X-linked congenital stationary night blindness. Review and report of a family with hyperopia
G. Khouri, M. B. Mets, V. C. Smith, M. Wendell and A. S. Pass
Department of Ophthalmology and Visual Science, University of Chicago, IL.
X-linked congenital stationary night blindness is almost always associated
with myopia. We have reviewed all previously reported pedigrees and have
found only two with patients without myopia. A recently proposed
classification of night blindness includes a complete type associated with
myopia and an incomplete type in which both hyperopia and myopia were
found. Complete and incomplete types did not occur within the same
pedigree. We report on a family in which three of the five affected members
had hyperopia and could be classified as the incomplete type and in which a
fourth member with myopia was more consistent with the complete type. The
lack of myopia in three members of our pedigree can be explained by two
hypotheses: crossing over of the night blindness and myopic genes on the
X-chromosome, or an autosomal dominant hyperopic gene that masks the myopic
gene. The data from our family support the first of these two hypotheses.
