Ординатура / Офтальмология / Английские материалы / Pediatric Ophthalmology for Primary Care 3rd edition_Wright, Farzavandi_2008

Figure 24 10.

Extraretinal neovascularization may form at the optic disc (A) or elsewhere in the retina (B). These new vessels extend from the retina into the vitreous. Extraretinal neovascularization is associated with vitreous hemorrhage and production of fibrovascular traction.

Complications of proliferative diabetic retinopathy include vitreous hemor rhage, retinal detachment, macular edema, and neovascular glaucoma. In children, the risk of developing proliferative diabetic retinopathy increases dramatically after puberty, and it is rare for children to have retinal changes before 10 years of age. Children with diabetes should have an initial baseline ophthalmic examination before puberty, then be followed every year until puberty, and then twice a year or as is indicated per the retinal findings.

Panretinal photocoagulation obliterates the hypoxic retina and reduces the vascular endothelial growth factor, thereby reducing the stimulus for neovascularization.

Figure 24 11.

Proliferative diabetic retinopathy. In this color photograph, several high-risk characteristics are apparent—severe neovascularization of the disc and pre-retinal hemorrhage. Immediate panretinal photocoagulation is indicated to induce regression of the new vessels.

Chromosomal Anomalies

The common ocular manifestations exhibited by many of the identifiable chromosomal anomalies include hypertelorism, epicanthus, blepharoptosis, up or down slanting of palpebral fissures, strabismus, and microphthalmia. Nearly all patients with autosomal defects present with some degree of men tal retardation. The more specific and common ocular and systemic features of well known chromosomal anomalies are described in Table 24 9.

Down Syndrome

Down syndrome, most commonly caused by an extra copy of chromosome 21 (trisomy 21), is the most common chromosome abnormality found in children with mental retardation, dysmorphic features, and major malfor mations. It occurs in around 670 to 800 births and is associated with advanc ing maternal age. Affected children have a characteristic facial appearance including flat occiput; up slanting palpebral fissures; depressed nasal bridge with short, anteverted nares; small, often C shaped pinnae; and a rosebud shaped mouth with frequent tongue protrusion. Hypotonia is the most common neurologic finding, though seizures occur occasionally. Major

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malformations most commonly affect the heart and gastrointestinal tract. Microcephaly, short stature, and obesity are typical of the older individual.

There is a high incidence of eye problems in children with Down syndrome. One of the most common disorders is blepharitis. Blepharitis presents with crusting on the eyelashes and erythema of the eyelid margin. A secondary conjunctivitis or even a keratitis (corneal inflammation) can occur in severe cases. Blepharitis can be controlled with baby shampoo eyewashes performed on a daily basis. One or two drops of baby shampoo mixed in warm water on a clean washcloth can be used to cleanse the eyelid margin. Have the child close his or her eyes and gently wash the eyelash margin. Baby shampoo eyewashes reduce the bacteria count and clean the eyelashes of crusting.

Patients with Down syndrome often have strabismus and amblyopia. Esotropia is the most common form of strabismus and is frequently associ ated with moderate to high hypermetropia. Because Down syndrome chil dren have a wide nasal bridge and large epicanthal folds, pseudoesotropia is extremely common. It can be difficult to distinguish pseudostrabismus from true esotropia.

Another eye problem associated with Down syndrome is congenital or juvenile cataracts. Cataracts can occur in up to 10% to 20% of children with Down syndrome; however, only 2% to 3% of these cataracts require surgery.

Refractive errors requiring spectacles pose another common problem for children with Down syndrome. Children with Down syndrome can have myopia, astigmatism, or hyperopia. Approximately 60% of children with Down syndrome will require glasses.

A less common ocular abnormality is euryblepharon, which is a sagging of the lower lid. In mild cases no specific treatment is indicated. However, if the euryblepharon is severe, it can result in drying of the cornea and may require oculoplastic surgery to tighten the lid.

A classic ocular finding in Down syndrome are iris spots called Brush field spots. Brushfield spots are whitish tufts of tissue that dot the periph eral iris. They are very small and are best seen with high magnification by a slitlamp. Brushfield spots are not harmful and are often found in normal individuals.

Motor nystagmus is another ocular problem in Down syndrome chil dren. It is present in approximately 15% to 20% of patients.

Finally, an unusual eye problem associated with Down syndrome is keratoconus. Keratoconus is a progressive ectasia of the cornea resulting is an outward bowing or cone of the central cornea. It also occurs as a familial trait or a sporadic occurrence in patients without Down syndrome. Kerato conus has been associated with severe ocular allergy and eye rubbing. The cornea takes on a cone shape resulting in irregular astigmatism. Children with keratoconus require glasses or contact lenses; in severe cases corneal transplant surgery may be needed. Acute hydrops of the cornea rarely occurs in association with keratoconus. This represents acute corneal edema caused by a break in the Descemet membrane (which lines the inner surface of the cornea and supports the corneal endothelium), so aqueous fluid

goes into the corneal stroma producing a white opacity. Treatment is usually conservative observation.

