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Elevation deficit caused by accessory extraocular muscle
C Valmaggia1, W Zaunbauer, I Gottlob
1Department of Strabismus and Neuroophthalmology, Kantonsspital St. Gallen, Switzerland.
American Journal of Ophthalmology
|April 1, 1996
Summary
A rare accessory extraocular muscle caused an elevation deficit in a 6-year-old boy. This supernumerary muscle, detected via advanced imaging, may be an atavistic retractor bulbi.
Area of Science:
- Ophthalmology
- Pediatric Ophthalmology
- Anatomy
Background:
- Extraocular muscles are crucial for eye movement and positioning.
- Congenital anomalies of extraocular muscles are rare but can cause significant visual impairment.
- Accurate diagnosis requires advanced imaging techniques.
Observation:
- A 6-year-old boy presented with an elevation deficit in his left eye.
- Computed tomography (CT) and magnetic resonance imaging (MRI) were performed.
- Imaging revealed a unique, well-defined structure in the retrobulbar space.
Findings:
- A supernumerary, fusiform, intraconal muscle was identified.
- This anomalous muscle was located between the annulus of Zinn and the posterior globe.
- The structure was confirmed as an accessory extraocular muscle.
Implications:
- This finding represents a rare anatomical variation.
- The anomaly may be an atavistic retractor bulbi muscle, a structure present in some non-primate mammals.
- Understanding such anomalies is vital for diagnosing and managing pediatric strabismus and motility disorders.