Systematic review 1

The systematic review aimed to identify the magnitude of risk of OAG attributable to age, ethnicity, family history, myopia and diabetes. Population-based cohort and cross-sectional studies, investigating the risk of developing OAG were included, as well as meta-analyses and systematic reviews of observational population-based studies. Studies reporting populations in UK, Europe, North America, Canada or Australia were included. Hospital or clinic-based setting were excluded. The review was restricted to English language publications. The methodological quality of the included studies was assessed.

4 383 reports were identified from the search for studies on epidemiology, risk and disease progression, of which 285 were selected for full assessment for this review. 92 reports describing 27 studies met the inclusion criteria for the review.

The overall quality of each study was summarised as (A) no major flaws or (B) possible important flaws. Studies were included when they rated ‘A' in all fields. Exceptions were made to include ‘B' studies when no better evidence was available. In most studies (81%), participants were sampled adequately and selected from a relevant population. Suboptimal approaches to diagnose OAG (e.g. high IOP, absence of a visual test, unstandardised criteria) were used in five studies (19%). IOP status was obtained from a secure record (examination or examination records) in most studies.

Crude and adjusted relative risks (or odds ratios depending on study design) of OAG for the risk factors under investigation were abstracted. Where two or more studies contributed data, a random effects meta-analysis was undertaken. If both an unadjusted and adjusted ratio were reported in a study, an age- and gender-adjusted odds ratio was used in the meta-analysis. A relative risk was generated when an adjusted odds ratio was not reported and raw data were available.

High IOP was defined as ≥ 1 measurements with readings ≥ 26 mmHg. Other IOP cut-offs were also investigated. Seven studies described the prevalence of OAG by a range of IOP levels. Across the studies, the proportion of people with OAG who had an IOP above 21 mmHg was consistently higher than those who had an IOP of ≤ 21 mmHg. The proportion of people with high IOP varied widely across studies. However, all but one included cases with previously detected OAG already under glaucoma therapy, and therefore underestimate the true prevalence of OAG in people with high IOP. The risk of having glaucoma for those with IOP measurements ≥ 26 mmHg was estimated to be 13 times higher than that for those with lower IOP [relative risk (RR) 12.58, 95% CI 5.07 to 31.24] «Burr JM, Mowatt G, Hernández R ym. The clinical ef...»1.

Systematic review 2

Structured Medline (January 1950 – January 2013) search and a hand search of references and citations of retrieved articles yielding 57 articles from 41 studies were included in a systematic review .

At the commonly used cutoff for high IOP (≥22 mmHg), the LR for developing glaucoma was 13 (95% CI, 8.2-17), while lower IOP made glaucoma less likely (LR, 0.65; 95% CI, 0.55-0.76) «Hollands H, Johnson D, Hollands S ym. Do findings ...»2.