The instillation of bromfenac 0.09% (Xibrom, ISTA Pharmaceuticals) results in less severe and less frequent patient discomfort compared with ketorolac tromethamine 0.4% (Acular LS, Allergan). However, the anesthetic effect of either commercially available nonsteroidal anti-inflammatory drug was statistically equivalent.
"One effect of topical NSAIDs is to decrease corneal sensitivity. NSAIDs have been used to reduce pain after traumatic corneal abrasion," said Dr. Chou, a cornea and external disease subspecialist with Ophthalmic Consultants of Long Island, Rockville Centre, NY. "Their use has also become a common adjunct in alleviating pain following refractive surgery including PRK, LASEK, LASIK, and RK. NSAIDs appear to decrease the sensitivity of corneal nerves to noxious stimuli. Ketorolac is specifically indicated for relief of ocular pain and irritation following corneal refractive surgery and is the current standard NSAID prescribed for this purpose."
The drug bromfenac, he explained, was approved recently to treat inflammation associated with cataract surgery.
Some previously published studies have reported differences in the ability of commercially available topical NSAIDs to provide anesthetic effects. Other studies have reported differences in patient tolerance of the drugs. With those factors in mind, Dr. Chou and colleagues designed a study to compare the ocular tolerability and anesthetic effects of bromfenac and ketorolac.
A total of 20 healthy volunteers participated in the study. The sensitivity of the central cornea was measured at baseline using the Cochet-Bonnet esthesiometer. Each patient randomly received one drop of ketorolac in one eye and one drop of bromfenac in the fellow eye. Following application of the drops, the participants graded their discomfort on an increasing scale from 0 to 3, with 0 indicating no burning and stinging and 3 indicating extreme burning and stinging. The central corneal sensitivity was measured again in each eye at regular intervals until the corneal sensitivity returned to the baseline value, Dr. Chou explained.
He reported that 65% of the participants (13 of 20 subjects) reported ocular discomfort after ketorolac, while 15% (three of 20 subjects) reported ocular discomfort after bromfenac was instilled. The difference was statistically significant (p = 0.001). The average discomfort score was 1.025 for ketorolac and 0.15 for bromfenac, a difference that also reached significance (p = 0.002).
"The baseline central corneal sensitivity values for all eyes except one was 6.0. The average values after 5 minutes were 5.85 for eyes in which ketorolac was instilled and 5.58 for eyes in which bromfenac was instilled (p = 0.164). Only five of 20 (25%) eyes that received ketorolac and six of 20 (30%) eyes that received bromfenac had a measurable anesthetic effect. When considering only subjects who had a response to the drugs, the average corneal sensitivity at 5 minutes was 5.4 for eyes that received ketorolac and 4.6 for eyes that received bromfenac (p = 0.008). All eyes in which ketorolac was instilled recovered their baseline sensitivity by 10 minutes after instillation. Three eyes with bromfenac instilled had prolonged recovery times of 40, 80, and 135 minutes, but the differences did not reach significance (p = 0.074)," Dr. Chou reported.
The findings of this study were that ocular discomfort from bromfenac 0.09% occurred significantly less frequently and was less severe than discomfort that developed after instillation of ketorolac 0.4%. The average overall anesthetic response to each drop was not significantly different between the drugs. However, among patients who experienced anesthesia, the anesthetic effect of bromfenac was substantially more profound and tended to be longer lasting than that measured after ketorolac.