September 2010

 

COVER FEATURE

 

IOLs

Assessing artificial tears for dry eye


by Vanessa Caceres EyeWorld Contributing Editor

   

No clear winner in tear treatment

There is no artificial tear yet that is perfect for all dry-eye patients. That's the conclusion that a number of dry-eye specialists make as they continue to try the expanding realm of tear productions available with their patients. "It is difficult to make an objective case that one type of product is superior over another, especially for so-called different types of dry eye," said Michael J. Doughty, Ph.D., professor, Department of Vision Sciences, Glasgow-Caledonian University, Glasgow, Scotland. Dr. Doughty recently co-authored a review article comparing artificial tears. "The overriding issue is what a patient can find acceptable to use, how well they tolerate it, and hopefully that it exerts some improvement in the health of the ocular surface," he said.

"A lot of [artificial tear] studies show failures or successes, and we're not sure how to interpret them," said Robert Latkany, M.D., founder and director, Dry Eye Clinic, New York Eye and Ear Infirmary, New York. "Not everyone is dry for the same reason. There are people who are dry from sitting at the computer, contact lens use, Sjogren's syndrome, LASIK, and diabetes, and they're not all the same We need to spend more time understanding the disease and its specific components," he said.

Some research also shows that patients do not find artificial tear treatment that helpful in relieving their dry-eye symptoms. A poster at the Association for Research in Vision and Ophthalmology (ARVO) meeting in Fort Lauderdale earlier this year found that only 26% of 766 dry-eye patients seen at 40 different sites were somewhat or very satisfied with their current dry-eye treatment. Of this group, 23% of patients reported using artificial tears more than five times a day.

The patients are part of a multicenter observational study called RESTORE, conducted by Allergan (Irvine, Calif.), Strategic Healthcare Solutions (Monkton, Md.), and MedNet Solutions (Minnetonka, Minn.).

Despite the range of artificial tears available, there are not many head-to-head studies comparing the effectiveness of these products, said Dr. Doughty, whose review article was published last year in Ophthalmic and Physiological Optics. "The actual number of clinical studies that could be used to make comparisons was rather fewer than I expected," he said. "Before starting to search the topic, I assumed there were countless studies documenting the efficacy of artificial tear treatment." In his article, Dr. Doughty and co-investigator Sara Glavin reviewed the outcome of clinical studies where rose bengal staining was used to evaluate the efficacy of artificial tear use in dry-eye patients. They found 33 suitable studiesof these, there was an overall average improvement of about 25% with tear use, with no clear statistical difference between products. The investigators focused on a 30-day baseline to follow-up time period to evaluate the effects of the tears.

"I hope that the sort of standardization I have attempted can be useful to people planning future studies and to anyone else trying to make comparisons," Dr. Doughty said.

Tear use

So, considering no specific tear product has been proven effective for everyone with dry eye, how are specialists suggesting patients use tears? Many times, patients have already tried artificial tears by the time they see a specialist, said Esen K. Akpek, M.D., associate professor of ophthalmology, and director, Ocular Surface Diseases and Dry Eye Clinic, Wilmer Eye Institute, Johns Hopkins University, Baltimore. If the patient finds some relief with the product they have and uses it less than three times a day, Dr. Akpek suggests they continue to use that particular product. If they have not tried a tear product but their condition seems mild, she will give samples of whatever tear she has readily available.

Dr. Akpek moves on to ointments or the Lacrisert insert (hydroxypropyl cellulose ophthalmic insert, Aton Pharma, Lawrenceville, N.J.) if the patient uses tears more than once an hour and has more severe signs of disease.

Similarly, Dr. Doughty looks for minimal ocular surface signs that indicate associated tear film volume deficiency or instability before discussing tears. He also confirms whether the patient should instead implement lid hygiene measures due to meibomian gland dysfunction.

Because of the nature of his practice, which specializes in dry eye, Dr. Latkany has a slightly different approach. "I've never been one to jump right into artificial tears, but I don't usually see patients initially," he said. By the time they come to him, many patients have already seen as many as 10 other physicians for their symptoms. "I always try and look for why they are dry." That could mean recommending tears, ointments or gels, prescription medications, punctal plugs, goggles, or even alternative therapies such as acupuncture.

Tear advances

Some recent advances are helping dry-eye specialists better understand artificial tears. A study published online in Cornea in February and led by Yan Wang, M.D., Eye and ENT Hospital of Fudan University School of Medicine, Shanghai, China, reported on the use of optical coherence tomography (OCT) to evaluate changes to the lower tear meniscus after the instillation of artificial tears. Dr. Wang and co-investigators found that tears provide a significant but temporary improvement in the tear meniscus. A significant increase in the lower tear meniscus area was found at 1 minute post-instillation of tears, with a return to baseline levels at 5 and 10 minutes. However, the study group that had carboxymethyl cellulose 1% instilled versus carboxymethyl cellulose 0.5% had a larger increase in tear meniscus area and height.

A poster presented at this year's ARVO meeting also tracked the use of OCT to study the longitudinal effect of the instillation of artificial tears on tear meniscus volume. Tear meniscus height, depth, and area increased by 212%, 488%, and 2212%, respectively at 1 minute after artificial tear instillation. "The time to depletion of half of the gains in tear meniscus were 2.75 minutes, 4.75 minutes, and 2 minutes for height, depth, and area, respectively," reported lead study investigator M.C. Bujak, Doheny Eye Institute, University of Southern California, Los Angeles. "Optical coherence tomography may serve as an invaluable tool in objectively quantifying the efficacy of dry eye treatments," the study investigators concluded.

Although the transient gain provided by tears does not surprise Dr. Latkanyhe found similar results a few years backhe'd like to see more studies use OCT to study the effects of tears.

"You'll see more of this. I'd love to look more into it and see how accurate it is. Accuracy and reproducibility will always be questions in my mind," he said.

The Lacrisert insert product that takes the artificial tear concept a step further is also attracting attention. The insert works like a "slow-release artificial tear" that can used once or twice daily, according to the product's website. Patients position it in the lid margin, and the product dissolves, releasing moisture as needed. It is recommended for patients with moderate to severe dry eye. Dr. Akpek has found success with Lacrisert in patients with severe dry eye who find little relief from tears and need some sort of sustained release. Most of her patients who have used Lacrisert find it provides relief for 6 to 8 hours. The Web site notes that some patients may feel as if they have something in their eye; a foreign body sensation may indicate the insert is not correctly placed in the eye. Sometimes, adding an artificial tear may help relieve that sensation, according to the Web site.

Editors' note: Dr. Latkany has financial interests with Alcon (Fort Worth, Texas) and Allergan (Irvine, Calif.). Dr. Doughty has no financial interests related to his comments. Dr. Akpek has financial interests with Allergan.

Contact information

Akpek: 410-955-5494, esakpek@jhmi.edu
Doughty: m.doughty@gcal.ac.uk
Latkany: 212-689-2020, relief@dryeyedoctor.com

Assessing artificial tears for dry eye Assessing artificial tears for dry eye
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