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Microstrabismus: Fixation point scotoma, a perimetric artefact
Joanna M N Otto1, Miriam Kromeier, Michael Bach
1Universitäts-Augenklinik, Killianstr. 5, 79106 Freiburg, Germany.
Vision Research
|February 10, 2009
Summary
Strabismic eyes contribute more to binocular vision than previously thought. New research using natural viewing conditions suggests diffuse suppression rather than a localized scotoma in the strabismic eye.
Area of Science:
- Ophthalmology
- Vision Science
- Neuroscience
Background:
- Previous studies on strabismus often used artificial viewing conditions.
- These conditions suggested a central suppression scotoma (fixation point scotoma) in the strabismic eye.
- The existence of this scotoma under natural viewing conditions was questioned.
Purpose of the Study:
- To investigate the contribution of the strabismic eye to binocular vision under natural viewing conditions.
- To compare stereoresolution with Vernier resolution in the strabismic eye.
- To determine if a circumscribed scotoma or diffuse suppression exists.
Main Methods:
- Employed stereoperimetry allowing natural viewing conditions.
- Presented stereotargets to the strabismic eye at various retinal locations (nasal and temporal to the fovea).
- Compared stereoresolution of strabismic observers with their monocular Vernier resolution and with non-strabismic controls.
Main Results:
- Mean stereoresolution for micro-esotropic observers was 96 arcseconds.
- Stereoresolution was reduced compared to monocular Vernier resolution and non-strabismic controls.
- Findings indicated a slight diffuse suppression, not a localized scotoma.
Conclusions:
- The strabismic eye contributes more to binocular vision than previously assumed.
- Previous assumptions were based on unnatural testing conditions.
- Diffuse suppression is a more accurate description of visual processing in strabismus under natural viewing.
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