Ординатура / Офтальмология / Английские материалы / Pediatric Ophthalmology for Primary Care 3rd edition_Wright, Farzavandi_2008
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Chapter 9
Abnormal
Optic Discs
In this chapter, causes of abnormal appearing optic discs are discussed. They will be classified as congenital or acquired and are listed in Table 9 1.
Congenital Optic Disc Anomalies
Congenital optic disc anomalies are discussed in this section, except for 2 important congenital abnormal optic discs that can cause blindness at birth, optic nerve hypoplasia and optic nerve coloboma, which are discussed in Chapter 6.
Morning Glory Disc Anomaly
Morning glory disc anomaly is a rare congenital optic disc anomaly that involves the peripapillary retina (area around the optic disc in addition to the optic disc). The optic nerve is large and excavated. The retinal ves
sels emanate from the mid periphery of the optic nerve in a straight radial fashion (Figure 9 1). There is lack of normal retinal pigment epithelium in
Table 9-1. Abnormal Optic Disc Appearance
Congenital
1.Optic nerve hypoplasia (Chapter 6)
2.Optic nerve coloboma (Chapter 6)
3.Morning-glory disc anomaly (this chapter)
4.Myelinated retinal nerve fibers (this chapter)
5.Pseudopapilledema (this chapter)
6.Grey pigmented optic disc (this chapter)
7.Tilt myopic scleral crescent (this chapter)
8.Optic nerve pit (this chapter)
Acquired
1.Papilledema (this chapter)
2.Papillitis (optic neuritis) (Chapter 7)
3.Optic disc drusen (this chapter)
4.Optic atrophy (Chapter 7)
5.Glaucoma (Chapter 12)
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Figure 9 1.
Morning-glory disc anomaly, black and white photo. Note the enlarged disc with straightened radial retinal vessels emanating from the mid-periphery of the optic nerve. Also note the lack of peripapillary pigmentation and consequent scleral show. The disc has an enlarged appearance.
the peripapillary area, producing scleral show. The retina around the optic disc has multiple radial folds emanating from the optic nerve, thus the term morning glory for its resemblance to the morning glory flower. The morning glory disc anomaly is distinct from optic nerve colobomas; how ever, their appearance can be similar. Morning glory configuration is distin guished by the pattern of the radial retinal folds coming from the disc and by glial proliferation overlying the peripapillary retina and retinal vessels.
Patients often present with strabismus because of poor vision in the affected eye. Vision is variable (depending on the extent of the macular changes), ranging from 20/50 to legally blind, but fortunately, most cases are unilateral. Bilateral cases do occur; however, visual acuity is usually better than in unilateral cases. Females tend to be affected more than males, but both sexes are involved. The most important late complication is the high risk for developing a retinal detachment, as almost 40% of affected eyes will develop one. Associated systemic findings include basal encephaloceles and midline facial defects such as hypertelorism, cleft lip, or cleft palate. These systemic findings have also been associated with optic nerve colobo mas, and it is possible that optic nerve colobomas have been falsely diag nosed as morning glory disc anomaly (see Chapter 6 for discussion of optic nerve coloboma).
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Myelinated Retinal Nerve Fibers
The presence of myelinated retinal nerve fibers is a very dramatic, albeit benign, anomaly. Myelinated retinal nerve fibers are often termed medul lated nerve fibers. Normally, the optic nerve is myelinated up to the point where the optic nerve enters the eye and becomes the optic disc (lamina cribrosa). Myelinated retinal nerve fibers occur when myelinization pro gresses past the optic disc into the retinal layers. This gives the appearance of a fluffy white material overlying and adjacent to the optic nerve (Figure 9 2). The feathery edge and striated appearance occur because the myelin follows the retinal nerve fibers. The blurred disc margins can give the appearance of pseudopapilledema. Occasionally, myelinated nerve fibers have been found to extend into the peripheral retina and macula.
Females are affected more than males, and approximately 80% of cases are unilateral. In the majority of cases, visual acuity is not affected. There is an increased incidence of refractive errors, including unilateral high myopia, and amblyopia may be present. In rare cases, the macula may be involved and macular hypoplasia may result in decreased vision. The condition is stable and does not require treatment other than associated refractive errors and amblyopia.
Figure 9 2.
Myelinated optic nerve fibers are the white feathery substance in the superior peripapillary area of the optic disc.
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Figure 9 3.
Pseudopapilledema (congenital) showing blurred disc margins but no retinal vessel engorgement, no nerve fiber edema (hazy appearance), and no flame-shaped hemorrhages.
