BACKGROUND: Ocular Motor Apraxia (OMA) is a congenital ocular-motor anomaly involving the intermittent inability to initiate horizontal saccades. Smooth pursuit movements are usually normal in these patients. Signs of OMA are most apparent during infancy. Compensatory behaviors include head thrusting, blinking, and tilted head posture. Previous studies have shown that most affected children are slow in attaining early developmental milestones, and later tend to be clumsy. Difficulties in speech were very common and reading difficulties are also very well recognized in this condition. OMA is considered rare but there are no prevalence studies. The literature has previously suggested that OMA is not a genetic anomaly.
CASE REPORT: Eight month old, MR, was brought in for a vision exam because her mother was worried of possible visual dysfunction. Only positive health history is bilateral sensory-neural hearing loss (BSNHL). Visual acuity was 201100 OU with Preferential Looking Cards. Retinoscopy revealed low hyperopia OU and visual fields full OU. Fixation was equal and central OD and OS. Vertical saccades and pursuits are normal. Horizontal pursuits were normal following abnormal head thrusting due to lack of horizontal saccades. Anterior segment and posterior segment exam were clear OU. MR was diagnosed with OMA. Upon examination of other family members, it was found that OMA is present in three consecutive generations. However, the presentation varied with all patients due to variable degrees of severity and expressivity. All family members positive for OMA also have BSNHL.
DISSCUSSION: OMA is not thought to be genetic; however, this case study indicates it is likely autosomal dominant with variable expressivity. Regardless of the underlying cause of OMA, it is important for the practitioner to be aware of the various ocular presentations and patient adaptations of OMA because it is often overlooked as a diagnosis in the routine exam.
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