Case of true cyclopia.

True cyclopia is a rare anomaly in which the organogenetic development of the two separate eyes is suppressed. A case of true cyclopia with normal karyotype is presented. There was a history of the use of an intrauterine device for contraception and of drug ingestion during early pregnancy. An anatomicopathological study of the monster with detailed presentation of the cyclopean eye is reported. The possible causes of cyclopia with particular relation to this case are discussed.