A congenital cystic eye is a fluid filled sack of tissue that forms in the eye socket instead of an eyeball. The sack, which has no seeing ability, is usually removed soon after birth and a prosthetic eye put in its place. Usually only one eye is affected with the condition, with the other eye developing normally. Cystic eye is caused when cells in a developing baby fail to form the precursor structure where the eyeball normally develops. The condition is extremly rare and it's not known what factors trigger the cells to fail. The growth of a cystic eye usually happens very early in development--about 35 days after conception and can sometimes "fix" itself later on in development becoming a less severe eye condition. In these cases, an individual may be born with a coloboma, a hole in one or more of the structures of the eye. Depending on the severity of the hole, an individual may have normal sight or be blind in that eye. Talk to your baby's doctor and eye specialist to decide on the best treatment plan for your baby.