The evidence for preventing cataracts and macular degeneration points in a positive direction for lifestyle measures such as UV protection, an antioxidant-rich diet and diabetes management, but most dietary studies are observational and therefore not conclusive. The surgical treatment of cataracts is strongly supported and highly effective. In practical terms: anyone who has their eyes checked after the age of fifty, addresses risk factors and eats a varied diet is doing what the science currently recommends.
Cataracts and macular degeneration are the two leading causes of blindness and serious vision loss worldwide. Cataracts were estimated to affect 15.2 million people over the age of fifty in 2020, while macular degeneration (AMD) caused blindness in 1.8 million people that same year. As the population ages, the absolute numbers are rising, even though the proportion of blindness per age group is falling thanks to improved eye care. Regular eye check-ups are therefore becoming increasingly important, because early detection is key for both conditions.
The main risk factors for cataracts are ageing and oxidative stress, as confirmed by several large systematic reviews. In addition, exposure to ultraviolet light and diabetes increase the risk. That is good reason to wear UV-filtering sunglasses on sunny days and to keep blood sugar under control. Diabetes also raises the risk of diabetic retinopathy, a retinal condition that led to serious vision loss in 2.6 million people worldwide in 2015.
When it comes to diet, several studies paint an encouraging picture. A dietary pattern rich in vegetables, fruit, legumes, nuts and fish is associated with a lower risk of cataracts; this pattern was analysed across 24 studies. The associations are, however, correlational: no proven causal relationship has yet been established. Lutein and zeaxanthin, pigments that occur naturally in the macula of the eye and are found in dark-green leafy vegetables such as kale and spinach, appear to slow the progression of both macular degeneration and cataracts. The evidence for this is encouraging, but large supplementation trials show mixed results. At present, the strongest support is for an overall plant-based, antioxidant-rich dietary pattern, not for any single specific supplement.
Once cataracts have developed, they cannot be reversed through diet or medication. Surgery in which the cloudy lens is replaced with an artificial lens is the only proven effective treatment and delivers rapid visual recovery for most patients. It is one of the most cost-effective surgical procedures in medicine. Anyone who notices that their vision is becoming blurry or glary does not have to accept this as an inevitable loss.
The practical message for long-term eye health is a combination of lifestyle, protection and monitoring. Wear UV-protective eyewear during outdoor activities, eat a varied diet with plenty of vegetables and fruit (also for their lutein and zeaxanthin content), keep blood sugar under control if you have diabetes, and have your eyes checked regularly, especially after the age of fifty. Those check-ups are not only for people who already have symptoms: macular degeneration and early cataracts are often discovered incidentally, and early intervention makes a difference.
Based on several large systematic reviews and global prevalence studies (pmids: 36565712, 15708105, 29032195, 33275949, 33271081, 29885291, 37960238, 26319346). Dietary studies are largely observational; causal claims for diet are therefore not possible.