Methodological quality of the review: Low confidence
Author: Fleming C, Whitlock EP, Beil T, Smit B and Harris RP
Geographical coverage: USA, however a trial from Sweden was included
Sub-sector: Primary open angle glaucoma
Equity focus: None specified
Review type: Effectiveness review
Quantitative synthesis method: Narrative
Qualitative synthesis method: Not applicable
Background: Primary open angle glaucoma (POAG) is one of the leading causes of blindness. For many years, glaucoma treatment with medications or surgery to lower intra-ocular pressure (IOP) had been the standard of care. There is no definitive evidence to support the benefit of treating persons with early glaucoma, and minimal visual impairment was not available.
Objectives: To assess the effectiveness of screening for and treatment of early POAG in asymptomatic persons.
Main findings: Two randomised controlled trials (RCTs) compared the efficacy of treatment to lower IOP with no treatment for persons who have early POAG. In a Swedish trial, treatment reduced progression at five years from 62% without treatment to 45% with treatment (absolute risk reduction [ARR] 17%, number needed to treat 5.8, P = .007).
In a US trial of patients with early POAG and normal IOP, progression at five years was observed in 39% of those without treatment and 33% of those with treatment (P = .21). The principal side effect of treatment is loss of visual acuity as a result of increased risk of cataract formation. Authors conclude that the benefit of delaying progression of visual field loss on vision-related function in patients with early POAG is unclear.
Methodology: Studies for glaucoma screening and treatment were identified from MEDLINE, the Cochrane Library and glaucoma experts. Relevant studies were appraised and data were extracted by two reviewers according to US Preventive Services Task Force criteria.
Applicability/external validity: No methods were used either to assess the applicability/external validity of the results or to discuss how generalizable the results are.
Geographic focus: This review focused on the USA. However, a relevant study from Sweden was included.
Summary of quality assessment: The inclusion criteria were not stated, although a fairly comprehensive literature search was carried out using standard databases. It is not clear from the methodology of this review whether language bias was avoided or not, also we are not sure whether screening and abstracting data from relevant studies were done independently. There is no list of excluded studies. Therefore, there is low confidence in the conclusions about the effects of this study.