A clinical study of contrast sensitivity and visual acuity in patients following retinal photocoagulation for diabetic retinopathy

This study is aimed to assess the effect of retinal photocoagulation on contrast sensitivity and visual acuity.In this prospective observational study,patients with diabetic retinopathy in either one or both eyes requiring retinal photocoagulation were included in the study. Eyes which were subjected to treatment for diabetic retinopathy were divided into 3 groups. Group 1 included eye which were subjected to pan retinal photocoagulation (PRP) alone, Group 2 included eyes which were subjected to PRP and macular laser (ML) and Group 3 included eyes which were subjected to ML alone. Assessment of visual acuity and contrast sensitivity were done before and three months post retinal photocoagulation.Descriptive statistics were used and where required. paired t test, One- way, ANOVA, Post HOC tests, Tukey HSD tests were used. The sample size was calculated to be 64 eyes. Total of 64 eyes of 37 patients, underwent retinal photocoagulation for diabetic retinopathy. Out of the 37 patients, only 16 patients (29 eyes) came for follow up at the end of 3 months of laser photocoagulation. Number of eyes requiring PRP was more when compared to PRP with ML and ML alone. Pre-laser and post-laser visual acuity following PRP, remained unchanged. Improvement in visual acuity was seen in eyes that underwent ML alone. There was worsening of visual acuity in eyes that underwent combination of PRP and ML. However, p value was not significant. Pre-laser and post-laser contrast sensitivity, improved in eyes that underwent only PRP and macular laser alone. There was a reduction in CS when both forms of treatment were combined, though p value was not significant Eyes which underwent PRP alone, showed improvement in contrast sensitivity without any change in visual acuity. While reduction in visual acuity and contrast sensitivity was observed in eyes which underwent combination treatment (PRP and ML), there was improvement in visual acuity and contrast sensitivity in eyes which underwent macular laser alone. Contrast sensitivity is necessary component of visual function. Abnormal contrast sensitivity can affect day to day activities. Hence it is important to counsel patients about the possibility of contrast sensitivity being affected to some extent following laser treatment for diabetic retinopathy.