The effect of filters and varying illumination on contrast sensitivity in eyes with moderate to severe visual impairment

Abstract

Purpose: To investigate the effect of filters and illumination on contrast sensitivity in persons with cataract, pseudophakia, maculopathy and glaucoma to provide a guide for eye care providers in low vision rehabilitation.Materials and methods: A within-subjects experimental design with a counter-balanced presentation technique was employed in this study. The contrast sensitivity of eyes with cataract, pseudophakia, maculopathy and glaucoma were measured with filters (no filter, yellow, pink and orange) combined with increasing illumination levels (100lux, 300lux, 700lux and 1000lux) using the SpotChecksTM contrast sensitivity chart. The data was analyzed using descriptive statistics and two-way repeated measures ANOVA.Results: The yellow filter in combination with 100lux significantly (p<0.01) improved contrast sensitivity by approximately 6.5% among eyes with cataract. There was also a significant interaction between illumination and filters, with Huynh-Feldt correction, F (7.20, 230.23) = 2.06, p=0.04. Eyes with pseudophakia performed best at 1000lux with or without filters. In eyes with maculopathy, the yellow filter combined with 300lux gave the best improvement in CS from 1.33-1.45logCS (p=0.01). Illumination of 1000lux without a filter improved CS best in eyes with Glaucoma.Conclusion: The effect of filters and illumination on contrast sensitivity is dependent on the cause of contrast sensitivity loss. Eye care professionals must consider the underlying cause of visual impairment if patient specific care is to be rendered.