Prevalance of open angle glaucoma and ocular hypertension as a risk factor for primary open angle glaucoma in Wroclaw population. Wroclaw Epidemiological Study

Objectives
The purpose of the study is to assess the prevalence of various types of open angle glaucoma (OAG) and ocular hypertension (OH) as a risk factor for AOG. The second aim of the study was to determine the detection level of glaucoma in the population of Wroclaw inhabitants aged 40-79.

Material and methods
The population based cross-sectional sample of 4853 Wrocław inhabitants aged 40-79 years underwent two stage examination. First stage of the study included medical history interview and five screening tests: tonometry, peripheric anterior chamber depth assessment by Van Herick technique, ocular nerve head (ONH) assessment by stereoscopic ophthalmoscopy, Heidelberg Retina Tomograph (HRT) and Nerve Fiber Analyzer (GDx) investigation. Second stage included complete ophthalmological examination with gonioscopy, static perimetry and 24 hours monitoring of intraocular pressure (IOP), and pachymetry in OH group.

Results
The prevalence of glaucoma in Wroclaw population aged 40-79 years was 1,6%. Open angle glaucoma (OAG) that includes primary open angle glaucoma (POAG), normal pressure glaucoma (NPG) and capsular glaucoma (PEX-glaucoma) was found in 1,53% of the population. Glaucoma detection level was low: 71% of all cases of glaucoma were diagnosed for the first time. The percentage of OH detected in Wrocław population was 1,9%. Following the criteria of Ocular Hypertension Treatment Study (OHTS) we found that the pachymetric value of central corneal thickness (CCT) in OH group was less than 555 µm (thin cornea) in 12,5%, from 555 µm to 588 µm (normal thickness of central cornea) in 26,14% and more than 588 µm (thick cornea) in 61,36% of the subjects.

Conclusions
The Wroclaw Epidemiological Study revealed OAG as 91% of overall glaucoma cases. The relatively high percentage of glaucoma cases was diagnosed for the first time. This number is higher than reported by other authors of population studies in white communities. In the OH group the 26,14% of the eyes with normal CCT has increased risk, and the 12,5% eyes with thin cornea has highly increased risk of POAG, according to OHTS results.