Pseudopapilledema
The appearance of blurred disc margins, and even a swollen disc, are not always indicative of disc edema. Any process that blurs the disc margins or causes a fullness of the optic nerve may give the appearance of disc edema and is termed pseudopapilledema. The most common cause of pseudopa pilledema is hyperopia associated with a relatively small eye and blurred disc margins. Myelinated nerve fibers are another common cause of blurred disc margins. Some patients have primary blurred disc margins without a specific association or cause (congenital pseudopapilledema) (Figure 9 3). Table 9 2 lists the differential diagnosis of pseudopapilledema.
In contrast to true disc edema, patients with pseudopapilledema have a normal nerve fiber layer and disc color, no vessel engorgement, no peripapillary hemorrhages, and no retinal exudates. Spontaneous retinal venous pulsations are usually present. Vision is normal with most forms of pseudopapilledema.
Congenital Gray Pigmented Optic Disc
The appearance of a congenitally gray optic disc occurs in premature infants with delayed visual maturation, in infants with ocular albinism, and in indi viduals with isolated chromosomal anomalies such as partial trisomy 10Q
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Table 9-2. Differential Diagnoses of Pseudopapilledema
(Blurred Disc Margin)
1.Hyperopia
2.Myelinated optic nerve fibers
3.Optic disc drusen
4.Congenital pseudopapilledema
5.Epipapillary hamartomas and tumors
syndrome. In premature infants and neonates, the gray appearance is proba bly the result of an optical effect, perhaps an overall hypopigmentation of the retina. Over time, the gray discoloration resolves as the retina matures. True pigmentation of the nerve secondary to melanin deposition is rare; however, it may be associated with a chromosomal abnormality of chromosome 17 and Aicardi syndrome. Visual acuity is not affected unless there is associated optic nerve anomaly such as optic nerve hypoplasia.
Congenital Tilted Disc
Congenital tilted disc is characterized by a scleral opening larger than the size of the optic nerve head (Figure 9 4). Typically, there is a peripapillary scleral crescent nasal of scleral show, and the vessels emanate in a scattered pattern rather than the normal distribution of nasal and retinal vascular arcades (normal disc—see Figure 1 8). Some tilted discs are associated with
Figure 9 4.
Tilted disc with a crescent of yellow-white scleral show crescent superiorly. This hypopigmented crescent is often seen in children with myopia.
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myopia, but visual acuity is generally not affected. In some cases, however, there may be a mild loss of visual acuity that may actually represent a variant of optic nerve hypoplasia. In general, however, there are no associated sys temic or neurologic diseases.
Optic Nerve Pit
This is a congenital anomaly of the optic nerve consisting of a focal depres sion within the optic nerve, usually in the temporal aspect of the disc. Optic nerve pits may represent a communication with the subarachnoid space of the optic nerve; however, this theory is still controversial. It is well docu mented that optic nerve pits are associated with serous retinal detachments in the area of the macula. Laser treatment may improve resolution of these retinal detachments.
Acquired Optic Disc Abnormalities
Optic Disc Edema
Papilledema is a term often loosely used to imply optic disc swelling or optic disc edema. The term optic disc edema should be used to refer to disc edema and swelling caused by a variety of optic nerve and systemic conditions including optic nerve inflammation (Table 9 3). Strictly defined, papilledema is optic disc edema secondary to increased intracranial
Table 9-3. Causes of Optic Disc Edema
1.Papilledema (increased ICP)
a.Obstructive hydrocephalus
b.Pseudotumor cerebri (see later in this chapter)
c.Intracranial hemorrhage (subarachnoid hemorrhage)
2.Papillitis (optic disc inflammation)
a.Optic neuritis (usually post-viral syndrome)
b.Toxocara of the disc
c.Neuroretinitis (chickenpox, mumps, hepatitis B, cat scratch disease, Lyme disease, leptospirosis, early neurosyphilis, tuberculosis, sarcoidosis, and toxoplasmosis
d.Malignant hypertension (ie, renal failure)
4.Optic nerve venous outflow obstruction
a.Venous sinus thrombosis
b.Craniosynostosis
c.Hyperviscosity syndromes
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pressure. Inflammation of the optic nerve head can produce disc edema and is termed papillitis. Pseudopapilledema is the term for conditions that pro duce blurred disc margins without associated disc edema (see Figure 7 3).
Ophthalmoscopically, disc edema is characterized by a full and swollen disc, a feathery blurred disc margin, thickened nerve fiber layer that obliterates underlying peripapillary retinal vessels (inferiorly first, then superiorly), disc hyperemia, small or nonexistent central cup, enlarged veins, and occa sional splinter nerve fiber layer hemorrhages (flame shaped hemorrhages) (Figure 9 5). Spontaneous venous pulsations are absent in papilledema associated with increased intracranial pressure.
