Global choroidal thickness in healthy eyes assessed by ultra-widefield swept-source optical coherence tomography

Abstract Purpose To evaluate differences in choroidal thickness (CT) throughout the fundus using ultra-widefield swept-source optical coherence tomography (UWF SS-OCT) and to assess its association with age, sex and axial length (AL). Methods Seventy-two eyes of 36 healthy subjects were imaged with an UWF SS-OCT using a 26 mm x 21 mm volume scan protocol. Mean CT by quadrant was computed within concentric rings centered on the optic nerve head (ONH). CT values were then plotted in 4 quadrants as a function of distance from ONH. Mean CT of each quadrant was correlated with age, sex and AL. Results All 4 quadrants demonstrated a rapid initial rise in CT with the superior, inferior, and nasal quadrants reaching peak values at 3.75 mm from the ONH center. The temporal quadrant peaked at 5.25 mm with the highest CT overall (341.41 ± 69 µm). The inferior quadrant had the lowest CT at 8.25 mm (177.62 ± 36.5 µm). In the temporal quadrant, CT was negatively associated with age and AL (both p < 0.05) and was thinner in females ( p = 0.036). Superior CT was negatively associated with AL ( p = 0.007). Inferior CT was associated with age and AL (both p < 0.05), with no impact of sex. Conclusion CT exhibited regional variation throughout the retina with the temporal quadrant demonstrating the greatest thickness and the inferior quadrant showing the lowest CT. Axial length was the most consistent determinant of CT across multiple quadrants while age and sex demonstrated quadrant-specific effects.