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is greater at near deviation than at distance because of the additional accommodation required to maintain a clear image at near.

28.How can nonrefractive accommodative esotropia be treated?

•Bifocals eliminate the additional accommodative effort required at near and therefore reduce the near esotropia.

•Surgery may be performed to eliminate the esotropia at near and to correct the AC:A ratio permanently.

•Observation. Some ophthalmologists choose simply to observe patients as long as the patients’ eyes remain straight at distance. The esotropia at near may resolve on its own as the AC:A ratio normalizes during childhood.

29.What is partial or decompensated accommodative esotropia?

Refractive or nonrefractive accommodative esotropias do not always occur in their “pure” forms. Glasses may reduce the esodeviation significantly. Sometimes the esotropia may initially be eliminated with glasses, but a nonaccommodative portion slowly becomes evident despite the maximal amount of hyperopic correction consistent with good vision. The residual esodeviation that persists is called the deteriorated or nonaccommodative portion. This condition commonly occurs with a delay of months between onset of accommodative esotropia and antiaccommodative treatment.

30.How is partial or decompensated accommodative esotropia treated?

•Surgery may be indicated if the deviation is larger than an amount that allows development of binocular vision.

•Surgery is generally performed for the nonaccommodative portion of the esotropia only, not for the full deviation that is present without glasses in place.

31.What is cyclic esotropia?

•A rare disorder that classically describes a large-angle esotropia alternating with orthophoria or a small-angle esodeviation on a 48-hour cycle

•It may result from an aberration in the biologic clock or a combination of defects in the clock, oculomotor nuclei, superior colliculi, or other nuclei

•Unpredictable response to various forms of therapy with the exception of surgery, which is usually curative

32.What are the characteristics of acute acquired comitant esotropia?

•Rare condition that occurs in older children and adults

•Dramatic onset of a large angle of esotropia with diplopia

•Normal levels of hyperopia

•Has been reported after periods of interruption of fusion, such as occlusion therapy for amblyopia

33.How should patients with acute acquired comitant esotropia be managed?

•A careful motility analysis to rule out a paretic deviation

•Consider further workup, including computed tomography or magnetic resonance imaging

References

1. Archer SM, Sondhi N, Helveston EM: Strabismus in infancy, Ophthalmology 96:133–137, 1989.

2. Pediatric Eye Disease Investigator Group: Spontaneous resolution of early-onset esotropia: experience of the Congenital Esotropia Observational Study, Am J Ophthalmol 133(1):109–118, January 2002.

3. Pediatric Eye Disease Investigator Group: The clinical spectrum of early-onset esotropia: experience of the Congenital Esotropia Observational Study, Am J Ophthalmol 133(1):102–108, January 2002.

4.Birch E, Stager D, Wright K, Beck R: The natural history of infantile esotropia during the first six months of life, J AAPOS 2:326–328, 1998.

5.Ing M, Costenbader FD, Parks MM, Albert DG: Early surgery for congenital esotropia, Trans Am Ophthalmol 62:1419–1427, 1966.

6.Hiles DA, Watson A, Biglan AW: Characteristics of infantile esotropia following early bimedial rectus recession, Arch Ophthalmol 98:697–703, 1980.

7.Coats DK, Avilla CW, Paysse EA, et al.: Early-onset refractive accommodative esotropia, J AAPOS 2:275–278, 1998.

8.Raab EL: Etiologic factors in accommodative esodeviation, Trans Am Ophthalmol Soc 80:657–694, 1982.

1.What is the differential diagnosis of exotropia?

•Congenital exotropia

•Sensory exotropia

•Third-nerve palsy

•Duane’s syndrome

•Craniofacial abnormalities with divergent orbit (e.g., Apert’s syndrome or Crouzon syndrome)

•Myasthenia gravis

•Thyroid disorder

•Medial wall fracture

•Slipped medial rectus muscle or excessively resected lateral rectus

•Orbital inflammatory pseudotumor

•Convergence insufficiency

•Internuclear ophthalmoplegia

2.A mother notices that her 4-month-old infant seems to be “wall-eyed.” What is your concern as a physician?

