Programs for diagnosis and therapy of visual field deficits in vision rehabilitation

Abstract-A suite of computer programms is descibed for visual field-assessment of residual vision in neuropsychological rehabilitation. 1. INTRODUKTION Recent findings of higher plasticity and limited functional recovery from visual field defects (Zihl 1979; Zihl and Cramon, 1981; Schmielau, 1989; Kasten et al., 1994, Kasten and Sabel, 1995) suggests that training patients having certain types of visual field loss is beneficial. Hence, the availability of specialised, easy-to-use techniques for restoring some aspects of visual function is important. Here we describe a suite of computer programs for the diagnosis and therapy of visual field deficits for use in neuropsychological rehabilitation. This set of programs complements commercially available perimeters. The aim is to concentrate measurements to a certain, patient-specific subfield and to provide, through automation, in that limited field more detailed information about certain low-level visual functions. Of particular interest are those functions that are typically affected, or provide differential information, in the various kinds of visual field deficits. Furthermore, a derived, slightly modified version of the programs allows the training of those same visual functions, with particular emphasis of the training in those parts of the visual field where residual function has been ascertained. The limitations of measurement when a computer monitor is used for perimetry purposes are a natural consequence of a number of physical and optical limitations. Minimum luminance of a black monitor screen is limited by phosphor characteristics and is often visible under dark adapted viewing conditions (e.g. Di Lollo et al., 1996). Visual field size is limited through the monitor’s physical screen size, through the min