Surgical release of a deep retro-equatorial band in congenital unilateral restrictive strabismus: a case report
Year: 2026
Type: article
Study design: Case Report
Abstract: Introduction and importance: Congenital unilateral restrictive strabismus may result from anomalous orbital tissue, extraocular muscle abnormalities, or congenital cranial dysinnervation. Forced duction testing can identify a passive mechanical component, but does not establish tissue identity or exclude coexisting dysinnervation. Presentation of the case: An 11-year-old girl had congenital ocular misalignment with 40 prism diopters (PD) of right hypotropia, 20 PD of exotropia, and left supraduction and infraduction each graded -3, with full abduction and adduction. Apparent right upper-eyelid asymmetry was formally evaluated by the oculoplastic service and diagnosed as pseudoptosis associated with the right hypotropia rather than true ptosis; margin reflex distance-1 was 3 mm bilaterally with each eye fixating, and levator function was >14 mm bilaterally. Computed tomography showed intact orbital walls without obvious extraocular muscle entrapment; dedicated orbital magnetic resonance imaging was not performed. Under general anesthesia, multidirectional forced duction testing demonstrated no appreciable restriction during passive elevation in adduction. Maximum resistance was localized to a focal central point in the superior plane, while passive infraduction and horizontal rotations were unrestricted. Superior exploration identified a focal tissue attachment at the nasal aspect of the normal-appearing superior rectus region and, more posteriorly, a deep retro-equatorial band. Stepwise release markedly improved passive elevation, although mild residual superior restriction remained because further posterior dissection was limited by the risk to deep orbital neurovascular structures and the optic nerve. No tissue was submitted for histopathological examination. A 10 mm left lateral rectus recession was performed for the associated exotropia. At 12 months, horizontal alignment was orthotropic, and residual right hypotropia measured 12 PD at distance and approximately 8-10 PD at near. Left supraduction and infraduction had both improved to approximately -2, while abduction and adduction remained full. Clinical discussion: The intraoperative response supports an important mechanical contribution, although the identity, full posterior extent, and anatomical relationships of the abnormal tissue remain uncertain. The documented diagnosis of pseudoptosis with preserved levator function, rather than true congenital ptosis, makes classic congenital fibrosis of the extraocular muscles (CFEOM)1 and CFEOM2 less characteristic; however, CFEOM3 cannot be excluded without dedicated orbital/cranial nerve imaging and, when indicated, genetic assessment. Residual vertical motility limitation may reflect the safely unreleased posterior restriction, coexisting extraocular muscle dysplasia or dysinnervation, or a combination of these factors. Conclusion: Stepwise partial release of a deep retro-equatorial band substantially reduced the accessible passive restriction while avoiding unsafe posterior dissection. At 12 months, vertical alignment and both supraduction and infraduction had improved, although residual right hypotropia and vertical motility limitation persisted. The findings support an important mechanical component but do not establish the precise tissue identity or exclude coexisting congenital dysinnervation.
Authors: Abdulrahman Alyahya, Fawzia Alhaimi
Institution: King Khaled Eye Specialist Hospital
Language: English
Subfield: Ophthalmology
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,090
OpenAlex ID: W7225713186