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Helmut Wilhelm, Jürgen Neitzel, Barbara Wilhelm, Stefan Beuel, Holger Lüdtke, Ulf Kretschmann, Eberhart Zrenner; Pupil Perimetry using M-Sequence Stimulation Technique. Invest. Ophthalmol. Vis. Sci. 2000;41(5):1229-1238.
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purpose. M-sequence stimulation technique 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
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) in 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 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
conclusions. Pupil perimetry using the M-sequence technique is a promising method of
objective perimetry that may find its entrance into clinical
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