Clinics & Inpatient Care Units

Ophthalmology

Strabismus

Dr. Meg Iizuka

What are the goals of strabismus surgery?

This is a very important question. When the eyes are too far apart, the brain has no way to bring the eyes together. The purpose of the surgery is to bring the eyes to a straighter position such that the brain has a better chance of adapting and moving the eyes closer to centre on its own.

The goal of surgery is to reduce the amount of crossing and/or the frequency of crossing. The crossing, however, may still appear when you’re tired or ill but less often and less severely.  This residual small amount of crossing (inward or outward) is expected and is sometimes technically referred to as a “monofixation” state. Studies have shown that a monofixation state leads to a lasting alignment over time. You will likely not even notice this small amount of crossing after surgery.

To summarize, the surgery can significantly improve your existing eye crossing but rarely, is it completely gone or “cured”. Therefore, the aim of surgery is to improve your existing condition enough so that your eyes seem essentially straight (or with a very small but acceptable deviation) most of the day, with the added benefits of improved appearance and functionality.

For individuals who have double vision, the goal of surgery here, is to alleviate the double vision in the straight ahead position and reading position (down gaze) or to expand the field of single vision. Some double vision in far side gaze or up-gaze may have to be tolerated after surgery, but these fields of gaze are generally less functionally important than straight ahead. Usually, most patients are not bothered by this, or compensate automatically with head movements.

How is eye muscle surgery performed?

In both children and adults, the surgery is usually performed under general anesthesia, although some adults can be done awake. Once asleep, an incision is made over the white part of the eye called the conjunctiva, which covers the muscle. The muscle of interest is separated from the eye and reattached with tiny sutures back to the eye but in a different position.  One or more eye muscles may be operated on. Changing the position of the muscle mechanically changes its ability to pull by either strengthening or relaxing/weakening it. This new position of the eye muscle changes the angle of the eye but still allows the eye to move in all directions.

Note that the eyeball is not removed and there are no lasers used. The sutures dissolve on their own in about six weeks. You may have a patch after surgery, which must be kept in place until it is removed on the day of or the next day after surgery.

We may recommend for some individuals, either on the same day, or the next day after surgery, that the position of the eye muscle be further adjusted while the patient is awake. This is performed with topical anesthetic in a procedure room or in the clinic. This takes about 10 - 30 minutes. Understandably the patient may be anxious during the adjustment, but this is not a painful experience in general and most people discover it’s not as bad as they imagined.

I’ve heard of using Botox instead of eye muscle surgery. Am I candidate for that?

In rarer cases, Botox (botulinum toxin) is injected into the muscle for patients in whom recovery of a muscle is expected. In general, Botox is not a permanent solution, requiring repeat injections; as such, it is used only in very special circumstances.

What are the costs associated with strabismus surgery?

The strabismus surgery and the follow-ups are covered by OHIP. The eye drops are not covered by OHIP unless you are over age 65. Also, in order to achieve the optimal results, be prepared for the following costs after surgery:

  1. Glasses:  Before surgery, a new pair of glasses without prism may be prescribed if your old pair has prisms in them (or you can use an old pair that does not have prism). After surgery you may need to wear glasses even if you don’t currently wear them.  Or you may be prescribed new glasses that have prism in them if you develop double vision. As your eye heals, you may even go through several pairs of new prescriptions up to one year after surgery.  We recognize that this is costly and sometimes we will avoid changing the prescription but instead prescribe Fresnel prisms, a cheaper temporary option. Please be prepared for the potential of these high costs.
  2. Fresnel prisms: these are temporary stick on prisms that are fitted by the optician onto a pair of glasses.  This can cost anywhere between $50 and $100 per prism plus the cost of the glasses if you do not currently own a pair.  You may require multiple changes up to a year after your surgery or none at all.

How successful is eye muscle surgery?

The success rate is 80 to 90 per cent.  About 10 to 20 percent of patients will need more than one surgery within three to six months of the first procedure.  This tends to occur in patients with more complicated surgery (e.g. a patient who has both a vertical and horizontal problem or who has had strabismus operations in the past). In general, when the surgery doesn’t work the first time, we wait a few months to reassess and let the eyes heal to a stable alignment. It is uncommon that we can't correct the alignment in a subsequent operation. About one in 25 patients will need three or more surgeries in the first year after surgery.  You may have double vision while waiting for surgery, which we can alleviate with Fresnel prisms or temporary occlusion with a semi opaque tape placed on the glasses.

So, it is still possible that you may have to come back a couple of months after surgery needing another operation. Over your lifetime, your eye muscles continue to grow and age.  Hence, there is a chance that you may need surgery at any time later in your life. Several patients only need one surgery for life. Often times, this is patient specific depending upon your type of strabismus.

What are the most serious risks of surgery?

  1. Risk of anesthesia: For a healthy individual, anesthetic risks are very small and are comparable or less than the risk of serious injury from a car accident.
  2. Vision loss:  Irreversible vision loss is very rare but may occur. In terms of vision loss, this surgery is safer than LASIK or cataract surgery.

What are some other complications or limitations of surgery?

