Hypertelorism is widely spaced eyes, as determined by increased interpupillary distance, and can occur in several congenital syndromes, including frontonasal dysplasia (with midline facial cleft, and brain abnormalities), craniofrontonasal dysplasia (with craniosynostosis), and Aarskog syndrome (with limb and genital anomalies).
Hypotelorism is closely spaced eyes, as determined by decreased interpupillary distance. This anomaly should raise suspicion of holoprosencephaly (a midline brain abnormality).
Coloboma is a gap in the structure of the eye that may affect the eyelid, iris, retina, or optic nerve of one or both eyes. Coloboma of the eyelid is frequently associated with epibulbar dermoid cysts and is common in Treacher Collins syndrome, Nager syndrome, and Goldenhar syndrome. Coloboma of the iris raises the possibility of CHARGE association (coloboma, heart defects, atresia of the choanae, retardation of mental and/or physical development, genital hypoplasia, and ear abnormalities), cat eye syndrome, Kabuki syndrome, or Aicardi syndrome.
Microphthalmia is a small eye globe, which may be unilateral or bilateral. Even when unilateral, mild abnormalities (eg, microcornea, colobomas, congenital cataract) of the other eye are frequently present. It causes sight-threatening complications such as angle-closure glaucoma, chorioretinal pathology (eg, uveal effusion), strabismus, and amblyopia.
Causes of microphthalmia include prenatal exposure to teratogens, alcohol, and infections (eg, TORCH [toxoplasmosis, other pathogens, rubella, cytomegalovirus, and herpes simplex]), and numerous chromosomal or genetic disorders, some of which are suggested by other clinical features. Growth and developmental delays are frequently present in microphthalmia that is caused by a chromosomal disorder. Facial asymmetry suggests Goldenhar syndrome or Treacher Collins syndrome, hand abnormalities suggest trisomy 13, oculo-dental-digital syndrome, or fetal alcohol syndrome, and genital abnormalities may suggest chromosomal defects, Fraser syndrome, or CHARGE association (coloboma, heart defects, atresia of the choanae, retardation of mental and/or physical development, genital hypoplasia, and ear abnormalities).
Anophthalmia is complete absence of the eye globe and occurs in > 50 genetic syndromes caused by chromosomal anomalies or mutations in one of several genes (eg, SOX2, OTX2, BMP4). When skin covers the orbit, the anomaly is called cryptophthalmos, which suggests Fraser syndrome, Nager syndrome, or ophthalmia-mental retardation.