First, check whether deviation or pseudostrabismus is present. A wide interpupillary distance or temporal dragging of the macula from retinopathy of prematurity or toxocariasis may cause pseudoexotropia. The light reflex test or cover testing elucidates this point. Also, make sure that the eyes move normally. Have the patient follow a light or a brightly colored toy to exclude paralysis or muscle restriction. If this test is normal and you notice true strabismus, quantify

it with prisms at near and far. Check the cycloplegic refraction, and do a complete dilated exam. Anisometropic amblyopia may cause an eye to deviate, but it usually presents as esotropia in the younger age group. Also, a corneal lesion, cataract, glaucoma, or retinal lesion such as a toxoplasmosis scar or retinoblastoma may cause the deviation. These conditions must be

ruled out.

Once you have determined that the remainder of the exam is normal, you realize that the infant has an alternating exotropia of 40 prism diopters. Congenital exotropia is much rarer than congenital esotropia, but they have much in common. Both have a large angle of deviation and rarely develop amblyopia because of alternating fixation. The refractive error is normal. Early surgery is recommended to allow development of stereoacuity.

3.A mother notices that her 2-year-old boy has a left eye that deviates outward when he is tired or has a fever. What is your concern as a physician?

Intermittent exotropia, which is the most common type of exotropia. The onset varies from infancy to 4 years of age. It may progress through the following three phases:

•Phase 1: Exophoria at distance and orthophoria at near occur when the patient is fatigued or daydreaming. He has diplopia and often closes one eye. When aware of the deviation, he is easily able to straighten his eyes, often after a blink.

•Phase 2: Exotropia at distance and exophoria at near. When the exotropia becomes more constant, suppression develops and the diplopia becomes less frequent. The exotropia remains after a blink.

•Phase 3: The exotropia is constant at distance and near. There is no diplopia because of suppression.

Vision must be equalized by correcting any significant refractive error and patching the nondeviating eye. Surgery should be done when the patient progresses beyond phase 1, but preferably before phase 3.

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4.An 18-year-old patient complains of blurred near vision and headaches while reading. Do you believe her, or is she just trying to get out of doing her homework?

Check her ocular deviations at near and far. She may be experiencing convergence insufficiency, which is common in teenagers and young adults. It is rare in children under 10 years of age. It is often idiopathic but may be exacerbated by fatigue, drugs, uveitis, or an Adie’s tonic pupil. Exodeviation is greater at near than at distance and causes asthenopia. Exophoria at near may be all that is seen. The near point of convergence is more distant than normal (>3 to 6 cm for patients younger than age 20; >12 cm for patients older than age 40), and the amplitude of accommodation is reduced.

Her fusional ability will be decreased. If you have her focus on a target at the reading distance that forces her to accommodate, you will see that she will have a low break point or a low recovery point when slowly increasing the amount of base-out prism in front of one eye. The break point is when she begins to see double vision with increasing prism; the recovery point is when she can fuse to single images working down from the higher amount of prism. Ten to 15 prism diopters is considered low.

Because she is symptomatic, treat her with base-in prisms for reading to help convergence. Nearpoint exercises or “pencil push-ups” can improve fusional amplitudes. These exercises are performed by having the patient slowly move a pencil from arm’s length toward the face while focusing on the eraser. Have the patient concentrate on maintaining one image of the eraser. Repeat 10 times several times a day. Once this is mastered, pencil push-ups can be done while holding a 6-D base-out prism over one eye. Rarely, medial rectus resection may be necessary.

5.What if the fusional capacities are normal and there is no exodeviation?

The problem may be accommodative insufficiency, which has similar symptoms in the same age group. However, accommodation is reduced. First check the manifest and cycloplegic refraction. The patient may be underplussed and need a stronger hyperopic refraction. If refraction is normal, pluslens reading glasses will help.

6.How do you differentiate a patient with convergence insufficiency versus accommodative insufficiency clinically?

