Contrast sensitivity following focal laser photocoagulation in clinically significant macular oedema due to diabetic retinopathy.

PURPOSE: To evaluate the influence of focal aser photocoagulation on contrast sensitivity in diabetic patients with clinically significant macular oedema (CSMO).
METHODS: A prospective non-comparative interventional study was performed on a group of patients with CSMO at Dr Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, a tertiary eye care centre. Thirteen diabetc patients (14 eyes) with CSMO and no history of prior photocoagulation were recruited for this study. Direct focal photocoagulation of all leaking microaneurysms was performed using an argon green laser (514 nm). A contact lens was used as a slit lamp delivery system. Evaluation of the best corrected Snellen visual acuity, contrast senstivity, slit lamp biomicroscopy, macular status on direct ophthalmoscopy and fluorescein angiography was carried out 1 month and 3 months after laser photocoagulation.
RESULTS: Following direct focal laser photocoagulation, focal CSMO resolved completely in all but one eye, 4-8 weeks later, as seen on slit lamp biomicroscopy and/or fluorescein angiography. Post-treatment, visual acuity remained stationary in eight eyes, improved by one line in three eyes, by two lines in two eyes and by three lines in one eye. The mean +/- SD pretreatment and post-treatment decimal visual acuities were 0.49+/-0.30 and 0.59+/-0.28, respectively. The mean +/- SD pre-laser contrast sensitivity score was 121.3+/-83.6, which increased significantly to a mean +/- SD of 151.6+/-80.5 fo lowing direct focal photocoagulation.
CONCLUSION: Focal argon laser photocoagulation in CSMO in diabetics helps in improving the contrast sensitivity and stabilizes the visual acuity. The changes in contrast sensitivity and visual acuity are independent of each other.