Photocoagulation in diabetic retinopathy. A multicentre study in Sweden

Two hundred and eleven patients with diabetic retinopathy were assigned to a multicentre prospective study on the effect of photocoagulation therapy. Twenty Swedish eye clinics took part in the trial. Good visual function and symmetrical diabetic retinopathy of the non-proliferative or proliferative type were required. No patients with advanced new vessels on the optic disc or widespread fibrous proliferations were included. Further criteria for inclusion were that at the time of entry into the study the patients would be in good general health, should have no other eye diseases and should be receiving no other treatment for diabetic retinopathy. One eye was randomly chosen for photocoagulation therapy. The patients were given mild treatment with the panretinal, focal or panretinal and focal techniques and in most cases the short-pulse, small-spot xenon arc or argon laser methods were used. The patients were examined before treatment, after 6 months and subsequently every year. All follow-ups included careful measurement of corrected visual acuity, tonometry, and evaluation of the optical media and fundus changes. A medical examination was performed every second year. Fundus photographs were taken at all examinations. The diabetic lesions were graded with the aid of a modified Airlie-House system. The classification of all diabetic lesions was checked by the author with the help of the fundus photographs. Visual acuity and morphological diabetic changes were analysed in the whole material and also in four subgroups, namely those with mild non-proliferative, moderate-severe non-proliferative, mild proliferative and moderate-severe proliferative retinopathy. This subgrouping was done with regard to the stage of retinopathy at entry into the trial. One hundred and eighty-five patients were followed up for 4 years and 138 for 5 years. Twenty patients died, most of them from diabetic complications. Forty-one control eyes were treated. The majority showed progression before treatment. Treated eyes had better average visual acuity and a lower rate of blindness than control eyes at late follow-up. The various stages of retinopathy differed greatly with respect to the visual outcome. Patients showing mild non-proliferative changes at the time of entry had good mean visual acuity and no eyes became blind during the follow-up period. Patients with moderate-severe non-proliferative changes had a better mean visual acuity in the treatment group at late follow-ups and more eyes became blind in the control group.(ABSTRACT TRUNCATED AT 400 WORDS)