Commonly referred to as crossed eyes, esotropia is a common type of strabismus in which one or both eyes turn inward toward the nose. It is most often identified in children between the ages of 2 and 4, although it can occur at any age. The opposite form of esotropia, exotropia, is characterized by eyes that point outward, toward the ears.
Esotropia Signs and Symptoms
The primary sign of esotropia is crossing of the eyes. The degree of esotropia may vary from small-angle (hardly noticeable) to large-angle (very noticeable). Children with esotropia are farsighted, meaning that they have difficulty seeing things close up. In accommodative esotropia, the eye crossing may only be evident when your child stares intently at a near object, or when your child is tired or not feeling well. Squinting or rubbing one of the eyes is another sign of esotropia. Your child may also complain of double vision.
Esotropia can be constant or intermittent. A constant esotropia is present all the time, whereas intermittent esotropia may become apparent only when looking at close objects or only when looking at distant objects, or if you are tired or sick. Intermittent esotropia requires treatment to prevent it from becoming constant. The different forms of esotropia include:
Infantile esotropia: Also called congenital esotropia, this condition is usually detected during the first six months of life. Infants with esotropia are otherwise developmentally and neurologically normal.
Acquired esotropia: Esotropia that develops later in life is termed acquired (or secondary), and can occur for a variety of reasons:
- Accommodative esotropia: This term describes eye crossing that results from the focusing efforts of the eyes. It is the most common form of esotropia in children, and it is caused by uncorrected farsightedness (hyperopia). The eyes cross when they converge in an attempt to focus. Correcting the hyperopic refractive error with eyeglasses can usually fix the deviation.
- Non-accommodative esotropia: This condition is often associated with an underlying neurologic or neoplastic disorder. Early surgical correction appears to benefit children with this condition more than vision correction with eyeglasses.
- Acute esotropia: This is the sudden development of crossed eyes from no apparent reason in a school-aged or older child with previously normal vision. Immediate evaluation of the child with acute esotropia is necessary to determine the underlying cause. Among the many causes are a few potentially life-threatening conditions such as meningitis, encephalitis, and head trauma.
- Mechanical esotropia: This is caused by a problem with the intraocular muscles. The intraocular muscles can become restricted or tightened because of thyroid myopathy, for example, or they may be physically obstructed as a result of a blowout fracture. Mechanical esotropia may be seen in children with Duane syndrome, an eye muscle disorder that can prevent outward movement of the eye (toward the ear).
- Sensory esotropia: A person with this condition suffers from reduced visual acuity in one eye, which hinders or disrupts the process of fusion in normal binocular vision (binocular vision is the coordination of both eyes so that the separate and slightly dissimilar images seen by each eye are appreciated as a single image). Sensory esotropia occurs most frequently in children younger than 5 or 6.
- Consecutive esotropia: This may occur after surgical overcorrection of an exotropia. Other oculomotor anomalies — such as vertical or cyclotorsional deviations — are often present in such cases. Consecutive esotropia may result in amblyopia and loss of normal binocular vision in young children and diplopia in adults.
What Causes Esotropia?
Esotropia can be hereditary, although it may occur differently in different family members. It is also associated with prematurity and various neurological and genetic disorders. Farsightedness is the most common vision problem associated with esotropia. Some systemic disorders, such as hyperthyroidism and diabetes, cause ocular misalignment. The appearance of crossed eyes in an infant is not always a sign of esotropia; it can be a result of the shape of the eyelids or nasal bridge, and as the infant grows, the misalignment goes away. This is called pseudostrabismus.
Infants and children with suspected esotropia are typically evaluated by a pediatric ophthalmologist or optometrist, who will review the child’s medical and family histories and then perform an examination to determine the child’s visual acuity. This includes an evaluation of the general health of the eyes and their refractive state (that is, whether the child is farsighted, nearsighted, or has astigmatism). The eyes will be dilated with eye drops to determine the degree of farsightedness. The ophthalmologist or optometrist will pay close attention to whether the acuity is equal in both eyes or if one eye is stronger than the other. If there is a strong preference for one eye over the other, a condition called amblyopia may occur. Amblyopia can be treated by patching the stronger eye, and is best treated at an early age. If ocular misalignment is detected, the degree of misalignment is measured so that the child can be fitted with the appropriate glasses.
Initial treatment of esotropia may involve the prescription of eyeglasses or contact lenses to correct the child’s hyperopic refractive error (farsightedness). Glasses should be worn all the time. Children with significant eye crossing even when wearing glasses or contact lenses may benefit from a bifocal lens. Surgery is rarely indicated but may be considered when eye glasses fail to straighten the eyes. However, surgery does not replace the need for glasses; it simply corrects the amount of eye crossing. The goals of treatment are to re-establish ocular alignment, maximize binocular vision, relieve any diplopia, and manage any associated amblyopia.
Esotropia cannot be prevented, but its complications can be prevented if the problem is detected early and treated properly. Children should be monitored closely during infancy and through the preschool years to detect potential eye problems, especially if a relative has strabismus.
In the United States, children are typically screened for eye health before they are six months old, and thereafter at each check-up with their pediatrician or family practitioner. A thorough eye examination by an ophthalmologist or optometrist is recommended when the child is between the ages of 3 and 5.
- American Optometric Association, Optometric Clinical Practice Guideline. “Care of the Patient with Strabismus: Esotropia and Exotropia,” 2011. http://www.aoa.org/documents/optometrists/CPG-12.pdf
- American Association for Pediatric Ophthalmology and Strabismus, “Esotropia,” Updated March 2012. http://www.aapos.org/terms/conditions/48
- B. G. Mohney. “Acquired nonaccommodative esotropia in childhood.” Journal of the American Association for Pediatric Ophthalmology and Strabismus. 2001;5(2):85-89.
- A. E. Greenberg, B. G. Mohney, N. N. Diehl, J. P. Burke. “Incidence and types of childhood esotropia: a population-based study.” Ophthalmology. 2007;114(1):170-174.