LONG-TERM TEMPORAL CHANGES OF PERIPAPILLARY RETINAL NERVE FIBER LAYER THICKNESS BEFORE AND AFTER PANRETINAL PHOTOCOAGULATION IN SEVERE DIABETIC RETINOPATHY

Abstract

Purpose: To analyze the long-term changes of peripapillary retinal nerve fiber layer (RNFL) thickness before and after panretinal photocoagulation (PRP) in patients with severe diabetic retinopathy. Methods: In this retrospective observational case series, we reviewed the records of 46 patients (68 eyes) with severe diabetic retinopathy, who were treated with PRP and could be followed for more than 6 months. Peripapillary RNFL thickness and foveal thickness were measured at baseline, 3-month intervals until 1 year post-PRP, and 6- to 12-month intervals after 1 year post-PRP using optical coherence tomography. Long-term changes of peripapillary RNFL thickness and foveal thickness as well as the correlation between the two parameters were analyzed. Results: The average RNFL thickness (360 degrees measurement) decreased significantly from 108.4 mu m to 103.5 mu m at 2 years post-PRP. The average RNFL thickness increased slightly during the initial 3 months post-PRP and thereafter gradually decreased, showing statistically significant reductions at 2 years post-PRP (false discovery rate adjusted P = 0.0051). The superior and inferior quadrant RNFL thicknesses were significantly decreased at 2 years post-PRP (false discovery rate adjusted P = 0.0119 and 0.0051, respectively). The decrease in the nasal quadrant RNFL thickness showed borderline significance at 2 years post-PRP (false discovery rate adjusted P = 0.0854). However, there was no significant decrease in RNFL thickness for the temporal quadrant at any follow-up time. In addition, there was no significant difference in the foveal thickness. But, the pattern of temporal changes in foveal thickness showed a similar pattern with that of temporal RNFL thickness. Conclusion: This study shows that average RNFL thickness after PRP undergoes early thickening and subsequent progressive thinning throughout the 2 years post-PRP. This temporal change varies according to the peripapillary RNFL quadrant. Our results also indicate that temporal RNFL and foveal thickness have a similar pattern of long-term change after PRP. RETINA 32: 2052-2060, 2012