Dry eye: It is not always what you think

Dry eye disease (keratoconjunctivitis sicca) is not always dry. Paradoxically, one of its symptoms may be excessive tearing. Other symptoms may include burning, stinging, itching, light sensitivity, dryness, blurred vision and foreign body sensation (Arch Ophthalmol. 2009;127:763-768).Dry eye is a result of either increased tear evaporation or decreased tear production.

Inflammation may play a role in causing or exacerbating dry eye, although the causes are not completely clear. It is associated with chronic diseases, such as diabetes and Sjögren’s syndrome. Some medications such as some antihistamines, some antidepressants, some sleeping pills and some blood pressure medications may also be contributing factors.

Dry eye is very common, affecting approximately 3.9 percent of men between the ages of 50 and 54. Its prevalence doubles to 7.7 percent as men reach 80 years old, according to the Physicians’ Health Study (Arch Ophthalmol. 2009;127(6):763-768). Sixty-six percent of dry eye disease occurs in women and also increases with age (Am J Ophthalmol. 2003;136(2):318-326). While we can’t reduce the risk from aging, this is only one of many factors.

There are a number of risk factors that are modifiable. Diet is one of them, since patients with dry eye may have low vitamin A and low omega-3 fatty acid levels. Vitamin A comes from foods like carrots and broccoli, and omega-3 fatty acids are in fish, nuts, seeds and fish oil. These deficiencies are easily rectifiable and should not go unnoticed.

Treatments of dry eye

There are a variety of treatments for dry eye, ranging from using artificial tears, consuming omega-3 fatty acids and potentially caffeine to the use of topical medications that reduce inflammation, such as cyclosporine and tofacitinib (in the early phases of development) to the placement of punctal plugs in the tear ducts — a minor procedure to block tear drainage.

The impact of omega-3 fatty acids

Why are omega-3 fatty acids important? Omega-3 fatty acids may work, at least partially, by blocking factors that increase inflammation, such as interleukin-1 and tumor necrosis factor-alpha. In the Women’s Health Study, involving 32,470 participants, those who were in the highest intake group for omega-3 fatty acids had a significantly decreased risk of developing dry eye disease, compared to those with the lowest intake of fatty acids (Am J Clin Nutr 2005;82:887-893).

But even more impactful was that those women with the highest ratio of omega-6 (pro-inflammatory) to omega-3 (anti-inflammatory) fatty acids had an increased risk of dry eye that was more than 2.5-fold greater than those with a much lower ratio of less than 4:1.

Interestingly, in the standard American diet that most of us eat, the ratio of omega-6 to omega-3 is about 20:1, whereas with a high nutrient, plant-rich diet, the ratio hovers around the optimal greater than 4:1 ratio.

Fish oil supplementation types: triglyceride vs. ethyl ester

The type of fish oil may also make a difference when supplementing with omega-3 fatty acids. A triglyceride formulation is the natural form of fish oil. In a study, it seems that the triglyceride formulation is absorbed to a greater extent than the ethyl ester formulation, which may translate into better results with treating dry eye (Biochem Biophys Res Commun. 1988 Oct 31; 156(2):960-3). Patients may be able to decrease the dose, and thus potential side effects, with the triglyceride formulation. To boost omega-3 levels, take fish oil with a meal containing some good fats. Eating fish may be the best way to get the natural triglyceride formulation (Lipids. 2003;38:415-418).

Caffeine effects

In a small double-blind crossover trial (meaning both groups in the study will eventually consume caffeine), caffeine appears to increase the capability of the dry eye patient to increase tear production (Ophthalmology. 2012 May;119(5):972-8). This may help overcome the symptoms of dry eye for patients. Caffeine seemed to increase the amount of tears in the eye — by 30 percent. There were 78 participants in the study, and it was only two sessions long, spanning a six day interval. Though the results are impressive, more study is obviously needed. Daily caffeine intake also seemed to have an impact on increasing tear production.

Disease association and inflammation

It makes sense that dry eye is associated with diabetes, rheumatoid arthritis and Sjögren’s syndrome — the latter two being autoimmune diseases — because these diseases have inflammatory components. In a study, there was a linear association between the risk of dry eye and diabetes (BMC Ophthalmology, June 2008). In other words, the longer patients had diabetes, the higher the probability of having dry eye disease. Also, patients who had diabetic retinopathy, a complication of diabetes affecting the back of the eye, were at greater risk of developing dry eye. This is just another reason that it is so important for diabetes patients to keep their blood glucose levels under control with lifestyle modifications and/or medications. Diabetic retinopathy occurs when blood sugar levels are too high on a chronic basis.

Thus, though dry eye is a common malady, there are a variety of ways to treat the disorder. It is important to not only get enough omega-3s, but also to optimize the ratio of omega-6 to omega-3s. This will only happen if patients embrace a nutrient-rich diet. Consult your ophthalmologist for the most effective treatment for you. However, increasing omega-3s with diet is only beneficial so it won’t hurt to embrace dietary changes.

Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website www.medicalcompassmd.com and/or consult your personal physician.