Fish oil supplements ineffective against dry eye: Study
Fish oil supplements do not ease the symptoms of dry eye, a condition that affects about one in seven U.S. adults, according to a new test of the treatment in hundreds of volunteers.
People who took 3,000 milligrams of omega-3 fatty acids each day for 12 months - the highest dose ever used in a trial of fish oil - experienced no more relief from their dry eye than a second group that received olive oil placebo capsules.
The findings were published online by the New England Journal of Medicine and reported at the annual meeting of the American Society of Cataract and Refractive Surgery in Washington, D.C.
Dry eye, also known as keratoconjunctivitis sicca, is estimated to cost the U.S. economy more than US$55 billion a year in medical care and lost productivity as people struggle to cope with the pain, itchiness, burning, fatigue and vision problems that occur when the surface of the eye becomes too dessicated.
"This study is significant because dry eye disease is a very common condition especially among women and older individuals, and is likely the most common reason to see an eye doctor," said Dr. Joann Kang of the division of ophthalmology and visual sciences at Montefiore Health System in New York in an email to Reuters Health.
The result "contradicts a popular and common treatment of dry eye disease as the study did not find any significantly better outcomes of patients treated with omega-3 fatty acids," said Kang, who was not involved in the research.
Other treatments doctors may recommend include over-the-counter lubricating eye drops, eyelid-cleansing regimens, tear duct plugs to slow the drainage of the eye's natural lubricant and two prescription drugs, including the widely-advertised Restasis prescription drops that cost more than US$500 a month. The other prescription drop, Xiidra, carries a similar price tag.
In contrast, fish oil therapy costs roughly US$30 to US$150 per month.
But even the highest dose of fish oil didn't produce more relief than placebo, according to the team from 27 sites, led by Maureen Maguire, a professor of ophthalmology at the University of Pennsylvania in Philadelphia.
All of the study's participants had been dealing with moderate to severe dry eye for at least six months, and were allowed to continue their current treatments during the fish oil trial. Neither patients nor their doctors knew which type of oil they were getting.
More than half the patients in both groups reported improvement in the symptoms yet fish oil consumers didn't score significantly higher than placebo recipients.
This illustrates that it's very difficult for clinicians to tell whether a treatment is being beneficial, Maguire said in a telephone interview, or whether it's random variability in the patient's condition from one week to the next, or the patient wanting to believe the treatment is working, that accounts for improvement.
Maguire said optometrists and ophthalmologists frequently suggest fish oil to their dry eye patients, although "many make the recommendation saying, 'I don't know if this will work, but you might try it.'"
How a patient will respond to a specific treatment, Maguire noted, "is really quite variable, which is one of the problems with this eye condition. Some people get relief from all of the various treatments, from lid hygiene to artificial tears, where different formulations work for different people. It's a difficult condition to manage."
Based on the new results, if patients are looking for relief of their dry-eye symptoms, she said, "they may want to look at other alternatives."