The Ocular Phenotype of Joubert Syndrome in an Adolescent: High Myopia with Oculomotor Apraxia and Torsional Nystagmus

Abstract

Background: Joubert syndrome (JS) is a rare autosomal-recessive ciliopathy defined by a characteristic mid-hindbrain malformation the “molar tooth sign” (MTS) with infantile hypotonia, global developmental delay, episodic neonatal breathing dysregulation and abnormal eye movements. Ocular involvement is frequent and often requires ophthalmic care.

Case presentation: A 15-year-old boy with a previously established diagnosis of Joubert syndrome presented with longstanding poor vision in both eyes. He had had infantile hypotonia with grossly delayed milestones (head control at 3 years, walking at 5 years, first words at 6–7 years), hearing impairment, and a history of episodic rapid breathing in infancy; his parents were non-consanguineous. Examination revealed bilateral high myopia with astigmatism (right −7.00/−4.00×180, left −13.00/−3.50×170; best-corrected acuity 6/18 and 6/60), ocular motor apraxia with compensatory head thrusts, torsional nystagmus, intermittent exotropia, an anomalous head posture (head tilt to the right, face turn to the left) and left pseudoptosis. The fundus showed myopic changes without retinal dystrophy or coloboma, and corneal topography showed high but regular astigmatism with normal pachymetry. Spectacles were prescribed, contact-lens correction was offered, and continued multidisciplinary care with genetic counselling was reinforced.

Conclusion: High myopia, oculomotor apraxia, nystagmus, strabismus and ptosis are characteristic ocular features of JS. Recognising and managing them refractive correction, amblyopia and low-vision care, and monitoring is an important part of the multidisciplinary care of these children; in an undiagnosed child, such findings should prompt neuroimaging.

Keywords: Joubert syndrome; molar tooth sign; ciliopathy; high myopia; oculomotor apraxia; nystagmus