Do findings on routine examination identify patients at risk for primary open-angle glaucoma? The rational clinical examination systematic review.

Importance

Glaucoma is the second leading cause of blindness worldwide, and its insidious onset is often associated with diagnostic delay. Since glaucoma progression can often be effectively diminished when treated, identifying individuals at risk for glaucoma could potentially lead to earlier detection and prevent associated vision loss.

Objective

To quantify the diagnostic accuracy of examination findings and relevant risk factors in identifying individuals with primary open-angle glaucoma (POAG), the most common form of glaucoma in North America.

Data sources: Structured Medline (January 1950-January 2013) search and a hand search of references and citations of retrieved articles yielding 57 articles from 41 studies.

Study selection: Population-based studies of high-level methods relating relevant examination findings of cup-to-disc ratio (CDR), CDR asymmetry, intraocular pressure (IOP), and demographic risk factors to the presence of POAG.

Results

The summary prevalence of glaucoma in the highest-quality studies was 2.6% (95% CI, 2.1%-3.1%). Among risk factors evaluated, high myopia (≥6 diopters; odds ratio [OR], 5.7; 95% CI, 3.1-11) and family history (OR, 3.3; 95% CI, 2.0-5.6) had the strongest association with glaucoma. Black race (OR, 2.9; 95% CI, 1.4-5.9) and increasing age (especially age >80 years; OR, 2.9; 95% CI, 1.9-4.3) were also associated with an increased risk. As CDR increased, the likelihood for POAG increased with a likelihood ratio (LR) of 14 (95% CI, 5.3-39) for CDR of 0.7 or greater. Increasing CDR asymmetry was also associated with an increased likelihood for POAG (CDR asymmetry ≥0.3; LR, 7.3; 95% CI, 3.3-16). No single threshold for CDR or asymmetry ruled out glaucoma. The presence of a disc hemorrhage (LR, 12; 95% CI, 2.9-48) was highly suggestive of glaucoma, but the absence of a hemorrhage was nondiagnostic (LR, 0.94; 95% CI, 0.83-0.98). At the commonly used cutoff for high IOP (≥22), the LR was 13 (95% CI, 8.2-17), while lower IOP made glaucoma less likely (LR, 0.65; 95% CI, 0.55-0.76). We found no studies of screening examinations performed by generalist physicians in a routine setting.

Conclusions and relevance: Individual findings of increased CDR, CDR asymmetry, disc hemorrhage, and elevated IOP, as well as demographic risk factors of family history, black race, and advanced age are associated with increased risk for POAG, but their absence does not effectively rule out POAG. The best available data support examination by an ophthalmologist as the most accurate way to detect glaucoma.