Aneurysms on new-formed pre-papillary and pre-retinal vessels in proliferative diabetic retinopathy.

RETINAL micro-aneurysms were observed histologically by Mackenzie and Nettleship as early as 1879. However, these observations passed unnoticed until 1943 when Ballantyne and Loewenstein found numerous spherical micro-aneurysms on the capillaries in flat histological sections of retinae from diabetics. These microaneurysms were conceived to be the histological substrate for the small sanguinolent spots-red dots-which are observed ophthalmoscopically in the retinae of patients with diabetes mellitus of long duration. Since then, attempts have been made to find analogous aneurysms in other parts of the eye and in other organs, but apart from the renal glomeruli, these investigations have largely been negative (Ashton, 1958). Biomicroscopically, aneurysms are rarely observed in the conjunctivae (Ditzel, 1962; Labram, 1964). Lundbaeck (1963) and Busacca (1964) found aneurysms on the finest vessels in patients with rubeosis iridis diabetica.