ONE IDENTICAL TWIN

Central suppression is found with different types of strabismus and amblyopia. Intermittent central suppression (ICS) is an intermittent loss of visual sensation in the area of central vision occurring in the absence of strabismus and amblyopia. Suppression found in either strabismus or amblyopia is considered a cortical competitive inhibition. The same mechanisms and risk factors that influence suppression in strabismus and amblyopia might be expected to be applicable in ICS. In addition, there is evidence that there are genetic markers for both strabismus and amblyopia. The heritability of ICS, however, has not been reported. A case study is presented. Data, derived from identical (monozygotic) twins shows one twin to exhibit ICS while the other does not, despite inheriting identical genes. This twin data may help to separate the characteristics of ICS from the more constant and possibly more inheritable defect of strabismic/amblyopic suppression.