Risk factors for incident open-angle glaucoma in clinical practice in Sweden: A population-based case-control study

PurposeTo study predictors of open-angle glaucoma (OAG) in newly diagnosed patients detected in clinical practice in a defined population and to estimate the frequency of normal-tension glaucoma (NTG). MethodsPredictors of OAG were analysed in a case-control study, nested in a cohort of 481 people, 55-84 years of age, in two rural districts in Sweden, examined at the Eye Department in Tierp from 1988 to 2003. To make the sample complete, 63 residents first examined at the Uppsala University Hospital (UUH), 60 of whom were identified with the help of registers, were invited to attend the study. In this way, the cohort included 544 individuals. Automated perimetry was used to find cases of OAG. ResultsIn people first examined in Tierp, incident OAG was found in 99 subjects. Of these cases, six were diagnosed with NTG. Increased intraocular pressure (IOP), higher age, male sex, a positive family history, pseudoexfoliation (PEX), and haemorrhages of the optic disc were associated with OAG. In a logistic regression model including PEX, every increase in IOP by 5 mmHg increased the risk for OAG four-fold (odds ratio 4.04; 95% confidence interval 2.91-5.62). The effect of PEX was essentially mediated by increased pressure. The inclusion of the 63 subjects first examined at the UUH had no impact on the results. ConclusionIn this study on patients aged 55-84-years old in clinical practice in Sweden, increased IOP was strongly associated with incident OAG, while NTG was a rare finding.