Rates of Structural and Functional Progression of Glaucoma and Their Risk Factors in an African Ancestry Cohort

Abstract

Purpose : To investigate the rates of structural and functional progression in an African ancestry cohort and to determine the risk factors for progression.

Methods : Glaucoma cases in the Primary Open-Angle African American Glaucoma Genetics cohort, with ≥2 retinal nerve fiber layer (RNFL) thickness values and ≥2 mean deviation (MD) measurements over ≥6 months follow-up, were examined. The rates of structural progression (change in RNFL thickness/year) and functional progression (change in MD/year) for each eye were calculated from linear mixed effects models, accounting for inter-eye correlation from the same subject and longitudinal correlation for the same eye over time. Eyes were categorized as slow, moderate, and fast progressors (Table 1). Demographic and clinical risk factors for progression rates were assessed using univariate and multivariate regression models.

Results : A total of 1424 eyes were classified as slow, moderate, or fast progressors (Table 1). The median (inter-quartile) rates of progression were -1.60 (-2.05, -1.15) μm/year for RNFL thickness and -0.40 (-0.44, 0.34) dB/year for MD. In multivariate analysis, faster RNFL progression was independently associated with thicker baseline RNFL (p<0.0001), lower (worse) baseline MD (p=0.005), and beta peripapillary atrophy (p=0.04; Table 2). Faster MD progression was independently associated with higher baseline MD (p<0.0001), higher cup-to-disc ratio (p=0.02), and lower body mass index (p=0.0004; Table 2).

Conclusions : This African ancestry cohort had faster median rates of structural and functional progression than other ethnic groups. Higher baseline RNFL thickness and MD values were associated with faster rates of structural and functional progression, respectively, likely due to a “floor effect,” where progression in early disease exhibits a steeper slope before plateauing in advanced stages. Results highlight the importance of monitoring structural and functional glaucoma progression to provide timely treatment in early disease stages.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Table 1: Classification of glaucoma patients as slow, moderate, and fast progressors. Structural progression: rate of change of global RNFL thickness per year from SD-OCT. Functional progression: rate of change of MD from visual fields per year.

 

Table 2: Multivariate analyses for baseline risk factors of progression rates