Strabismus

Strabismus describes any condition of the eyes when they do not work in parallel, and is most commonly associated with an eye muscle weakness. Typically, one eye wanders "off center," as a crossed or wandering eye. It could be present at all times, or only when a child is tired, sick, or trying to focus or concentrate on an object up close.

Strabismus could show up at birth, or develop even up through childhood and into adulthood. Babies typically display a "wandering eye," since the eye muscles are not well coordinated at birth. Within a few weeks, babies normally learn to move the eyes in parallel. After this time, if the condition persists, prompt medical attention is warranted.

With time, the wandering eye sends a blurry or unresolved image to the brain, which is rejected, and eventually, that eye ceases to see. This is a condition called amblyopia, or "lazy eye." It can lead to permanent blindness in the unused eye if not treated promptly. If detected and diagnosed early, the situation is often reversible.

The condition tends to run in families. Some children develop it after birth. Strabismus can sometimes develop as the result of an eye disease. Many times, the symptoms are subtle. In any case, routine examinations should be adhered to by a pediatrician or family doctor; and its never too early for a full exam by an ophthalmologist or other specialist; even infants and toddlers can be tested and treated successfully. Waiting until a child is school-aged is sometimes too late, so the earlier, the better.


Goals of Treatment

There are three basic goals:

1. To preserve vision
2. To straighten the eye
3. To make the eyes work together

Any course of treatment requires adherence; with children, this could be difficult. However, any deferral of eye patches, exercises, glasses, etc. will mean deferring reaching the goals of treatment.


Parallel Eyes

Pairs of eyes behave like a complex stereo-camera, with two lenses to make two pictures, which blend in a process called fusion into a 3-dimensional image in the brain. To do this, the eyes must move precisely; six pairs of muscles outside the eyeball help pull and relax the correct muscle pairs to allow the eyes to move correctly.

If one eye wanders, that eye sends a blurry picture to the brain. The brain will try to fuse the sharp and blurry images together, but the result can be double vision, where two of the same image is seen. Within a short time, the brain ignores the fuzzy image in a process called suppression. The stronger eye takes over all the work of seeing, causing the wandering eye to stop seeing from lack of use. Eventually, unless treatment intervenes, permanent loss of vision is the result.

There is a condition called false strabismus or epicanthus where the epicanthal fold that will later form the sides of the nose, lie flat across the bridge, making the eyes appear crossed. As children grow, this condition will disappear, making it appear as if the child has outgrown strabismus. True strabismus will not go away by itself. In addition to the normal tests, drops may be placed in the eyes to dilate the pupils, so that a ophthalmoscope can be used to check for eye disease. For a child, a few drops will keep the eyes dilated for a few hours or days, but the pupils will return to normal size.


Treating Strabismus

There is not standard course of treatment since every person's vision is different. Ask your doctor if you have any questions. Treatment will consist of a combination of patching, glasses, surgery, eye drops and exercises. All the treatments will take time, and it is important that parents must stay focused on the three goals: preserving the child's vision, straightening the eyes, and to make the eyes work together if possible. The more diligent the treatment, the more likely and sooner the goals will be reached.


Patching for Amblyopia

When a case of strabismus turns into amblyopia, treatment is critical to preserving vision. Patching is a simple and effective treatment. The patch must be worn consistently and regularly; sometimes, part-time use of an eye patch is appropriate. To prevent a child from removing it easily, use the adhesive-backed patch, rather than cloth or eyeglass patches.

The earlier treatment starts, the faster vision can be restored. By the age of 6 or 7, amblyopia is no longer treatable with simple patching.

Parents may need to be inventive, perhaps by wearing a patch themselves for the first few days, or putting gold stars on a calendar for every day the patch is worn, or organizing games around the patch. Ask your doctor for ideas for dealing with an unhappy or angry child, or if the child keeps removing the patch.


Glasses

People sometimes squint to sharpen their view of an object just out of focus. The lens of the eye will automatically adjust the focus for objects of different distances and sizes in a process called accommodation. People with myopia or near-sightedness have eyeballs which are too long, causing the light coming through the pupil to focus in front of the retina. People with astigmatism have irregularly shaped corneas, which does not allow the lens to focus properly on objects at all distances. Strabismus can occur with near-sightedness, astigmatism, or both.

People who are far-sighted have eyeballs that are too short, so the light coming into the pupil tried to focus behind the retina, rather than on it. Closer objects are more blurred. A child's eye can more easily accommodate this, and can sometimes cause the child to become cross-eyed all or some of the time.

By prescribing glasses, the focusing is being done by the glasses, rather than the eye's lens, giving relief to the eye muscles, so that they do not need to accommodate to focus. This is especially true for far-sighted children, whose vision is otherwise sharp. For children with astigmatism or myopia, glasses can help overcome amblyopia and achieve fusion in vision.

Glasses alone can sometimes be enough to solve the problem. Patching or surgery may also be needed, especially in cases of amblyopia. Glasses, since they are not give to far-sighted children to sharpen vision, but to straighten the eyes, must be worn at all times.

As children grow, the eye also grows and changes, and far-sighted children may need weaker glasses, or sometimes they no longer need glasses, by the time they reach adolescence. Children with astigmatism and myopia may still require glasses to help them focus.


Surgery

The muscles of the eyes allow the eye to move by adjusting tension; for example, to see an object to the left, the muscles on the left are tensed, and the ones on the right are relaxed. A combination of tensing and relaxing muscles allow sight in a large range of directions. In some cases, a muscle is too far forward on the eyeball, causing the eye to pull more strongly in that direction. Moving the muscle back to weaken it (recession), or removing a section of the muscle to shorten and strengthen it (resection), can even-out the muscle strength.

However, if the surgery is performed on an older child or adult, the eyes will appear straight, but fusion may not be achievable. Talk to your doctor before electing this surgery.


The Hospital Experience

Children are normally admitted the night before the scheduled surgery. Ask the hospital, doctor or head nurse if parents may stay overnight in the same room, if desired. Some blood and urine tests are performed, and the ophthalmologist and anesthesiologist will visit, to answer any questions.

On the day of surgery, medications and anesthetics will be given, and the anesthesiologist will make sure the child is fully and safely asleep during the whole operation. After surgery, trained pediatrics recovery nurses will be on hand to monitor the child until they awaken. At this point, the child is taken back to the hospital room. There may be some nausea from the anesthetic, but otherwise, there should be little, if any, pain in the eyes. One or both eyes are covered by a surgical patch for a time.

Your child may be able to go home that day, or the doctor may want them to keep them overnight for observation. When the child returns home, be sure to follow all specific instructions, such as eyedrops or ointment application, eye patch adhesion, follow-up appointments, when a normal routine can be followed again, etc. The adjusted muscles will be red, but this should go away in about two weeks. The child can follow his or her normal routine in about two days.


Follow-up Treatment

One surgery is often enough to correct strabismus, but it is always possible that a second, or more, surgeries are needed. Remember that surgery is supposed to correct only what other non-surgical treatments cannot. Over-correcting, or too much surgery could be detrimental to the child as they grow.

Though the eyes may now appear straight, it is important to remember that for the child, this is a "new" pair of eyes, and they will need to learn how to see through them. They will need help under supervision of an eyecare professional to use their eyes correctly.

Follow-up treatments with glasses, patching or eye exercises (orthoptics) are likely needed to deal with amblyopia and to help the eyes move together and achieve fusion. If these treatments were needed before surgery, they are likely needed after. Speak to an orthoptist or your eye doctor.

For the sake of a child's site, it is necessary to be diligent, and to follow instructions carefully and precisely.