Retinal arteriolar collaterals in man.

ARTERIOLAR collaterals can form within the retinal vascular bed of man and animals although, in contrast with their venous counterpart, they are rare. Only some twenty reports of their occurrence are extant, as well as three papers dealing with their production experimentally. The following case is presented as an example of un- usually extensive retinal arteriolar collaterals in which anastomotic vessels attained the size and appearance of normal arterioles. These vessels appeared not to be influenced by the patient's severe hypertension, which had caused marked sclerotic changes and irregular narrowing in the normally distributed arterioles.