A team of scientists in Australia have produced two studies showing that consuming two types of foods help to prevent macular degeneration, an incurable disease that slowly robs people of their eyesight.
Based on assessing 2,000 adults, aged 49 and over, for a total of 15 years, it was discovered that those who ate between 100 and 142 mgs of leafy green vegetables each day had a 35% lower risk of falling prey to failing eyesight.
A second related study, using the same base of test subjects, further found that eating an orange a day helps to keep macular degeneration at bay. The key seems to be the flavonoids in oranges, which reduces the disease risk by 60% in those having a steady orange diet.
Though apples and red wine also contain flavonoids, there didn't seem to be any relationship between consuming those and protecting the eyes from disease. For some unknown reason, it is only oranges which confer the protective effects.
"Association of Dietary Nitrate Intake with the 15-Year Incidence of Age-Related Macular Degeneration." Gopinath B. Et al. Journal of the Academy of Nutrition and Dietetics. October 2018.
"Dietary flavonoids and the prevalence and 15-y incidence of age-related macular degeneration." Gopinath B. Et al. American Journal of Clinical Nutrition. August 2018.