Abstract
Purpose::
To evaluate the short-term anesthetic properties and ocular tolerability of two commercially-available topical non-steroidal anti-inflammatory drugs (NSAIDs), ketorolac tromethamine ophthalmic solution 0.4% (Acular LS, Allergan, Inc., Irvine CA) and bromfenac ophthalmic solution 0.09% (Xibrom, ISTA Pharmaceuticals, Irvine, CA).
Methods::
20 healthy volunteer subjects with no active corneal pathology were studied. Baseline central corneal sensitivities were determined using the Cochet-Bonnet esthesiometer (CBE). A single drop of ketorolac and of bromfenac was then administered in random order and double-blind fashion to each subject, with a different drug in each eye. The subjects were asked to grade their discomfort on a scale from 0 to 3, corresponding to increasing severity of burning and stinging. Esthesiometry was re-measured in each eye at regular time intervals, until sensitivity returned to baseline levels.
Results::
13 of 20 (65%) subjects reported ocular discomfort after ketorolac; by contrast, discomfort was noted in only 3 of 20 (15%) eyes after bromfenac. The average discomfort score was 1.025 for ketorolac and 0.15 for bromfenac. Baseline corneal sensitivity as measured on the CBE was 6.0 for every study eye except one, which was 5.5. The average CBE reading at five minutes was 5.85 for all ketorolac eyes and 5.575 for all bromfenac eyes. Only 5 of 20 (25%) ketorolac eyes showed a measurable anesthetic effect after five minutes, versus 6 of 20 (30%) bromfenac eyes. When comparing only those anesthetic eyes, average corneal sensitivity was 5.5 for the ketorolac group and 4.6 for bromfenac. All five eyes with anesthesia from ketorolac recovered their baseline sensitivity at ten minutes. Three out of the six eyes with anesthesia from bromfenac also recovered by ten minutes. The remaining three of the anesthetic bromfenac eyes demonstrated prolonged recovery times, only returning to their baseline corneal sensitivity after 40, 80, and 135 minutes, respectively.
Conclusions::
In this study, ocular discomfort from bromfenac 0.09% was less frequent and less severe than from ketorolac tromethamine 0.4%. Measurable corneal anesthesia was demonstrated in only about 1/4 of subjects for each topical NSAID, respectively. When present, the anesthetic effect of ketorolac was mild and limited to less than ten minutes. Bromfenac's anesthetic effect, when observed, was more profound and often longer-lasting.
Keywords: drug toxicity/drug effects • cornea: clinical science