Glaucoma currently ranks as a leading cause of irreversible blindness worldwide, but many of those afflicted are unaware that they have this painless, progressive neurodegenerative disease. Visual impairment is costly in terms of lost productivity and quality of life. Although the office-based identification of glaucoma can permit the early detection and treatment of the disease and can be cost-effective,1 it has yet to prove a cost-effective strategy in a community setting.
NOT SO SIMPLE
Glaucoma screening appears simple at first glance, but myriad problems conspire to make it a complex process. They include the lack of a gold standard for glaucoma diagnosis, the prevalence of disease in various populations, the challenge of performing screenings in real-world populations, the cost of screening equipment and personnel, the difficulties of providing screened patients with access to a health care system, and the risks of the treatments themselves. 2 From a societal perspective, in an environment of limited resources, maximizing the effectiveness of every health care dollar with the goal of preserving vision and quality of life is important.
ASSESSING UTILITY
One way to evaluate the usefulness of glaucoma screening is to determine the examination cost per case detected. The Nettie Taylor Project in Philadelphia may be used as an example. Designed to be low cost and roughly following the Friends of the Congressional Glaucoma Caucus Foundation screening protocol, this project involved medical students and glaucoma research fellows (free) and a supervising junior ophthalmologist ($75/hr). The equipment used was frequency-doubling perimeters (two machines at $7,000 each), a Tono-Pen XL (Reichert, Inc., Depew, NY; $1,500 on eBay), and a direct ophthalmoscope ($350 on eBay).
More than 2,000 people received free screening examinations at Philadelphia senior centers and African American churches from 2000 to 2004. About 20 2-hour sessions were held each year, and approximately 10% of people were newly diagnosed with glaucoma or as glaucoma suspects (J. D. Henderer, MD, unpublished data, 2004). This translates into a cost of about $140 per diagnosis. A more technologyintensive protocol might now include imaging with a spectral domain optical coherence tomographer ($40,000- $65,000) or a nonmydriatic fundus camera ($30,000), which would increase the previous cost to $290 to $465 per diagnosis. In contrast, the Hoffberger project was a very large community screening effort with referrals for definitive examinations.3 The cost per eye disease diagnosis in the Hoffberger project was $1,500, according to Harry Quigley, MD (written communication, February 2011).
Equally important is factoring in societal costs such as when money is diverted from other activities to support screening and the preservation of quality of life. The current data on the cost-effectiveness of glaucoma screening are limited and are primarily derived from economic models.4-6 Because of inadequate evidence, these models are inevitably built on assumptions, which makes them imperfect. The most recent articles that model the cost-effectiveness of glaucoma screening agree that insufficient evidence exists to support its widespread use in the developed world.4-6
More targeted screenings within populations both at high risk for glaucoma and likely to benefit from earlier treatment, however, might be cost-effective.7,8 This strategy was employed in the Nettie Taylor Project, which specifically focused on elderly African Americans, with the intent to maximize the positive predictive value of screening examinations. Although that strategy helped to increase the screening yield, ultimately, the effort was ineffective because the participants had a very low follow-up rate (J. D. Henderer, MD, unpublished data, 2005). These results mirrored the findings of the Hoffberger Project.3
WHY TRY?
If population glaucoma screening seems to have little or no merit, and if even targeted screenings have little impact on subsequent care, is there any point in making these efforts? Despite significant obstacles, glaucoma screening has a role. First, to maximize the chance of helping participants, the screening should be for eye diseases in general, not just glaucoma. Second, not only should populations be carefully targeted based on disease prevalence, but they should also be targeted based on the likelihood that subsequent care will be delivered. Third, the examination should mimic the gold standard stereo biomicroscopic slit-lamp and fundus examinations as much as possible.9 Tests such as optic nerve imaging and visual field testing are helpful adjuncts in the clinical care of glaucoma patients, but they cannot currently replace the skills of someone trained to evaluate the optic nerve to make a diagnosis, especially in cases of early disease. These tests also are not as helpful when screening for the other major causes of ocular morbidity such as cataract, diabetes, and macular degeneration. Fourth, education about eye disease needs to be continuously delivered so that participants understand its implications (especially since these are diseases associated with aging) and the importance of caring for themselves. Fifth, research is needed to help predict who is likely to get worse so that people facing an unfavorable natural history of the disease can be selectively and more aggressively targeted.
CONCLUSION
Glaucoma screening is an appealing concept. The morbidity associated with the disease is immense, the number of undiagnosed people is high, and the goal of preserving quality of life is laudable. That screening is currently of little use should not end such efforts. Rather, using lessons learned from previous work, those involved can refocus screenings in a manner that makes them cost-effective and clinically important.10 Given the population and the financial pressures that the world faces, there really is no other option.
Jeffrey D. Henderer, MD, is a professor of ophthalmology and the Dr. Edward Hagop Bedrossian chair of ophthalmology at Temple University School of Medicine in Philadelphia. He acknowledged no financial interest in the product or company mentioned herein. Dr. Henderer may be reached at (215) 707-2374; jeffrey.henderer@tuhs.temple.edu.
Richard K. Lee, MD, PhD, is an associate professor of ophthalmology at The University of Miami Miller School of Medicine. He acknowledged no financial interest in the product or company mentioned herein.
Renata Picciani, MD, is a first-year resident in the Temple University School of Medicine in Philadelphia. She acknowledged no financial interest in the product or company mentioned herein.
