The infant who is visually unresponsive on a cortical basis

Abstract

Objective To further explain cortical abnormalities in infants without visually guided behaviors with anatomically normal eyes by using a battery of objective visual tests and neuroimaging studies. Design A cohort study. Participants Thirty-one infants with clear ocular media and normal fundi, who were visually unresponsive by clinical examination, and 31 control subjects. Methods Full clinical examinations including Teller Acuity Cards (TAC) and developmental assessment. Infants with reduced acuities and/or developmental delay underwent pattern visual evoked potential (VEP) testing and brain neuroimaging studies. Eye movement recordings were done in individual infants. Main outcome measures Visual acuity, VEPs, eye movement recordings. Results Infants were separated into two groups on the basis of being developmentally normal (DN) or developmentally delayed (DD). Fourteen DN infants had normal acuities for age and three of three infants had normal VEPs. On the basis of having normal visual function, these infants were considered to have visual inattention (VI). Sixteen DD infants had acuities ranging from normal to no visual orienting to the low vision TAC. All 16 DD infants had abnormal VEPs and abnormal neuroimaging studies (brain computed tomography, magnetic resonance imaging, or both) or microcephaly. On the basis of having structural and functional abnormalities of the brain, these infants were diagnosed as having cortical visual impairment (CVI). One additional infant with DD failed to orient to TACs but had a normal VEP and normal magnetic resonance imaging. In this infant and two infants with CVI the inability to “fix and follow” was attributed completely or partially to an oculomotor apraxia (OMA), which was confirmed by eye movement recordings. Conclusions The infant who is visually unresponsive on a cortical basis has either VI or CVI. Infants with OMA can also seem to be visually unresponsive. These disorders can be delineated in infancy on the basis of developmental status and a unique set of responses to visual acuity, VEPs, and oculomotor testing.