Fiber Optics and Video-oculography Associated with Pupillary Responses and Visual Evoked Potentials for Objective Perimetry
Ernesto Suaste, Palmira Rivera, Laura Solis · Journal of Clinical Engineering · 1997
To quantity the pupillary response, the pupillary escape, and the Visual Evoked Potentials (VEPs) during a visual field examination, a new technique is described, based on a signal-image processing system. Visual field evaluation is important in the detection, diagnosis and assessment of ophthalmologic and neurologic dysfunction. A large pupil is considered an initial condition during the perimetric study; with use of a small-step light stimuli, pupillary escape is present, wherein the pupil responds with a very fast constriction and then redilates almost back to its original size. In order to measure the pupil size changes, automatic and objective determination of the pupillary response is obtained for certain stimuli spots of light in peripheral and central visual zones. The automatic perimeter used is based on the physical dimensions of the Coldmann perimeter; the light index projector is based on a fiber optics target. The pupillary response and the pupillary escape are captured by means of an infrared camera with spectral sensitivity of 400 to 1300 nm and recorded in a video cassette recorder (VCR) for off-line analysis with an image processing system. The VEPs are obtained from the electroencephalogram (EEC) using averaging techniques.