Prevalence of glaucoma and distribution of intraocular pressure in a population. The Casteldaccia Eye Study.

IOP was measured in 1062 middle-aged and elderly subjects of a small Sicilian town, enrolled in a population based survey. The mean IOP was 15.1 +/- 3.7 mmHg without interocular or sex differences. A small but significant age-dependent increase of IOP was found. Circadian and seasonal influences were recorded: IOP was higher in the morning and in winter. The prevalence of chronic open-angle glaucoma was 1.2%, but it grew to 3.6 if only subjects aged 70 years or more were considered. IOP of 24 mmHg or more was found in 2.7%, while 4.3% of subjects showed IOP of 21 mmHg or more. This survey shows that mean IOP of the Mediterranean population studied is similar to the IOP found in other epidemiologic investigations; the prevalence of glaucoma, however, seems to be rather high.