Report of a Rare Case and Literature Review of Combined Marcus Gunn Jaw Winking Synkinesis and Monocular Elevation Deficiency.

Marcus Gunn Jaw Winking Synkinesis (MGJWS) is a rare congenital condition characterized by unilateral ptosis that improves with ipsilateral jaw movement. It frequently presents alongside other ocular abnormalities, including strabismus and anisometropia, which significantly increase the risk of amblyopia. Monocular elevation deficiency (MED), a type of strabismus marked by impaired elevation of the eye in all gaze positions, is most commonly associated with MGJWS. We report the case of a 14-year-old male with a history of refractive amblyopia who presented with both MGJWS and MED. This case supports emerging evidence that MGJWS and MED may represent phenotypic variations of the same neurodevelopmental disorder, with the severity of ptosis possibly potentiating the co-occurrence of MED. It also underscores the importance of early and comprehensive ophthalmologic evaluation in patients with MGJWS for the detection of coexisting ocular abnormalities that increase the risk of amblyopia.