Which condition is characterized by midline fusion of the orbits with a single midline eye and is associated with holoprosencephaly and trisomy 13?

• A. Cyclopia
• B. Anophthalmia
• C. Microphthalmia
• D. Exophthalmos

Answer: (A)

Cyclopia is a malformation in which the forebrain fails to divide into two hemispheres, causing the orbits to fuse along the midline and produce a single eye centered on the midline. This midline orbital fusion is a hallmark of holoprosencephaly and is strongly associated with trisomy 13 (Patau syndrome). The other conditions describe different orbital presentations: absence of ocular tissue (anophthalmia), an abnormally small eye (microphthalmia), or outward displacement of the eye (exophthalmos), none of which capture the midline fusion and single eye characteristic seen with cyclopia.