CHANGES IN RETINAL NERVE FIBER LAYER ON OPTICAL COHERENCE TOMOGRAPHY AFTER PANRETINAL PHOTOCOAGULATION IN PATIENTS WITH PROLIFERATIVE DIABETIC RETINOPATHY

OBJECTIVE: To study changes in retinal nerve fiber layer (RNFL) measured on optical coherence tomography (OCT) after panretinal photocoagulation (PRP) in patients with proliferative diabetic retinopathy (PDR). METHODS: This quasi experimental study was conducted at Department of Ophthalmology, Lahore General Hospital, Lahore from 1-4-2017 to 30-3-2018. All patients (n=38) diagnosed with PDR requiring PRP were included. Patients having any coexisting ocular pathology hindering the OCT measurement were excluded. Pre-operatively, RNFL thickness in four quadrants and signal strength was measured on OCT and visual acuity (VA) on Snellen's chart. Post-operatively, patients were followed-up after one-month and three-months and VA was measured and OCT performed. RESULTS: The mean age of patients was 60.66 +/- 5.51years with 23(60.5%) males. PRP was performed in right-eye of 22 patients. Pre-laser VA in 28 patients was 6/60. Pre-laser total RNFL was 84.32 +/- 4.78 mu m reduced to 83.74 +/- 4.61 mu m one-month and 81.89 +/- 4.40 mu m three-months post-laser (p<0.001). Pre-laser, superior RNFL thickness was 84.97 +/- 4.13 mu m, reduced to 84.39 +/- 3.95 mu m one-month and to 82.21 +/- 3.84 mu m at three-months post-laser (p<0.024). Pre-laser inferior RNFL thickness was 84.89 +/- 4.68 mu m, reduced to 84.00 +/- 4.44 mu m one-month and to 81.71 +/- 4.50 mu m three months post-laser (p=0.032). Pre-laser temporal RNFL thickness was 83.26 +/- 3.47 mu m, reduced to 82.34 +/- 3.44 mu m one-month and to 80.21 +/- 3.49 mu m three-months post-laser (p<0.001). Pre-laser nasal RNFL thickness was 85.16 +/- 3.78 mu m, reduced to 84.26 +/- 3.88 mu m one-month post-laser and to 82.08 +/- 3.74 mu m at three-months post-laser (p=0.043). Pre-laser, signal strength on OCT was 8.26 +/- 0.69 and 8.66 +/- 0.48 after one-month post-laser and 8.55 +/- 0.50 at three-months laser (p=0.009). CONCLUSION: PRP leads to a decrease in thickness of RNFL after one month and three months as compared to pre-laser RNFL thickness.