How does uveal coloboma happen?
To understand how uveal coloboma happens, we first have to understand how the eye forms in the developing baby. The eyes start as stalks coming out of the brain. The tip of each stalk will become the eye itself, while the rest of the stalk will become the optic nerve linking the eye to the brain. There is a seam at the bottom of each stalk, where blood vessels originally run. This seam is known as the optic fissure, or the choroidal fissure, or the embryonic fissure. Starting at the fifth week of gestation (pregnancy), this seam must close. The closure starts roughly in the middle of the developing eye, and runs in both directions. This process is finished by the seventh week of gestation. If, for some reason, the closure does not happen, a uveal coloboma is formed. Depending on where the closure did not happen, the baby can have an iris coloboma (front of the fissure), a chorio-retinal coloboma (back of the fissure), or any combination of these. Uveal coloboma can affect one eye (unil
