Full threshold versus quantification of defects for visual field testing in glaucoma

Nineteen glaucoma patients, 17 ocular hypertensives, and 16 normal subjects underwent visual field testing on the Humphrey Field Analyzer using two programs: full threshold (thresholding of all test points with double-crossing technique) and quantification of defects (thresholding only points that deviated more than 6 dB from a presumed normal retinal contour). The purpose of the study was to compare the diagnostic value of information gained by the latter, less time-consuming test with that of the full threshold procedure. The average time requirement per eye was 13 min 11 s for full thresholding and 4 min 22 s for quantification of defects. Of the 104 sets of fields, the diagnosis was at variance in 18. The differences were most often due to shallow defects in otherwise normal fields or shallow defects surrounding deeper scotomas that had been detected by both programs. The shallow defects placed the fields in more advanced diagnostic categories and were all detected with the full threshold technique.