[Optic nerve head circulation in alloxan-induced diabetic rabbits].

The blood flow volume at the laminar portion of the optic nerve head in alloxan-induced diabetic and normal rabbits was measured employing the hydrogen clearance method. Ten 6-month-old albino rabbits (10 eyes) were rendered diabetic with 10% alloxan monohydrate solution (80 mg/kg, injection into the auricular vein). The rabbits with nonfasting blood glucose levels of more than 200 mg/dl and showing no significant electroretinographic abnormalities during 24 weeks were treated as the diabetic group in this study. At intraocular pressure (IOP) levels from 5 to 15 mmHg, the mean blood flow volume in the diabetic group was almost the same as the volume in the age-matched control group (11 eyes of 11 rabbits). But when the IOP was raised to 25, 35, and 45 mmHg in a stepwise fashion, the mean blood flow volume in the diabetic group significantly decreased, compared with the control group. These findings suggest that blood microcirculation in the optic nerve head may be damaged by ocular hypertension in the early stage of diabetes mellitus without retinopathy.