Microtopia

Microtropia (monofixation syndrome) can be primary or occur as a result of surgical intervention after correction of a large angle of deviation.

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Symptoms of microtropia

1. Anisometropia occurs in almost 90% of all cases and is often accompanied by hypermetropia or hypermetropic astigmatism.
2. A very small angle of deviation (8 D or less) may or may not be detected by the cover test.
3. Central suppression scotoma in the deviated eye prevents the phenomenon of confusion and can be detected by:

• Bagolinu striped glasses. Observe the interruption of the oblique line in the figure of the cross at the point of intersection, visible to the microtropic eye with suppressive scotoma.
• test with a 4D prism with the base facing outwards
  • When a 4 D prism is placed base outward in front of a normal eye, an unexpected shift of the image occurs from the fovea and parafoveal region, the temporal side of the retina, which provokes a refixation movement.
  • There are no adjustment movements in the microtropic eye, since the image shift occurs within the eupression scotoma.
  • According to Hering's law, the fellow eye deviates outward when the eye under the prism refixes, followed by a fusional movement in the opposite direction to correct the image displacement.
  • If the central scotoma affects the function of the fovea, then the adjustment movement does not occur.

4. Other features: ACS, normal or near-normal peripheral fusion amplitude, and decreased stereopsis.

Treatment of microtropia

Spectacle correction of anisometropia and occlusion is performed to treat amblyopia, but restoration of bifoveal fixation is almost impossible.