How soon can cyclopia be detected in an affected fetus?

End of 1st trimester. Cyclopia is very rare, but can probably be detected by the end of the 1st trimester using a good quality ultrasound.
Late first trimester. With improved ultrasound techniques including 3d images it is possible to diagnose this rare anomaly as early as 11 weeks gestation according to some authorities. As more screening ultrasounds are done at 11-14 weeks to detect potential chromosomal changes with focus on the fetal face and head, this anomaly has the potential for earlier diagnosis.