Article Date: 7/1/2005

nutrition
Nutrition and Dry Eye: A Natural Relationship
Put omega-3 fatty acids to work for your patients.


The new millennium has ushered in significant change in just about every arena, from personal communication systems to the global internet. While these shifts in technology and lifestyle have been heavily publicized, they are not always universally integrated into our culture. However, there is one area that has gained significant public acceptance, directly impacts our practice and has been almost universally adopted: the use of nutritional supplements and vitamins, not the least of which are omega-3 fatty acids. Interestingly, the vast majority of patients in this rising population initiate supplementation without any advice from you, doctor.

Studies indicate that, in addition to promoting eye health, omega-3 fatty acids play a role in the regulation of blood clotting and vessel constriction, as well as depression and irritable bowel syndrome. They are also important for pre- and postnatal development and alleviate the symptoms of rheumatoid arthritis.

So do our patients know something we don't? Or is this just another New Age fad? In fact, our patients are leading the way, and we as clinicians need to catch up. The problem is in determining which claims are clinically significant, and which are nothing more than hype associated with an unregulated industry.

A good start

In the area of eye care, we have two well-established modalities of nutritional treatment: macular degeneration therapy and ocular surface disease management. The literature from Age Related Eye Disease Study (AREDS) has been reviewed extensively. Most clinicians have adopted its guidelines in the treatment of patients with clinically qualified macular disease. While the AREDS recommendations are essential to the successful management of dry AMD, this population group is a very small segment of the average practice's patient base.

Ocular surface disease, on the other hand, is one of the most common problems in clinical practice today, occurring in up to 25% of all patients. The incidence rate will only continue to rise as we see the Baby Boomers start their inevitable passage through the fifth, sixth and seventh decades of life. Demographic studies show that in the year 2030, 25% of the population of North America will be over 65 years of age.

So, the question is: What is the role of nutrition and vitamin therapy in this rapidly expanding area, and how can clinicians integrate this modality into their patient care regimens? The beginning of this trend started with research that demonstrated the cause of most ocular surface disease to be inflammation. Pro-inflammatory Interleukin I is more prevalent in the tear film and conjunctiva of dry eye patients than in normal eyes. In

fact, cytokine-mediated disease has been identified as a universal etiologic agent associated with a wide range of age-related chronic disease states such as diabetes, atherosclerosis and osteoporosis. Its role in dry eye has now been well defined and is associated with clinical conditions such as pre-/peri- and postmenopause, systemic autoimmune diseases like Sjogren's, lupus, Rheumatoid Arthritis and thyroid conditions, as well contact lens intolerance and post-LASIK dry eye.

Clinical care

Most of you are aware of the surge of new topical drugs directed toward the treatment of dry eye, newly developed secretagoges, and research into the male hormone, androgen. While these agents are important, one of the key elements they do not address is the role of meibomian gland disease in chronic dry eye.

Numerous studies have demonstrated the efficacy of omega-3 essential fatty acids (Black currant seed oil, flaxseed, borage oil and fish oils) in the treatment of dry eye disease. In a 2000 study, researchers demonstrated Sjogren's patients have decreased blood serum levels of DHA, EPA and GLA, all of which are essential to the control of inflammation on the ocular surface. Additional work with mass spectroscopy showed that omega-3 fatty acids are the basic building blocks of healthy meibomian oils.

There are three types of omega-3 fatty acids: ALA, EPA and DHA. EPA and DHA, which are longer molecules than ALA, seem to provide the greatest health benefits.

Another study identified the role of omega-3 fatty acids in the clinically observed improvement of meibomian oils with chronic oral therapy. The Women's Health Study, which included 34,000 subjects, showed a direct correlation between dietary levels of omega-3 fatty acids and dry eye symptoms.

Starting at home

The American diet is far too heavy in omega-6 and has too little omega-3 fatty acids. Recent studies show an ideal ratio of these fats is 1:1, but American habits currently weigh in at 20:1 in favor of the omega-6 group. This is due in large part to consumption of beef, vegetable oils, dairy products and pre-prepared food. Given the marked imbalance, it is difficult to create the ideal ratio with dietary adjustments alone. Instead, the use of nutritional supplementation has become the adjunctive therapy of choice for long-term management of chronic dry eye.

Pharmacologically speaking, this therapy produces a marked decrease in the presence of inflammatory mediators, which assists in returning the eye to a state of natural tear production. It also increases both the quantity and quality of meibomian secretions.

The majority of clinical experience with the omega-3s is based on the use of a 2000mg p.o., q.d. dose. This can be taken all at one time or split-up through the day, depending on a patient's gastric response. In some individuals, the GI tract has difficulty processing the full dose all at once and the patient can experience lower GI symptoms (diarrhea, cramping).

Unlike doxycycline, which has a relatively rapid onset of action (2-4 weeks), omega-3 fatty acid therapy typically takes months to demonstrate significant improvement. While this presents a challenge in some instances, a recent- ly published study showed an increased risk of breast cancers with chronic doxycycline therapy. This should create sufficient concern to make omega-3 fatty acids the primary choice in all patients without contraindications (platelet abnormalities, anticoagulant therapy and high dose aspirin therapy).

Omega-3 fatty acid therapy has become standard in the treatment of dry eye, gives the clinician an excellent, natural therapy that can be used indefinitely to help the patient maintain a normal, healthy ocular surface and general overall health.

Know your fish

Though fish oil supplements are an excellent source of OM3s, many experts believe natural sources provide the most benefit. Foods rich in OM3s include flaxseed, walnuts, wheat germ and fish. There are other benefits to eating fish, as well. Fish is a high-protein, low-fat food rich.

While white fish are particularly low in fat, oilier fish are high in OM3s. However, many of your patients may have questions about the safety of eating fish. It can be contaminated with substances like heavy metals (mercury and lead), industrial chemicals (PCBs) and pesticides (DDT). These contaminants build up in the body over time and can pose a range of health risks from hard-to-detect changes to birth defects. Children and women of childbearing age may be particularly susceptible. Studies show it can take five to six years for women to rid their bodies of PCS and 12-18 months to reduce their mercury levels.

So, what do you tell patients when they ask you which fish is safe? There are some general guidelines and resources available.

Fish that are high in OM3 and low in contaminants include wild salmon, Atlantic mackerel, sardines and farmed oysters. Wild striped bass, a popular fish today, tends to be high in PCBs because it is often found in contaminated rivers and estuaries.

Raw oysters, clams and other shellfish are filter feeders, straining particles on the sea floor for food. If the water contains disease-causing bacteria, the fish will accumulate it. Also, tuna, mackerel, bluefish and mahimahi begin to decompose very quickly and must be stored properly to avoid bacterial development. Check all fish carefully for bruises or brown spots that indicate decomposition.

Because mercury binds to the proteins in fish tissue, no amount of preparation can reduce those levels. However, cooking methods can also reduce the levels of chemicals and pesticides in fish. Removing the skin, fat and internal organs prior to cooking fish greatly reduces risk of chemical exposure. Avoid frying fish as this cooking method seals in chemical pollutants that. Also be sure to let the fat drain away.

Advise patients to heed local/national fish advisories and buy fish from a reliable source. You and your patients can also check with the Food and Drug Administration (FDA) and Environmental Protection Agency (EPA), the government agencies responsible for monitoring the safety of the nation's food supply.

References available on request.

Dr. Thimons is a nationally and internationally acclaimed speaker and serves as medical director at Ophthalmic Consultants.



Optometric Management, Issue: July 2005