[Pupillographic perimetry using the "Octopus"].

Abstract

The Octopus 2000 computerized perimeter (Interzeag, Schlieren, Switzerland) is combined with an infrared videopupillograph (Demel, Haan, FRG) which at the same time records the direct pupil light response and controls fixation. Digital processing of the pupil video image is performed at a rate of 25 cps. A transient oscilloscope display of the pupil surface after each light stimulus covers the subsequent 1000 ms, so that either pupillary light reflexes or the lack of a response can immediately be identified. An additional continuous penwriter printout shows light stimuli, pupil responses and the subject's responses. Thus, potential discrepancies between the pupil response and the subject's response are clearly revealed. The examination conditions slightly deviate from the standard ones used with the Octopus. Stimulus size is analogous to the target Goldmann/V, the stimulus duration 100 ms and the adaptive illumination 1 cd/m2. Pupil fatigue considerably exceeds visual fatigue. Therefore standard Octopus perimetric programs are inconvenient for pupilloperimetric purposes. A Sargon-based pupilloperimetric program determines pupillomotor increment thresholds at 12 stimulus locations throughout the visual field (20 degrees nasal, 0 degrees, 20 degrees and 40 degrees temporal/15 degrees above the 0 degrees meridian, 0 degrees meridian and 15 degrees below the 0 degrees meridian) while applying the normal Octopus strategy of threshold calculation. Instead of the patient's subjective responses, the examiner's assessment of pupil responses provides the basis for threshold determination by the Octopus program. The subjects are unaware of the mode of examination. Their rating of "seen" or "not seen" ist displayed together with the pupil responses, thus providing a hard copy as proof of malingering or of appropriate cooperation.