Cartographic Deformations in an Orthogonal Perimetric Map

Some modern perimeters have replaced the meridians and the parallel circles of the classical perimetric map with an orthogonal grid. Analysis of cartographic deformations in the two maps disclosed practically negligible differences within the central visual field. The intermediary and peripheral parts of the field are depicted differently, however. This may cause difficulties in comparing some types of field defects, particularly those located in octants neighboring the vertical meridian, or in the temporal crescent. Both maps are inappropriate for measuring visual field areas.