Download Esotropia - Dr. Sandip Mitra

Dr Sandip Mitra, MD FRCS
Consultant ophthalmologist,
Fellow cornea and refractive surgery Melbourne Australia (Royal Victoria eye and ear hospital)
Esotropia (Crossed Eyes)
Esotropia is a type of strabismus or eye misalignment. In esotropia, the eyes are "crossed"; that is,
while one eye looks straight ahead, the other eye is turned in toward the nose. This inward
deviation of the eyes can begin in infancy or later in childhood.
Congenital (Infantile) Esotropia
Congenital (infantile) esotropia is a type of strabismus which first appears sometime within the
first six months of life. This esotropia may be present at birth but often develops within the first
few months. In the first months of life, it is common for the eyes to intermittently become
misaligned. If a misalignment of the eyes persists after the first few months, a consultation with a
pediatric ophthalmologist is required.
Child with infantile esotropia before and after eye muscle surgery.
One to two percent of children have congenital esotropia. Though the cause is unknown, it is
thought that the underlying problem lies in the brain's inability to coordinate the movement of the
eyes. These children will often alternate their vision between the two eyes by sometimes crossing
one eye, and at other times the other. Some children will constantly cross the same eye. This is
often an indication that amblyopia (lazy eye) or decreased vision, is developing in one eye.
Treatment of congenital esotropia usually requires eye muscle surgery. Before surgery is
performed, other factors must be considered. If amblyopia has developed in one eye, this poor
vision must be treated right away. This is accomplished by patching the better eye to force the
brain to use the eye with poorer vision. Though this will not correct the eye crossing, it will
equalize the vision which improves the prognosis for a successful outcome from surgery. The
presence of farsightedness must also be detected prior to an operation. Though this is an
uncommon cause of esotropia in infants, glasses must be tried when there is significant
farsightedness present as glasses, alone may diminish the eye crossing.
(See photo below and Accommodative Esotropia)
This six month old child with esotropia measured to be significantly farsighted. With the
appropriate glasses in place, the eye crossing resolved.
Children do not outgrow infantile esotropia. Surgical correction is usually recommended
between six and nine months of age. The reasons for correction go beyond the obvious drastic
improvement in the child's appearance. When the eyes are misaligned in childhood, binocular
vision, or the ability of the brain to use the two eyes together, does not develop. Early alignment of
the eyes allows for the development of the brain’s ability to experience normal depth perception
and fine 3-dimensional vision. Achieving this binocularity at a young age will also afford a child
the best chance of maintaining normal ocular alignment throughout life. Additionally, a child with
good ocular alignment is at decreased risk for developing amblyopia.
Even after successful surgery, periodic follow-up is necessary to detect associated eye
problems. Vertical misalignments of the eye, especially when looking to the side (see photo
below), recurrent eye crossing and amblyopia may occur months, years or decades after successful
eye muscle surgery.
Despite successful surgical correction of congenital esotropia in infancy, years later, this child
developed a vertical imbalance of the eyes in both right and left gaze.
Accommodative Esotropia
Accommodative esotropia is a form of strabismus due to a need for farsighted glasses
Acquired Non-Accommodative Esotropia
Esotropia can occur after infancy and not be responsive to farsighted glasses, thereby not
falling into the categories of congenital (infantile) or accommodative esotropia which are
described elsewhere on this web site. Acquired esotropia can have multiple causes. Most common
are children who have been farsighted for awhile and have not had glasses, or children who were
initially responsive to glasses but later developed an additional eye crossing even when wearing
the proper glasses. All children with acquired eye crossing require a prompt evaluation by a
pediatric ophthalmologist. Eye muscle surgery can correct such deviations and restoration of
binocular vision is usually possible.
Pseudoesotropia
Pseudoesotropia refers to the appearance of crossed eyes in a child whose eyes are actually
perfectly aligned. This is common in infants and younger children who have a broad, flat bridge of
the nose which allows the skin on the inner part of the eyelids to extend over and cover the inner
part of the eye. The sclera (the white part of the eye) closest to the nose becomes covered,
especially when the child looks toward either side, and a crossed eye appearance is simulated (see
photo below). As the face matures and the nasal bridge grows, the skin is pulled forward and away
from the eye, thereby eliminating the crossed eye appearance.
Pseudoesotropia as a result of a
broad bridge of the nose. This is
not a real eye crossing.
Accommodative Esotropia
This refers to a crossing of the eyes ("esotropia") caused by farsightedness.
Accommodative esotropia is a type of strabismus. Strabismus refers to any misalignment of the
eyes.
Children who are farsighted easily and automatically focus on objects at distance and near
through "accommodation". Accommodation refers to the contraction of a small muscle inside the
eye to cause the natural lens in the eye to change its shape and allow images to focus properly on
the back surface of the eye. As a result, a child who is farsighted usually does not have blurred
vision. However, in some children who are farsighted, this accommodative effort is associated
with a reflex crossing of the eyes. Hence the term, "accommodative esotropia."
Accommodative esotropia can begin anywhere from 4 months to 6 years of age. The usual
age of onset is between 2 and 3 years of age.
What are the Signs of Accommodative Esotropia?
