Contrast Sensitivity and Optical Quality of the Eye after Instillation of Timolol Maleate Gel-Forming Solution and Brinzolamide Ophthalmic Suspension

Abstract

To investigate the influence of timolol maleate 0.5% gel-forming solution and brinzolamide 1% ophthalmic suspension on contrast sensitivity, ocular higher-order aberration (HOA), and corneal surface light scattering. Prospective, comparative study. Forty normal volunteers were enrolled in this study. We evaluated contrast sensitivity, ocular HOA, and corneal light scattering before and 2, 5, 10, and 15 minutes after instillation of antiglaucoma eyedrops. Contrast sensitivity function was assessed with the CSV-1000RN chart (Vector Vision Co., Greenville, OH). Higher-order aberration was measured for a 4-mm pupil using the Hartmann-Shack aberrometer (KR-9000PW; Topcon, Tokyo, Japan). Corneal surface light scattering was quantitatively evaluated by using the Scheimpflug camera (EAS-1000, Nidek, Aichi, Japan). Time course of changes in contrast sensitivity, ocular HOAs, and corneal light scattering. Both timolol gel-forming solution and brinzolamide significantly decreased contrast sensitivity for at least 5 minutes after instillation (P<0.01). There were no significant differences in contrast sensitivity between the drugs at any time points. Higher-order aberration, such as third- and fourth-order aberrations and total HOAs, significantly increased after instillation of each drug (P<0.001). Timolol gel-forming solution significantly increased HOA up to 5 minutes after instillation (P<0.05), whereas brinzolamide significantly increased HOA for at least 2 minutes after instillation (P<0.001). Corneal surface scattering significantly increased for 5 minutes after instillation of brinzolamide (P<0.01), but not after instillation of timolol gel-forming solution. Both drugs temporarily deteriorate contrast sensitivity function and optical quality of the eye. However, the mechanism underlying contrast sensitivity reduction seems to be different between the drugs. The reduction may be mainly attributed to increased HOA after instillation of timolol gel and increased light scattering after instillation of brinzolamide. The authors have no proprietary or commercial interest in any materials discussed in this article.