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A method for comparing electrophysiological, psychophysical, and structural measures of glaucomatous damage
Vivienne C Greenstein1, Phamornsak Thienprasiddhi, Robert Ritch
1Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, 635 W 168th Street, New York, NY 10032, USA.
Objective:
To develop a method for comparing multifocal visual-evoked potential (mfVEP) responses and behaviorally determined visual fields with structural measures of the optic nerve head.
Methods:
Humphrey 24-2 visual fields and mfVEPs were obtained from each eye of 20 patients with open-angle glaucoma. Monocular and interocular analyses were performed to identify locations with abnormal mfVEP responses. Optic discs were assessed with a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph II). The image of the optic nerve head was divided into 6 sectors. The rim and disc area measurements for each sector were compared with those in a normal database using Moorfields regression analysis. The optic nerve head measurements for the 6 sectors were related to the Humphrey visual field locations and the 60 sectors of the mfVEP display.
Results:
Of 240 sectors tested (40 eyes x 6 sectors), 18.8% on Humphrey visual field, 22.1% on mfVEP, and 10.8% on confocal scanning laser ophthalmoscopic testing were significantly different from those of control subjects. There were no significant deficits in 165 sectors. There was agreement for 86.7% of the sectors when the Humphrey visual field and mfVEP results were compared. The confocal scanning laser ophthalmoscopic results were in agreement for 84.6% of these sectors.
Conclusions:
The method used allows for a comparison among measures of visual function and a structural measure of the optic nerve head. In general, the results of the functional and structural measures showed agreement; however, there were clear examples of disagreements that merit further study.