title: Elliptical features of the human optic nerve head.
abstract: Ocular fundus photographs of the optic nerve head of 396 normal eyes were obtained. An ellipse was fitted to points digitized around the circumference of each nerve head. The length of the major and minor axes, and the orientation of the major axes were determined. This paper gives frequency distributions for the degree of ellipticalness of 396 nerve heads. The long axis is on average 11.5% longer than the short axis and the top of the long axis tends on average to be tilted toward the midline of the head by 10 degrees. In addition, it appears that the population of Elschnig type III nerve heads includes higher elliptical values than that for the Elschnig type II nerve heads.
mesh_terms: D005654:Fundus Oculi; D006801:Humans; D008433:Mathematics; D009898:Optic Disk / Q000033:anatomy & histology*; D010781:Photography