M. Reza Dana, M.D., M.P.H., M.Sc., Director of Cornea and Refractive Surgery Services at the Massachusetts Eye and Ear Infirmary (MEEI) Cornea Service and colleagues at Schepens Eye Research Institute conducted a study using topical eye drop applications to relieve symptoms of DES.
Dana says his research shows that topical eye drops containing a fatty acid people can't make inside their bodies could be the key to solving some patient's extreme dry eye problem.
People with DES don't produce enough tears to keep their eyes from becoming dry, irritated and sometimes inflamed.
And tears are important are important, according to a statement on the Mayo Clinic website.
"Tears are much more than just water. They're a complex mixture of water, fatty oils, proteins, electrolytes, bacteria-fighting substances and growth factors that regulate various cell processes. This mixture helps make the surface of your eyes smooth and clear. Without tears, good vision is impossible," the statement says.
Vision problems caused by a lack of tears is often what prompts people to seek help from their doctor. More than 10 million people in America alone suffer from DES, which often causes people trouble when they try to read or drive.
Eye discomfort from DES includes such things as stinging, burning or a feeling of scratchiness - all tip offs to people that their dry eyes might need medical attention. In fact, DES is the leading condition that causes patients to go see their eye doctor.
However, Dana says that treatment options have been limited because some treatments haven't worked very well while others caused side effects.
Dana said his research showed that using an application of alpha-linolenic acid (ALA) resulted in significantly decreasing signs of dry eye syndrome DES in animal studies using mice.
ALA is a fatty acid that can't be made in the body, but it is necessary for human health and must be supplied in the diet. Since it is a necessary fatty acid, using it in topical eye drops did not introduce anything foreign to the body.
Dana agreed to an email question and answer interview with AHN media.
The questions that AHN asked about the dry eye syndrome study along with Dana's answers follow.
Q. Has the problem of dry eyes gotten significantly worse over the years? If so, since when and have you noticed any trends?
A. "There are no data trends available. The best systematic studies on the prevalence of dry eye using large Harvard cohorts suggest that the prevalence is much higher than previously thought (Schaumberg DA, Dana MR, Am J Ophthalmol, 2003 Aug; 136(2):318-26). Of note, the prevalence is higher in females as compared to males and increases with age.
"While there is no historic date to go by, there are certainly more reports of dry eye prevalence these days, most likely because of the use of computers and other work that requires sustained visual activity."
Q. You used mice in your research, how close are their eyes to ours?
A. "The dry eye animal model we used reproduced the clinical (human) dry eye with very high fidelity."
Q. What are some of the side effects of taking fatty acids orally?
A. "The main side effect of oral intake of fatty acid is gastrointestinal related, like diarrhea, abdominal bloating and pain. Acid reflux and indigestion has been reported as well. Increase in bad cholesterol (low-density lipoprotein) has also been reported.
"Omega-3 fatty acid when taken orally can decrease the platelet aggregation, thereby leading to increased risk of bleeding if taken in large amounts.
"Long-term oral use is also associated with Vitamin E deficiency."
Q. In a press statement you issued on your research you said the "study tested three formulations of fatty acids: 0.2 percent alpha-linolenic acid (an omega-3 fatty acid); 0.2 percent linoleic acid (an omega-6 fatty acid); and 0.1 percent alpha-linolenic acid combined with 0.1 percent linoleic acid. An eye drop containing each of the three formulations was applied topically to the eye of a mouse once daily. An untreated group did not receive eye drops."
Your statement continued saying, "Signs of dry eye were then measured 24 hours after the last dose. Eyes treated with ALA showed a significant reversal in epithelial damage to the cornea, the transparent dome that covers the pupil. Results show a beneficial effect of the topical application of ALA in reversing the signs of dry eye syndrome as well as the inflammatory changes seen in dry eye syndrome."
What was the source of the linoleic acid and the alpha-linolenic acid you used, I mean where did it come from and was it natural or synthetic? What are the differences between linoleic and alpha linolenic acid and why did you use both? What do they do?
A. "Both linoleic acid (LA) and alpha-linoleic acid (ALA) came from plant sources. Both LA and ALA are essential fatty acids, meaning that they cannot be synthesized in the human body and must be provided in the diet. ALA is omega-3 fatty acid and LA omega-6, based upon their structure. In general, omega-3 fatty acids are thought to be anti-inflammatory and omega-6 fatty acids pro-inflammatory. Epidemiological data shows a beneficial effect of oral intake of omega-3 fatty acid on dry eye. There have been few reports in literature as well about beneficial effect of oral intake of omegA-6 (LA) fatty acid in dry eye. Therefore, both LA and ALA were tested separately and as a combination."
Q. Your press statement says the eyes of the mice were checked 24 hours after they had drops and the drops were applied daily, but how many days did they get drops and how significant was the improvement? Do you know how long that improvement lasted or would the drops be needed every day forever?
A. "Depending on the time point studied, the mice either received eye drops for three days or eight days. At end of 8 days, mice receiving omega-3 eye drops showed 68 percent decrease in dry eye related corneal surface disease, and anywhere between 37 percent to 54 percent decrease in amount of inflammatory cells and mediators in the cornea, the clear part of the eye needed for transparent vision.
"The improvement lasted through the maximum duration of experiments (10 days). At this point, it is hard to comment if the drops would be needed for forever."
Findings from the study are published in the February 2008 issue of Archives of Ophthalmology.
