Effects of Intraocular Pressure Elevation on the Blood Flow in the Optic Nerve Head in Alloxan-Induced Diabetic Rabbits

Yoshika Takahashi, Minako Nirei, Shiro Hatta, Minoru Endo, Yuji Sasaki, Junji Hamamoto, Masao Nagata and Akihiko Tamai

Department of Ophthalmology, Faculty of Medicine, Tottori University, Yonago 683, Japan

The effects of intraocular pressure (IOP) elevation on the blood flow at the laminar portion of the optic nerve head in alloxan-induced diabetic rabbits were investigated 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 of the preparation period were treated as the diabetic group in this study. At IOP levels from 5 to 15 mmHg, the mean blood flow in the diabetic group was almost the same as the blood flow in the age-matched control group (11 eyes of 11 normal rabbits). However, when the IOP was elevated to 25, 35 and 45 mmHg in a stepwise fashion, the mean blood flow 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 stages of diabetes mellitus without retinopathy.

Key words: alloxan-induced diabetic rabbits; blood now; hydrogen clearance method; intraocular pressure; optic nerve head

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