Pupil campimetry in patients with retinitis pigmentosa and functional visual field loss

Abstract

The aim of our study was to test in a small series of cases if pupil perimetry can prove real concentric visual field loss in retinal degeneration and distinguish from feigned visual field loss. By means of infrared-video-pupillography, light responses to perimetric stimuli were recorded. The stimulus pattern consisted of 41 stimuli presented in the central 30 degrees visual field. Stimulus intensity was 140 cd/m(2). 5 healthy subjects, 6 patients with retinitis pigmentosa and 2 patients with suspected functional visual field loss were examined. Pupil perimetry was able to reproduce the visual field in retinitis pigmentosa very well. Normal subjects and patients with suspected feigned visual field loss showed normal pupillomotor fields, different from the findings in retinitis pigmentosa. This study provides sufficient evidence that pupil campimetry is applicable for differentiating between retinal dystrophy and functional concentric visual field loss. Possible residual light sensitivity of the blind retina due to melanopsin ganglion cells is obviously not sufficient to provide a pupillary light response to perimetric stimuli.