Laser Scanning Tomography of the Optic Nerve Head in a Normal Elderly Population: The Bridlington Eye Assessment Project

Abstract

To assess optic nerve head topographic parameters using the Heidelberg Retina Tomograph (HRT) II (Heidelberg Engineering GmbH, Dossenheim, Germany) in a normal elderly population. Optic nerve head analysis of 918 eyes of 459 normal elderly patients was performed. All patients were consecutive in a cohort screened for eye disease. Normal subjects were defined with a normal visual field on automated suprathreshold screening, intraocular pressure less than 22 mmHg, and minimum corrected visual acuity of 6/12. All optic discs were contoured by two investigators and the mean parameters analyzed. The effects of age, sex, and disc size were assessed. Subjects' (262 women and 197 men) mean age was 72.6 +/- 5.1 (SD) years (range, 65.5-89.3). Mean +/- SD global disc area, cup/disc area ratio, and neuroretinal rim area were 1.98 +/- 0.36 mm2, 0.22 +/- 0.14, and 1.52 +/- 0.31 mm2, respectively. Disc area did not differ significantly based on eye side or sex. The women were found to have a significantly larger rim volume, mean retinal nerve fiber layer (RNFL) thickness, and cross-sectional area than the men and tended to have smaller cup areas/volumes and cup/disc area ratios. Most tomography parameters were found to be significantly influenced by disc size. To the authors' knowledge, this is the first large study of optic nerve head parameters in the elderly normal population using the HRT II. This age range is particularly relevant to glaucoma detection and pertinent to discriminant analyses separating normal subjects from glaucoma in screening for the disease. Given the systematic differences between the parameters in men and women, reference ranges should be quoted by sex.