RELATIVE DISPERSION ANALYSIS ENHANCES PERIMETRIC SENSITIVITY

Objective identification of minor visual field defects is problematic. A possible solution is to examine spatial correlations by means of re lative dispersion analysis, a tool of fractal analysis, We studied pat ients with glaucoma, previous optic neuritis, chiasmal compression and lesions of the brain hemispheres, using high-pass resolution perimetr y, One-hundred visual field records were drawn consecutively for each category and ranked according to severity of defects. Records with sco res ranking below the 35th percentile, i.e. those with the smallest fi eld defects, were analysed. Relative dispersion analysis recognized 1. 3-2.4 times more abnormal subjects than did pattern standard deviation . A previously described form index was intermediate in sensitivity. S pecificity was 96%. Relative dispersion analysis appears to capture a novel aspect of visual field abnormality, with good sensitivity and sp ecificity. The analysis is easily performed.