Abstract
Purpose: :
To describe changes in retinal nerve-fiber layer (RNFL) thickness, perimetry and pain scores after micropulsed panretinal photocoagulation (PRP) for proliferative diabetic retinopathy (PDR).
Methods: :
Scatter PRP was performed using a green 532-nm laser (Visulas. Carl Zeiss Meditec), with standard pulse duration (SPD) (150msec) in the right eye and micropulsed parameters (20 msec) in the left eye, divided in three sessions separated by one month interval. A Stratus OCT (Carl Zeiss Meditec) was used to assess RNFL thickness and a 24-2 standard protocol from the Humphrey Field Analyzer (Carl Zeiss Meditec) for perimetric analysis, before the first and one month after the third PRP session. To assess pain during PRP, a numerical analogue rating scale 0-10 (being 0 "no pain at all" and 10 the "worst pain imaginable or ever experienced") was asked to the patients after each laser treatment in each eye.
Results: :
56 eyes of 28 patients with PDR were prospectively enrolled in the study. Mean age was 56,4±11,8 years and 60,7% were male. 85,7% suffered type II diabetis mellitus. Pain scores were significantly lower with the micropulsed parameters after all three PRP sessions (p=0,000, p=0,0001 and p=0,000, respectively). Pattern standard deviation was not significantly different after the PRP, in the right or left eye, but a significant increase in the mean deviation was observed in the eyes with SPD (p=0.048) but not with micropulsed laser. No differences were observed in RNFL thickness in the OCT examination after the laser, in neither of the 4 quadrants (nasal, superior, inferior or temporal).
Conclusions: :
Theoretical benefits of micropulsed PRP include less painful laser treatments and less RNFL lesion as the laser energy remains in the outer layers of the retina. In our study we have shown lower pain scores and no significant perimetric changes after micropulsed laser. Nevertheless no differences were observed in RNFL thickness in the OCT after 3 PRP sessions between the eyes treated with SPD and micropulsed laser.
Keywords: laser • diabetic retinopathy • retina