DESCRIPTION: : A term used to describe an apparent lack of visual functioning, in spite of anatomically and structurally intact eyes. The cause is assumed to be a lack of cortical functioning (i.e., the visual cortex of the brain is non-functionalj. Children with "cortical blindness" do not exhibit nystagmus, however. (Nystagmus may be the way the nervous system responds to bad vision, since it occurs simultaneously with many visual impairments.) Neither a CAT scan nor a VEP can confirm cortical function. In the absence of other abnormalities (e.g., optic atrophy, microcephaly, frequent seizuring), the prognosis is good for regaining some degree of visual functioning in children with "cortical blindness."
TREATMENT: Vision stimulation activities of all kinds are appropriate, over a long period of time. However, the potential for improved visual functioning is probably better in the younger child than in the adult. Fibers of the optic tract and their connections (the extrageniculostriate system) may be important in visual recovery, since they are theorized to be 1) important in the maintenance of a stationary optical image on the retina via reflex eye movements; 2) essential for the provision of visual feedback for cerebellar coordination of learned skilled movements; and 3) mediators in visual functioning with the geniculostriate system.
IMPLICATIONS: It is currently believed* that the pliability of the young brain may be a factor in this positive prognosis. The recovery pattern is not easily detected by standard ophthalmic tests, since visual behaviors are unique and somewhat unusual (e.g., many children recover the ability to identify single letters of large print when well isolated; most recover the ability to name colors; most can detect moving targets in the peripheral field better than in the central field). Short term evaluations should not determine visual potential, since progress may take time. Dramatic and significant visual recovery can happen over a long term (a decade or more).
*This information taken from a presentation by Creig Moyt, M.D. (a pediatric ophthalmologist) at the 10th International Seminar on Preschool Blind Children, October 7-10, 1984, Asilomar, California.