Central Corneal Thickness and Its Association With Intraocular Pressure in Very Old French Subjects: The Alienor Study

Abstract

Purpose: : Although central corneal thickness appears to be an important factor to take into account when evaluating the risk of glaucoma, epidemiological data on its distribution in general populations, and in particular in the elderly, are limited. Therefore, we describe the distribution of central corneal thickness (CCT) and its association with intraocular pressure (IOP) in a population-based study of French subjects aged 73 years or more.

Methods: : Subjects are being recruited from a population-based cohort study on the vascular risk factors of dementia. Subjects were initially aged 65 years or more, recruited in the city of Bordeaux, France in 1999-2001 and followed up every 2 years since. The ALIENOR (Antioxydants, LIpides Essentiels, Nutrition et maladies OculaiRes) study consists in an eye examination, simultaneous to the third, ongoing, follow-up examination. Currently, data are available for 612 subjects. The total expected number of subjects is 1000. Corneal thickness is measured using Pach Pen (Accutome, Inc) and IOP using a pneumotonometer (KT - 800, Kowa).

Results: : Of the first 612 subjects, corneal thickness was available in at least one eye of 512 subjects (83.7 %), mostly because of history of allergy to eye drops, impeding us to use oxybuprocaine drops. Mean age was 79.5 years (range=73-94 years). CCT was normally distributed, with a mean of 550 microns (SD=35 microns) at right eye and 553 microns (SD=36 microns) at left eye. There were no significant associations with age or gender. Mean IOP was 13.7 and 14.1 mmHg in right and left eyes, respectively. IOP was strongly associated with CCT (r=0.35 and 0.39 at right and left eye, respectively), with an increase of 0.23 and 0.29 mmHg per 10 microns increase in CCT, in right and left eyes respectively.

Keywords: clinical (human) or epidemiologic studies: risk factor assessment • clinical (human) or epidemiologic studies: prevalence/incidence