TABLE 4.

Human-based studies relating to vitamin A in AMD, with PICO characteristics summarised.

Citation	Participants	Interventions	Comparisons	Outcomes
Age-Related Eye Disease Study Research Group (241)	3640 AREDS patients aged 55–80 years	Antioxidant supplement including β-carotene; zinc/copper supplement; antioxidant and zinc supplement	Placebo	Progression to advanced AMD; visual acuity loss
Owlsey et al. (237)	104 adults within AREDS steps 1–9	High dose retinol	Placebo	Dark adaptation
Age-Related Eye Disease Study Research Group (238)	4,519 AREDS patients aged 60–80 years	Dietary lutein/zeaxanthin intake	–	Neovascular AMD; geographic atrophy; large/extensive drusen
Age-Related Eye Disease Study 2 Research Group (239)	4,203 AREDS patients aged 50–85 years	Lutein/zeaxanthin supplement; docosahexaenoic acid/eicosapentaenoic acid supplement; lutein/zeaxanthin/docosahexaenoic acid/eicosapentaenoic acid supplement	Placebo	Development of advanced AMD
Munch et al. (243)	848 Inter99 patients aged 30–60 years	Vitamin A intake	–	Macular drusen
Agrón et al. (242)	4504 AREDS patients without AMD at baseline	Vitamin A and carotenoid intake	–	Progression to advanced AMD
Chew et al. (244)	3882 AREDS patients	β-Carotene supplement	No β-carotene supplement	Self-reported late AMD

AMD, age-related macular degeneration; AREDS, age-related eye disease study grading system; PICO, participants, interventions, comparisons, outcomes.