Abstract
Abstract: :
Purpose: Brinzolamide and dorzolamide, topical carbonic anhydrase inhibitors (CAI), are used to treat many kinds of glaucoma. Because topical brinzolamide is an emulsion, patients often feel transient blurred vision after instillation. The aim of this study was to compare brinzolamide with dorzolamide in regard to blurred vision after instillation. We also compared saline with two topical CAI drugs. Methods: The study population comprised 21 healthy volunteers ranging in age from 23 to 46 yrs. (35.6 ± 6.9 yrs. Mean ± SD). None had a history of external eye diseases or subjective sensations such as itching, foreign body sensation or burning; their best corrected visual acuity was 20/20 or better. Brinzolamide 1% or dorzolamide 1% was applied to one eye; the contralateral eye was exposed to the other drug. At 30 sec after instillation, visual acuity was measured every 30 sec until best visual acuity was recovered. Because visual acuity can fluctuate widely with blinking, subjects blinked for 5 sec before visual acuity measurement. As control, we applied saline alone to both eyes and measured the change in visual acuity in the same way. Subjective sensations in each eye were recorded after measurement. Results: Average visual acuity (logarithm of minimum angle of resolution [logMAR]) at every 30 sec until 5 min was 0.54, 0.38, 0.22, 0.16, 0.09, 0.04, 0.03, 0.03, –0.03 and –0.04 after brinzolamide instillation, and 0.39, 0.25, 0.17, 0.06, 0.06, 0.02, –0.02, –0.03, –0.05 and –0.05 after dorzolamide instillation. In contrast, the average visual acuity after saline instillation until 2 min was –0.04, –0.05, –0.06 and –0.06. Of the 21 subjects, 15(71.4 %)felt moderate or severe irritation when dorzolamide was instilled; 2(9.5 %)felt moderate or severe irritation when brinzolamide was instilled. Conclusions: Both brinzolamide and dorzolamide caused significantly prolonged vision blurring, from 30 sec to 3 min after instillation, as compared with saline only. With brinzolamide, however, the blurring was significantly more severe than with dorzolamide at 1 min after instillation. Judging from subjects’ sensations, it is suggested that with dorzolamide the prolonged blurred vision was due to reflex tearing from irritation as explained above, whereas with brinzolamide it was due to opaque tear.
Keywords: drug toxicity/drug effects • visual acuity • clinical (human) or epidemiologic studies: outcomes/complications