JUN 18, 2012
This study in the March issue of the Archives of Ophthalmology simulated the clinical impact of routine glaucoma screening on visual outcomes in middle-aged African-Americans. The results indicate that universal, community-based glaucoma screening of this population is a potentially clinically effective and economical method for reducing the burden of glaucoma-related visual impairment and blindness, although its overall impact on these factors may be relatively modest. The model projects significant costs, which are a limiting factor in effective glaucoma screening.
Screening for glaucoma has been fraught with difficulties for decades. Even when screening identifies a patient at risk, getting the patient to enter and remain within the ophthalmology care domain has limited success. Screening obviously has no means of detecting progression or longitudinal change. Challenges in screening with FDT include false positives, and screening by visual impairment may underestimate the potential value of the screenings by only sorting for advanced loss.
The authors used data from the Eye Diseases Prevalence Research Group and Baltimore Eye Study to develop a Monte Carlo microstimulation model to project visual outcomes in African-American individuals screened for glaucoma under a national screening policy using frequency-doubling technology (FDT).
The results project that implementation of a national glaucoma screening policy for a cohort of African-American individuals between the ages of 50 and 59 years without known glaucoma would reduce the lifetime prevalence of undiagnosed glaucoma from 50 to 27 percent, the prevalence of glaucoma-related visual impairment from 4.6 to 4.4 percent and the prevalence of glaucoma-related blindness from 6.1 to 5.6 percent. The authors defined glaucoma-related visual impairment as acuity worse than 20/40 but better than 20/200 in the better-seeing eye and blindness as acuity of 20/200 or worse in the better-seeing eye.
They project the cost of the program at $80 per screened individual, considering only the cost of FDT and confirmatory eye examinations. The number needed to screen to diagnose one person with glaucoma is 58. The number needed to screen to prevent one person from developing visual impairment is 875.