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

Figure 11 4.

The oculosympathetic pathway. The origin begins in the hypothalamus with connections down through the brainstem to synapse in the upper cervical cord (central or first neuronal pathway). Fibers then travel around the subclavian artery and over the base of the lung to join in the thoracic sympathetic trunk, which then synapses in the superior cervical ganglion (preganglionic or second neuronal pathway). The third-order neuron travels with the first branch of the trigeminal nerve and passes through the ciliary ganglion to reach the pupillary dilator muscle.

fibers innervate the Müller muscle, which helps to elevate the upper eyelid. Since nerves for facial perspiration travel with the sympathetic nerves along the external carotid artery, ipsilateral facial anhydrosis can be associated with some cases of Horner syndrome.

Lesions that cause Horner syndrome are localized at the first order neuron (central), second order neuron (pre ganglion), or third order neu ron (post ganglion) (Figure 11 4). First order, or central, lesions include hypothalamic infarcts and tumors. Symptoms are not limited to Horner syndrome because of the proximity of other structures. Second order neu ron lesions are often produced by significant pathology in the area of the

lung apex or neck. Third order neuron lesions are usually benign and may be caused by aneurysms, trauma, vascular headaches, or inflammatory dis orders. Acquired Horner syndrome in children is an important diagnosis because it may be a sign of an occult tumor such as neuroblastoma.

Congenital Horner Syndrome

This is an uncommon condition consisting of small pupil, ipsilateral ptosis, and ipsilateral decreased pigmentation of the iris (heterochromia). The decreased pigmentation is usually noted after 2 to 3 years of age when the normal iris undergoes the physiologic process of increased pigmenta tion. The Horner iris fails to have normal melanocyte development. Birth trauma to the brachial plexus is the most common cause of Horner syn drome, although other causes include vascular occlusion, chest or neck tumors, and pneumothorax.

Tonic Pupil (Adie Syndrome)

Adie syndrome, or Adie tonic pupil, is characterized by a large pupil with no constriction to light and slow constriction to near stimulus (Figure 11 5). This produces anisocoria that is greater in bright light than dark condi tions, just the opposite of Horner syndrome. Adie syndrome is caused by an abnormality of the parasympathetic fibers in the ciliary ganglion. It is usu ally seen in females who are between the ages of 20 and 40 years but occa sionally can occur in children. The condition is almost always unilateral and is associated with decreased deep tendon reflexes in approximately half the cases. Patients may be otherwise completely asymptomatic when the aniso coria is noted on routine examination. Adie tonic pupil is generally felt to be a benign condition; however, 20% will be associated with other disorders such as herpes zoster, neurosyphilis, sarcoidosis, perineal plastic syndrome, diabetes mellitus, and neuropathies such as Charcot Marie Tooth disease and Guillain Barré syndrome.

Argyll Robertson Pupil

This condition is usually bilateral and consists of small, often irregularly shaped pupils that are nonreactive to light but briskly react to the near response and accommodation. The lesion is believed to be near the Edinger Westphal nucleus of the third nerve. The lesion occurs from

Figure 11 5.

Patient with a right Adie pupil. Note that the pupils are larger under room light (top left) than with the lights off (top right). The pupil constricts poorly to light (bottom left) and better to near (bottom right).

both the ipsilateral and contralateral pretectal areas, thereby sparing the fibers from the near response. The Argyll Robertson pupil is typically associ ated with neurosyphilis.

Iris Abnormalities

Iris Coloboma

Iris coloboma is caused by a localized absence of a normal iris so that the pupil takes on a keyhole shape (Figure 11 6). Typical iris colobomas are caused by an abnormality of closure of the fetal optic fissure. Because the optic fissure closes inferiorly at the 6 o’clock position, typical iris colobomas are located inferiorly. The optic fissure closes first at the equator of the globe and then progressively closes in an anterior and posterior direction. The 2 most common locations for colobomas are at the anterior extent of the globe (iris colobomas) and the posterior extent of the globe (optic nerve colobo mas). Isolated iris colobomas do not interfere with vision. Colobomas that involve the macula or the optic nerve often reduce binocularity. (See

Figure 11 6.

Photograph of a typical iris coloboma with a keyhole pupil located inferiorly and slightly nasally at approximately 5-o’clock position. The eye is slightly small.

Chapter 6 for further discussion of choroidal and optic nerve colobomas.) Isolated iris colobomas are common and usually not associated with a systemic abnormality. Posterior colobomas, however, are more commonly associated with a systemic abnormality and with microphthalmia. Because iris colobomas may be associated with a posterior coloboma or optic nerve coloboma, patients with iris coloboma should be referred for a

full ocular examination.

Aniridia

Aniridia, as the name implies, is the absence of an iris (Figure 11 7). This is, however, somewhat of a misnomer because there is almost always some amount of iris present. More importantly, aniridia is not confined to the iris but involves the entire eye. It is associated with optic nerve hypopla sia and foveal hypoplasia resulting in poor vision, often 20/200 or worse. Other ocular associated abnormalities include cataracts, lens subluxation, glaucoma, and corneal opacification occurring later in life. Infants typically

present with nystagmus, large pupils, and very poor vision. Patients are often sensitive to light (photophobia).

Aniridia can be inherited as an autosomal dominant trait or can be sporadic. Approximately one third of sporadic cases will have an associated

Figure 11 7.

Aniridia. Note the large pupil with minimal iris present. The complete lens is seen because the iris is absent. The lens is slightly subluxed up and to the right.

