Contrast Sensitivity Improvement with Yellow Filter in Low Vision Patients

摘要

OBJECTIVES: To measure the effects of yellow filter on contrast sensitivity in patients with low vision.STUDY DESIGN: A descriptive cross sectional study.PLACE AND DURATION: The study was carried out in the LVD of Al Shifa Trust Eye Hospital from 1st July to 31st December 2015.METHODOLOGY: One hundred and ten patients from low vision department with decreased contrast were selected and Visualacuity of all the patients was measured using Early Treatment Diabetic Retinopathy Study (ETDRS) chart at a distance of 4 meters.The contrast sensitivity was measured with Pelli Robbson chart with full optical correction on place. Then, a yellow filter wasapplied on the existing optical correction if any, and the contrast sensitivity was again measured.RESULTS: Median score for the contrast sensitivity without yellow filter (Med=7.00) was statistically lower than the median score(Med=8.00) for the contrast sensitivity with yellow filters. So the Wilcoxon Sighned Rank test revealed a statistically significantimprovement in contrast sensitivity with Z=-6.885, p<0.001, with a large effect size (r=0.66). In retinitis pigmentosa, contrast of69% of patients was improved after measuring it with the yellow filter. All participants with pathological myopia showed significantresults. There was no improvement in contrast sensitivity in participants with Albinisim and Stargardt’s disease. In Glaucoma,Diabetic retinopathy and in Macular scaring there was significant improvement.CONCLUSION: A significant improvement in contrast sensitivity was seen with yellow filters in low vision patients. The contrastsensitivity of patients with Retinitis Pigmentosa, Pathological Myopia, Glaucoma, Macular Scaring and Diabetic Retinopathy wasimproved significantly with yellow filter.