Choroid fissure
The choroid is the middle, vascular coat of the eye which is between the sclera and the retina. Early in development the choroid fissure is the slit observed between the two edges of the eye cup. During development it is through the choroid fissure that the retinal vessels enter the eye and neural components (e.g. axons and retinal ganglion) exit the eye to form the optic nerve. The fissure is eventually sealed when the edges of the retina join together. Failure of this fissure to close results in .
References
Retrieved from : http://en.wikipedia.org/wiki/Choroid_fissure
