Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/118408
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- Title
- Multifocal VEP latency in glaucoma
- Related
- (Florida, USA)
- Related
- Investigative ophthalmology and visual science, Vol. 43, E-Abstract 2165,
- Publisher
- Association for Research in Vision and Ophthalmology
- Date
- 2002
- Author/Creator
- Klistorner, A
- Author/Creator
- Balachandran, C
- Author/Creator
- Graham, S. L
- Author/Creator
- Billson, F
- Description
- Purpose: To evaluate the effect of glaucoma on multifocal VEP latency and to assess the influence of risk factors on VEP latency in pre-perimetric suspects. Methods: A multifocal VEP was recorded using the AccuMap (ObjectiVision) on age-matched groups of 92 normal subjects, 158 glaucoma patients and 149 suspects. A pseudorandom cortically scaled pattern stimulus was presented at 58 locations (eccentricity 32deg) within the visual field of the individual. For each location a mean latency and standard deviation was determined from the normal population. Using these, latency values of individuals at all 58 locations, were linearly transformed to a z-score. Results: In the study eye of patients with glaucoma, the average latency z-score for the population was +0.833 , indicating a significant (p<0.001) increase in latency compared with normals (+0.04). The histogram of latency z-score values (from all segments) shows a positively skewed distribution with a wider spread (stdev 2.4) than in normals (stdev 1.0). The areas of increased latency z-score occurred in areas of visual field with normal and reduced amplitude. In the study eye of suspects the mean population latency z-score was 0.58. The histogram of latency z-score, shows the suspect population's distribution to lie in between that of the normal and glaucoma populations. Like the glaucoma population, it is also skewed positively and has a wider spread (stdev 1.94) than normals. In suspects a significant increase in latency z-score was noted in presence of such risk factors as high cup disc ratio and intraocular pressure. Family history alone had no significant effect on latency. Average latency z-score was found to increase with mean deviation (MD derived from subjective perimetry) in suspects and to plateau in glaucoma. Conclusion: These findings suggest that increase in latency is an early feature of glaucoma, occurring before a focal field defect develops on subjective perimetry. The increase in latency develops earlier than reduction in amplitude and plateaus in more advanced glaucoma, while VEP amplitude continues to decline.
- Description
- 1 page(s)
- Subject Keyword
- electrophysiology : clinical
- Subject Keyword
- perimetry
- Subject Keyword
- visual cortex
- Resource Type
- conference paper abstract
- Organisation
- Macquarie University. Australian School of Advanced Medicine
- Identifier
- http://hdl.handle.net/1959.14/118408
- Identifier
- ISSN:0146-0404
- Identifier
- mq-rm-2008003737
- Language
- eng
