Strabismus is a condition in which the eyes are not aligned correctly. While one eye looks at the target, the other eye is looking in a different direction. Esotropia is a type of strabismus where the straying eye is crossed inwards. Exotropia is another type of strabismus where the straying eye is drifting outwards. Hypertropia describes a straying eye which looking upwards or downwards instead of at the target.
Strabismus surgery seeks to readjust the alignment of the eyes. The goals of surgery include:
- Enabling the brain to use the eyes together
- Cosmetically improving eye position and movement
There are six muscles responsible for moving each eye. During surgery, these muscles can be weakened or tightened. By adjusting the muscles, the surgeon aligns the eyes. The patient’s brain must then learn to use the eyes together. The success of the surgery depends on how difficult it is to re-align the eyes and how well the patient’s brain adjusts to using the eyes together.
The pre-operative evaluation is a very important part of strabismus surgery. During the pre-operative evaluation, Dr. Goldberg will measure the misalignment of the eyes in different gaze positions. The patient’s ability to move the eyes will be evaluated. Dr. Goldberg will consider optical and visual factors which might influence the results of surgery. In almost all cases, Dr. Goldberg will measure the mis-alignment on at least two separate occasions before surgery. If your child is very young or difficult to examine, it may take several visits until accurate and stable measurements can be obtained.
In some patients, their strabismus is incomitant. Incomitant means that the amount of misalignment varies on up, down, or side gaze. Surgery is planned to achieve alignment in all gaze positions. However, it is most important to have the eyes aligned when looking straight ahead. In some cases, there will still be some mis-alignment on side gaze even after surgery. In children, there may still be some drifting of the eyes when your child looks up or to the side. Adults may still have double vision when looking to the side or down.
During strabismus surgery, the muscles which move the eyeball can be weakened or strengthened. The position of the muscles can also be moved. To weaken the muscle, a suture is placed in the muscle. The muscle is then removed from the eyeball and reattached farther back. To strengthen the muscle, the muscle is shortened to increase its ability to pull the eye.
The eyes always move together. While it appears that either the right or left eye is misaligned, the problem is actually the balance between the eyes. Therefore, surgery can be performed on either one eye or both eyes in order to balance and straighten the eyes. Strabismus surgery is performed as an outpatient, usually under general anesthesia. During the surgery, incisions are made in the conjunctiva. The conjunctiva is the thin covering over the eye. In children, the incisions are usually made in the pocket between the eyelid and eyeball to hide the scars.
In older patients and patients with previous surgeries the incisions may be made where the iris touches the white part (the limbus). In most cases the scar is not visible. After the surgery, the white of the eye will be very red in the area of the incision. This is a blood spot. The blood spot will dissolve in about two weeks. However, the white of the eye may stay inflamed and red for several more weeks. In some cases, particularly if there is scarring from a previous surgery, the area may always stay a little red. If surgery is performed in both eyes, then both eyes will not be patched.
- Continued misalignment– Overcorrections and undercorrections are by far the most common complications of strabismus surgery. After surgery for esotropia (cross-eyes) the eyes will initially appear a little turned out. This will usually resolve. However, the eyes may become significantly turned out either soon after surgery or many years later.After surgery for exotropia, the eyes may cross inwards causing double vision. More commonly, the eyes are straight for months or years but eventually drift outwards again. Overcorrections and undercorrections may require treatment with glasses, prisms, or patching. Further strabismus surgery may be needed in many cases.
- Infection – The eyes will look red in the area of the incision. If an infection develops the entire white of the eye may look red. There may be pus and the eyelids may become red or swollen. Children may develop fever or become sleepy. Infections usually can be treated with eye drops, oral antibiotics, or intravenous antibiotics. Rarely a serious infection can occur inside the eyeball. This would cause decreased vision and pain. To prevent infection, please do not have the patient play in a playground or work in the yard, or in any dirty environment. You may shower, bathe, or wash your hair the day after surgery.
- Loss of vision – Loss of vision may occur if an infection occurs inside the eyeball. In addition, the needles used in surgery may damage the retina, the film inside the eye. If the retina is damaged, laser or freezing treatment may be needed.
Not every condition is listed. Consult Dr. Goldberg if you have any questions about a condition not described here.