Anisometropic amblyopia : spatial contrast sensitivity deficits in inferred magnocellular and parvocellular vision
Zele, Andrew J., Pokorny, Joel, Lee, David Y., & Ireland, Dennis (2007) Anisometropic amblyopia : spatial contrast sensitivity deficits in inferred magnocellular and parvocellular vision. Investigative Ophthalmology and Visual Science, 48(8), pp. 3622-3631.
Purpose: To measure achromatic spatial contrast sensitivity in patients with anisometropic amblyopia under conditions favoring inferred parvocellular (PC) or magnocellular (MC) pathway mediation.
Methods: Fourteen anisometropic amblyopes (VA amblyopic eye ≤ 6/12; better eye > 6/7.5) and ten age-matched, non-amplyopic controls participated (VA 6/6). Foveal spatial contrast sensitivity was measured using localized, spatially narrow band targets (0.25 – 8.0 cpd) presented in the center of a steady-pedestal (favoring MC detection) or pulsed-pedestal (favoring PC detection) that was set within a uniform surround (Leonova, Pokorny and Smith, 2003, Vision Research, 43, 2133 –2139).
Results: Spatial contrast sensitivity functions were bandpass for the steady-pedestal and lowpass for the pulsed-pedestal. Under steady-pedestal adaptation, the amblyopes showed reduced spatial contrast sensitivity at intermediate frequencies (1-2 cpd), consistent with MC sensitivity loss. For the pulsed-pedestal condition, there was a generalized loss of sensitivity across all spatial frequencies (0.5-4 cpd), consistent with PC sensitivity loss. The magnitudes of inferred MC and PC loss were similar. In the steady and pulsed-pedestal paradigms, results for the better eye of greater than 75 % of the amblyopes were normal or near normal at low and intermediate spatial frequencies.
Conclusions: Anisometropic amblyopia produces spatial contrast sensitivity losses in both inferred PC- and MC-mediated vision, suggesting there may be anomalous processing of MC and PC signals in higher visual areas, including those with orientation and spatial frequency selective cells in the visual cortex. With spatially localized stimuli and a paradigm designed to distinguish between MC-and PC-vision under conditions that differ only in pre- and post-adaptation, the better eye of the amblyopes was normal or near normal.
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|Item Type:||Journal Article|
|Additional Information:||Articles free to read on journal website after 6 months|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
|Copyright Owner:||Copyright 2007 The Association for Research in Vision and Ophthalmology|
|Deposited On:||17 May 2007 00:00|
|Last Modified:||03 Feb 2015 00:25|
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