African Descent and Glaucoma Evaluation Study (ADAGES): Racial differences in the risk of developing visual field damage vary by level of IOP

Abstract

 

Purpose

 

To investigate racial differences in the development of visual field (VF) damage and the rate of rim area in glaucoma suspects.

 

Methods

 

636 eyes from 357 glaucoma suspects and ocular hypertensive patients with normal VF at baseline and >2 years of follow-up from the multicenter ADAGES were included. Racial differences in the development of VF damage and rate of rim area loss were examined using multivariable Cox Proportional Hazard models and mixed effects models.

 

Results

 

31 (25.4%) of the 122 African descent (AD) participants and 47 (20.0%) of the 235 European descent (ED) participants developed VF damage (p=0.078) after a mean follow-up of 7.1 + 2.4 years. In multivariable analysis, worse baseline VF mean deviation, higher mean arterial pressure during follow up, and a race-IOP interaction term were significantly associated with the development of VF damage suggesting that racial differences in the risk of VF damage varied by IOP. At higher IOP, AD was predictive of the development of VF damage; after adjusting for corneal thickness, disc area, baseline VF mean deviation, age, and other parameters. At the highest quartile of mean IOP during follow-up (> 21 mm Hg), the multivariable HRs (95%CI) for development of VF damage in AD compared to ED subjects was 5.22 (1.81-15.08) while at lower mean IOP (<21 mmHg) during follow-up, AD was not predictive of the development of VF damage HR: 0.81 (0.43-1.51) (See Figure). By including race in the model, the R² increased from 36% to 54%. Moreover, among those developing VF damage, the mean rate of rim area change was significantly faster in AD compared to ED subjects (multivariate global rim area, -2.42 mm²*10^-2/year versus -0.79 mm²*10^-2/year, P<0.001), respectively.

 

Conclusions

 

In this cohort of glaucoma suspects with similar access to treatment, at higher IOP during follow-up, individuals of AD were more likely to develop VF damage than individuals of ED, and they tend to progress at a faster rate. Further research is needed to evaluate the complex interaction of ophthalmic, genetic, systemic and other factors to improve our understanding of racial differences in the earlier onset of glaucoma and its faster progression at various levels of IOP.