Ординатура / Офтальмология / Английские материалы / Handbook of Pediatric Strabismus and Amblyopia_Wright, Spiegel, Thompson_2006

multicenter study of 2- to 3-month-old infants with esotropia, 56% of patients were characterized as having a constant esotropia, 25% a variable deviation, and 19% had an intermittent esotropia. Only half had a deviation measured to be 40 PD or greater. Larger deviations tended to be constant, whereas the majority of the smaller-angle deviations were intermittent or variable.

Spontaneous Resolution of Esotropia

Until the data from the CEOS collaborative group52 became available, there was limited information on spontaneous resolution of early-onset esotropia. Birch et al.5 prospectively followed 80 infants with esotropia who were first seen at 2 to 4 months of age. Resolution without surgery occurred at 6 months of age in 3 of 8 patients whose initial deviation was intermittent or variable, 3 of 23 patients with a constant esotropia of 35 PD or less (2 of whom were given spectacle correction for hypermetropia), and 0 of 49 with a constant esotropia of 40 PD or more. Clarke and Noel16 described 3 cases of constant esotropia diagnosed by 6 months of age that spontaneously decreased to less than 10 PD after 1 year of age but retained persistent signs of abnormal motor development including dissociated vertical deviation and latent nystagmus. Friedrich and de Decker27 described 1 case of a transient variable large-angle esotropia and 6 cases of smallto moderate-angle, mostly intermittent, esotropia first noted between 1 and 3 months, of age, that spontaneously resolved.

The findings of CEOS provide the best data on spontaneous resolution of infantile esotropia.52 This multicenter prospective study found of 170 patients, 46 (27%) spontaneously resolved to within 8 PD of orthotropia at the outcome exam either with or without spectacle correction. Patients with a small angle ( ) 40 PD, and intermittent esotropia had a 50% to 78% rate of spontaneous resolution. In contrast only 2 of (3%) 64 patients with a constant esotropia of 40 PD or more on both the baseline and first follow-up exam and with a refractive error of 3.00 diopters or less, the esotropia resolved at the outcome exam. One patient had a persistent 40 PD esotropia at the outcome exam; however, the esotropia improved without treatment to ET 5 PD. The conclusion of CEOS was that early-onset esotropia frequently resolves if the esotropia is less than 40 PD and is intermittent or variable. If the esotropia is constant or greater than 40 PD pre-

senting on 2 exams with less than 3.00 D refractive error, then the likelihood of spontaneous resolution is remote.

Ing37 reported that in 41 cases of esotropia seen at an average age of 6 months, the esotropia increased between the first examination and the time of surgery by 10 PD or more in 61% and did not decrease by 10 PD or more in any patients. Because this was a retrospective study of patients who had undergone strabismus surgery, there might have been a selection bias for patients with an increasing esotropia.

Thus, spontaneous resolution of infantile esotropia does occur, especially if the deviation is small, variable, or intermittent. However, infants with a constant deviation of 40 PD or more on two exams and with less than 3.00 D of hyperopia have a low likelihood of spontaneous resolution and can be considered for early surgery.

Amblyopia Associated with Infantile Esotropia

The ability to alternate fixation, or hold fixation well with either eye, indicates equal vision (Fig. 7-2).72 Strong fixation preference, on the other hand, indicates amblyopia of the nonpreferred eye, and should be treated by patching the preferred eye before strabismus surgery.72 The incidence of amblyopia seems to be proportional to the duration of the esotropia. In the CEOS,51 amblyopia was diagnosed in 19% of patients at the first visit (2 months of age) and doubled to 42% at subsequent visits (after 6 months of age). This frequency is similar to the 22% rate reported by Hiles et al.31 and to the 13% rate reported by Hoyt et al.32 for patients examined before 1 year of age. Higher rates of amblyopia (41%–72%) have been reported in postsurgical case series extending over many years of follow-up.19,59 Some have blamed surgery for causing amblyopia because the rates of amblyopia were higher in the postsurgery patients. It is more likely, however, that this higher rate of amblyopia reflects the higher incidence of amblyopia having a longer duration of esotropia.

Refractive Error

Costenbader found that more than half of 500 children with congenital esotropia had significant hypermetropia ranging from2.25 to over 5.00.19 The CEOS showed that mild to moderate hypermetropia was present in most patients, with about 20%

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FIGURE 7-2A,B. Patient with infantile esotropia and alternating fixation, no amblyopia. (A) Patient is fixing with the right eye. (B) Patient is fixing with the left eye.

being above 3.00 D, 12% above 4.00 D, and less than 10% being myopic.51 Similar results have been reported in other infantile esotropia series, as Birch et al.8 found 17% of cases and Ing39 found 25% of cases with hyperopia of 3.00 or more. In a

series by Hiles et al.31 on older children, hyperopia greater than3.00 D was present in 15% of the 54 cases.

Mutti et al.47 reported similar incidence of refractive errors in a study of 288 normal 3-month-old infants with a mean refractive error of 2.10 1.3 D; 21% were greater than 3.00 D, 8% were greater than 4.00 D, and 3% had myopia of 0.50 D or greater. It seems, from a review of the literature, that infants with esotropia have, on average, refractive errors similar to the normal age-matched population. There are selected patients, however, with moderate to high hypermetropia who appear to have esotropia on the basis of accommodative convergence.

