Impact of cataract on the results of frequency-doubling technology perimetry

Abstract

Purpose To determine the effect of cataract on the results of frequency-doubling technology (FDT) perimetry. Design Consecutive cohort study. Participants Forty-four patients with normal ophthalmic examinations, with the exception of cataract, scheduled to undergo phacoemulsification and posterior chamber lens implantation were prospectively identified and completed the study. Methods All subjects underwent FDT perimetry using the full-threshold C-20 strategy. Both eyes were tested within 1 month before cataract surgery and up to 3 months after surgery. The unoperated fellow eyes served as controls. Main outcome measures Changes in visual acuity (VA), mean deviation (MD), and pattern standard deviation (PSD) were evaluated. For each subject, the change in MD and PSD in the eye that underwent cataract surgery was adjusted for change in the control eye that is thought to occur due to a learning effect. Results Among the eyes that underwent cataract surgery, the median preoperative VA was 20/60 (range, 20/30–20/800) and the mean preoperative MD was −4.00±3.72 decibels (dB). Postoperatively, the median VA improved to 20/30 (range, 20/20–20/70) and the mean postoperative MD was −0.26±3.09 dB ( P<0.001). Among the control eyes, MDs were −1.74±3.71 dB preoperatively and −0.94±3.85 dB postoperatively ( P = 0.019). The adjusted improvement in MD among eyes that underwent cataract surgery was 2.94±3.44 dB ( P<0.001). There was no significant change in PSD. Preoperative VA correlated significantly with preoperative MD ( r = 0.39, P = 0.01). The improvement in VA correlated significantly with the adjusted improvement in MD ( r = 0.38, P = 0.01). Conclusions Cataract has an adverse effect on the MD but not the PSD in FDT perimetry. Among eyes with visually significant cataract, the MD correlates significantly with VA. After cataract surgery, the change in VA correlates significantly with the adjusted change in MD.