adjusting for age, sex and spherical equivalent (SE). Main outcome measures were regional CT differences between normal and pachychoroid eyes. Results 60 subjects were included in the study. 37 participants (61.7%) were males and 23 (38.3%) were females. 24 participants (40%) were classified as pachychoroid and 36 (60.0%) as normal. Across all sectors and eccentricities, pachychoroid eyes demonstrated significantly greater CT compared with normal eyes (p<0.001). The largest differences were observed in the temporal sector. In mixed-effects models, pachychoroid status remained a significant independent predictor of increased CT in all sectors (p<0.05) after adjusting for age, SE and sex. SE was independently associated with CT in the inferior, superior and temporal sectors, whereas age and sex were not consistently associated. Conclusions UWF SS-OCT shows that pachychoroid disease is associated with diffuse, sectorally heterogeneous choroidal thickening extending beyond the fovea. These findings support the concept of pachychoroid disorders as conditions of global choroidal remodelling and highlight the value of regional, distance-based choroidal assessment as a potential imaging biomarker.