Alagille Syndrome

Alagille syndrome is an autosomal dominant syndrome with multi organ involvement. It was first described and is still most commonly recognized as an association between cholestatic liver disease and a heart murmur, both most commonly diagnosed during infancy. The hallmark of Alagille syn drome is a paucity of bile ducts, and the gold standard for this diagnosis is liver biopsy.

In addition to the paucity of bile ducts, a patient must have 3 of the fol lowing 5 major criteria for the diagnosis of Alagille syndrome: chronic cho lestasis, congenital heart defect, skeletal anomalies, characteristic facies, and posterior embryotoxon.

Along with direct hyperbilirubinemia, the liver disease can be progres sive and is associated with slightly elevated transaminases and dispropor tionately elevated gamma glutamyl transpeptidase. The congenital heart disease is most commonly peripheral pulmonic stenosis (70%), although other defects are also noted, especially tetralogy of Fallot (9%–14%). The classic associated skeletal abnormality is butterfly vertebrae, which are caused by incomplete fusion of the anterior arches of the vertebral body and are usually apparent on radiograph. Other skeletal abnormalities may include shortened ulna or distal phalanges. The characteristic facies of Alagille syndrome have been described as an “inverted triangle,” with a

broad prominent forehead, deep set eyes, broad nasal bridge, and small pointed chin. These facies may be less apparent during infancy.

The characteristic ophthalmologic finding is an ocular anomaly of the cornea called posterior embryotoxon. Posterior embryotoxon represents an anterior displacement and thickening of the Schwalbe line, and delineates the posterior aspect of the cornea from the trabecular meshwork and the sclera (see Figure 15 2, page 211). Schwalbe line indicates the change from clear cornea to white sclera. Approximately 90% of patients with Alagille syndrome have posterior embryotoxon, compared with 10% to 15% of the general population. Other ocular anomalies include pigmentary retinopathy, iris hypoplasia, optic nerve anomalies, strabismus, and microcornea.

The gene defect almost always implicated in Alagille syndrome is a muta tion in JAG1, which codes a protein ligand for the NOTCH pathway. This pathway appears to be important in early angiogenesis in the liver, heart, eyes, and neural tube. Even though its inheritance is autosomal dominant, Alagille syndrome is thought to be commonly underdiagnosed because of its variable expression. Current estimates of incidence range between 1 in 70,000 and 1 in 100,000 live births. Approximately 60% of JAG1 mutations are sporadic.

Medical management of Alagille syndrome is largely supportive. Alagille patients commonly are treated with ursodiol for cholestasis and with a vari ety of medicines for pruritus management. Approximately 15% of patients with Alagille syndrome will have progressive liver failure eventually requir ing transplantation; Alagille syndrome is responsible for about 2% of pedi atric liver transplants annually in the United States. Cholestatic disease does not recur in the transplanted livers.

The long term prognosis of Alagille syndrome is governed largely by the severity of the associated defects. In general, the 20 year survival rate for patients after diagnosis is about 80%. This rate falls to 60% in patients requiring liver transplantation and 40% in patients with significant cardiac lesions. A recently recognized source of mortality is unexplained cerebro vascular bleeding. Patients in whom a diagnosis of Alagille syndrome is suspected should undergo screening for associated disorders, including an ophthalmologic examination.

Prader Willi Syndrome

Prader Willi syndrome is characterized by hypogonadism, hypotonia, obe sity, small hands and feet, mental retardation, strabismus, and occasionally, hypopigmentation or albinism. Patients with Prader Willi syndrome have an insatiable appetite and will eat virtually anything. Their appetite increases with age and parents are often forced to lock the refrigerator to prevent malignant obesity. Micro deletion of the long arm of chromosome 15 and maternal uniparental disomy for chromosome 15 are the most common causes of Prader Willi syndrome.

Velocardiofacial Syndrome

Velocardiofacial syndrome (Shprintzen syndrome) appears to be the most common microdeletion syndrome in humans with an estimated incidence of about 1 in 3,500 live births. Velocardiofacial syndrome is typically associated with a cryptic deletion of chromosome 22q11.2, though some cases have

no detectable deletion. Typical facial appearance includes short palpebral fissures, minor pinna anomalies, and a bulbous nose, especially in older children. Overt or submucous cleft palate or velopharyngeal incompetence occur commonly, as do conotruncal cardiac anomalies. Speech and motor delay, learning disabilities, or mental retardation occur commonly. Ocular features include small eyes, narrow palpebral fissures, mild orbital hyper telorism, strabismus, prominent corneal nerves and iris nodules, posterior embryotoxon, and small optic discs. Iris and retinal colobomas have been reported occasionally. Puffy eyelids and suborbital congestion suggest an “allergic” appearance.