Factors Influencing OCT Central Anterior Lamina Cribrosa Surface Depth within a Normal Population: A Multi-Center Study

Abstract

Purpose : To quantify the effects of age, axial length (AL), ethnicity and gender on OCT anterior lamina cribrosa surface depth (ALCSD) in 1 eye of 362 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) of the optic nerve head (ONH) using a 24 radial B-scan pattern aligned to the Foveal-Bruch’s Membrane Opening (BMO) axis. BMO, ALCS, anterior scleral canal opening (ASCO), Bruch’s membrane (BM), and the anterior scleral surface (SS) were manually delineated in each B-scan. ALCS visualization was quantified within 72 ASCO subsectors, requiring ≥1 delineated point per subsector. OCT B-scans from 9 eyes were each delineated by 4 operators and the intra-class correlation coefficients (ICC) were calculated. Central (central 24 subsectors) ALCSD was quantified relative to 4 reference planes: BMO, ASCO, BM (1700um from the BMO centroid), and SS (1700um from the ASCO centroid). The effects of age, gender, ethnicity, BMO area, ASCO area and AL on Central ALCSD were assessed by ANOVA and univariate and multiple regression.

Results : Median LC visualization within the central sub-sectors was 89%, (range 69-95%, Fig. 1). Central ALCSD ICCs were ≥0.87 for each reference plane. The final analysis included 339 subjects, (median age 50, range 20-90; 143 male, 196 female; 232 European descent, 43 Hispanic, 43 African descent (AD), 18 Asian, 3 Native American) after exclusion of 23 eyes for poor laminar (18) and scleral (5) visualization. By ANOVA, central ALCSD-BMO was shallower in females (p=0.005) and was shallower in eyes with greater age (p=0.0005), BMO area (p=0.03) and AL (p=0.001) (Fig. 2). Central ALCSD-BM behaved similarly, but was the only parameter influenced by ethnicity, being deeper in AD eyes (p=0.0002). Central ALCSD-ASCO was shallower in females (p=0.04) and was shallower in eyes with greater ASCO area (p=0.0003) and AL (p=0.01). Central ALCSD-SS was influenced by ASCO area (shallower in eyes with greater ASCO area (p=0.007)), and gender (shallower in females (p=0.04)), only.

Conclusions : OCT Central ALCSD is modestly shallower in females and also shallower in eyes with greater age, AL, ASCO area and BMO area, being affected by the fewest of these when measured relative to the ASCO and SS.

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