CONFRONTATION VISUAL-FIELD LOSS AS A FUNCTION OF DECIBEL SENSITIVITY LOSS ON AUTOMATED STATIC PERIMETRY - IMPLICATIONS ON THE ACCURACY OF CONFRONTATION VISUAL-FIELD TESTING

Purpose: To evaluate the accuracy of confrontation visual field testin g with regard to the density of the visual field defect and its locati on in the peripheral visual field. Methods: A prospective comparison o f confrontation visual field testing with full-threshold Humphrey auto mated static perimetry C24-2 or C30-2 was conducted at a university ey e center over a 3-month period. Seventy-two patients with a variety of neurologic and ophthalmologic conditions underwent confrontation visu al field testing and automated perimetry as a part of their evaluation . One visual field from each patient was analyzed for this study. Resu lts: Confrontation visual field testing yielded an overall sensitivity for detecting an abnormal visual field (full-field analysis) of 63%, when sensitivity of confrontation testing rested on the detection of j ust one abnormal quadrant. The sensitivity of confrontation testing va ried depending on the type of visual field loss present: 51% for arcua te scotomas, 67% for visual field constriction, 78% for altitudinal sc otomas, and 90% for hemianopias. The sensitivity of detecting abnormal visual field quadrants, rather than the full-field analysis, was, how ever, poor at 38%. The sensitivity of confrontation testing was lower for superior quadrant defects and higher for inferior quadrant defects . The estimated probability of detecting an abnormal visual field quad rant occurring at a -26-decibel sensitivity loss from age-matched heal thy patients for superior quadrant defects and a -19-decibel sensitivi ty loss for inferior quadrant defects was 50%. The increased sensitivi ty noted for visual field defects and for inferior quadrant defects ap pears to be related, in part, to the density of the visual field loss present. Conclusion: Confrontation visual field testing is relatively insensitive unless a moderate to dense defect is present, and as such is a poor screening test. However, when visual field defects are ident ified with confrontation visual field testing, the defects often are r eal as per the high specificity (97%) and high positive predictive val ue (96%).