Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to coloboma ?
    ### Response:
    Coloboma arises from abnormal development of the eye. During the second month of development before birth, a seam called the optic fissure (also known as the choroidal fissure or embryonic fissure) closes to form the structures of the eye. When the optic fissure does not close completely, the result is a coloboma.
    