Studies on Intravitreal Blood Vessels

II. Effectiveness of Xenon Arc and Argon Laser Photocoagulation in Blood Vessel Closure

¹ Department of Ophthalmology, Eye and Ear Infirmary, University of Illinois

We produced complete displacement of the vascular and myelinated portion of the rabbit retina into the vitreous by intravitreal injection of NH₄Cl. This was followed by degeneration of the myelinated portion of the retina, leaving the retinal vessels free within the vitreous. We used this model to compare the short-term effectiveness of xenon-arc coagulation and argon laser coagulation in treating intravitreal vessels. Fluorescein angiography and angioscopy both immediately after treatment and one week later were used to confirm vessel closure. Xenon-arc coagulation was entirely ineffective in closing intravitreal vessels. Argon laser achieved immediate closure of all types of intravitreal vessels except small arteries. At the end of one week, 20 per cent of the large veins, 75 per cent of the large arteries, and 100 per cent of the small veins remained closed. Minimal cataract increased the amount of energy needed to achieve closure. Background reaction increased with pigmentation and decreased as the distance from the fundus of the coagulated vessel increased. The rate of hemorrhage was 18 per cent for argon laser. Most hemorrhages were less than one-half disc diameter in area. Argon laser caused vitreal hemorrhage when using high energy on vessels accompanied by fibrous tissue.

Key Words: xenon arc photocoagulation • argon laser • intravitreal vessels • closure • hemorrhage

Submitted on January 10, 1974