Topography and Choroidal Thickness Measurement in Healthy Asian Indian Subjects using RTVue XR 100 Optical Coherence Tomography.

Purpose: The purpose was to study the choroidal thickness and its profile, derived from different point locations in healthy Asian Indian subjects using RTVue XR 100 optical coherence tomography (OCT) and to determine its correlation with age, refractive error, and axial length.

Methods: In this cross-sectional study, 300 eyes of 150 healthy subjects, with no ocular pathology, were scanned in a single session, using a line scan protocol of RTVue XR 100 OCT. Choroidal thickness was measured at the subfoveal region, and six measurements were obtained on either side of the fovea (temporal and nasal) at 500 μm interval apart, up to 3000 μm. The correlation between subfoveal choroidal thickness and age, refractive error, and axial length was assessed.

Results: Three hundred eyes of 150 healthy subjects were included in the analysis. Median age of the study participants was 55 years (interquartile range [IQR]: 44-61). The median subfoveal choroidal thickness was 235 μm (IQR: 210-263). The choroidal thickness was minimum at nasal 3000 μm from the fovea, while it was maximum in the subfoveal region. The point zones which were near the fovea showed thicker choroidal thickness than the outer zones, both nasally and temporally (P < 0.00001 at all locations), and at all point locations the choroid were thicker temporally than nasally (All P < 0.00001). Subfoveal choroidal thickness showed negative correlation with age (coefficient = -0.62, P = 0.03) and axial length (correlation = -8.52, P = 0.02). A decrease in subfoveal choroidal thickness of 0.62 μm/year was found by regression analysis.

Conclusion: Our study provides normative database and topographic profile of choroidal thickness in the normal Asian Indian eyes using RTVue XR 100 OCT.