Measurement of Friedmann Visual Field Analyzer tests in primary open-angle glaucoma

A method is described to allow an IBM PC/AT compatible microcomputer program to compute a score from the visual field data collected from a standard Friedmann Visual Field Analyzer (FVFA) Mk II testing procedure. The method could, in principle, be applied to any visual field data which provide quantitative information on the sensitivity of different retinal locations. The score takes into account the depth of any defects, their position in the visual field, and the clustering of defects into scotomata. Visual fields in 119 normal eyes, 82 ocular hypertensive (OH) eyes, and 75 glaucomatous eyes were assessed to provide the data necessary to implement this method. Analyzing the frequency of missed points against point luminance demonstrates that the most effective cut-off from which to regard points as defective is a miss at 0.8 log units or more above the working threshold. A statistical method of analyzing the distribution of defects following Bayesian principles is described and shows that points in the superior nasal, superior arcuate, and inferior arcuate areas provide the most information for detecting glaucoma. The program, written in Turbo Pascal v5.5, incorporates these findings in producing the score.