[Ocular carbon dioxide reactivity in retinitis pigmentosa. Perimetry results]

Ocular pulse volumes (POV) measured by oculo-oscillo-dynamography were markedly reduced in Retinopathia pigmentosa (R.P.) patients (n = 52) compared to healthy subjects (n = 107). During breathing increased carbon dioxide concentrations (6.5%) POV returned nearly to normal values [15,17]. In an attempt to evaluate the effects of increased inspiratory carbon dioxide concentrations on the visual field in R.P. patients the following study was performed. In 24 patients (24 right eyes, 23 left eyes) suffering from a clinically and electrophysiologically confirmed R.P. kinetic visual field testing was performed. After a standardized kinetic Goldmann-perimetry (V/4; III/4; I/4; I/3; I/2; I/1) during breathing normal air the visual field testing was repeated during breathing increased carbon dioxide concentrations (6.5%). The visual field area was measured with a planimeter (Hewlett Packard 9874 A Digitalizer) separately for each isopter. For a better comparison of the results the change in the visual field was expressed as a percentage value of the initial visual field area of each isopter. During breathing increased carbon dioxide concentrations the visual field area improved, expressed as the median of all isopters, by x = 29% in 24 right eyes and by x = 18% in 23 left eyes. The results presented suggest that breathing of increased carbon dioxide concentrations improve ocular hemodynamics and furthermore have a beneficial effect on the remaining visual field area in R.P. patients.