Abstract
Abstract: :
Purpose: To assess the effect of PCO (Posterior Capsule Opacification) on colour contrast sensitivity. Introduction: Achromatic contrast sensitivity can be affected by PCO. However, the effect of PCO on colour contrast sensitivity is less well known. We assessed this variable further. Methods: Thirty eyes in 30 pseudophakic patients with symptomatic PCO requiring YAG laser capsulotomy were recruited for the study. Eyes with any other ocular disease were excluded. EDTRS visual acuity, achromatic contrast sensitivity and colour contrast sensitivity were measured in each patient and compared with readings taken 2 weeks after YAG laser capsulotomy. Achromatic contrast sensitivity was measured using sinusoidal gratings of 0.33, 0.66, 2.20, 3.40, 10 and 17cpd. Colour contrast sensitivity was measured along the red/green (constant S-cone) and tritan (constant L/M-cone) confusion axes. Both tests were carried out using a sensitive computer controlled cathode-ray-tube-based system. Results: After laser capsulotomy, there was a statistically significant improvement in EDTRS visual acuity by 0.26 LogMAR units. Achromatic contrast sensitivity and colour contrast sensitivity also improved significantly. After capsulotomy, contrast sensitivity changes were more marked along the tritan axis than the red/green axis. Conclusion: PCO decreases the ability of the human eye to differentiate between colours. The fact that short wavelength light is subject to greater scatter than longer wavelengths may explain why the tritan axis is affected more than the red/green axis. Reduced colour contrast sensitivity is a significant variable that should be considered alongside changes in visual acuity and achromatic contrast sensitivity when assessing patients with PCO.
Keywords: 522 posterior capsular opacification (PCO) • 362 color vision • 368 contrast sensitivity