Does diet or nutrition affect eyesight?
It is very common for  people to wonder if changes in diet, food intake, or the use of vitamins can affect eyesight. There is no easy answer to this question, but we do have evidence that certain substances can affect the eyes positively or negatively. One of the biggest questions is whether there is any benefit to taking vitamins, or if altering diet will change the health of the eyes. Vitamin stores sell many supplements for the eyes, and for all kinds of eye conditions such as dry eye, glaucoma, macular degeneration and cataracts. Most of these do not have any good scientific evidence to back their statements, and the label may even read "These statements are not supported by the FDA". This post will attempt to sort through some of the issues and advise patients regarding use of supplements.
Omega-3 fatty acids have been touted as a solution to dry eye syndrome, and many patients take this supplement. They will state that they have less dry eye symptoms due to this supplement, even though their health insurance does not pay for it. These patients indicate that they have been able to decrease their use of artificial tear, improve their vision, and decrease their feelings of soreness and dryness. In spite of this, there is no real research to support its use, either in a pill or in the form of fish oil.
Recently, a journal article proved that excessive intake of caffeine can actually make glaucoma worse by increasing the pressure in the eye. It found that more than three cups of coffee per day can cause this problem, and indicates that caffeine intake should be limited. This study definitely indicates that moderation is the best bet where caffeine intake is concerned, and that people who drink too much coffee may have problems more than just the 'jitters'.
One area where nutritional supplements are definitely proven to work well is in macular degeneration. Multivitamins that follow the AREDS study, which was completed about 10 years ago. were shown to slow down the progression of macular degeneration in patients who had medium-sized drusen in the macula. Preventing age-related macular degeneration is important because it is the leading cause of blindness in our aging population.
Nutritional supplement and vitamins have not been proven to help with cataracts, but limiting exposure to ultraviolet light and sunlight will decrease progression. Smoking has also been shown to make cataracts progress faster.
Most supplements are unproven for the eyes, but in the case of AREDS vitamins, smoking and ultraviolet light, we can control the progression of disease in our eyes.
