Racial Differences in Visual Function in Healthy Eyes in the African Descent and Glaucoma Evaluation Study (ADAGES)

Abstract

Purpose: : To investigate differences in visual function between the healthy eyes of people of African (AD) and European (ED) descent.

Methods: : Visual function was assessed in both eyes (when eligible) of 393 AD and 367 ED participants selected from the African Descent and Glaucoma Evaluation Study (ADAGES) and Diagnostic Innovations in Glaucoma Study (DIGS). Participants had normal appearance of the optic disc on stereophotographs and intra-ocular pressure ≤22 mm Hg. Visual field data were not used for classification. Each participant had two reliable 24-2 tests on Standard Automated Perimetry (SAP) using the Swedish Interactive Thresholding Algorithm (SITA), Short-Wavelength Automated Perimetry (SITA and/or Full-Threshold) and Frequency-Doubling Technology (FDT Matrix) perimetry, all within a 3 month window. The average result of the two visual fields of each test is reported for Mean Deviation (MD), Pattern Standard Deviation (PSD) and proportion of abnormal Glaucoma Hemifield Test (GHT). The Generalized Estimating Equation approach was used to adjust for the inter-eye correlation.

Results: : Participants of AD (46.2±13.2 years) were significantly younger than those of ED (49.5±16.6 years) (p=0.003) and all results were adjusted for age. People of AD had significantly worse mean MD than people of ED on SWAP-SITA (AD: -3.90±3.27; ED: -3.48±3.35; p=0.02), SWAP-FT (AD: -4.40±3.25; ED: -3.73±3.32; p=0.001) and FDT (AD: -1.69±2.73; ED: -0.73±2.64; p=<.0001). They also had significantly worse mean PSD values on all tests: SAP (AD: 1.91±0.93; ED: 1.79±0.87; p=0.003); SWAP-SITA (AD: 3.06±0.96; ED: 2.89±0.83; p=0.0001); SWAP-FT (AD: 2.98±0.84; ED: 2.87±0.79; p=0.001); FDT (AD: 3.00±0.78; ED: 2.86±0.69; p=0.0001). All mean values for MD and PSD for both racial groups were within the normal range for all tests. A significantly larger proportion of people of AD had an abnormal GHT compared to people of ED for SAP (AD: 0.23±0.42; ED: 0.19±0.39; p=0.003) and FDT (AD: 0.35±0.48; ED: 0.30±0.46; p=0.008). No racial differences were found in the proportion of abnormal GHT for SWAP-SITA or SWAP-FT.

Conclusions: : People of AD had significantly worse performance than people of ED on all tests of visual function. These small differences may be signs of early disease or they may point to the need for race-specific normative database for each of the visual function tests.

Keywords: visual fields • perimetry • ganglion cells