[Ophthalmological study on the M-strain of stroke-prone spontaneously hypertensive rat (M-SHRSP) (1). Classification of hypertensive fundus changes in M-SHRSP].

To differentiate the functional changes from the organic changes in malignant hypertension, the author studied the changes in the blood vessel of ocular fundus by ophthalmoscopical and histopathological methods using malignant strain of stroke-prone spontaneously hypertensive rat (M-SHRSP; Okamoto, K et al., 1986), an animal model of human juvenile malignant hypertension, in which the systolic blood pressure elevates rapidly with age and death appeared by the 15th month of life, if they are untreated. Fundus changes progressed with age and duration of hypertension and they altered from functional changes to organic ones. In M-SHRSPs with age of 8 weeks, systolic blood pressure was 220mmHg or more and retinal arterioles showed generalised narrowing but no dye leakage was recognized by fluorescein angiography (FAG). Dye leakage was observed on the 9th week of age. Death of M-SHRSP appeared, after the 13th week of age, coincidentally with appearance of wide retinal edema. Papilledema appeared often in this period. Little histological change was found in the retinal arterioles in spite of severe and marked ophthalmoscopic changes. No feature of angionecrosis was observed in the retina while it was recognized in choroidal arteriole with thrombosis. The fundus changes in M-SHRSP were ophthalmoscopically classified by using scores as following. Grade 0: normal fundi, Grade I (score 1): slight generalized narrowing, caliber irregularity and tortuosity of the retinal arterioles, slight retinal edema and choroidal changes. Grade II (score 2): moderate generalised narrowing, caliber irregularity, tortuosity of the retinal arterioles, moderate retinal edema and choroidal ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)