Prolongation of activity of single intravitreal bevacizumab by adjuvant topical aqueous depressant (Timolol-Dorzolamide)

Abstract

Background: To evaluate the efficacy of timolol-dorzolamide drops used to decrease aqueous outflow from the eye on the prolongation of the biological activity of intravitreal bevacizumab.

Methods: Thirty-eight eyes of 38 patients with macular edema (ME) following retinal vein obstruction (RVO) were enrolled. These patients were randomly assigned into 2 groups: timolol-dorzolamide drops twice daily (n = 19) or no eyedrops (control; n = 19). All patients received 1.25 mg (in 0.05 mL) of bevacizumab intravitreally and were examined before treatment, 1 week after injection, and then every 4 weeks after injection. For each patient, visual acuity (VA), intraocular pressure (IOP), and central retinal thickness (CRT) by optical coherence tomography (OCT) were recorded before injection and at each visit after injection. The mean CRT at each timepoint was considered to directly reflect the biological activities of bevacizumab at those times.

Results: The mean CRT measured by OCT showed a significant decrease 1 week after treatment in both groups, and this difference was maintained for a total of 9 weeks (paired t-test, <0.001). The mean CRT at 1 week post-injection showed no significant between-group difference (p = 0.781). At 5 weeks post-injection, the timolol-dorzolamide group showed a significantly smaller mean CRT than the control group (p = 0.032). The difference in mean CRT between the 2 groups disappeared, however, at 9 weeks post-injection (p = 0.462). In both groups, VA improved significantly 1 week after injection, and these changes were maintained to 9 weeks post-injection in both groups. The mean VA of the 2 groups showed no difference at any time.

Conclusions: Timolol-dorzolamide aqueous depressant drops may delay the elimination of intravitreal bevacizumab but clinical efficacy of the eyedrops have not been proven in this study.