Primary care screening for ocular hypertension and primary open angle glaucoma: evidence synthesis

Methodological quality of the review: Low confidence

Author: Fleming C, Whitlock E, Beil T, Smit B

Geographical coverage: Not reported

Sector: Glaucoma

Sub-sector: Primary open angle glaucoma

Equity focus: None specified

Review type: Other review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background: Primary open angle glaucoma (POAG) is a leading cause of blindness and vision-related disability. This review examines the effectiveness of screening and treatment of asymptomatic individuals with early POAG.

Objectives:  To assess the effectiveness of screening and treatment of asymptomatic individuals with early POAG.

Main findings: In this review, authors included 13 studies and one ongoing study. No randomised controlled trials (RCTs) of population screening for POAG have been reported. Authors found no population-based studies demonstrating that screening is feasible, accurate or reliable for detecting early glaucoma.

Two RCTs examined the efficacy of treatment to lower intra-ocular pressure (IOP) compared with no treatment for persons with early POAG. In a Swedish trial, authors noted, treatment reduced progression at five years from 62% without treatment to 45% with treatment (ARR 17%, NNT 5.8, p = 0.007). In a US trial of patients with early POAG and normal IOP, progression at five years was observed in 39% without treatment and 33% with treatment (p = 0.21).

Authors noted that the benefit of delaying progression of visual field loss on vision-related function in patients with early POAG was unclear. In addition, reviewers stated that the principal harm of treatment is loss of visual acuity due to an increased risk of cataract formation. Authors concluded that treatment to lower IOP may delay progression of visual field deficits in some asymptomatic individuals with early POAG.

Authors noted that further studies of population screening are needed to demonstrate that early recognition and treatment of glaucoma in asymptomatic patients is effective in improving vision-specific functional outcomes and health-related quality of life.

Methodology: Studies of glaucoma screening and treatment were identified from MEDLINE, the Cochrane Library, glaucoma experts and review of study bibliographies. Titles and abstracts were reviewed for possible inclusion by two investigators, and articles graded according to US Preventive Services Task Force (USPSTF) criteria. The quality assessment of included trials was based on accepted USPSTF criteria.

The quality was rated as good if adequate randomisation methods were used; treatment and control groups were comparable at baseline; loss to follow-up was accounted for and comparable groups were maintained throughout the study; outcomes were determined by objective criteria or by assessors masked to group randomisation assignment; appropriate statistical methods were used; and analysis was based on intent-to-treat.

Applicability/external validity: Authors did not discuss the applicability/external validity.

Geographic focus: This review focuses on all countries.

Summary of quality assessment: Overall there is low confidence in the conclusions about the effects of this study as important limitations were identified. Authors conducted a search of the literature in relevant databases. However, authors did not avoid restriction bias (language, date and publication), which may indicate the presence of publication bias within the review. In addition, it’s not clear from the review if two authors independently screened studies for inclusion and extracted data of included studies.