Spontaneous Venous Pulsations
Spontaneous venous pulsations are pulsatile collapse and reformation of the retinal veins close to or on the optic disc. The presence of spontaneous venous pulsations over the disc is an important sign because it indicates that the intracranial pressure is less than 200 mm water. Approximately 20% of
the normal population, however, do not have spontaneous venous pulsations and therefore the absence of spontaneous venous pulsations does not mean that the intracranial pressure is high.
Figure 9 5.
Fully developed papilledema with disc elevation, hyperemia, edematous nerve fiber layer, loss of central cup, and splinter hemorrhages. Note the blurred disc margins and the blurred appearance of the vessels in the mid-periphery of the optic disc.
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Differentiating Papilledema, Papillitis, and Pseudopapilledema
This is based on ophthalmoscopic appearance and can be difficult and some times impossible to differentiate. Table 9 4 lists the characteristics of papil ledema, papillitis, and pseudopapilledema. Papilledema and papillitis have a similar appearance because both have true optic disc edema. Because papil litis is an inflammatory condition and inflammation interferes with optic nerve function, papillitis is associated with poor visual acuity and an afferent pupillary defect. In contrast, papilledema usually is associated with excellent visual function. Optic nerves with the appearance of pseudopapilledema are not edematous and do not have signs of true disc edema.
Pseudotumor Cerebri
Pseudotumor cerebri (benign intracranial hypertension) is a self limited dis order consisting of increased intracranial pressure of unknown etiology. This diagnosis is made once an intracranial mass lesion and other causes of elevated
Table 9-4. Characteristics of Papilledema, Papillitis,
and Pseudopapilledema
|
Papilledema |
Papillitis |
Pseudopapilledema |
|
|
|
|
Disc |
Blurred margins, |
Disc appearance |
Blurred margins, ± |
Appearance |
elevated disc, loss |
similar to papilledema, |
elevated disc, no loss of |
|
of cup, dilated |
and vitreous cells with |
cup (except with dru- |
|
vessels, splinter hem- |
“hazy fundus” view. |
sen), usually no hemor- |
|
orrhages, Obliterated |
Macular exudates |
rhage, no dilated ves- |
|
peripapillary vessels, |
are common. |
sels, vessels seen clearly. |
|
no spontaneous |
|
Retinal vessels may be |
|
venous pulsations. |
|
anomalous, spontane- |
|
|
|
ous venous pulsations |
|
|
|
usually present. |
|
|
|
|
Symptoms |
Headaches, emesis, |
Acute vision loss with |
No symptoms. |
|
may have transient |
metamorphopsia |
|
|
visual obscurations. |
(distorted vision), may |
|
|
|
have pain with eye |
|
|
|
movement. |
|
|
|
|
|
Visual Acuity |
Usually normal— |
Usually very poor |
Normal; vision is usually |
|
late visual loss is |
vision around 20/200 |
20/20 unless there is a |
|
associated with optic |
to hand motion; vision |
refractive error. |
|
nerve atrophy. |
often improves after |
|
|
|
the acute episode. |
|
|
|
|
|
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intracranial pressure are excluded. Typically, intracranial pressure is elevated over 250 mm water and the cerebrospinal fluid is normal. The most common symptoms include headaches and transient visual obscurations that last a few seconds. Pseudotumor cerebri may be associated with the use of tetracycline, corticosteroid withdrawal, vitamin A excess, or hyperviscosity syndromes including polycythemia and thrombocytosis. Table 9 5 lists drugs and endo crine abnormalities associated with pseudotumor cerebri.
In most cases, visual acuity is quite good, in the range of 20/20 to 20/30, even though severe papilledema is present. The typical patient with pseudo tumor cerebri is an obese older child or teenager, and the incidence is higher in females. Patients may present with a sixth nerve palsy without other focal signs, as the sixth nerve palsy is secondary to increased intracranial pressure. The treatment of pseudotumor cerebri is to lower the intracranial pressure by serial lumbar punctures or pharmacologically with carbonic anhydrase
Table 9-5. Causes of Pseudotumor Cerebri
Endocrine
Hypothyroidism
Hyperthyroidism
Adrenal insufficiency
Renal insufficiency
Exogenous growth hormone
Drug
Corticosteroid use/withdrawal
Vitamin A
Tetracycline
Lithium carbonate
Nalidixic acid
Phenytoin
Indomethacin
Oral contraceptives
Amiodarone
Sulfa
Other
Sarcoidosis
Systemic lupus erythematosus
Pregnancy
Iron deficiency anemia
Obesity