Appearance of the optic disk and retinal nerve fiber layer in atherosclerosis and arterial hypertension: An experimental study in rhesus monkeys

PURPOSE: To evaluate changes in the appearance of the optic nerve head and retinal nerve fiber layer of rhesus monkeys with chronic arterial hypertens ion and atherosclerosis. METHODS: Color stereoscopic fundus photographs of 25 eyes of 25 rhesus monk eys (mean age +/- SD of 20.4 +/- 1.87 years) with chronic experimental syst emic arterial hypertension and atherosclerosis (for a mean duration of 89.1 +/- 39.1 months and 104.6 +/- 62.2 months, respectively) were morphometric ally evaluated. They were compared with color stereoscopic fundus photograp hs of 17 eyes of 17 normal monkeys (mean age +/- SD of 19.76 +/- 2.19 years ) without any detectable systemic or ocular disease. There was no significa nt difference in age between the two study groups (P = .22). RESULTS: In the atherosclerotic arterial hypertensive group, visibility of the retinal nerve fiber layer was significantly (35.691 +/- 5.95 units vs 2 8.72 +/- 9.18 units, P = .009) less and frequency of localized retinal nerv e fiber layer defects was significantly (six of 25 or 24% vs zero of 17 or 0%, P = .01) more than in the normal control group. The two groups did not differ significantly in size of the neuroretinal rim (P = .66), shape of th e neuroretinal rim (P > .15), size of alpha (P > .44) and beta (P > .65) zo nes of parapapillary chorioretinal atrophy, or regional distribution of alp ha and beta zones (P > .40). CONCLUSIONS: Chronic experimental arterial hypertension and atherosclerosis do not markedly change the size and shape of the neuroretinal rim or parap apillary atrophy; however, they do lead to reduced visibility of the retina l nerve fiber layer, with localized retinal nerve fiber layer defects indic ating optic nerve damage. Thus, unlike glaucomatous optic neuropathy, exper imental arterial hypertension and atherosclerosis are not associated with a significant change in the parapapillary atrophy or the neuroretinal rim of the optic disk despite the loss of nerve fibers. (C) 2000 by Elsevier Scie nce Inc, All rights reserved.