Oculomotor dysfunction in cerebral visual impairment following perinatal hypoxia

Abstract

The aim of the study was to describe ocular motility in a sample of 56 patients affected by cerebral visual impairment (CVI) of hypoxic-ischemic origin. The sample consisted of 56 participants (37 males and 19 females), ranging in age from 2 to 16 years. In all cases CVI was associated with MRI-verified damage of the cerebral visual system. A complete ophthalmologic and neurological assessment was performed. Behaviour of gaze was studied in four conditions: during scanning of the surrounding environment, during fixation, execution of saccades, and pursuing. In addition, strabismus, nystagmus, and paroxysmal ocular deviations were evaluated. Ocular motility was studied by video recording the patients' eye motility during orthoptic examination. Each pattern of ocular motility studied revealed profound alterations in all the individuals examined. Typical features of ocular motility in CVI were: paroxysmal ocular deviations (present in 78%); the presence of variable angle strabismus (86%); and defective coordination of saccades (93%). Exploration of the environment and fixation were also impaired (88% and 84%, respectively). Disorders of initiation and performing saccades, absence of smooth pursuit, vergence abnormalities, nystagmus beats, instability of fixation, and difficulty in the systematic exploration of the environment were observed. These abnormalities characterize lack of gaze coordination found in children with brain damage. An early and detailed evaluation of ocular motility in individuals with CVI is important, especially when rehabilitation intervention is intended.