[Treatment of central retinal venous and arterial occlusion by isovolemic hemodilution (author's transl)].

(1) Ten patients (mean age 71) with fully developed central retinal venous occlusion were treated by isovolemic hemodilution over a period of four to six weeks. Hematocrit was lowered in steps to about 30% to improve retinal microcirculation. For two to four days, 500 ml whole blood were exchanged daily for about 250 ml hydroxyethyl starch and 250 ml plasma. The procedure was repeated every five to ten days whenever the hematocrit exceeded 35%. Visual acuity was considered to be improved when the patient could read at least two more lines on the test card. Four to six weeks after starting hemodilution therapy visual acuity had improved in seven patients, deteriorated in one, and was unchanged in two. In the follow-up study six months after treatment visual acuity, as compared to data before treatment, had improved in four patients, deteriorated in two and was unchanged in four. Three patients developed a neovascular glaucoma and had to undergo photocagulation treatment. (2) As expected, hemodilution failed to improve visual acuity in five patients who had had a complete central retinal arterial occlusion for more than four hours. (3) This is the first time that a beneficial effect of isovolemic hemodilution on visual acuity, probably mediated by an improvement in retinal blood flow, has been demonstrated in man. However, only in retinal tissue with at least minimal blood flow (venous but not arterial occlusion) can this method be effective. Except for severe anemia or thrombocytosis there are no absolute contraindications. No adverse side-effects were observed. To prevent neovascularization it is planned to use a combination of hemodilution and photocoagulation.