Pupil Perimetry Using Liquid Cristal Display

Abstract

Abstract: : Purpose: Pupil perimetry using a conventional perimeter has been reported to provide objective measurement of the visual field. However, with a conventional perimeter, it has been difficult to obtain sufficient pupil reaction with limited stimulation. In this study, we report on a new pupil perimeter which we devised using a liquid crystal display (LCD) which generates various stimulations, and applied it to patients with a glaucomatous visual field defect. Methods: The new pupil perimeter consists of a 19 inch LCD for stimulations and an infrared CCD camera for recording pupil reaction. The diameter of the pupil is measured for evaluation of the pupil reaction, and the pupillary contraction ratio is analyzed. There were stimulus positions at 21 points in a meridian visual field of 45° and 135° (each direction 2.5, 5, 10, 15, 20 degrees, and the center of the visual field) . The subjects of the present study were 8 glaucoma patients with visual field disturbance and age–matched normal controls. Results: Increasing stimulus luminance or size caused a larger pupil reaction and a decline in the contraction ratio from the center to the periphery of the visual field. In glaucoma patients, in the position where scotoma and a visual field defect existed, there was a decrease in the contraction. In some cases, pupil reaction was obtained by color (blue) stimulation. Conclusions: A liquid crystal display (LCD) improved the flexibility of size, luminance, and color as stimuli. A decrease in the pupil reaction indicated the existence of scotoma and a visual field defect, and it was possible to evaluate the visual field objectively. We expected that our pupil perimeter using a LCD will find future clinical application for the evaluation of an objective visual field. With changing of the kind of stimulus, such as color, it may be possible for pupil perimetry to detect glaucomatous visual field disturbances more sharply than by subjective visual field evaluation.

Keywords: pupillary reflex • visual fields • perimetry