Variation of laminar depth in normal eyes with age and race

To determine if laminar depth (LD) and prelaminar tissue volume (PTV) are associated with age and race in healthy human eyes.

Optic nerve head images from enhanced depth imaging spectral-domain optical coherence tomography of 166 normal eyes from 84 subjects of African descent (AD) and European descent (ED) were manually delineated to identify the principal surfaces: internal limiting membrane, Bruch's membrane (BM), anterior sclera (AS), and anterior surface of the lamina cribrosa. These four surfaces defined the LD and PTV using Bruch's membrane opening (BMO) and AS for reference structures. Generalized estimating equations were used to evaluate whether the effect of age on each outcome was differential by race.

When age was analyzed as a continuous variable, the interaction term between age and race was statistically significant for mean LDBMO (P = 0.015) and mean LDAS (P = 0.0062) after adjusting for axial length and BMO area. For every 1-year increase in age, the LDAS was greater on average by 1.78 μm in AD subjects and less by 1.71 μm in ED subjects. Mean PTV was lower in the older subjects (1248 × 10(6) μm(3) AD, 881 × 10(6) μm(3) ED) compared to the younger subjects (1316 × 10(6) μm(3) AD, 1102 × 10(6) μm(3) ED) in both groups.

With increasing age, the LD changes differently across racial groups in normal subjects. The LD in ED subjects showed a significantly decreasing slope suggesting that the lamina moves anteriorly with age in this group.