Functional loss in the magnocellular and parvocellular pathways in patients with optic neuritis

Cao, Dingcai, Zele, Andrew J., Pokorny, Joel, Lee, David, Messner, Leonard, Diehl, Christopher, & Ksiazek, Susan (2011) Functional loss in the magnocellular and parvocellular pathways in patients with optic neuritis. Investigative Ophthalmology and Visual Science, 52(12), pp. 8900-8907.

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Abstract

Purpose

  • To evaluate contrast threshold and contrast gain in patients with optic neuritis under conditions designed to favor mediation by either the inferred magnocellular (MC) or parvocellular (PC) pathway.

Methods

  • Achromatic and chromatic contrast discrimination was measured in 11 patients with unilateral or bilateral optic neuritis and in 18 age-matched controls with normal vision, using achromatic steady- and pulsed-pedestal paradigms to bias performance toward the MC or PC pathway, respectively. In addition, L-M chromatic discrimination at equiluminance was evaluated using the steady-pedestal paradigm. A physiologically plausible model could describe the data with parameters accounting for contrast gain and contrast sensitivity in the inferred MC or PC pathway. The fitted parameters from the eye affected by optic neuritis were compared with those from the normal eye using generalized estimation equation (GEE) models that can account for within-subject correlations.

Results

  • Compared with normal eyes, the affected eyes had significantly higher saturation parameters when measured with both the achromatic pulsed-pedestal paradigm (GEE: β [SE] = 0.35 [0.06]; P < 0.001) and the chromatic discrimination paradigm (β [SE] = 0.18 [0.08]; P = 0.015), suggesting that contrast gain in the inferred PC pathway is reduced; the affected eyes also had reduced absolute sensitivity in the inferred MC pathway measured with the achromatic steady-pedestal paradigm (β [SE] = 0.12 [0.04]; P = 0.005).

Conclusions

  • Optic neuritis produced large sensitivity losses mediated by the MC pathway and contrast gain losses in the inferred PC pathway. A clinical framework is presented for interpreting contrast sensitivity and gain loss to chromatic and achromatic stimuli in terms of retinal and postretinogeniculate loci contributions to detection and discrimination.

Impact and interest:

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ID Code: 52175
Item Type: Journal Article
Refereed: Yes
Additional Information: Articles free to read on journal website after 6 months
Funders: ARC
DOI: 10.1167/iovs.11-7644
ISSN: 0146-0404
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Funding:
Copyright Owner: 2011 Association for Research in Vision and Ophthalmology
Deposited On: 19 Jul 2012 06:28
Last Modified: 16 Dec 2016 01:42

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