title: The ratio of the size of the optic cup (as determined by the place where the vessels deviate) to size of the disc.
abstract: The vessel deviation to disc ratio (VDR) of the optic nerve head can be defined for a given meridian as the ratio of the size of the cup as indicated by small blood vessel deviation in that meridian to the size of the disc. Thus, VDR is a relative measure similar to cup/disc ratio. The difference between VDR and other methods of measuring cup/disc ratio is that the former identifies the rim of the cup with the deviation or bending of the small blood vessels as they fan out over the disc, whereas the latter determine the location by the other criteria which vary from examiner to examiner. The purpose of this study is to quantify the variation in VDR and its relation to age, refractive error, and sex.
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000033:anatomy & histology* / Q000473:pathology; D012030:Refractive Errors / Q000473:pathology*; D012171:Retinal Vessels / Q000033:anatomy & histology*; D012737:Sex Factors