Perspective
The Value of Tests in the Diagnosis and Management of Glaucoma

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Purpose

To assess the noneconomic value of tests used in the diagnosis and management of glaucoma, and explore the contexts and factors that determine such value.

Design

Perspective.

Methods

Selected articles from primary and secondary sources were reviewed and interpreted in the context of the authors' clinical and research experience, influenced by our perspectives on the tasks of reducing the global problem of irreversible blindness caused by glaucoma. The value of any test used in glaucoma is addressed by 3 questions regarding: its contexts, its kind of value, and its implicit or explicit benefits.

Results

Tonometry, slit-lamp gonioscopy, and optic disc evaluation remain the foundation of clinic-based case finding, whether in areas of more or less abundant resources. In resource-poor areas, there is urgency in identifying patients at risk for severe functional loss of vision; screening strategies have proven ineffective, and efforts are hindered by the inadequate allocation of support. In resource-abundant areas, the wider spectrum of glaucoma is addressed, with emphasis on early detection of structural changes of little functional consequence; these are increasingly the focus of new and expensive technologies whose clinical value has not been established in longitudinal and population-based studies. These contrasting realities in part reflect differences among the value ascribed, often implicitly, to the tests used in glaucoma.

Conclusions

The value of any test is determined by 3 aspects: its context of usage; its comparative worth and to whom its benefit accrues; and how we define historically what we are testing. These multiple factors should be considered in the elaboration of priorities for the development and application of tests in glaucoma.

Section snippets

Addressing Glaucoma in Resource-Poor Settings

Glaucoma is the world's leading cause of preventable irreversible blindness, affecting an estimated 60.5 million persons and responsible for vision loss among 8.4 million in 2010.14 Damage to vision from glaucoma has been associated with a significant impact on activities of daily living, even at levels well before blindness.15 As pressure-lowering treatment for glaucoma has been demonstrated to reduce the rate of progression of vision damage,16, 17 there is potential value in screening for the

Addressing Glaucoma in Resource-Abundant Settings

The basic technologies essential for diagnosis of glaucoma in resource-poor circumstances are, in resource-abundant areas, universal and familiar. But they are available with so many variations and alleged enhancements that confusion often surrounds what is genuinely essential for glaucoma care. The fundamentals remain simple: IOP is the only physiological parameter we can currently alter to interrupt the progression of glaucoma; the optic nerve (and surrounding nerve fiber layer) is our

The Value of Glaucoma Tests in the Context of Time

Having surveyed testing technologies used in glaucoma from the contexts of focus (structure or function), of resources, and of conceptual frameworks, we now address an important but implicit context that also affects any assessment of a test's value: the perspective of time. Looking backwards to ophthalmic history, it is important to remember the primacy of technology in defining any disease such as “glaucoma.”94 The direct ophthalmoscope revealed to von Graefe the optic nerve's pallor;

Discussion

Let us summarize by integrating the multiple contexts we have touched upon. For the vast majority of the world's patients with glaucoma, most of whom live in settings of constrained resources, the importance of disease management pales before a larger reality: most glaucoma in the world remains undiagnosed, screening paradigms are neither useful nor practical, and access to therapy is severely limited. At the most basic level we have yet to determine: 1) at which stage of disease is the

Conclusions

There is a great gulf of values between the woefully inadequate allocation of funds to prevent glaucoma blindness among the resource-poor and the enormous expenditure on unproven technologies to address early disease without significant functional loss among the resource-abundant. More thoughtful prioritization in our use of wealth in both resource-poor and resource-abundant (but not resource-infinite) areas could alleviate much suffering—but insufficient consideration is given to how these

Marc F. Lieberman, MD, completed his medical degree at the Johns Hopkins Medical School in Baltimore, Maryland and his internship at St. Joseph Mercy Hospital in Ann Arbor, Michigan. He then pursued an ophthalmology residency at the Wilmer Institute, Johns Hopkins, and a glaucoma fellowship at University of Calfornia, San Francisco. He is currently the Director of Glaucoma Services, Department of Ophthalmology, California Pacific Medical Center, and Clinical Professor Ophthalmology at

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  • Marc F. Lieberman, MD, completed his medical degree at the Johns Hopkins Medical School in Baltimore, Maryland and his internship at St. Joseph Mercy Hospital in Ann Arbor, Michigan. He then pursued an ophthalmology residency at the Wilmer Institute, Johns Hopkins, and a glaucoma fellowship at University of Calfornia, San Francisco. He is currently the Director of Glaucoma Services, Department of Ophthalmology, California Pacific Medical Center, and Clinical Professor Ophthalmology at University of California, San Francisco. He founded and serves as Executive Director of the Tibet Vision Project, voluntarily teaching modern ophthalmic skills to Tibetan surgical teams since 1995.

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