Prostaglandin analogues show similar ocular surface tolerability at 3 months

William B. Trattler

Prostaglandin analogues were similarly acceptable to the ocular surface in patients with open-angle glaucoma or ocular hypertension, according to a study.

The agents yielded similar scores on objective clinical measurements for 3 months.

Switching prostaglandin analogues is not an effective strategy for treating glaucoma patients with concomitant ocular surface conditions, William B. Trattler, MD, the corresponding study author, said in an interview with Ocular Surgery News.

“[Rather] one should focus on treating the underlying cause,” Dr. Trattler said. “For example, using topical azithromycin, warm compresses and lid hygiene can be effective in glaucoma patients with ocular surface disease related to blepharitis. Just switching from one prostaglandin agent to another will not magically fix their problem.”

“In addition, prostaglandin analogues such as Xalatan, Lumigan or Travatan Z remain safe and effective when used in combination with other medications, such as topical cyclosporine, topical azithromycin and other medication used to treat ocular surface disease,” Dr. Trattler, an OSN SuperSite Board Member, said.

The study was published in the Journal of Ocular Pharmacology and Therapeutics.

Hypothesis and methods

Glaucoma medications are commonly associated with ocular surface discomfort, so the study authors compared the ocular surface tolerability of Xalatan (latanoprost 0.005%, Pfizer), Lumigan (bimatoprost 0.03%, Allergan) and Travatan Z (travoprost 0.004%, Alcon).

The authors set out to determine the benefits, if any, of switching from a glaucoma medication with the preservative benzalkonium (BAK) to one with sofZia. Latanoprost is preserved with 0.02% BAK, and bimatoprost is preserved with 0.005% BAK. Travoprost is preserved with sofZia.

“The question is whether changing the preservative to a preservative that’s not BAK has any obvious benefit to patients,” Dr. Trattler said. “If patients are using one product vs. another, is there a difference as far as the ocular surface health?”

The randomized study included 106 patients with open-angle glaucoma or ocular hypertension who had previously used latanoprost alone for a minimum of 4 weeks. At baseline, 35 patients received bimatoprost, 38 patients received latanoprost and 33 patients received travoprost. All medications were administered once daily.

Investigators conducted follow-up examinations at 1 week, 1 month and 3 months. Physician-graded conjunctival hyperemia, corneal fluorescein staining and tear breakup time were measured at baseline and all follow-up points.

Mean baseline conjunctival hyperemia values were 0.74 in the bimatoprost group, 0.74 in the latanoprost group and 0.86 in the travoprost group.

Baseline corneal staining values were 0.59 in the bimatoprost group, 0.70 in the latanoprost group and 0.48 in the travoprost group.

Baseline tear breakup times were 9.1 seconds in the bimatoprost group, 8.6 seconds in the latanoprost group and 7.9 seconds in the travoprost group.

The differences between baseline values for each outcome measure were statistically insignificant.

Outcomes and observations

At 3 months, conjunctival hyperemia values were 0.80 in the bimatoprost group, 0.74 in the latanoprost group and 0.98 in the travoprost group.

Final corneal staining values were 0.71 in the bimatoprost group, 0.47 in the latanoprost group and 0.36 in the travoprost group.

Final tear breakup times were 9.7 seconds in the bimatoprost group, 9.2 seconds in the latanoprost group and 9.7 seconds in the travoprost group.

The differences between 3-month values were statistically insignificant for each outcome.

“We found that over 3 months, all of the drops were pretty similar in how they affect the ocular surface,” Dr. Trattler said. “There’s no benefit from switching from one to another or being on one vs. another. I think that’s due to the fact that the BAK levels in both Xalatan and Lumigan are very low. It may also be that even though the sofZia preservative in Travatan is different than BAK, it may not necessarily be less toxic or irritating.”

Bimatoprost afforded the greatest reduction in IOP, followed closely by travoprost, Dr. Trattler said.

All three medications had similar effects on subjective patient comfort outcomes.

Further study of ocular surface tolerance to prostaglandin analogues is warranted, the researchers said. – by Matt Hasson

Reference:

• Whitson JR, Trattler WB, Williams J. Hollander DA. Ocular surface tolerability of prostaglandin analogs in patients with glaucoma or ocular hypertension. J Ocul Pharmacol Ther. 2010;26(3):287-292.

• William B. Trattler, MD, can be reached at Center for Excellence in Eye Care, 8940 N. Kendall Drive, #400, Miami, FL 33176; 305-598-2020; fax: 305-274-0426; e-mail: wtrattler@gmail.com. Dr. Trattler does consulting for, receives research support from and is on the speaker’s bureau for Allergan.

This study provides valuable information on an important topic. It would be interesting for the authors to perform this study on a subset of dry eye patients, as most glaucoma patients are older than 40 years, and a significant percentage of them also have ocular surface disease. In patients with ocular surface disease, the outcomes may be different.

It would also be interesting to include psychometric testing in the next study (and the subset study), as patient intolerance is really the bottom line; it is intolerance that leads to noncompliance.

– Marguerite B. McDonald, MD
OSN Refractive Surgery Board Member