Macular Pigment Spatial Profiles in South Asian and White Subjects

Abstract

Variability in central macular pigment optical density (MPOD) has been reported among healthy individuals. These variations seem to be related to risk factors of AMD, such as female sex, smoking, and ethnicity. This study investigates variations in the spatial profiles of MPOD among ethnicities. Using heterochromatic flicker photometry (HFP), MPOD was measured at seven retinal locations in 54 healthy, young South Asian and 19 white subjects of similar age. Macular pigment spatial profiles were classified as either typical exponential, atypical ring-like, or atypical central dip. Central MPOD was significantly greater in South Asian (0.56 ± 0.17) compared with white subjects (0.45 ± 0.18; P = 0.015). Integrated MPOD up to 1.8° (i.e., average MPOD [MPODav(0-1.8)]) was also significantly increased in South Asian (0.34 ± 0.09) compared to white subjects (0.27 ± 0.10; P = 0.003). Average MPOD(0-1.8) was significantly increased in all subjects presenting a ring-like profile (0.35 ± 0.08) or central dip profile (0.39 ± 0.09), compared with typical exponential profiles (0.28 ± 0.09; P < 0.0005). We found a statistically significant association between ethnicity and spatial profile type (P = 0.008), whereby an exponential profile was present in 79% of white compared with 41% of the South Asian subjects. Central MPOD, MPODav(0-1.8), and the prevalence of atypical spatial profiles were significantly increased in South Asian compared with white subjects. Atypical profiles resulted in increased integrated MPOD up to 1.8°, and may therefore offer enhanced macular protection from harmful blue light.