Classification of angioid streaks.

ANGIOID streaks of the retina were first described by Doyne (1889). They have since been the subject of much controversy. More than 200 cases have been reported in the literature, but histological studies have been few and the changes described have varied. The condition is frequently associated with pseudoxanthoma elasticum, with cardiovascular disease, and with Paget's disease of bone. A similar appearance may also be found after detachments of the choroid, folds of the retina, and other conditions. The fundus picture consists of reddish or dark brown streaks radiating outwards from the disc, and often seeming to originate from a similar streak running partly or completely round the disc. The constancy of this picture led Collins (1923) to postulate a definite anatomical basis for their distribution and he attributed them to deposits of altered blood pigment lying in the perivascular spaces of the posterior ciliary arteries. However the streaks occur below the retinal vessels and above those of the choroid, so that they must be located either in the deep layers of the retina or in the inner layers of the choroid. Furthermore, the streaks have been seen to be interrupted by areas of choroidal atrophy, an observation which makes it unlikely that they are related to the choroidal vessels (Spicer, 1914; Wildi, 1926). That the cause of angioid streaks might be breaks in the membrane of Bruch was first suggested by Kofler (1917). His conclusions were drawn solely from clinical observation, and confirmation was not forthcoming until Bock (1938) described such lesions in microscope sections. Bock's report was soon followed by those of Hagedoorn (1939), Klien (1947), Verhoeff (1948), and Winkelman (1948). By courtesy of Sir John McNee, I was able to examine the eyes of a 59-year-old woman in his wards in the Western Infirmary, Glasgow. Angioid streaks were seen. The patient was suffering from essential hypertension and died a few days later from a cerebral haemorrhage. Histological examination of the eyes showed breaks in the lamina vitrea corresponding to the site of one streak (McWilliam, 1951). There is then agreement that the clinical picture of angioid streaks is associated, in at least a proportion of cases, with a histological picture showing degeneration and gaps in Bruch's membrane. These gaps may not be the only cause, or indeed the cause at all. Ballantyne (1938) and Law (1951) remark that the ophthalmoscopic picture of angioid streaks may not represent one pathological entity. Somewhat similar streaks occur after choroidal detachments, and Law (1938) described plications of the retina with pigmentary debris causing a similar fundus picture.