Abstract
Abstract: :
Purpose:To provide a functional test for the detection ofglaucoma. A new type of pattern ERG measurement has grown out of studies by the senior author of color opponency at different afferent retinal layers. By stimulating with alternate spectral and white checks in a reciprocating checkerboard pattern, the luminance and color–opponent responses cancel each other. When the white checks are held constant and the spectral checks are varied in intensity in log10 steps, a minimum ERG amplitude results at some balancing intensity. It was found that this intensity is consistently different in glaucoma patients from what it is in normal subjects. Methods:A 17o by 10o checkerboard was viewed binoculary. The checks subtended 1 cpd. Alternate checks were blue and white. The white checks were held canstant at 1200 Trolands; the blue checks were varied in eight log10 steps from less to more intense than the white checks. The ERG was recorded binocularly with thread electrodes under the eyelids relative to metal electrodes on the side of the head, with a common electrode on the forehead. The recording was triggered by each alternation of the spectral/white checks. Average waveforms were obtained from 150 alternations for each intensity step. Results:ROC analysis of the intensity steps which either produced a minimum ERG voltage or below which no pattern ERG response was visible, have shown very good sensitivity and specificity, with area under the ROC curves of 0.926 (+/– SE 0.0503) for the right eyes of 41 glaucoma patients and 9 normals (to date) and of 0.785 (+/– SE 0.1001) for the left eyes, as diagnosed according to preset rules involving observation of the optic disc and the visual fields by a glaucoma specialist, with the person scoring the tests masked from the diagnosis. These results are significant at P < .0001 for the right eyes and P< .01 for the left eyes. The amplitude of the Photopic Negative Response was also measured for each subject. The area under the ROC curve was 0.733 (+/– 0.1195, P< .05) for the right eyes and 0.700 (+/– SE 0.1141, P> .05) for the left eyes. Conclusions: The Spectral Pattern ERG test shows good promise for distinguishing glaucomatous from normal eyes.
Keywords: electroretinography: clinical • neuro–ophthalmology: diagnosis • detection