Congenital bilateral supranuclear vertical gaze palsy with striking large-angle exotropia in young adult

Purpose: Congenital supranuclear vertical gaze palsy is an extremely rare ocular motility disorder, typically presenting with vertical gaze limitation despite normal extraocular muscles and cranial nerves. The coexistence of congenital supranuclear vertical gaze palsy with large-angle horizontal and vertical deviations is scarcely reported. Hence, we are reporting such a case. Methods: A 20-year-old male presented with lifelong outward deviation of both eyes and inability to look upward. Clinical evaluation included detailed ocular motility assessment, vestibulo-ocular reflex (VOR) testing, and neuroimaging. The possibility of bilateral third nerve palsy with aberrant regeneration was ruled out based on preserved adduction, normal pupillary reactions, and absence of ptosis or globe retraction and intact VORs. Surgical correction was undertaken for large-angle horizontal deviation using left eye muscle transplantation technique involving medial rectus resection and lateral rectus recession. Results: Ocular motility testing demonstrated complete upgaze restriction bilaterally with preserved downgaze and horizontal movements, intact Bell's phenomenon, and normal VORs, confirming supranuclear involvement. Neuroimaging was unremarkable. On postoperative day 1, there was marked improvement in ocular alignment, with residual 40 prism diopters of exotropia and 20 prism diopters of hypotropia. Long-term follow-up could not be obtained. Conclusion: This case highlights a rare congenital form of bilateral supranuclear vertical gaze palsy associated with large-angle exotropia and hypotropia in the absence of neurological deficits. Recognition of intact supranuclear reflexes and normal imaging is crucial for accurate localization. Autologous muscle transplantation offers a useful surgical option for correcting large-angle deviations. Also, this case highlights the importance of detailed motility and vestibular reflex testing in the assessment of atypical strabismus.