Ординатура / Офтальмология / Английские материалы / Oxford American Handbook of Ophthalmology_Tsai, Denniston, Murray_2011

636 CHAPTER 18 Pediatric ophthalmology

Optic nerve anomalies

These include optic disc pits, optic disc hypoplasia, coloboma, and morning glory anomaly (p. 535). Although disc pits are often isolated findings, more severe disc abnormalities are often associated with systemic pathology.

Patients with bilateral optic disc hypoplasia should be evaluated for other cerebral midline abnormalities (e.g., septo-optic dysplasia) and pituitary dysfunction. Patients with morning glory anomaly have a higher incidence of intracranial vascular abnormalities, including moyamoya disease (arterial occlusive disorders).

Retina

Premature cessation of peripheral retina vascularization may occur as a result of an inherited defect (familial exudative vitreoretinopathy [FEVR], Ch11q) or acquired insult (retinopathy of prematurity). This results in fibrovascular proliferation, traction, exudation, and retinal detachment.

Retinal dysplasia may occur in isolation but is usually part of a syndrome such as Edward, Patau, Norrie, or Warburg syndrome or incontinentia pigmenti. Severe forms present with bilateral leukocoria and very poor vision.

Macular hypoplasia may occur in isolation or with syndromes such as albinism or aniridia. There is variable loss of the normal foveal reflex and, in some cases, loss of the avascular zone.

Nasolacrimal duct

Cannulation of the nasolacrimal cord may be delayed distally, resulting in congenital obstruction. More commonly, there is simply an imperforate mucosal membrane at the valve of Hasner, which opens within the first year of life.

Overall, 90% spontaneously resolve by 1 year of age. In those that persist, a probing and irrigation carries a 90% success rate (see Box 18.2). In older children or those with more complex pathology, intubation or balloon dacryoplasty (using Lacricath®) should be considered as the primary procedure. Where blockage is sufficient to prevent the passage of the probe, a DCR is usually required.

Box 18.2 Outline of syringe and probe for congenital nasolacrimal obstruction

•Anesthesia (usually GA)

•Introduce nasolacrimal cannula into the lower or upper canaliculus.

•Inject fluorescein-stained saline solution to confirm nasolacrimal obstruction.

•Pull the lower lid laterally and introduce probe into the inferior punctum and then medially to the sac.

•Turn the probe 90*so as to direct it inferiorly down the nasolacrimal duct to perforate membrane.

•Repeat syringing to confirm patency of nasolacrimal duct with recovery of fluorescein from the nose.

638 CHAPTER 18 Pediatric ophthalmology

Chromosomal syndromes

Trisomy syndromes

Down syndrome

Down syndrome (trisomy 21) is the most common autosomal trisomy, with an incidence of 1 in 650 live births. It is also the most common genetic cause of learning difficulties (see Table 18.29). Most cases arise by nondisjunction (94%), some by translocation (5%), and rarely by mosaicism (1%). Mosaic cases usually have a milder phenotype.

Edwards syndrome

Edwards syndrome (trisomy 18) (Table 18.30) is the second most common autosomal trisomy at 1: in 8000 live births. Life expectancy is <1 year.

Patau syndrome

Patau syndrome (trisomy 13) (Table 18.31) is the third most common autosomal trisomy at 1 in 14,000 live births. Life expectancy is <3 months.

Deletion syndromes

Turner syndrome

Turner syndrome (XO) (Table 18.32) occurs in 1 in 2000 live female births. Only half are XO (also known as 45, X), with 15% being mosaics and the remainder having partial deletions or other abnormalities. The Turner phenotype arises from X-linked genes that escape inactivation (e.g., the SHOX, short stature homeobox gene).

Other deletion syndromes

Although microdeletions are probably fairly common, macrodeletions other than Turner syndrome are rare. Syndromes with ophthalmic features include the cri-du-chat syndrome (5p-), DeGrouchy syndrome (18q-), and the 13qdeletion syndrome. Common features are hypertelorism and epicanthal folds. In addition, in 13q-, there is a significantly increased risk of retinoblastoma.

Table 18.29 Clinical features of Down syndrome

Ocular • Mongoloid palpebral fissures, hypertelorism, epicanthic folds, ectropia, blepharoconjunctivitis

•Myopia, astigmatism

•Strabismus, nystagmus

•Keratoconus, Brushfield spots, cataracts

•Hypoplastic optic disc

Systemic • Short stature, macroglossia, flat nasal bridge, broad hands, single palmar crease, clinodactyly, sandal-gap toes, hypotonia

•Congenital heart disease (ASD, VSD), duodenal atresia, hypothyroidism, diabetes mellitus, irisk of leukemia

•dIQ and early Alzheimer’s dementia

CHROMOSOMAL SYNDROMES 639

Table 18.30 Clinical features of Edwards syndrome

Ocular • Epicanthal folds, blepharophimosis, ptosis, hypertelorism

•Microphthalmos, corneal opacities, congenital glaucoma, cataracts

•Uveal colobomas

Systemic • Failure to thrive

•Small chin, low-set ears, overlapping fingers, rockerbottom feet

•Congenital heart defects, renal malformations

Table 18.31 Clinical features of Patau syndrome

Ocular • Cyclopia, microphthalmos, colobomas

•Corneal opacities, cataracts, intraocular cartilage, retinal dysplasia, optic nerve hypoplasia

Systemic • Failure to thrive

•Microcephaly, scalp defects, hernias, polydactyly

•Congenital heart defects, renal malformations, apneas

Table 18.32 Clinical features of Turner syndrome

Ocular • Antimongoloid palpebral fissures, epicanthus, ptosis, hypertelorism

•Strabismus, convergence insufficiency

•Cataracts

•Male levels of X-linked recessive disease (e.g., red-green color blindness)

Systemic • Neonatal lymphedema of hands and feet

•Short stature, webbed neck, low posterior hairline, wide carrying angle, broad chest with apparent wide-spaced nipples

•Congenital heart defects (notably coarctation of the aorta)

•Primary gonadal failure

•Normal IQ, sensorineural deafness, delayed motor skills

642 CHAPTER 18 Pediatric ophthalmology

Metabolic and storage diseases (2)

Table 18.36 Disorders of glycosaminoglycan metabolism (mucopolysaccharidoses)

All of the above conditions are autosomal recessive, other than Hunter’s, which is X-linked.

Table 18.37 Disorders of mineral metabolism

The above conditions are autosomal recessive.

Marfan’s, and Stickler’s are autosomal dominant; Weill–Marchesani is autosomal recessive; Ehlers–Danlos, pseudoxanthoma elasticum, and osteogenesis imperfecta have dominant and recessive forms.