Refractive Scotomata in Perimetry

Adequate correction is an essential prerequisite for precise perimetry. Therefore, not only the correct glasses have to be chosen, but also their positioning should be properly determined. Otherwise, a distortion of the stimulus grid, as well as a (area enlarging/reducing) distortion of the stimuli themselves, can occur. Therefore, scotomata may be simulated in visual fields which are purely optically evoked (so-called refraction scotomata), because the light stimulus is mapped on an enlarged/reduced retinal area, thereby reducing/increasing light density.