A 1-day-old infant who exhibits absence of the ocular lens is admitted to the pediatric intensive care unit. Laboratory examination reveals a mutation in the PAX6 gene. Which of the following conditions is the most likely diagnosis?

A mutation of the PAX6 gene usually results in congenital aphakia (absence of lens) and aniridia (absence of iris). Cyclopia is a condition in which there is a single eye and is usually caused by a mutation of the SONIC HEDGEHOG gene (SHH), leading to a loss of midline tissue and underdevelopment of the forebrain and frontonasal prominence. Coloboma occurs if the choroid fissure fails to fuse, which is usually caused by a mutation of the PAX2 gene. Anophthalmia is a disorder in which there is a complete absence of the eye. In microphthalmia, the eye is small in development, typically less than two thirds its normal size. This condition usually results from an infection such as cytomegalovirus and toxoplasmosis.