Genetic and Environmental Links to Aging Visual Function

February’s Ophthalmology

Using a classical twin study, Hogg et al. investigated the relative contribution of genetic and environmental influences to the significant losses in visual function associated with normal aging.
They evaluated cone function in 42 pairs of twins (21 monozygotic and 21 dizygotic, ages 57 to 75) with normal visual acuity. Cone function was evaluated by establishing absolute cone contrast thresholds to flicker (4 and 14 Hz) and isoluminant red and blue colors under steady-state adaptation.
The researchers found a strong genetic contribution to cone absolute threshold, color (red and blue) and flicker (4 and 14 Hz) thresholds. However, the dynamic aspects of adaptation and the rod absolute thresholds demonstrated less genetic input—thus implying a greater potential influence from environmental factors.
They conclude that while many common visual parameters are inherited, other vital neuronal processes are significantly influenced by environmental factors over a lifetime—leading to new possibilities in preventing or delaying visual dysfunction or disease.