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The paracentral visual field in multiple sclerosis: evidence for a deficit in interneuronal spatial summation?
A Antal1, J F Aita, I Bodis-Wollner
1Department of Physiology, University of Szeged, P.O. Box 427, 6720 Szeged, Hungary. aantal@phys.szote.u-szeged.hu
Vision Research
|May 12, 2001
Summary
Visual complaints in multiple sclerosis (MS) may not stem from optic nerve damage. Contrast perimetry reveals visual pathway dysfunction, suggesting MS impacts visual cortex networks.
Area of Science:
- Neuroscience
- Ophthalmology
- Clinical Neurology
Background:
- Blurred vision is an early sign of multiple sclerosis (MS).
- Optic nerve demyelination is often cited but may not fully explain visual deficits.
- Standard visual field tests can be inconclusive for MS-related visual abnormalities.
Purpose of the Study:
- To investigate the cause of visual dysfunction in multiple sclerosis (MS).
- To assess visual pathway function using contrast perimetry (CP).
- To determine if MS affects visual cortex networks rather than solely the optic nerve.
Main Methods:
- Contrast perimetry (CP) was used to test the central 16 degrees of the visual field.
- Four paracentral visual field quadrants were tested in 31 MS patients and 26 controls.
- Stimuli included varying sizes of sinusoidal gratings (Gabors) to measure contrast sensitivity (CS).
Main Results:
- Significant differences in CP data were found between MS patients and controls across all tested pattern sizes.
- The largest differences in contrast sensitivity were observed at Gabor diameters of 2.5-3.7 degrees.
- Findings challenge the notion that optic nerve pathology alone explains visual dysfunction in MS.
Conclusions:
- Optic nerve pathology does not fully account for subclinical and manifest visual dysfunction in MS.
- Results support the hypothesis that MS affects a visual cortex network involving myelinated axonal branches.
- This network likely binds monocular neuronal columns with specific like-with-like organization.