Vascular occlusion of the retina--an experimental model. II. Platelet aggregates.

Using a new technique to mimic arteriolar occlusion syndromes, different microparticles were injected into the ophthalmic artery of pigs. These microparticles were platelet aggregates of various sizes ranging from 0.15 mm to more than 0.8 mm. Aggregation was induced using adenosine diphosphate and thrombin. In some experiments, acetylsalicylic acid and histamine were also applied. In a further series of experiments, mixed aggregates containing platelets and leukocytes were injected. The results were observed by indirect ophthalmoscopy and consisted of superficial and deep retinal infarction. Large platelet aggregates resulted in arterial branch occlusion, whereas mixed and small platelet aggregates produced occlusion of small arterioles. This technique seems to be valuable in studying retinal arteriolar occlusion syndromes.