A Longitudinal Analysis of Choroidal Thinning in Healthy and Glaucoma Subjects

Abstract

Purpose : We performed a longitudinal observational study to evaluate the rate of peripapillary choroidal thinning in glaucomatous subjects and healthy controls using spectral domain optical coherence tomography (SD-OCT).

Methods : One hundred thirty-two eyes from 68 healthy subjects and 165 eyes from 115 glaucomatous subjects were selected from the multicenter African Descent and Glaucoma Evaluation Study (ADAGES) and Diagnostic Innovations in Glaucoma Study (DIGS). Subjects were imaged using Spectralis SD-OCT. Peripapillary choroidal thickness (PCT) was assessed from a 3.4-mm diameter circular scan centered on the optic nerve head. The San Diego Automated Segmentation Algorithm (SALSA) was used to automatically segment and measure the PCT from the posterior edge of Bruch’s Membrane (BM) to the choroid-scleral interface. The rate of PCT thinning over time was calculated using a mixed effects model.

Results : The participants in the healthy group (mean ±SD, 56±14 years) were significantly younger than in the glaucoma group (68±11 years) (P<0.001). In comparison to the healthy group, the glaucoma group had longer mean axial length (24.0±1.0 vs 23.7±0.9, respectively; P=0.02), worse baseline MD (-0.31±1.2 dB vs -5.3±7.2, respectively; P<0.001), more Spectralis visits (median[IQR], 7 visits[5-8] vs 5 visits[4-7], respectively; P<0.001), and longer follow up periods (median 3.0 years [IQR 2.6-3.4] vs 1.6 years [1.2-2.5], respectively; P<0.001). At baseline, the global mean PCT was significantly thinner in glaucoma subjects compared to healthy controls (141.74±66.3 µm vs 155.66 ±64.8 µm, respectively; P<0.001). However, when the age was included in the model, this difference was no longer significant (P = 0.38). No significant difference was found between glaucoma and healthy controls in rate of PCT change (-1.88 µm/year vs -2.18 µm/year, respectively; P=0.28) or PCT percentage change over time (2.85%/year vs -3.32%/year, respectively; P=0.23).

Conclusions : Although the choroid was significantly thinner in glaucoma eyes compared to healthy eyes at baseline, the rate of PCT change was not significantly different in the 2 groups during this relatively short follow-up period. Longer follow-up is needed to determine whether monitoring the rate of PCT change has a role in glaucoma management.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.