Glaucoma and intraocular pressure in EPIC-Norfolk Eye Study : cross sectional study

Abstract

Objectives : To report the distribution of intraocular pressure (IOP) by age and sex and the prevalence of glaucoma. Design: Community based cross sectional observational study. Setting: EPIC-Norfolk cohort in Norwich and the surrounding rural and urban areas. Participants: 8623 participants aged 48-92 recruited from the community who underwent ocular examination to identify glaucoma. Main outcome measures: Prevalence and characteristics of glaucoma, distribution of IOP, and the sensitivity and specificity of IOP for case finding for glaucoma. Results: The mean IOP in 8401 participants was 16.3 mm Hg (95% confidence interval 16.2 mm Hg to 16.3 mm Hg; SD 3.6 mm Hg). In 363 participants (4%), glaucoma was present in either eye; 314 (87%) had primary open angle glaucoma. In the remaining participants, glaucoma was suspected in 607 (7%), and 863 (10.0%) had ocular hypertension. Two thirds (242) of those with glaucoma had previously already received the diagnosis. In 76% of patients with newly diagnosed primary open angle glaucoma (83/107), the mean IOP was under the threshold for ocular hypertension (21 mm Hg). No one IOP threshold provided adequately high sensitivity and specificity for diagnosis of glaucoma. Conclusions: In this British community, cases of glaucoma, suspected glaucoma, and ocular hypertension represent a large number of potential referrals to the hospital eye service. The use of IOP for detection of those with glaucoma is inaccurate and probably not viable.