Genetic Associations of Rod- and Cone-Mediated Vision in Aging and Age-Related Macular Degeneration.

PURPOSE

To compare genetic associations of rod- and cone-driven vision with those previously defined for delayed rod-mediated dark adaptation (RMDA), a functional risk indicator for incident age-related macular degeneration (AMD).

METHODS

In adults aged ≥60 years with two normal eyes (per the Age-Related Eye Disease Study 9-step scale) or with AMD in one or both eyes, we measured RMDA at 5° superior retina, photopic vision (acuity, contrast sensitivity, light sensitivity), and mesopic vision (low luminance acuity and deficit). Vision associations of risk-conferring single-nucleotide polymorphisms in CFH and ARMS2 genes were adjusted for age and smoking and stratified for the presence of subretinal drusenoid deposit (SDD).

RESULTS

Of 608 participants, 462 had normal maculas and 146 had AMD. Neither ARMS2 nor CFH was significantly associated with AMD stage. Across all eyes, RMDA worsened significantly in association with ARMS2 (P = 0.0005). Associations were stronger in normal eyes than in AMD (P = 0.0012 vs. 0.0580) and in normal eyes lacking SDD (n = 384, P < 0.0024). Across all eyes, RMDA was significantly associated with CFH (P = 0.0023) but not in normal and AMD eyes separately (P = 0.270 vs. 0.0596). RMDA was significantly associated with the number of risk alleles in normal and AMD eyes (P < 0.0001). Low luminance deficit was associated with gene dose for AMD eyes only (P = 0.477).

CONCLUSIONS

Of six vision tests, only RMDA was consistently associated with major risk alleles, including ARMS2 (not CFH) in normal eyes, with or without SDD. RMDA assesses dynamic retinoid resupply from the circulation, perhaps presaging SDD. Results are interpreted considering localization of key proteins in Bruch's membrane.