IOVS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

(Investigative Ophthalmology and Visual Science. 2004;45:4510-4519.)
© 2004 by The Association for Research in Vision and Ophthalmology, Inc.
DOI:  10.1167/iovs.04-0188
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (11)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Alexander, K. R.
Right arrow Articles by Smith, V. C.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Alexander, K. R.
Right arrow Articles by Smith, V. C.

Contrast Sensitivity Deficits in Inferred Magnocellular and Parvocellular Pathways in Retinitis Pigmentosa

Kenneth R. Alexander,1,2 Claire S. Barnes,1,3 Gerald A. Fishman,1 Joel Pokorny,4 and Vivianne C. Smith4

1From the Departments of Ophthalmology and Visual Sciences and 2Psychology, University of Illinois at Chicago, Chicago, Illinois; and the 4Department of Ophthalmology and Visual Sciences, The University of Chicago, Chicago, Illinois.

PURPOSE. To define the contrast sensitivity deficits of patients with retinitis pigmentosa (RP) under testing conditions designed to emphasize threshold mediation by either the magnocellular (MC) or parvocellular (PC) pathway.

METHOD. Contrast sensitivity was measured with spatially localized, narrow-band test patterns at peak spatial frequencies ranging from 0.25 to 8 cycles per degree (cpd), using a steady-pedestal paradigm (brief presentation of the test stimulus against a continuously presented luminance pedestal) and a pulsed-pedestal paradigm (simultaneous brief presentation of the test stimulus and luminance pedestal) to favor the MC and PC pathways, respectively. The contrast sensitivity functions of 12 patients with RP who had visual acuities ranging between 20/12.5 and 20/40 were compared to those of 10 visually normal, age-equivalent control observers.

RESULTS. Five of the patients with RP who had Snellen visual acuities better than 20/25 had contrast sensitivity functions that were within the normal limits at all spatial frequencies for both testing paradigms. The other seven patients with RP had reduced contrast sensitivities for both paradigms, with the greatest reduction in sensitivity occurring at the highest spatial frequency. Their contrast sensitivity deficits were equivalent for the steady- and pulsed-pedestal paradigms.

CONCLUSIONS. As observed in previous studies, the degree of contrast sensitivity loss shown by the patients with RP was greatest at the highest stimulus spatial frequency. However, in comparison to prior studies of contrast discrimination in patients with RP, there was no evidence of a preferential contrast sensitivity loss within the MC pathway. This apparent discrepancy is attributed to differences in the test targets and psychophysical judgments that were used in the studies, which emphasizes the importance of task characteristics in evaluating relative deficits within the MC and PC processing streams in visual disorders.




This article has been cited by other articles:


Home page
 IOVSHome page
S. Maia-Lopes, E. D. Silva, M. F. Silva, A. Reis, P. Faria, and M. Castelo-Branco
Evidence of Widespread Retinal Dysfunction in Patients with Stargardt Disease and Morphologically Unaffected Carrier Relatives
Invest. Ophthalmol. Vis. Sci., March 1, 2008; 49(3): 1191 - 1199.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
A. J. Zele, J. Pokorny, D. Y. Lee, and D. Ireland
Anisometropic Amblyopia: Spatial Contrast Sensitivity Deficits in Inferred Magnocellular and Parvocellular Vision
Invest. Ophthalmol. Vis. Sci., August 1, 2007; 48(8): 3622 - 3631.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
A. M. McKendrick, G. P. Sampson, M. J. Walland, and D. R. Badcock
Contrast Sensitivity Changes Due to Glaucoma and Normal Aging: Low-Spatial-Frequency Losses in Both Magnocellular and Parvocellular Pathways
Invest. Ophthalmol. Vis. Sci., May 1, 2007; 48(5): 2115 - 2122.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
E. Stifter, S. Sacu, A. Thaler, and H. Weghaupt
Contrast Acuity in Cataracts of Different Morphology and Association to Self-Reported Visual Function
Invest. Ophthalmol. Vis. Sci., December 1, 2006; 47(12): 5412 - 5422.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
A. Jaworski, A. Gentle, A. J. Zele, A. J. Vingrys, and N. A. McBrien
Altered visual sensitivity in axial high myopia: a local postreceptoral phenomenon?
Invest. Ophthalmol. Vis. Sci., August 1, 2006; 47(8): 3695 - 3702.
[Abstract] [Full Text] [PDF]

Home page
 IOVSHome page
K. R. Alexander, A. S. Rajagopalan, W. Seiple, V. M. Zemon, and G. A. Fishman
Contrast Response Properties of Magnocellular and Parvocellular Pathways in Retinitis Pigmentosa Assessed by the Visual Evoked Potential
Invest. Ophthalmol. Vis. Sci., August 1, 2005; 46(8): 2967 - 2973.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2004 by the Association for Research in Vision and Ophthalmology