HYPOTELORISM

Hypotelorism = decreased interorbital distance.

Video clip of Hypotelorism

EMBRYOLOGY / PATHOGENESIS

Link to Embryology / Pathogenesis

1. Holoprosencephaly.
2. Microcephaly.
3. Meckel-Gruber syndrome.
4. Maternal phenylketonuria.
5. Myotonic dystrophy.
6. Williams syndrome.
7. Oculodental dysplasia.
8. Trigonocephaly.
9. Trisomy 13 and trisomy 18.

CYCLOPIA

• Extreme form of hypotelorism.
• Caused by suppression of midline cerebral structures derived from the cranial aspect of the neural plate.
• Eyes are either partially or completely fused, but enclosed in a single orbit.
• Strong association with alobar holoprosencephaly.

Orbital/Facial Anomalies Associated With Holoprosencephaly

SYNOPHTHALMOS

• Failure of separation of the globes associated with severe malformations of the nose and forebrain.
• Brain fails to separate into two hemispheres.
• Eyes show varying degrees of fusion from just the optic nerves to a joint sclera-covered eyeball containing two retinas (1-3).
• Associated with trisomy 13.

REFERENCES

1. Totczynski E, Jacobiec FA, Johnson MC et.al. Synophthalmia and cyclopia: a histopathologic, radiographic, and organogenetic analysis. Doc Ophthalmol 1977;44:311.
2. Elejalde BR, de Elejalde MM, Hamilton PR et.al. Prenatal diagnosis of cyclopia. Am J Med Genet 1983;14:15.
3. Meizner I, Mazor M, Drawall D et.al. Sonographic findings in a rare case of cyclopia. Isr J Med Sci 1987;23:910.