A noticeable crossing of the eyes is usually the primary sign. This crossing may only be
evident when your child intently views a near object or when your child is tired or not feeling well.
Some children will complain of double vision or may be seen squinting or rubbing one of the eyes.
Four-year old girl with accommodative esotropia. Farsighted glasses
control all of the eye crossing.
Diagnosis and Treatment
The pediatric ophthalmologist will perform all of the necessary tests to confirm that your
child has an accommodative esotropia. This includes an examination with dilating eye drops to
determine the degree of farsightedness and to make sure the eyes are otherwise normal.
Full-time use of the appropriate farsighted glasses will often control the esotropia. When
wearing the glasses, your child will not need to accommodate and hence the associated eye
crossing reflex will disappear. However, after removing the glasses, the crossing will reappear,
perhaps even more than before your child began wearing glasses.
Sometimes the glasses will only cause the crossing to disappear when your child looks in the
distance. However, when gazing at near objects, crossing may persist despite the use of the
glasses. In these circumstances, a bifocal lens is usually prescribed to permit your child to have
straight eyes at all viewing distances .
What about Eye Patches?
It is not uncommon that children with accommodative esotropia will have decreased vision in one
eye (usually the eye that does most or all of the crossing). This is known as amblyopia. If there is a
significant amblyopia present, the pediatric ophthalmologist will prescribe the appropriate eye
patch to be worn over the stronger eye or Atropine eye drops that will blur the stronger eye to
force your child to use and strengthen the eye with amblyopia. The glasses must also be worn
when using the patch or Atropine eye drops.
Can Surgery Correct the Problem?
If the farsighted glasses control the crossing of the eyes, eye muscle surgery is never
recommended! In some children, the glasses will diminish the crossing partially or not at all. Some
children whose esotropia was previously controlled with glasses may "deteriorate" and have a
significant crossing even when wearing the glasses. If a significant crossing is evident despite the
proper glasses, eye muscle surgery is then required to establish good ocular alignment.
Will My Child Outgrow This Problem?
The degree of farsightedness will often increase gradually until age eight years. After age eight
years, the farsightedness typically diminishes each year. Many children will be able to maintain
straight eyes without glasses in their early teen years. Some children will no longer need their
glasses at an earlier age while others will need the proper farsighted glasses or contact lenses to
control the esotropia even as adults. At the appropriate time, our physicians will attempt to wean
your child’s dependency from glasses.
Why is Good Ocular Alignment Important in Childhood?
Aside from the obvious improvement in your child's appearance when misaligned eyes are
corrected, there are other functional benefits to consider.
When a significant ocular misalignment exists in childhood, the brain's developing visual system
does not acquire binocular vision. Aside from improved depth perception, a person with binocular
vision tends to maintain good ocular alignment throughout life. Additionally, a child with good
ocular alignment is at decreased risk for developing amblyopia.
Strabismus Surgery
Eye muscle surgery, or "strabismus surgery", involves either increasing or decreasing the tension
of the small muscles on the surface of the eye. These muscles move the eye in all directions.
The physicians at Pediatric Ophthalmic Consultants are all accomplished strabismus surgeons. We
have a very large strabismus surgical service. We regularly operate upon patients from the New
York Metro Region, other areas of the U.S. and abroad.
Strabismus Surgery
This type of surgery is typically performed in a hospital outpatient surgical facility. During the
surgery the eye is never removed! Rather, a small incision is made on the clear membrane covering
the white part of one or both eyes. Through this incision, the appropriate surgery is then performed
on the surface of the eye to eliminate the strabismus. The inside of the eyeball is not entered during
this type of surgery. Contemporary strabismus surgical techniques involve "hidden" incisions,
leaving virtually no visible scarring of the eye surface as a result of this surgery.
When strabismus surgery is recommended for a child, the earlier in life it is done the better the
chance of the child achieving binocular vision, or "depth perception".
Despite having the appropriate surgery, some patients may require further eye muscle surgery in
the months, years or decades following their initial operation to further refine their ocular
alignment.
Photograph of child in recovery room following strabismus surgery (two hours after surgery). This
child had an esotropia. The tension of the inner muscle of each eye has been relaxed. The ocular
surface redness slowly resolves over the course of two weeks.
Before and after (one year later) strabismus surgery in child with congenital esotropia.
Adjustable Suture Surgery For Adults
As with children, adults who undergo eye muscle surgery can usually achieve precise surgical
results with standard surgery. There are occasions, however, when such precision is not possible
due to the underlying cause of the strabismus, such as scarring from old surgery, inflammation
from eye muscle diseases, or neurological weakness. In these cases, it is sometimes advisable to
adjust the tension of the muscles postoperatively.
In adjustable suture surgery, the surgery is performed under general anesthesia in the typical
fashion except that temporary suture knots are placed. Several hours after awakening from
anesthesia, the eye alignment is evaluated. If it is good, permanent knots are tied. If the eyes are
not adequately aligned, an adjustment in the muscle tension can be performed. These final steps
are completed with the patient awake and the surface of the eye anesthetized with eye drops. When
appropriate, this technique can enhance the surgical outcome.