Whole Layer Photocoagulation on the Rabbit Retina with Indirect Diode Laser Ophthalmoscopy

ABSTRACT

In the treatment of retinopathy of prematurity, it is necessary to coagulate retina including inner retinal layer to achieve regression. However, diode laser has long wavelength, thus damage to bruch`s membrane or choroid can occur when one attempts to coagulate whole retinal layers. We evaluated whether or not we could coagulate whole retinal layer without damage to Bruch`s membrane or choroid in rabbit eyes with indirect diode laser ophthalmoscopy. We palaced laser spots on retina of pigmented rabbits with various laser powers(150, 300, 500mW) and durations(0.3, 0.5, 1.0 second). Fundus photographs were taken immediately after photocoagulation. then we took fundus photographs and enucleated the eyes at one day, one week, 3 weeks, and 5 weeks after photocoagulation to perform pathologic examination. With laser setting of 150mW and 0.3 second, the coagulated retina revealed damaged outer layer but inner retinal layer was spared. We could coagulate whole retinal layer without any damage to Bruch`s membrane or choroid with laser power of 300mW and 0.3 second duration. In 300mW, 0.5 second laser burns and 500mW, 0.3 second burns, internal limiting membrane remained intact while Bruch`s membrane and whole retinal layers were damaged We found whole layer rabbit retina could be coagulated without damage to Bruch`s membrane and choriocapillaries with indirect diode laser opthalmoscopy. and we think it would be necessary to adjust laser power and duration in clinical situation to minimize possible deep tissue injury by diode laser.