The main limitation is that surgery might not correct the problem. Despite our best efforts and careful measurements and adjustable sutures, some patients end up needing more surgery. This is because our muscles act like rubber bands that react to surgery in a bell-curve-like distribution.  This means that although most people have average eyes and fit within the normal distribution, others may be over or under corrected after surgery. We cannot predict who these individuals are. Therefore, in some cases, this may mean you develop double vision that you didn't have before, or the double vision that you did have doesn't go away until subsequent surgery. 

Other complications that can occur but are highly unlikely include:

  • Infection deep in the eye leading to permanent loss of vision requiring hospitalization, treatment with antibiotics and removal of infection with surgery.
  • Loss of the muscle (slips or does not stick down to the eye ball) during or immediately after surgery with permanent damage to the control of the movement of the eye
  • Perforation of the eyeball requiring additional laser or cryotherapy or retinal surgery
  • Uncontrolled bleeding and vision loss
  • Persistent scarring of the white part of the eye that doesn’t go away
  • A change in eyelid position that requires surgery to correct.
  • Reaction to the suture material requiring it to be removed.

If any of these complications, you will require more follow up appointments. However, many of them can be managed successfully to a certain degree.

What do I expect to see and feel after surgery?

The eye(s) will be red and weepy after surgery. The eyes will feel scratchy, sore or feel like something is in your eye for the first few days after surgery. This is due to sutures that will gradually soften over time until they are completely absorbed at approximately six weeks. You will also notice slight swelling of your lids, light sensitivity, and mild blurry vision. These symptoms are not so bad that you can't function around the home. Usually the symptoms in the eye that had the adjustable suture are a little worse and lasts a little longer.  All these symptoms should get better in the first few days and not worse.

Do not be alarmed when you experience some double vision immediately after surgery. The double vision may be present all the time, only once in a while or only when looking in certain directions. This is a result of your brain getting use to the new position of your eyes.  The double vision gradually improves over several weeks.  Eye exercises may be prescribed one week after surgery to improve the alignment.

In the mean time, if you have double vision that is interfering with your job or driving, you can put piece of semi clear cellophane tape to the backside of the lens, alternating between the left and right eye every other day.  Try to spend a few hours at the end of each day with the tape removed to train the brain to get used to the new position of the eyes.

Most of the time, any persistent double can be successfully treated with a new pair of glasses with prisms approximately two months after surgery.  Unfortunately, there are no such things as contact lenses with prisms in them. These glasses will feel like an ordinary pair of glasses.  I may use Fresnel prisms first to test this first.  If these prisms are inadequate, you may need a second operation.  This will not be decided for several weeks/months after you heal. Note that some double vision may have to be tolerated in far side, up or down gazes (see goals of strabismus surgery above).

What activities can I do after surgery?

Most adults only need to be off of work for about a week or less. Some patients are back to work in a few days, others may take more than a week if there is double vision or unusual discomfort. The redness can take months to completely resolve, but each day is a little better than the day before.

Avoid swimming/saunas or hot tubs for three weeks after surgery. If you have double vision, cover one eye when you are driving until this resolvesOtherwise, there are no limitations. You can read, watch television and use the eyes as much as you want. You will need to put eye drops in the operated eye(s) four times a day for 10 days after surgery.

Are there any worrisome signs after surgery?

Watch for any warning signs problems that could indicate infection or slipped muscle in the first week to 10 days after surgery such as:

  • Worsening vision
  • Increasing redness, or greenish discharge
  • Increasing pain, especially on movement
  • Inability to move the eye, making the eye appear frozen or stuck (slipped or lost muscle)
  • One eye not healing as well as the other eye in bilateral surgery

Any of these symptoms are a medical emergency. If they develop call my office immediately to be seen that day.  If it is after hours or on a weekend, call locating at St. Michael’s hospital at 416-864-5431 and ask to speak to the resident on call. Or go to your nearest emergency department immediately.

What follow up appointments are necessary? Will I still need glasses?

You are usually seen on the same day or one day after surgery, one week after surgery and one month after surgery.  Thereafter, you will be seen three to six months after surgery for a year, then annually either by the referring physician or an ophthalmologist.

Yes, you will still need your glasses after surgery. You may be prescribed glasses after surgery, even if you didn’t wear them before surgery (see costs question).

One final comment: 

There are many websites in the United States that advocate vision therapy or orthoptic exercises over surgery. The World Wide Web is open to all who have an opinion.  Most of these therapists have good intentions but their methods are often based on anecdotal evidence. In fact, some exercises may worsen your condition and cause double vision. When we think exercises can help, we will offer that, or in some cases prisms, patching, glasses or Botox as we have mentioned earlier. Dr. Iizuka has personally been involved with and treated hundreds of patients with eye muscle surgery, and the large majority are quite satisfied with the results. 

For patients with a surgery date: If you have any concerns or questions, do not hesitate to call the office and ask the informed booking staff. If you wish to speak to Dr. Iizuka directly and you live in the city, please book an appointment before your pre-operative appointment so we can talk in person about any concerns you may have. For those who live out of town or cannot book an appointment with Dr. Iizuka, please let us know how to get in touch with you after hours via phone or Internet.