The Macular Mapping Test
The Macular Mapping Test (MMT) is a tool for the assessment of the topography of vision. It is a quick and low-cost alternative to conventional perimetry in practical low vision care.
While standard perimetry uses a detection task, the MMT measures the recognition of single letters in the center and near periphery (+/- 10 deg) of the visual field. Their sizes increase according to eccentricity and can be shown at different contrast levels. Each letter is displayed only for a brief moment (250 ms). One test run of 36 trials takes only about 3 minutes.
We have tested patients with early age-related maculopathy (ARM) and control subjects of varying ages. In healthy subjects, overall performance at 10% contrast begins to decline linearly as a function of age from the age of 54 years on. The differences between patients and control subjects was enhanced if performance was analyzed at low contrast. In 18/27 patients, whose fellow eye had early signs of a maculopathy, performance was significantly lower than in the control group.
What have we learned? Using parafoveal test locations, a recognition task and diminished contrast increases the chance of detection of functional defects due to early ARM and can differentiate them from those due to aging alone.
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