GMC tear garners patient preference

August 15, 2006

At 1 week, three-fourths of patients noted a difference in the soothing effect of the drops.

Fort Lauderdale, FL-Results of a randomized, double-masked, paired-eye comparison study show patients with dry eye prefer a carboxymethylcellulose (CMC)-based artificial tear product (Refresh Tears, Allergan) over one formulated with propylene glycol, polyethylene glycol, and hydroxypropyl (HP) guar (Systane, Alcon Laboratories), reported Milton M. Hom, OD, FAAO, at the annual meeting of the Association for Research in Vision and Ophthalmology.

The multicenter study enrolled 55 patients who were randomly selected to instill one of the two mid-viscosity lubricant drops in one eye and the alternate product contralaterally three times a day for 1 week. Five minutes after instilling the first treatment, patients were asked to rate features relating to comfort, efficacy, and tolerability as well as overall product preference. In that initial assessment, the majority of patients noted differences between drops, and among those individuals, the ratings consistently favored the CMC product.

When asked again to rate their experiences at the end of the study, 5 minutes after instilling the last drop, all of the assessments showed statistically significant differences favoring the CMC product.

To be eligible for study inclusion, patients had to be at least 18 years old and have a history of dry eye symptoms treated previously only using artificial tears. Patients were excluded if they presented with active ocular infection or inflammatory disease or if they were contact lens wearers.

The patients had a mean age of about 46 years and were about two-thirds female. In addition, about two-thirds reported moderate symptoms of dry eye, while with a few exceptions, the rest were bothered by mild symptoms.

At the initial assessment, 66% of patients found a difference between eyes in blurring and a statistically significant majority of those individuals (70%) considered the HP-guar product more blurring. The results were essentially the same after 1 week.

A difference between products in stickiness was noted by about 85% of patients both initially and after 1 week. While the majority of patients, 58%, found the HP-guar product to be the stickier of the two upon the first administration, the difference was not statistically significant. After 1 week, however, there was a statistically significant product-related difference because the patients considering the HP-guar product as stickier outnumbered those who rated the CMC product as more sticky by 2:1.

When asked about the soothing properties of their drops, 57% of patients initially found a difference and 58% of those patients rated the CMC product as more soothing. That benefit was not statistically significant, but at 1 week, almost three-fourths of patients noted a difference in the soothing effect of the drops and almost three-fourths of those individuals favored the CMC product.

After the first instillations, about 70% of patients expressed a preference for one product over the other, and a slight majority of those individuals favored the CMC solution. At 1 week, 80% of patients had a product preference, and two-thirds of them favored CMC.

Patients were also asked to rate dryness and crusting, but there were no statistically significant differences between products in those measures. One patient did discontinue CMC use because of stinging.

"The key behind artificial tears is residence time," Dr. Hom said. "Most of today's drops accomplish this with increased viscosity. The HP-guar drop increases viscosity when triggered by the pH shift from bottle to eye.

"Nonetheless, it is still the same basic viscosity play we see in other drops," Dr. Hom added. "We wanted to compare the HP-guar drop against CMC to see if there were really any differences between the two. Many times, the bottom line is the patient responses."