Pattern Scan Laser System vs. Conventional Photocoagulation System: Electroretinogram Changes After Treatment

Abstract

Purpose: : To compare electrorretinographic changes after panretinal photocoagulation (PRP) with conventional laser vs the Pattern Scan Laser system (PaScaL)

Methods: : A prospective, interventional and comparative study was performed in patients with severe non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) without evidence of macular edema, and without previous laser treatment or anti-angiogenic drug therapy. PRP with conventional laser was performed in the right eye (OD) and with PaScaL in the left eye (OS); the eye to be treated first was assigned in a randomized fashion. PRP was performed in two sessions of 750 burns with an interval of 2 weeks. Best corrected visual acuity (BCVA) measurement and electrorretinogram (ERG) were performed in all patients at baseline and day 28. All t-paired tests were two-tailed with alpha=0.05.

Results: : Thirty eyes of 15 patients were included. Baseline BCVA was 42 letters (range: 23 to 55) in OD and 43 letters (range: 35 to 55) in OS. BCVA at 28 day was 30 letters (range: 24-51) in OD and 40 letters (range: 27-49) in OS. The a-wave decreased 59.01±12.53 µV (p: 0.0005) in OD and increased 10.35±16.72 µV (p: 0.9002) in OS. The b-wave decreased 200.94±164.73 µV (p: 0.0526) in OD and 91.48±3.19 µV (p: 0.5228) in OS. The implicit time increased 11.52±1.13 msec (p: 0.1208) in OD and 2.88±3.77 msec (p: 0.5851) in OS. Statistical significant differences were found in a-wave and b-wave of OD when final and initial amplitude were compared.

Conclusions: : We observed decreased statistically significant of a-wave in the conventional laser and increased no statistically significant in the PaScaL system. The b-wave decreased statistically significant in the conventional system and no statistically significant in the PaScaL system. The implicit time increased in both systems without statistically significant differences.

Clinical Trial: : www.clinicaltrials.gov NCT00563043

Keywords: laser • diabetic retinopathy