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. Postoperatively, 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±4.78μm reduced to 83.74±4.61μm one-month and 81.89±4.40μm three-months post-laser (p 0.001). Pre-laser, superior RNFL thickness was 84.97±4.13μm, reduced to 84.39±3.95μm one-month and to 82.21±3.84μm at three-months post-laser (p 0.024). Pre-laser inferior RNFL thickness was 84.89±4.68μm, reduced to 84.00±4.44μm one-month and to 81.71±4.50μm three months post-laser (p=0.032). Pre-laser temporal RNFL thickness was 83.26±3.47μm, reduced to 82.34±3.44μm one-month and to 80.21±3.49μm three-months post-laser (p 0.001). Pre-laser nasal RNFL thickness was 85.16±3.78μm, reduced to 84.26±3.88μm one-month post-laser and to 82.08±3.74μm 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.