title: Inter-observer variation in clinical optic disc biometry.
abstract: This study investigated the inter-observer reproducibility of measurements of the optic nerve head as carried out with a clinical optic disc biometer. This instrument employs a modification of indirect ophthalmoscopy to enable measurement of fundus structures. Measurements were made independently by two observers on 84 eyes of 47 patients. The median inter-observer differences for each measurement were as follows: maximum disc diameter, 0.085 mm; minimum disc diameter, 0.080 mm; maximum cup diameter, 0.098 mm; minimum cup diameter, 0.078 mm; disc area, 0.225 mm2; neuroretinal rim area, 0.215 mm2. Utilising the above measurements, the instrument automatically calculates a 'rim index' to take account of variations in disc size. It then interprets the disc as normal, suspicious or glaucomatous. The optic disc biometer produced seriously conflicting interpretations in 8 discs, 7 of which had been judged by both observers to have indistinct boundaries of the disc or cup.
authors.affiliation: Department of Ophthalmology, Southern General Hospital, Glasgow, UK.
authors.forename: A A
authors.initials: AA
authors.lastname: Pyott
authors.forename: D M
authors.initials: DM
authors.lastname: Montgomery
mesh_terms: D001699:Biometry; D005128:Eye Diseases / Q000473:pathology; D005901:Glaucoma / Q000473:pathology; D006801:Humans; D015588:Observer Variation; D009898:Optic Disk / Q000473:pathology*; D015203:Reproducibility of Results