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Abstract #5666 Published in IGR 2-1
Pupil perimetry using M-sequence stimulation technique
Wilhelm H; Neitzel J; Wilhelm B; Beuel S; Lüdtke H; Kretschmann U; Zrenner EInvestigative Ophthalmology and Visual Science 2000; 41: 1229-1238
PURPOSE: The M-sequence stimulation allows mapping of the retinal function by multifocal electroretinographic (ERG) recordings. However, the information provided about visual field is limited to retinal function. Optic nerve diseases and diseases of the higher visual pathways usually show normal multifocal ERGs. Using pupillary responses instead of the electrical retinal responses might enhance the diagnostic possibilities of this system. The problems of local ERG recordings are very similar to those encountered in pupil perimetry: local stimuli have to be dim to avoid or at least reduce stray-light responses. Dim stimuli, close to the absolute threshold, elicit only subtle pupillomotor responses. Therefore, techniques that are able to detect small focal responses are promising. METHODS: Pupillography was done by means of an infrared video camera and real time image processing (50 Hz) using a custom-designed videoboard in a personal computer (486). Recording conditions: the stimulus was presented on a monitor (75 Hz) at 26-cm distance from the patient's eyes. It contained 37 hexagons in a 25° visual field. Each element changed between black (1.6 cd/m2) and white 160 cd/m2) after a binary M-sequence independently from other elements. Four thousand and ninety-six different stimulus pictures of 120-msec duration were shown during a single pupillogram recording. Thirty-seven local pupillograms were calculated in a cross-correlation of stimulus sequence and the pupil diameter. RESULTS: The pupillomotor fields in normals showed a shape and sensitivity distribution as known from conventional pupil perimetry techniques. Artificial paracentral scotomas (5°) created by masking different locations could be demonstrated convincingly. Even in patients with optic nerve lesions, it was possible to demonstrate visual field defects. CONCLUSION: Pupil perimetry using the M-sequence technique is a promising method of objective perimetry that may find its way into clinical application.
Dr. H. Wilhelm, Universitäts-Augenklinik, Department of Pathophysiology of Vision and Neuro-ophthalmology, D-72076 Tübingen, Germany. helmut.wilhelm@uni-tuebingen.de
Classification:
6.6.3 Special methods (e.g. color, contrast, SWAP etc.) (Part of: 6 Clinical examination methods > 6.6 Visual field examination and other visual function tests)
