The value of different screening techniques for glaucoma

The role of tonometry has been relegated from case finding to risk stratification, because intraocular pressure poorly differentiates between health and glaucomatous eyes. Led by the evidence that optic disc and retinal nerve-fiber layer change may precede glaucomatous visual field loss by several years, enormous efforts have been made to accurately measure these parameters for case definition; however, the wide variability in optic nerve head topography among the normal eyes, and the marginal quality of a substantial proportion of fundus photographs limit the usefulness of biomorphometry as a screening tool. Scanning laser ophthalmoscopy may potentially overcome the limitations of conventional photographic techniques for accurate biomorphometry, but this technology remains expensive. In light of the limitations of tonometry and biomorphometry in a general screening setting, the value of psychophysical testing has assumed an increasing importance. The low prevalence of glaucoma in an unselected adult population, combined with the lack of a valid screening technique, argues for a shift in focus from widespread population-based screening with a single test to case finding targeted at high-risk individuals.