Factors Influencing OCT Peripapillary Choroidal Thickness (ppCT) in a Normal Population: A Multi-Center Study

Abstract

Purpose : To quantify ppCT by OCT at 100, 300, 500, 700, 900 and 1100 ums from the anterior scleral canal opening (ASCO) within 12 clock-hour sectors oriented to the Foveal-Bruch’s Membrane Opening (FoBMO) axis in 1 eye of 362 normal subjects who represent the ethnic composition of the US population.

Methods : Subjects from 8 centers in Canada, Europe and the US and who were normal by ocular and visual field examination underwent OCT enhanced depth imaging (Spectralis) using a 24 radial B-scan pattern centered on the optic nerve head (ONH) and oriented relative to the FoBMO axis. BMO, Bruch’s membrane (BM), ASCO, and the anterior scleral surface (SS) were manually delineated in each B-scan. OCT B-scans from 9 eyes were each delineated by 4 operators and the intra-class correlation coefficients (ICC) were calculated (two-way ANOVA). The effects of age, axial length (AL), ethnicity, gender, sector, ASCO area, distance from ASCO (ASCO distance) and their interactions, were assessed globally and by sector, by ANOVA, and univariate and multiple regression.

Results : The final analysis included 357 subjects (median age 50.3, range 19.8 to 90.3; 156 male, 201 female; 244 European descent (ED), 46 Hispanic, 45 African descent (AD), 19 Asian, 3 Native American), following exclusion of 5 eyes with poor SS visualization (< half B-scans delineated). Inter-operator ICCs ranged from 0.65 to 0.89. Globally, ppCT was thicker as ASCO distance increased, thicker in AD subjects, thinner in eyes with greater age, AL and ASCO area, (all p<0.001), and slightly thinner in females (p=0.05). Among these, Age and AL explained the greatest proportion of variance (Fig. 1). The rate of age-related decline increased with ASCO distance (p<0.001) (Figs. 1-2). By sector, ppCT was thinnest, and also showed the greatest decline with Age, in the inferior temporal sectors (Fig. 2). Sector 7 (Fig. 2), 500 um from the ASCO, and sectors 7 and 8 at all distances ≥ 700 μm, were significantly thinner than sector 12 and demonstrated a significantly higher rate of age-related loss (data not shown).

Conclusions : In normal eyes, OCT ppCT was thinnest within the inferior temporal sectors and thinner closest to the ASCO. Thinner ppCT was also associated with being female, ED, older (age), larger ASCO area, and longer AL. Among these effectors, age had the strongest influence, and its effect was greatest within the inferior temporal sectors.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.