In accommodative insufficiency, a 4-D base-in prism will cause blurring during reading, whereas patients with convergence insufficiency will note that print becomes clearer.

7.Some patients have the opposite problem: esotropia that is worse at distance than at near. What is this condition called?

This is divergence insufficiency. Fusional divergence is reduced. Treatment is with base-out prisms and, rarely, lateral rectus resections. However, divergence insufficiency is a diagnosis of exclusion, and divergence paralysis must be ruled out because it may be associated with pontine tumors, head trauma, and other neurologic abnormalities. Neuro-ophthalmic evaluation is necessary.

8.What is Duane’s syndrome? What are the different types of this disorder?

Duane’s syndrome is a congenital motility disorder characterized by limited abduction, limited adduction, or both. The globe retracts, and the palpebral fissure narrows on attempted adduction. A “leash effect” may cause upward deviation at the same time. There are three types of the syndrome:

•Type 1—limited abduction (most common) (Fig. 26-1)

•Type 2—limited adduction

•Type 3—both limited abduction and limited adduction (rarest type)

There are three females to every two males afflicted with Duane’s syndrome. The left eye is involved in 60% of cases; in 18% of cases, both eyes are involved. Sixty percent of patients also have an associated esotropia, 15% have exotropia, and 25% are orthophoric. A and V patterns are common. Amblyopia, attributable to anisometropia, occurs in approximately one-third of cases. Surgery is done to correct a head turn, but resection should not be performed because it exacerbates the narrowing of the fissure and globe retraction.

9.What is the cause of Duane’s syndrome?

The cause is unclear, but it appears that the lateral rectus muscle is innervated by the third nerve, causing cocontraction of the medial and lateral rectus muscles. This theory explains the globe retraction and fissure narrowing.

10.What other features may be associated with Duane’s syndrome?

Goldenhar’s syndrome, deafness, crocodile tears, and uveal colobomas.

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Figure 26-1.  Duane’s syndrome affecting the right eye. In primary position (middle), the eyes are aligned. There is reduction in the right palpebral fissure height on left gaze (top) and right upper eyelid retraction as well as an abduction deficit on right gaze (bottom). (From Burde RM, Savino PJ, Trobe JD: Clinical decisions in neuro-ophthalmology, ed 3, St. Louis, Mosby.)

11.What is the differential diagnosis of hypertropia?

•Myasthenia gravis

•Thyroid eye disease

•Orbital inflammatory pseudotumor

•Orbital trauma (may cause inferior rectus entrapment)

•Fourth cranial nerve palsy

•Pseudohypertropia

•Skew deviation—see Chapter 30

KEY POINTS: BROWN’S SYNDROME

1. Inability to elevate affected eye when adducted.

2. Hypertropia may be present in primary gaze.

3. Patient may turn head away from affected eye with chin-up position. 4. Ten percent of cases are bilateral.

5. Forced adduction reveals superior oblique muscle restriction.

12.What is the cause of Brown’s syndrome?

Brown’s syndrome (Fig. 26-2) may be congenital or acquired. The cause may be related to mechanical restriction of the superior oblique tendon. Examples include trauma, surgery, or inflammation in the region near the trochlea.

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A

B

C

Figure 26-2.  Brown’s syndrome affecting the right eye. A, Usually straight in the primary position. B, Limited right elevation­ in adduction and occasionally also in the midline. C, Usually normal right elevation in abduction. (From Kanski JJ: Clinical ophthalmology: a systematic approach, ed 5, New York, Butterworth-Heinemann, 2003.)

13.How is Brown’s syndrome treated?

Acquired cases may be observed because they may improve spontaneously. Some improve with steroid injections near the trochlea. If no improvement is seen by 6 months, the superior oblique muscle may be weakened with a tenotomy. Some surgeons recess the ipsilateral inferior oblique at the same time to prevent an inferior oblique overaction postoperatively. Patients need to be aware that they will never be able to elevate the affected eye normally in adduction.

