Effectiveness of testing visual fields by confrontation.

Abstract

Many tests are used to examine visual fields by confrontation, but such methods have not been thoroughly compared with an accepted reference standard. The choice of test might affect the identification of subtle defects in the visual field. We prospectively compared seven confrontation field tests with full-threshold automated static perimetry among 138 outpatients in an eye clinic. Our primary outcome was detection of a defect in the visual field. With automated perimetry, most field defects were small or shallow. Most confrontation field tests were insensitive in the identification of field loss. The most sensitive method was examination of the central 20o visual field with a small red target (73% [95% CI 63–82]). Assessment of the visual field should thus include such a test. Lancet 2001; 358: 1339–40 Visual-field loss is routinely identified by testing visual fields by confrontation. Defects in the visual field are rarely absolute. They are usually relative, corresponding to a rise in the visual threshold. Thus, if the stimulus intensity of the target is increased, the target becomes visible. Large and dense visual-field defects are easily identified even by gross tests, but for detection of smaller or shallower defects, the choice of test is crucial. We prospectively compared the results of confrontation field tests with those of full threshold automated static perimetry (reference standard) in 138 consecutive outpatients attending an eye clinic at our hospital. We had no exclusion criteria and all patients gave written informed consent. Every patient had seven confrontation field tests,which were done by one ophthalmologist (RJP),who was masked to the results of automated perimetry and to the diagnosis. After automated perimetry,patients were examined in the same room,in usual room lighting,with a plain background behind the examiner. During tests,the examiner was seated about two-thirds of a metre in front of the patient,and targets were introduced in an equidistant plane. Each eye was examined in turn,with the other eye occluded. The patient was asked to maintain fixation on the opposing eye of the examiner for all tests apart from subjective description of the examiner’s face,in which the patient focused on the examiner’s nose. So that the patient’s visual field was compared with that of the examiner,the examiner’s other eye was kept occluded during kinetic boundary tests. Confrontation tests have been well described, 1 and were