When straight eyes won't move: Phenotypic overlap of genetically distinct ocular motility disturbances

Objective: To describe the phenotypic similarity in a series of patients with genetically distinct ocular motility disturbances involving straight eyes and different ocular motor pathology. Design: Retrospective case series. Participants: Clinical and genetic evaluation of 5 patients with straight eyes in the primary position and abnormalities of ocular motility. Results: Patients with oculopharyngeal muscular dystrophy, congenital myasthenic syndrome, congenital fibrosis of the extraocular muscles type 3, Bosley-Salih-Alorainy syndrome, and horizontal gaze palsy and progressive scoliosis all had straight eyes in primary position and restricted ocular motility. History, ocular motility patterns, systemic features of individual syndromes, and genetic screening were important diagnostically. Conclusions: A number of congenital and genetic ocular motility syndromes may result in substantial phenotypic overlap, particularly when eyes are straight in primary position and nonophthalmologic features are not apparent or not observed. The range of disorders that may fall into this category is discussed.