Associated Motor Abnormalities

The classic triad of motor abnormalities associated with congenital esotropia is inferior oblique overaction, dissociated vertical deviation (DVD), and latent nystagmus.36 These three associated findings may occur individually or in any combination and usually become manifest some time after 1 year of age.68 CEOS found inferior oblique overaction and DVD to be almost nonexistent at the initial exam at approximately 2 months of age.51 Eight percent (8%) of patients had inferior oblique overaction and 4% had DVD at 6 months of age.51 Hiles et al.31 reported the rate of 15% for inferior oblique overaction and 2% for DVD between 3 and 10 months of age, but both increased to approximately 75% at long-term follow-up examinations. (See Chapter 9 for a discussion of inferior oblique overaction and Chapter 10 for DVD.) Latent nystagmus occurs less frequently than inferior oblique overaction or DVD. CEOS51 found only a 4% frequency at 6 months of age, and Robb and Rodier59 reported a frequency of 16%. Smooth pursuit asymmetry is another motor finding present in virtually all patients with infantile esotropia (see Chapter 4, p. 158).1,65 Smooth pursuit asymmetry is a marker of early disruption of binocular visual development.

LATENT NYSTAGMUS

Latent nystagmus is a bilateral nystagmus that becomes manifest when one eye is occluded, or the eyes are dissociated by blurring the vision of one eye, or by suppression of one eye associated with manifest strabismus; this is a jerk-type nystagmus with the fast phase toward the fixing eye. Velocity recordings show that

the velocity of the slow phase decreases toward the end of the slow-phase eye movement (decreasing velocity slow phase).23 Latent nystagmus is also associated with conditions that disrupt early binocular visual development, such as congenital monocular cataracts.

Systemic Associations

In most cases, congenital esotropia occurs as an isolated problem in an otherwise healthy child; however, it can be associated with systemic diseases such as Down’s syndrome, albinism, and cerebral palsy. The differential diagnosis of esotropia occurring in infancy includes Möbius syndrome, congenital fibrosis syndrome, Duane’s syndrome, infantile myasthenia gravis, and congenital sixth nerve palsy. Congenital sixth nerve palsy is rare and usually spontaneously resolves over a few weeks. Neurological processes such as hydrocephalus and intracranial tumors can present as an infantile esotropia. Most clinical studies on congenital esotropia exclude patients with neurological or systemic disease. Thus, congenital esotropia is usually defined as a primary esotropia not associated with a sixth nerve palsy, a neurological condition, or a significant restriction, and occurs before 6 months of age.

Clinical Assessment

Evaluation should start with amblyopia assessment, usually by fixation preference. Assessment of ductions and versions are important to diagnoses an abduction deficit possibly related to a sixth nerve palsy or oblique dysfunction. Patients with infantile esotropia often show some limitation of abduction. In these cases, it is important to verify the abduction deficit by vestibular stimulation with the doll’s head maneuver or by spinning the infant. Vestibular stimulation is best performed in infants by gently spinning the child (Fig. 7-3). Many children who show an abduction deficit to voluntary abduction will have full abductions by vestibular stimulation. If an abduction deficit persists, assess lateral rectus function by examining the abduction saccade. If there is a brisk abduction saccade, then the lateral rectus is functioning and the limited abduction is restrictive, probably secondary to a tight medial rectus muscle. A slow or absent abduction saccade indicates a weak lateral rectus, possibly caused by a sixth nerve palsy or a Duane’s syndrome. Opto-

FIGURE 7-3. Diagram of an infant in examiner’s hands. Infant is moved to the right, which stimulates eye movement to the left. If the right eye fully abducts, then lateral rectus function is normal and there is no significant restriction of the medial rectus muscle. Spinning an infant will cause the eyes to move opposite to the spin, an excellent way to examine horizontal ductions in an otherwise uncooperative infant.

kinetic stimulation (OKN drum or tape) is a good way to stimulate saccadic eye movements.69 The angle of deviation is measured by cover/uncover testing or with Krimsky light reflex, and near and distance measurements should be obtained if possible. A cycloplegic refraction and a dilated fundus exam are also indicated.

Inheritance

The inheritance of congenital esotropia remains undefined; however, it is well known that it runs in families.44,45,55 Affected family members may have congenital esotropia, but other types of strabismus are often found, including accommodative esotropia and congenital superior oblique palsy. Maumenee et al.,44 in an analysis of a large group of families, concluded that the inheritance is consistent with a Mendelian codominant model in which there is an admixture of primarily autosomal recessive cases, some dominant cases, and possibly nongenetic

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FIGURE 7-4A,B. Pseudo-strabismus. (A) Note the large epicanthal folds giving the appearance of esotropia even though the eyes are well aligned.

(B) Pinching the epicanthal skin folds demonstrates the eyes are well aligned.

deviation ( 60 PD), (2) bilateral limited abduction with intact abduction saccades, (3) fixing eye in adduction, (4) nystagmus on attempted abduction with no nystagmus in adduction, and (5) face turn to the side of the fixing eye (Fig. 7-5). In Ciancia’s

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FIGURE 7-5A,B. Patient has Ciancia’s syndrome with bilateral tight medial rectus muscles causing a large-angle esotropia and limited abduction. The patient is most comfortable with the fixing eye in adduction. To establish this, the patient adopts a face turn toward the fixing eye, thus placing the fixing eye in adduction. In (A), the patient is fixing the right eye, with face turn to the right; in (B), patient is fixing the left eye and has a face turn to the left. This patient with Ciancia’s syndrome is showing a pattern of cross-fixation.