Background: Congenital microcoria, a bilateral condition of the iris dilatator, is defined as a pupil with a diameter of less than 2 mm when looking at a distant object. Although it is usually a hereditary condition resulting from autosomal dominant transmission with no marked difference between the sexes, it is sometimes sporadic. The ocular abnormalities associated with this condition (myopia, astigmatism, and glaucoma) have never been linked to the malformation.
Method: Forty-two members of a family were examined: 23 had microcoria and 19 did not. The two groups were studied to identify symptoms of the condition and its associated abnormalities.
Results: There was a very strong correlation between microcoria and myopia (Fisher's exact test, P < 0.00001), between microcoria and astigmatism (Fisher's exact test, P < 0.0001), and between microcoria and glaucoma (Fisher's exact test, P = 0.011).
Conclusions: There is a statistical correlation among myopia, glaucoma, and microcoria, and the disorders are associated with the condition in a nonfortuitous way. The functional prognosis for microcoria appears to be extremely poor because of refractive disorders and, particularly, a link between microcoria and glaucoma that is difficult to explain.