Wilms tumor. It is important to obtain an abdominal ultrasound and inves tigate for renal abnormalities and Wilms tumor in patients with sporadic aniridia. Because there have been a few reported cases of Wilms tumor in a family with aniridia, it is probably best to work up all aniridic cases for the possibility of Wilms tumor. The aniridia gene has been localized to chro mosome 11p13. Large deletions in this area produce a syndrome with the triad of aniridia, mental retardation, and genitourinary abnormalities (ARG triad). This triad has been linked with a deletion of the short arm of chromo some 11(11p). Aniridia appears to be secondary to a mutation of the PAX 6 gene, a key regulator for eye development. Associated with aniridia and PAX 6 gene mutations are other ocular developmental anomalies such as auto somal dominant keratitis and some forms of Peter anomaly (congenital corneal opacification; see Figure 15 4 A–C). Dominant keratitis consists of progressive vascularization of the cornea and partial aniridia, with or with out nystagmus. The ocular prognosis in aniridia is relatively poor because foveal hypoplasia usually limits vision to 20/200 or worse and many patients will develop progressive corneal opacification, vascularization, glaucoma, and cataracts.

Heterochromia Irides

Heterochromia irides is a difference in iris color. This can be caused by either increased pigmentation in one eye or decreased pigmentation in the other eye. Table 11 1 lists some of the more common causes of hetero

chromia irides. Significant difference in iris color should prompt an immedi ate pediatric ophthalmology referral.

Table 11-1. Causes of Heterochromia Irides

Increased Iris Pigmentation

1.Congenital pigmented tumors and nevus

2.Oculodermal melanocytosis

3.Iris ectropion

Decreased Iris Pigmentation

1.Congenital Horner syndrome

2.Accidental or surgical trauma

3.Waardenburg syndrome

Rieger Anomaly

Rieger anomaly is an ocular malformation characterized by an abnormal iris that is hypoplastic. Patients may have multiple defects, termed pseudopoly coria. In most cases, the pupil appears irregular. There is also dysgenesis of the anterior segment, including the peripheral aspect of the cornea. Glau coma occurs in approximately half of patients with Rieger anomaly. Rieger syndrome is an autosomal dominant oculoskeletal syndrome consisting of Rieger ocular anomaly with systemic anomalies including teeth abnormali ties (microdontia, hypodontia), facial anomalies (maxillary hypoplasia, flat tening of the mid face), deafness, and umbilical hernia. The most important ocular complication of Rieger anomaly or syndrome is the development of glaucoma, which can be difficult to control.

Chapter 12

Tearing

Nasolacrimal Duct Obstruction, Congenital Glaucoma,

and Dry Eye

Tearing is a common presenting complaint in a pediatric examination. The causes of abnormal tearing (epiphora) are classified according to the age of onset—neonatal or acquired tearing. Table 12 1 lists the most common causes of tearing in childhood.

At birth, there is minimal baseline tear production by the lacrimal gland. Normal tearing develops several days to 2 weeks after birth. Tears are pro duced in the lacrimal gland and cross the cornea to exit via the superior and inferior puncta. Tears then travel through the canaliculus into the lacrimal sac, to the nasolacrimal duct, and finally through the Hasner valve into the posterior nasal pharynx—then they are swallowed (Figure 12 1). There are 2 physiologic types of tearing: basal tear production that keeps the eye moist

Table 12-1. Pediatric Epiphora

Neonatal Epiphora

1.Nasolacrimal duct (NLD) obstruction (this chapter)

2.Amniotocele (dacryocystocele) (this chapter)

3.Punctal atresia (this chapter)

4.Trichiasis—“lashes rubbing the eye” (epiblepharon or congenital entropion) (Chapter 17)

5.Corneal exposure (craniosynostosis with proptosis, orbital mass such as congenital hemangioma, congenital facial nerve palsy, congenital anesthetic cornea)

(this chapter)

6.Congenital glaucoma (this chapter)

Child Onset Epiphora

1.Corneal trauma (foreign body or abrasion) (Chapter 23)

2.Allergic conjunctivitis (Chapter 13)

3.Crocodile tears (this chapter)

4.Dry eyes (this chapter)

5.Trichiasis (Chapter 17)

6.Posterior fossa brain tumor

7.Exposure (acquired proptosis and facial palsy, such as Bell palsy)

Figure 12 1.

Three integral components of the lacrimal system include the secretory system (lacrimal glands), distribution system (eyelid blinking), and excretory system (puncta, canaliculus, nasolacrimal duct). The nasolacrimal duct is the entire structure that connects the canaliculus to the nose (red-colored structure). Most nasolacrimal duct obstructions are caused by a persistent tissue membrane over the Hasner valve at the distal end of the nasolacrimal duct.

during normal conditions, and reflex tearing that occurs in response to ocu lar irritation or emotion. Epiphora can be caused by an increased production of tears (hypersecretion) or obstruction of the nasolacrimal outflow system.

The fact that tears drain into the back of our nose is why we have a runny nose when we cry.

Nasolacrimal Duct Obstruction

Congenital obstruction of the nasolacrimal duct is by far the most common cause of tearing in early infancy, occurring in approximately 5% of new borns. The nasolacrimal drainage system develops from an invagination of surface ectoderm that originates in the nasal optic fissure. Canalization of this system first occurs in the middle of the nasolacrimal passage and then proceeds superiorly and inferiorly. Normally, the process of canalization

is completed by the end of the ninth month of gestation, but it may fail to completely canalize. Incomplete canalization results in an obstruction of tear outflow. The most common location of the obstruction is at the distal end of the nasolacrimal duct (Hasner valve) (Figure 12 1). There are other less