Malformations and anomalies

Malformations and anomalies of the eye

The eye may develop to be abnormally small (microphthalmia) or, in extreme cases, not form at all (anophthalmia).
Cyclopia is the condition in which only one eye forms in an orbit oriented in the median plane. This abnormality is often combined with a nose in the form of a proboscis and a single prosencephalic vesicle, situated in the median plane. In synophthalmia, some of the structures are duplicated and situated in a unique eye bulb oriented in the median plane.
In rare cases, the iris (aniridia) or the lens (aphakia) may be missing.
A slit remains if the retinal fissure fails to close, generally located at the iris. This is called iris coloboma. The slit may continue up to the optic nerve.
Congenital cataract is signified by a cloudy lens. This malformation may have a genetic origin or it may be due to rubella having been contracted by the mother during the first trimester of pregnancy.
A fibrous net remains on the pupil if the pupillary membrane formed during development does not disappear completely (persistent pupillary membrane).
The hyaloid artery normally degenerates during the last 3 months of pregnancy. This degeneration may fail completely or partially (persistent hyaloid artery).