Detecting early functional damage in glaucoma suspect and ocular hypertensive patients with the multifocal VEP technique.

PURPOSE

To determine whether the multifocal visual evoked potential (mfVEP) technique can detect early functional damage in ocular hypertensive (OHT) and glaucoma suspect (GS) patients with normal standard achromatic automated perimetry (SAP) results.

PATIENTS AND METHODS

Twenty-five GS patients (25 eyes), 25 patients with OHT (25 eyes), and 50 normal controls (50 eyes) were enrolled in this study. All GS, OHT and normal control eyes had normal SAP as defined by a pattern standard deviation and mean deviation within the 95% confidence interval and a glaucoma hemifield test within normal limits on the Humphrey visual field 24-2 program. Eyes with GS had optic disc changes consistent with glaucoma with or without raised intraocular pressure (IOP), and eyes with OHT showed no evidence of glaucomatous optic neuropathy and IOPs >or=22 mm Hg. Monocular mfVEPs were obtained from both eyes of each subject using a pattern-reversal dartboard array with 60 sectors. The entire display had a radius of 22.3 degrees. The mfVEPs, for each eye, were defined as abnormal when either the monocular or interocular probability plot had a cluster of 3 or more contiguous points with P<0.05 and at least 2 of these points with P<0.01.

RESULTS

The mfVEP results were abnormal in 4% of the eyes from normal subjects. Abnormal mfVEPs were detected in 20% of the eyes of GS patients and 16% of the eyes of OHT patients. Significantly more mfVEP abnormalities were detected in GS patients than in normal controls. However, there was no significant difference in mfVEP results between OHT patients and normal controls.

CONCLUSIONS

The mfVEP technique can detect visual field deficits in a minority of eyes with glaucomatous optic disks and normal SAP results.