Foveal contrast processing of increment and decrement targets is equivalently reduced in glaucoma

Sampson, G. P., Badcock, D. R., Walland, M. J. and McKendrick, A. M. 2008, Foveal contrast processing of increment and decrement targets is equivalently reduced in glaucoma, British journal of ophthalmology, vol. 92, no. 9, pp. 1287-1292, doi: 10.1136/bjo.2007.130880.

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Title Foveal contrast processing of increment and decrement targets is equivalently reduced in glaucoma
Author(s) Sampson, G. P.ORCID iD for Sampson, G. P.
Badcock, D. R.
Walland, M. J.
McKendrick, A. M.
Journal name British journal of ophthalmology
Volume number 92
Issue number 9
Start page 1287
End page 1292
Total pages 6
Publisher BMJ Group
Place of publication London, England
Publication date 2008
ISSN 0007-1161
Keyword(s) individual precortical visual pathways
Summary Background
Psychophysical measurement of the function of individual precortical visual pathways (magnocellular, parvocellular and koniocellular) has enabled the development of sensitive tests for glaucoma and has enhanced understanding of its pathophysiology. Such pathways can be further subdivided into their “On” and “Off” components, which have anatomical and physiological asymmetries. This study investigated whether On and Off subdivisions of the magnocellular (M) pathway are differentially affected by glaucoma.

20 participants with glaucoma and 20 controls underwent two psychophysical procedures that have been shown to assess the M pathway (steady pedestal task) and its On and Off subdivisions (pedestal-delta-pedestal task) respectively. Luminance discrimination thresholds were measured foveally, using both increment and decrement stimuli.

The steady pedestal (undifferentiated M-pathway) task separated the glaucoma and control groups (p = 0.04) with equivalent outcomes for increment and decrement targets. The pedestal-delta-pedestal task (isolated On and Off M-pathway subdivisions) also differentiated between groups (p = 0.025), but the outcome was not dependent on which subdivision was isolated.

This study found that increment and decrement targets can be used with equal effectiveness for detecting contrast processing deficits in early glaucoma. Outcomes further suggested that glaucoma affects On and Off subdivisions of the M-pathway equivalently.
Language eng
DOI 10.1136/bjo.2007.130880
Field of Research 119999 Medical and Health Sciences not elsewhere classified
Socio Economic Objective 970111 Expanding Knowledge in the Medical and Health Sciences
HERDC Research category C1.1 Refereed article in a scholarly journal
Copyright notice ©2008, BMJ Group
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Document type: Journal Article
Collection: School of Health and Social Development
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