14.What is the differential diagnosis of Brown’s syndrome?

•Inferior oblique palsy: The three-step test reveals a superior oblique overaction that is not present in Brown’s syndrome. In patients with diplopia, vertical deviations in primary gaze, or an abnormal head position, a superior oblique tenotomy or recession of the contralateral superior rectus is done. Forced ductions reveal no restriction.

•Double elevator palsy: Patients cannot elevate the affected eye in any field of gaze (Fig. 26-3). Ptosis or pseudoptosis may be seen. A chin-up position helps to maintain fusion if a hypotropia is present in primary gaze. If no chin-up position is seen with hypotropia, amblyopia is present.

Treatment for a large vertical deviation or an abnormal head position is inferior rectus recession, if the inferior rectus is restricted, or transposition of the medial and lateral rectus toward the superior rectus (Knapp procedure), if no restriction is present.

•Blow-out fracture with entrapment of the inferior rectus muscle: History elucidates this injury, and forced ductions show restriction. Confirm with an orbital computed tomographic (CT) scan.

•Thyroid disease: Restriction is found on forced ductions, the strabismus is acquired and incomitant, lid retraction also may be noted. A CT scan reveals enlarged extraocular muscles.

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Figure 26-3.  Right monoelevation deficit showing defective elevation in all positions. (From Kanski JJ: Clinical ophthalmology: a systematic approach, ed 5, New York, Butterworth-Heinemann, 2003.)

15.What is Möbius syndrome?

This is a congenital syndrome with varying abnormalities of the fifth through twelfth cranial nerves. Patients may have a unilateral or bilateral esotropia with inability to abduct the eyes even on doll’s head maneuvers. Patients also may exhibit limb, chest, and tongue defects and may have significant feeding difficulties.

16.A 48-year-old man undergoes medial rectus resection and lateral rectus recession for a sensory exotropia of 35 prism diopters in the left eye. He presents the next day with an exotropia of 60 prism diopters in primary position and an inability to abduct the eye. What is your diagnosis?

The diagnosis is a slipped or lost medial rectus muscle. It is important to double-lock the suture through the tendon and muscle when reattaching the rectus muscle to the globe to prevent this complication. Reoperation is necessary to find the muscle and reattach it in the appropriate position. If you cannot locate the muscle, a transposition of the superior and inferior rectus muscles helps to correct the exotropia.

17.A patient complains that her right eye is hypertropic. The light-reflex test and covering test show her to be orthophoric. What may be going on?

Pseudohypertropia. She may have a vertically displaced macula from retinopathy of prematurity or toxocariasis. Eyelid retraction of the right eye may cause the right eye to appear hypertropic. Vertical displacement of the globe superiorly by a mass, such as a mucocele, may cause a similar appearance.

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Figure 26-4.  Chronic progressive external ophthalmoplegia. (From Kanski JJ: Clinical ophthalmology: a test yourself Atlas, ed 2, New York, Butterworth-Heinemann, 2002.)

18.A young boy has developed chin-up position and seems to move his head rather than his eyes to locate objects. On examination, he has poor ductions and versions in all fields of gaze as well as bilateral ptosis. Forced ductions reveal restrictions in all extraocular muscles. What is your diagnosis?

The diagnosis is congenital fibrosis syndrome. The normal muscle tissue is replaced by fibrous tissue to varying degrees. It may be unilateral or bilateral. The eyes may exhibit little to no vertical or horizontal movements, depending on the number of muscles involved, as well as esotropia or exotropia. Amblyopia is common. Ptosis with chin elevation is a frequent manifestation. The cause is unknown. The goal of surgery is to restore orthophoria in primary gaze.

19.A 20-year-old man with no history of strabismus complains that he cannot open his eyes well. You notice that ductions and versions are severely reduced and that he has bilateral ptosis. There is no restriction on forced ductions. What is your diagnosis?

The diagnosis is chronic progressive external ophthalmoplegia (CPEO). This condition begins in childhood with ptosis and progresses slowly to total paresis of the eyelids and extraocular muscles (Fig. 26-4). It may be sporadic or familial. Patients usually do not have diplopia. A frontalis sling procedure may be necessary to elevate the eyelids.

