Nerve Fiber Layer Thickness in Eyes Treated with Red versus Green Laser in Proliferative Diabetic Retinopathy: Short-Term Results

PURPOSE: To evaluate changes of retinal nerve fiber layer (RNFL) thickness after panretinal photocoagulation (PRP) in red versus green laser-treated eyes. PROCEDURE: This is a prospective, randomized, fellow-eye controlled clinical trial conducted on 60 eyes of 30 patients (mean age 52.3 ± 7.8 years; 57% male) with early- to high-risk proliferative diabetic retinopathy type II diabetes who received standard red or green laser treatment. Scanning laser polarimetry (GDx) was performed to evaluate RNFL thickness at baseline and at week 6. RESULTS: Only 22 patients (44 eyes) could perform reliable GDx tests. At week 6 after PRP, the RNFL thickness increased by an average of 3.35 ± 9.18 µm (p = 0.02) and 2.08 ± 4.75 µm (p = 0.04) in the red and green laser groups, respectively. There was no significant correlation between changes in RNFL thickness and the number of laser burns, age, HbA1c or blood pressure. The difference in the change of the RNFL thickness between the red and green laser groups was not significant (p = 0.8). CONCLUSION: Though RNFL thickness was increased significantly 6 weeks after PRP with red and green laser in comparison to baseline, there was no significant difference in RNFL thickness between red and green laser groups.