It is believed that uveal coloboma is primarily genetic in origin. "Genetic" means that the coloboma was caused by a gene that was not working properly when the eye was forming. Sometimes coloboma is part of a specific genetic syndrome, for which the genetics are known. For instance, coloboma is one feature of CHARGE syndrome, which is associated with a change in, or a complete deletion of a gene called CHD7.
Researchers have found genes associated with coloboma in a few cases. To date, however, we still do not know which genes explain most cases of coloboma.
Some researchers have proposed that certain environmental factors may contribute to developing coloboma, either in humans or in animals. These findings have been published over time in the research literature, but there have been no systematic analysis of possible links. For instance, it is known that babies exposed to alcohol during pregnancy can develop coloboma - but they also have other anomalies. There are no known strong links between environmental exposures and isolated coloboma.
It is always possible that coloboma happens strictly by chance. In summary, there is little data to presently say why coloboma happened to a person in a family where no one else is affected.
Read more articles on Coloboma