20.What other evaluations are important?

Check for retinal pigmentations, and order an electrocardiogram to check for heart block. The triad of CPEO, retinal pigmentary changes, and cardiomyopathy is known as Kearns-Sayre syndrome (Fig. 26-5). Patients may require pacemakers to prevent sudden death. Inheritance is by maternal mitochondrial DNA.

21.What other diseases may be associated with chronic progressive external ophthalmoplegia?

•Abetalipoproteinemia (Bassen-Kornzweig syndrome): Patients have retinal pigmentary changes similar to retinitis pigmentosa (RP), diarrhea, ataxia, and other neurologic signs.

•Refsum’s disease: Patients have an RP-like syndrome with an increased phytanic acid level. They also may have neurologic signs.

•Ocular pharyngeal dystrophy: Patients have difficulty with swallowing. The condition may be autosomal dominant.

22.What is congenital ocular motor apraxia?

In this rare disorder patients are unable to generate normal voluntary horizontal saccades. To change horizontal fixation, a head thrust that overshoots the target is made. The head is then rotated back in the opposite direction once fixation is established. Vertical saccades are normal, but vestibular and optokinetic nystagmus are impaired. Strabismus may be associated.

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Figure 26-5.  Kearns-Sayre syndrome. (From Kanski JJ: Clinical ophthalmology: a test yourself Atlas, ed 2, New York, Butterworth-Heinemann, 2002.)

23.A patient complains of diplopia. On examination, he has paresis of the third, fourth, and fifth cranial nerves on the right side. What can cause multiple ocular motor nerve palsies?

Anything that damages the cavernous sinus and/or superior orbital fissure, including the following:

•Arteriovenous fistula—carotid–cavernous sinus dural shunts

•Cavernous sinus thrombosis

•Tumors metastatic to cavernous sinus

•Skin malignancy with perineural spread to cavernous sinus

•Pituitary apoplexy—patients often have extreme headache with bilateral signs and decreased vision; need emergent intravenous steroids and neurosurgical consultation

•Intracavernous aneurysm

•Mucormycosis—more likely in diabetics, especially in ketoacidosis, and any debilitated or immunocompromised patient; look for an eschar in the nose and palate; emergent consultation with otolaryngology for débridement imperative

•Herpes zoster

•Tolosa-Hunt syndrome—acute idiopathic inflammation of the superior orbital fissure or anterior cavernous sinus (diagnosis of exclusion)

•Mucocele

•Meningioma

•Nasopharyngeal carcinoma

Multiple cranial nerve palsies also may occur with brain-stem lesions and carcinomatous meningitis.

Other entities that can mimic multiple cranial nerve palsies include:

•Myasthenia gravis

•CPEO

•Orbital lesions such as thyroid disease, pseudotumor, or tumor

•Progressive supranuclear palsy

•Guillain-Barré syndrome

24.What is Parinaud’s syndrome?

Also known as dorsal midbrain syndrome, Parinaud’s syndrome is characterized by a supranuclear gaze paresis with nuclear oculomotor paresis and pupillary abnormalities. Active upward gaze is diminished, but elevation is seen with doll’s head maneuver. Attempts at upward gaze cause retrac- tion-convergence nystagmus and palpebral fissure widening (Collier’s sign). Pupils are middilated and do not react to light but react normally to accommodation.

25.What is the cause of Parinaud’s syndrome?

In children, pinealoma and aqueductal stenosis are the most common causes. In adults, demyelination, infarct, and tumor are most common.

26.Describe the presentation of a patient with internuclear ophthalmoplegia

A young woman with a history of optic neuritis complains of double vision when looking to one side. She is unable to adduct on attempted contralateral gaze and exhibits horizontal nystagmus in the abducting eye. Adduction on convergence is normal. The condition may be unilateral or bilateral. Exotropia may be present if the condition is bilateral.