Arcuate Cluster Analysis in Glaucoma Perimetry

Abstract

Typical glaucomatous visual field defects are often contiguous areas of diminished differential light sensitivity presenting as clusters of abnormally depressed points in the visual field chart. We investigated the value of recognizing arcuate cluster patterns, corresponding to the anatomy of the normal retinal nerve fiber layer. Cluster sizes were quantified using cluster volume and surface area. Clusters were analyzed separately in different regions of the visual field. Central 30 degrees static threshold fields from 87 eyes of 87 normal subjects and 101 eyes of 101 patients with glaucoma were studied. The two groups were discriminated with logistic regression. Central and nasal clusters were more indicative of glaucoma than were equally large clusters in other areas. Discrimination of normal and glaucoma eyes was significantly better with arcuate cluster analysis than with a traditional cluster analysis, which did not take cluster shape into account. Thus, arcuate cluster analysis was more sensitive to early central, paracentral, or nasal glaucomatous field loss and at the same time capable of deemphasizing common test artifacts and nondiagnostic field disturbances. Arcuate cluster volume gave better classification than did arcuate surface area. The results indicate that analysis of arcuate clusters offers substantial advantages as compared with traditional cluster analysis for recognition of early glaucomatous visual field loss.