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Multifocal VEP offers possibility of objective perimetry
The objective testing method is less invasive and places fewer demands on the patient than subjective testing.
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Multifocal visual evoked potential is a diagnostic modality that may allow objective documentation of visual field defects, glaucoma researchers say. The test can be done relatively quickly with high patient acceptance, making it ideal for use in children, according to investigators.
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Ivan Goldberg |
Ivan Goldberg, MBBS, FRANZCO, FRACS, spoke about the potential for multifocal visual evoked potential (mfVEP) to provide “no more tears visual fields” at the American Academy of Ophthalmology meeting in Chicago.
Dr. Goldberg said mfVEP, which he also referred to as multifocal objective perimetry, requires no patient response except to monitor fixation. It is noninvasive, and it can be done in patients with undilated pupils with low stress and a minimal learning curve. In contrast, he said, standard perimetry is subjective, is dependent on patient cooperation and understanding, is stressful for patients and subject to their fatigue, and has a learning curve that some never master.
In an e-mail exchange after the AAO meeting, Dr. Goldberg outlined the results of the clinical trial conducted with colleagues Stuart L. Graham and Alex I. Klistorner, who developed this technology, which was published in the American Journal of Ophthalmology.
Dr. Goldberg said the trial, which included 100 patients, compared mfVEP using the ObjectiVision AccuMap perimeter to Humphrey perimetry.
The mfVEP demonstrated a sensitivity of 97% in identifying patients with visual field defects on Humphrey perimetry, Dr. Goldberg said. The topographic location of defects on the mfVEP was well correlated with the Humphrey fields.
Moreover, in the same clinical trial, in 37 confirmed glaucoma cases with no scotoma in the fellow eye, 22 (59%) had an abnormal mfVEP, whereas only eight (21%) had some aspect of their Humphrey fields flagged as abnormal, Dr. Goldberg said. Nineteen of those 22 eyes also had a suspect or glaucomatous disc, he said.
Dr. Goldberg and colleagues concluded that mfVEP can detect glaucoma field defects. Their results suggest that mfVEP may be helpful in patients with unreliable visual field results and may detect changes before they are seen in white-on-white perimetry, the study authors said.
Dr. Goldberg said mfVEP detected neurological field defects, and there is usually good correlation with the structural parameters of the Heidelberg Retina Tomograph. The study authors found that the procedure could be used in children with a short sequence protocol.
They also found that cataract reduces the amplitude of central field responses, which should be considered when interpreting results.
For Your Information:Reference:
- Ivan Goldberg, MB, BS, FRANZCO, FRACS, can be reached at 187 Macquarie St., Floor 4, Sydney, NSW 2000, Australia; fax: 61-292323086; e-mail: igoldber@bigpond.net.au.
- Goldberg I, Graham SL, Klistorner AI. Multifocal objective perimetry in the detection of glaucomatous field loss. Am J Ophthalmol. 220;133(1):29-39.
- Erin L. Boyle is an OSN Staff Writer who covers all aspects of ophthalmology.