The African Descent and Glaucoma Evaluation Study (ADAGES): Racial differences in rate of change of SD-OCT measured minimum rim width and retinal nerve fiber layer thickness

Abstract

Purpose : Considerable evidence suggests that the rate of change of structural measurements in glaucoma eyes depends on risk factors such as race, IOP, age and disease severity. We investigated whether race-related differences exist in the rate of change of minimum rim width (MRW) and circumpapillary retinal nerve fiber layer thickness (RNFLT) in healthy, glaucoma suspect and glaucoma eyes of individuals of European descent (ED) and African descent (AD).

Methods : Rate of change of MRW and RNFLT was investigated in 120 healthy eyes (60 ED, 60 AD), 239 glaucoma suspect eyes (102 ED, 137 AD) and 175 glaucoma eyes (82 ED, 93 AD) of ADAGES participants followed for approximately 3 years and tested with Spectralis spectral domain OCT (Heidelberg Engineering) approximately every 6 months. Suspect eyes were defined as those with a history of untreated IOP ≥ 22 mmHg or suspicion of glaucoma by masked assessment of stereoscopic optic disc photographs with no consecutive, repeatable abnormal standard automated perimetry results (SAP, Carl Zeiss Meditec). Glaucoma eyes were defined as eyes with repeatable abnormal SAP results (GHT ONL or PSD ≤ 5%). The San Diego Automated Layer Segmentation Algorithm (SALSA) was used to segment and measure global MRW and RNFLT from OCT images. Mixed effects models were used to estimate the rate of change after controlling for age and optic disc size

Results : After an average of 2.7 years follow-up, a significant race-related difference in rate of change of MRW but not RNFLT in suspect eyes was observed. Rate of change of MRW was -1.85 μm/year and -2.20 μm/year in ED and AD eyes, respectively (p =0.03, see Figure). Rate of change of RNFLT was -0.48 μm/year and -0.49 μm/year in ED and AD eyes, respectively (p =0.90). No race-related differences in rate of change were found in measurements from healthy or glaucoma eyes. In suspect eyes, age and SAP MD were similar in the ED and AD groups at baseline (p ≥0.05). However, average IOP over study duration was significantly higher in AD eyes (p <0.001).

Conclusions : Results indicate that race is an important consideration when assessing structural change in glaucoma, particularly in glaucoma suspect eyes. Observed racial differences in rate of structural change may help explain racial disparities in glaucoma susceptibility.

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