Photopic tangential perimetry

A large absolute paracentral ring scotoma was found in both eyes of a 60-year-old woman with progressive cone dysfunction but with normal rod function using for the perimetry a white tangential screen of 200 cd/m2 luminance and a 632 nm laser test light. No visual field defect could be found in this patient using the Goldmann perimeter employing white test objects on the standard 10 cd/m2 white background. Further developments of a photopic tangential perimetry system are suggested.