Jost B.Jonas Sohan Singh Hayreh Tao Yong

　　Department of Ophthalmology and Eye Hospital，and the Medical Faculty Mannheim of the Ruprecht-Karls-University Heidelberg，68167 Mannheim，Germany Departments of Ophthalmology and Visual Sciences，College of Medicine，University of Iowa，Iowa City，Iowa 52242，USA 100005

　　Purpose:To examine the histology of parapapillary atrophy(PPA)in a direct ophthalmoscopic-histologic comparison.

　　Method:The study involved 17 eyes of rhesus monkeys including 4 eyes with experimental glaucoma，5 eyes with an experimental temporary occlusion of the central retinal artery，and 8 normal eyes.PPA was assessed both on histological sections and fundus photographs.

　　Results:The size of clinical alpha zone of PPA was significantly correlated with the size of the histological region of irregularities of the RPE;and with the size of a decreased density of photoreceptors.The size of clinical beta zone of PPA was significantly correlated with the size of the histological region of complete loss of the RPE;with the size of a complete loss of photoreceptors;and with a closed choriocapillaris.

　　Conclusions:The histological correlates of the clinical alpha zone of PPA are parapapillary irregularities of the RPE and a decreased density of retinal photoreceptors.The histological correlates of the clinical beta zone of PPA are a complete loss of the RPE，a complete loss of photoreceptors，and a closure of the choriocapillaris.