Evolution of the Retinal Lesions

THE advent of proliferative retinopathy gravely influences the prognosis with regard to vision in a diabetic, and the management of this complication is one of the most difficult medical problems of the present time. The term proliferative retinopathy is here used in its widest sense, to include not only the more obvious neovascular and connective tissue lesions which arise from the disc area, but also the smaller collections of new vessels which appear in the superficial retinal capillary plexus. Proliferative diabetic retinopathy (P.D.R.) has a particularly complex fundus picture, for not only do the larger lesions project into the vitreous and acquire an extra dimension, but they are superimposed on a background of simple diabetic retinopathy which may be of'any degree of severity. Superimposed on the proliferative vessels in their turn are subhyaloid and vitreous haemorrhages. In the final stages occlusions of the retinal vessels, retinal detachments, and secondary glaucoma complicate an already confused picture. Observers vary greatly in their assessment of the incidence of the complication, presumably because some have accepted only the more florid examples in their patients. Thus, of the larger series reported in the last decade, Porstmann (1954) in a series of 720 diabetics found an incidence of P.D.R. of 1 7 per cent., Engelson (1954) in 623 diabetics found 4 per cent., and Dekking (1954) in 383 diabetics found 7 per cent. Higher rates are given by Kornerup (1958) 8 4 per cent. in 1,402 unselected diabetics, by Scott (1953) 9*7 per cent., and by Wilson, Root, and Marble (1951) 16-3 per cent. Root, Mirsky, and Ditzel (1959) estimated that it was found in one out of every five cases of diabetic retinopathy. There is a familial tendency to P.D.R. as in simple diabetic retinopathy. Fischer (1954) found a family history of P.D.R. in 37-5 per cent. of cases, and Root and others (1959) in 52 per cent. Since the first descriptions of new vessel and connective tissue formations in the retinae of diabetics by Manz (1876), a wealth of'facts concerning the association of proliferative diabetic retinopathy (P.D.R.) and the general diabetic state has accumulated. It is well established that P.D.R. may occur at any stage of diabetes, but is most commonly found between the ages of 25 and 50, and particularly in those who have become diabetic before the age of 20. Patients in whom the control of the diabetes has been unsatisfactory, either because of extreme variability of the insulin requirements ('labile' or 'brittle' diabetics) or because of failure to keep to dietary restrictions, are especially liable to develop the condition. It is also well known