Nonsynostotic Craniofacial Conditions
Many craniofacial syndromes do not involve synostosis. Nonsynostotic syndromes and conditions of particular importance to the ophthalmologist are discussed in the following sections.
Anophthalmia (anophthalmos), the absence of tissues of the eye (Fig 18-7), is the most severe and rare phenotypic expression of a spectrum of abnormalities that includes typical coloboma and microphthalmia (see also Chapter 21). These conditions may be isolated, but they are frequently associated with other congenital anomalies. Anophthalmia and severe microphthalmia are associated with hypoplastic orbits and eyelids. Various techniques have been utilized for orbital expansion. The best results are achieved with early treatment.
A, Anophthalmia, both eyes. B, Magnetic resonance image from a patient with unilateral anophthalmia shows absence of ocular structures.
(Part A courtesy of Steven Couch, MD; part B courtesy of Alice Bashinsky, MD.)
Branchial arch syndromes
Branchial arch syndromes are caused by disruptions in the embryonic development of the first 2 branchial arches, which are responsible for formation of the maxillary and mandibular bones, the ear, and facial musculature. The oculoauriculovertebral spectrum (OAVS), which includes hemifacial microsomia and Goldenhar syndrome, and Treacher Collins syndrome are the best-known branchial arch syndromes. Hemifacial microsomia is a milder form of OAVS. Patients with OAVS may have vertebral abnormalities such as hemivertebrae and vertebral hypoplasia. They may also have neurologic, cardiovascular, and genitourinary abnormalities. Most cases are sporadic.
Patients with Goldenhar syndrome have hemifacial microsomia (unilateral or bilateral) and characteristic ophthalmic abnormalities (Fig 18-8). Most cases are sporadic.
Epibulbar (limbal) dermoids and dermolipomas are characteristic ocular signs. Dermolipomas (also termed lipodermoids) usually occur in the temporal quadrant, covered by conjunctiva and often hidden by the lateral upper and lower eyelids. Epibulbar limbal dermoids occur more frequently than dermolipomas and can be bilateral (approximately 25% of cases). They occasionally impinge on the visual axis but more commonly interfere with vision by causing astigmatism and anisometropic amblyopia. Eyelid colobomas may occur. Other ocular conditions include microphthalmia, cataract, and iris abnormalities. Duane retraction syndrome is more common in patients with Goldenhar syndrome.
Figure 18-8 Goldenhar syndrome with hemifacial microsomia. The patient has facial asymmetry, a hypoplastic left ear (microtia), an ear tag near the right ear, epibulbar dermolipoma in the left eye, and esotropia. The patient also has Duane retraction syndrome, left eye.
Treacher Collins syndrome
Treacher Collins syndrome (mandibulofacial dysostosis) is caused by abnormal growth of the first and second branchial arches, with underdevelopment and even agenesis of the zygoma and malar eminences. The lateral orbital rims are depressed and the palpebral fissures slant downward because of lateral canthal dystopia (Fig 18-9). Pseudocolobomas (uncommonly, true colobomas) occur in the outer third of the lower eyelids. Meibomian glands may be absent. The cilia of the lower eyelid medial to the pseudocoloboma may also be absent. The ears are malformed and hearing loss is common. The mandible is typically hypoplastic, leading to micrognathia. Intelligence is normal. The syndrome is inherited in an autosomal dominant fashion. Most affected patients have a mutation in the TCOF1 gene.
Pierre Robin sequence
The Pierre Robin sequence (also anomaly, deformity) is characterized by micrognathia, glossoptosis, and cleft palate. The sequence is a frequent finding in Stickler syndrome. Associated ocular anomalies include retinal detachment, microphthalmia, congenital glaucoma, cataracts, and high myopia.
Fetal alcohol syndrome
Fetal alcohol syndrome is caused by in utero exposure to ethanol. It is characterized by prenatal and postnatal growth retardation, central nervous system and craniofacial abnormalities, and intellectual disability.
The classic ocular features of fetal alcohol syndrome are short palpebral fissures, telecanthus, epicanthus, ptosis, microphthalmia, and esotropia (Fig 18-10). Anterior segment dysgenesis, optic nerve hypoplasia, and high refractive errors have been reported. Fifty percent of children with this underdiagnosed syndrome have some form of visual impairment.
Figure 18-9 Treacher Collins syndrome (mandibulofacial dysostosis). Note the downward slant of the palpebral fissure, low-set abnormal ears, notch or curving of the inferotemporal eyelid margin, and maxillary and mandibular hypoplasia.
(Reproduced with permission from Peyman GA, Sanders DR, Goldberg MF. Principles and Practice of Ophthalmology. Philadelphia: Saunders; 1980:2411.)
Figure 18-10 Fetal alcohol syndrome. Asymmetric ptosis; telecanthus; strabismus; long, flat philtrum (arrow); anteverted nostrils. This child also had Peters anomaly, left eye, and myopia, right eye.
(Reproduced with permission from Miller MT, Israel J, Cuttone J. Fetal alcohol syndrome. J Pediatr Ophthalmol Strabismus. 1981;18(4):6–15.)
Nonsynostotic disorders of bone growth
Infantile malignant osteopetrosis
In this rare and severe autosomal recessive form of osteopetrosis, proliferation of bone results in narrowing of the foramina of the skull. Stenosis of the optic canal increases the risk of compressive optic neuropathy. Bone marrow transplant has been reported to reverse the stenosis.
Craniometaphyseal dysplasia is a rare disorder of osteoclast resorption that causes hyperostosis of the cranial bones. The typical facial appearance includes frontal and paranasal bossing. Progressive stenosis of cranial nerve foramina can result in compressive optic neuropathy.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.