and Yi Ning J. Strube2
(1)
Wright Foundation for Pediatric Ophthalmology and Adult Strabismus Medical Center, Los Angeles, CA, USA
(2)
Queen’s University, Kingston, Ontario, Canada
Keywords
Acquired esotropiaAccommodative esotropiaHigh AC/A ratioPartially accommodative esotropiaAugmented surgery formulaPrism adaptationConsecutive exotropiaNon-accommodative acquired esotropiaDivergence paresis esotropiaCyclic esotropiaSensory esotropiaAcquired esotropia requires an urgent consult for at least three important reasons:
1.
Patients with acquired strabismus have fusion potential that diminishes in proportion to the duration of the esotropia. Early intervention can result in restoration of high-grade binocular fusion.
2.
Prompt dispensing of hypermetropic spectacle correction reduces the occurrence of amblyopia and increases the likelihood that spectacles alone will correct the esotropia, obviating the need for surgery.
3.
Acquired esotropia can be a presenting sign of a neurological process such as myasthenia gravis, chronic progressive external ophthalmoplegia (CPEO), Arnold-Chiari malformation, or an intracranial tumor causing a sixth nerve paresis.
This chapter covers accommodative esotropia, non-accommodative acquired esotropia, cyclic esotropia, and sensory esotropia.
4.1 Accommodative Esotropia
4.1.1 Clinical Features
Esotropia usually acquired between 1 and 3 years of age but may occur in infancy (see Chap. 3)
Variable moderate to large-angle esotropia (20–50 PD)
Initially intermittent; then can progress to a constant esotropia
Associated with hypermetropia, usually +2.00 to +6.00 sphere
4.1.2 Etiology
Hypermetropia is associated with increased accommodation to achieve a clear image, resulting in overconvergence and esotropia.
4.1.3 Clinical Evaluation
4.1.3.1 Cycloplegic Refraction
Use cyclopentolate 1 % (two doses, 5 min apart) and refract 30 min after the last dose. Consider using atropine if the cycloplegia with cyclopentolate is inadequate.
4.1.3.2 Amblyopia
First prescribe the full hypermetropic correction. After the patient wears full correction for 4 weeks, evaluate for fixation preference. Strong preference for one eye indicates amblyopia. Treat amblyopia by patching the dominant eye 4–6 h per day until the patient holds fixation well with the nondominant eye.
4.1.3.3 Measure Deviation
Prism alternate cover test is most accurate and usually can be performed on these children. Use an accommodative target (i.e., a target with fine detail requiring full accommodation to see). The deviation should be measured for distance and near, with and without correction.
4.1.4 Management
The first step is to prescribe full hypermetropic correction; the second step is to operate if there is a residual esotropia >10 to 15 PD and no fusion with full correction. Patients with accommodative esotropia usually have straight eyes during the early period of binocular visual development and become esotropic around 1–3 years of age. Because they had developed binocular fusion in infancy, they have the potential for binocular fusion and stereo acuity. Our goal is to align the eyes as soon as possible, in order to reestablish binocular fusion and prevent amblyopia. Over time, cortical suppression associated with the esotropia will reduce binocular potential. In patients with strong fixation preference, cortical suppression will result in amblyopia of the nonpreferred eye. The late Dr. Marshall Parks considered acquired esotropia an urgent consult and would see these patients the same day they called for an appointment. The goal is to align the eyes and obtain binocular fusion with the patient wearing full hypermetropic correction. High-grade stereo acuity frequently can be achieved if early alignment is obtained.
4.1.4.1 Optical Correction
A refractive error significant enough to warrant spectacles is usually +2.00 sphere or more. Give the full hypermetropic correction as soon as the esodeviation is identified, even as early as 2 months of age. These patients accept their full correction. In most cases, the family will notice a significant improvement in visual behavior with the spectacles. Do not reduce the plus unless an exophoria develops with correction. Remember, even a small esotropia disrupts binocular fusion. Some try to reduce the plus in order to wean the patient out of the spectacles, but there are no data indicating that reducing the plus increases the patient’s chances to “grow out of spectacles.” There are data, however, showing that the full plus correction will not interfere with the natural reduction of hypermetropia [1]. Reducing the plus usually produces a small esotropia, compromising the development of binocular fusion.
Most children with accommodative esotropia will accept their spectacles if they are prescribed correctly. If a child objects to wearing hypermetropic spectacles, check the refraction. If the proper refraction was given and the child still refuses to wear the spectacles, try giving atropine 0.5 % (<2 years old) or 1 % (older children) for 2 or 3 days to both eyes, to help the child accept the full hypermetropic correction. Children must wear their spectacles full time for 4–6 weeks before deciding if the optical correction will correct the esotropia. Three responses are commonly possible.
4.1.5 Responses to Hypermetropic Correction
There are three common responses to hypermetropic spectacle correction for acquired accommodative esotropia:
1.
Corrects the esotropia for both distance and near to within 8 PD
2.
Corrects the esotropia for distance, but there is a residual esotropia >10 PD for near
3.
Residual esotropia >10 PD is present for both distance and near
4.1.5.1 Esotropia Corrected Distance and Near
If full hypermetropic spectacle correction results in a tropia less than 8 PD for distance and near, then single-vision spectacles (without bifocals) are to be continued, and surgery is not indicated (Example 4.1). This is termed accommodative esotropia.
Example 4.1
Accommodative Esotropia
Cycloplegic refraction: +3.25 sphere OU
Dsc ET 25 PD | Dcc E 2 PD |
Nsc ET 35 PD | Ncc E 4 PD |
(D—distance; N—near; sc—without correction; cc—with correction; ET—esotropia; E—esophoria)
Stereo acuity 100 s arc
Treatment: Single-vision spectacles, no need for bifocals.
4.1.5.2 Distance Corrected, but Residual Esotropia at Near (High AC/A Ratio)
If the full hypermetropic correction corrects the distance deviation, resulting in fusion (i.e., ET <10 PD), but a residual esotropia persists at near that cannot be fused (usually an ET >8–10 PD), then prescribe a bifocal add. These patients have accommodative esotropia with a high accommodative convergence to accommodation ratio (AC/A) (Example 4.2). Prescribe the least amount of near add to obtain fusion and correct the near esotropia. Most patients will require a +2.50 to +3.00 sphere add at the start. Example 4.2 shows a perfect bifocal candidate: fusing in the distance with full hypermetropic correction and having an esotropia at near, but fusing at near with a +3.00 sphere bifocal add. Note that strabismus surgery is indicated if there is a significant esotropia in the distance that disrupts fusion, even if a bifocal add results in fusion at near. A flat-top bifocal that splits the pupil is preferable until the child learns to use the bifocal well; then change to a progressive add if desired for cosmetic reasons.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
