Abstract
Purpose: :
It is well known that topical application of timolol gel-forming solution causes blurred vision. Quality of vision and optical quality of the eye after instillation, however, have not been examined in detail. We conducted the current study to investigate sequential changes in ocular higher-order wavefront aberrations and contrast sensitivity after instillation of 0.5 % timolol gel-forming solution.
Methods: :
In 20 eyes of 20 normal subjects (mean age, 22.8 ± 4.2 years old), ocular wavefront aberration and contrast sensitivity were assessed before and 2, 5, and 30 minutes after instillation of 0.5 % timolol gel-forming solution. Ocular higher-order aberration for a 4-mm pupil was measured with the Hartmann-Shack wavefront analyzer every second for 10 seconds, and the root-mean-square (RMS) of the third-order, fourth-order, and total higher-order aberrations were determined. From the time-course of changes in higher-order aberration for 10-second, the stability index and fluctuation index were calculated. Stability index (SI) was defined as the slope of the linear regression line of the higher-order aberrations. Fluctuation index (FI) was defined as the average of the standard deviation of higher-order aberrations. Contrast sensitivity was evaluated at four spatial frequencies; 3, 6, 12, and 18 cycles per degree, and the area under the log contrast sensitivity function (AULCSF) was calculated.
Results: :
Total higher-order RMS significantly increased 2 and 5 minutes after instillation (P < 0.05, paired t-test), but returned to the baseline level 30 minutes after instillation. AULCSF was significantly reduced 2 and 5 minutes after instillation (P < 0.01 and P < 0.05, respectively), but recovered to the baseline level thereafter. The induced changes in AULCSF showed significant correlation with changes in total higher-order RMS (Pearson, r = -0.421, P < 0.05). FI increased significantly 2 minutes after instillation (P = 0.0001), and then returned to the pre-instillation level. SI showed no significant changes throughout the study period.
Conclusions: :
Instillation of timolol gel-forming solution temporarily increases ocular higher-order aberrations, leading to reduction in contrast sensitivity.
Keywords: aberrations • contrast sensitivity • drug toxicity/drug effects