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The Early Manifest Glaucoma Trial is one of the prominent multicenter trials in glaucoma that has had an important, meaningful impact on how eye care specialists manage and treat patients with glaucoma. In this paper, the authors have evaluated approximately eight years of follow-up results to determine the ability of functional (perimetry) and structural (optic disc photos) test procedures to detect glaucomatous progression.
The results are somewhat surprising since it has been repeatedly found over the past 150 years that structural glaucomatous deficits tend to be detected earlier and more frequently than functional losses
The findings indicated that for eyes with normal visual fields at baseline, there was no difference between structural and functional indicators of glaucomatous progression, both indicating that it occurred 15-18% of the time over the eight year period of evaluation. However, in eyes with visual field abnormalities at baseline, visual field evaluations were able to determine progression about four times greater than structural indicators (52% versus 12%). These results are useful for practitioners who manage patients with glaucoma or are at risk of developing glaucoma. The results are somewhat surprising since it has been repeatedly found over the past 150 years that structural glaucomatous deficits tend to be detected earlier and more frequently than functional losses, in spite of dramatic variations in technology and diagnostic procedures.1 "The results are somewhat surprising since it has been repeatedly found over the past 150 years that structural glaucomatous deficits tend to be detected earlier and more frequently than functional losses,..."
There are several factors that should be kept in mind when assessing the conclusions from this study. The performance of a particular method of assessing progression depends on the decision rules that are used and the analysis method employed.2 Previous investigations have demonstrated that structural and functional glaucomatous changes are not necessarily detected clinically at the same time, either structure or function can be the initial indicator of change, and that both structure and function are important factors to be monitored for proper management of glaucoma patients and glaucoma suspects.3-6 Additionally, the recent advent of new technologies (optic disc and retinal nerve fiber layer imaging, continuous IOP monitoring and other issues) reminds us that the management of glaucoma is constantly changing and that prior evaluations of older technologies may not be relevant for more current procedures. Non-stereo optic disc photographs are but one method of evaluating structural damage, and glaucoma change probabilities is one of many approaches to the assessment of functional loss.