The relationship between optic disc area and open-angle glaucoma: The Baltimore eye survey

Purpose: To determine if eyes with larger optic disc area are more likely to have open-angle glaucoma or to have glaucoma at lower intraocular pressure (IOP). Methods: Data were collected from a population-based sample of adults residing in East Baltimore, consisting of demographic information, ocular examinations, automated and static/kinetic visual field tests, IOP as measured by applanation tonometry, and image analysis of the optic disc. Optic disc area was calculated using refractive error to correct magnification. Open-angle glaucoma was defined by visual field and optic disc criteria. One eye from each of 75 patients with glaucoma was compared to those of 3,518 subjects without glaucoma. Results: Although optic disc area was somewhat larger among patients with glaucoma than control subjects, in a regression model adjusting for age, gender, and race, the significance of this difference had a probability of 0.06. Among patients with glaucoma, disc area was not related to IOP level measured at study examination. Conclusion: Disc area is a weak risk factor for open-angle glaucoma. Disc area did not differ between patients with glaucoma who had lower IOP and those who had higher IOP among a group with glaucoma that were identified in a population survey.