Efeito crônico do LED de alta potência na retina de rato wistar

Abstract

Introduction: The increase in the power of light-emitting diode (LED) light cure has contributed to reduce the curing time of restorative and orthodontic procedures. However, the effect of the LED on the retina of those who make the chronic use of light units without using protection filters is unknown. Objective: To evaluate the possible effects of the chronic use of a high-power LED light curing device on the retinas of Wistar rats. Material and methods: In this experimental study in vivo, six healthy male rats were used and their ocular structures being the objects of study. The left eyes of the animals were exposed to high potency LED light, 3.200mW/cm2 (Valo Ortho - Ultradent), for 144 seconds at a distance of 30cm, three times a day, for 7 days. The right eyes were covered with removable plastic opaque tampon, composing the control sample. On the eighth day, the animals were anesthetized, euthanized, the eyes dissected and histologically processed. The slides were scanned using a camera coupled to an optical microscope and their images analyzed by two and three dimensional histomorphometry. Results: No statistically significant intergroup differences were found for total retinal volume (p = 0.655) or for the volume of the retinal layers ganglionic (p = 0.375), internal plexiform (p = 0.327), internal nuclear (p = 0.693), external plexiform (p = 0,177), external nuclear (p = 0.355) and the extension of cones and rods (p = 0.871), when evaluated individually. The histomorphometric analyzes presented statistically significant reduction for the cellular areas, with a reduction of 25,32% for the internal nuclear layer, 17,59% for external nuclear layer and 16,76% for ganglionic layer. Although the numerical density of the internal and external nuclear layers decreased, and the ganglion layer increased, they showed no statistically significant difference. Conclusion: Chronic exposure of the high-power LED (3.200mW/cm2) induced cellular atrophy in the internal nuclear layer, external nuclear layer and ganglionic layer.