Strabismus surgery is both safe and effective in adults, despite widespread misconceptions to the contrary. “Many adult patients defer strabismus surgery for years, even though they are very bothered by the problem,” said David K. Coats, MD, associate professor of ophthalmology and pediatrics at Baylor College of Medicine in Houston.
“Patients often have double vision and have been wearing patches, but doctors have told them that strabismus surgery does not work in adults,” said Sean P. Donahue, MD, PhD, associate professor of ophthalmology at Vanderbilt University. “The data just don’t support [those claims]. The majority of these adults can have their strabismus safely improved by surgery.”
Risks and Benefits
Adults might choose to have strabismus surgery because they have double vision or other symptoms—or simply because they do not like the appearance of their misaligned eyes, Dr. Coats explained. “Patients may have driving difficulties, headaches, eye strain, excessive sleepiness, reading aversion and so forth. Often, they do not even realize that such problems are related to their strabismus.”
Risks. Serious complications during and after adult strabismus surgery are uncommon. Nonetheless, the surgery has the following long-term risks:
- postoperative acquired diplopia,
- loss of binocular fusion and
- the need for unplanned re-operation. Perioperative risks related to deep scleral suture passes also may occur, in addition to lost or slipped muscles, infection and anterior segment ischemia.1
|In some cases of adult strabismus, as with sixth nerve palsies (shown here), surgery and Botox may be used together.
“Diplopia is not a common problem postoperatively,” said Monte D. Mills, MD, assistant professor of ophthalmology at the University of Pennsylvania. He noted that “long-term over- or undercorrection is probably the biggest risk, but the increasing use of adjustable sutures may help to minimize this.”
Benefits. On the other hand, the benefits of strabismus surgery in adults include:
- improved ocular alignment,
- reduction or elimination of diplopia,
- restored sensory binocular fusion,
- expansion of binocular visual field,
- improvement of an abnormal head position and
- improved social skills and self-image.
While there are no population-based studies on adult strabismus, estimates range as high as 4 percent of all adults, according to Dr. Coats. “The condition is about as common in adults as in children.”
Adults with strabismus fall into two groups:
- Those who had childhood strabismus before they reached visual maturity. These adults may not have received appropriate treatment or correction when they were young. Alternatively, they may have received correction as children, but their strabismus recurred, Dr. Mills explained. “With surgery, these patients typically have expansion of their peripheral vision, and they may achieve improvement in their binocular vision. There is very little risk of postoperative diplopia,” Dr. Donahue said.
- Those who develop strabismus as adults. Strabismus that occurs after visual maturity usually is caused by trauma, stroke, cranial nerve palsies, thyroid disease or eye surgery for other problems. For small-angle, acquired strabismus that is associated with double vision and is reasonably comitant, Dr. Donahue noted that a prism is a simple, cost-effective way to manage the strabismus without surgery or any significant risk. In patients with large-angle, acquired strabismus that is associated with double vision and is incomitant, prisms alone rarely are a satisfactory solution. “With surgery, we can typically eliminate or at least reduce double vision, or decrease the degree of misalignment enough so that a prism can be used effectively,” Dr. Donahue said.
Comparing outcomes. In patients with untreated or recurrent childhood strabismus, outcomes are similar to those seen in children undergoing strabismus surgery, Dr. Coats said.
“Patients who develop strabismus for the first time as adults and who experience double vision, tend to do better, on average, than the former group. Once alignment and binocular vision are restored, such patients tend to stay aligned. More often than not, double vision can be reduced or eliminated,” Dr. Coats said.
Evaluation. “Strabismus surgery starts in the office, where we carefully assess the patient’s alignment and eye movements and develop a surgical plan,” Dr. Coats said.
During the preoperative evaluation, you can stimulate the effect of strabismus surgery with prism sensory evaluation. “This might show who is at higher risk for postoperative double vision or other complications,” Dr. Mills said.
Basic approach. Treatment techniques are similar to those used in children: The muscle or muscles are exposed, then either weakened or strengthened as needed to produce the new ocular alignment and function, Dr. Coats explained.
Certain situations may require other, more complex, operations, such as muscle transposition and posterior fixation sutures.
Adjustable sutures. The experts agree that using adjustable sutures during surgery helps reduce the risk of under- or overcorrection in adults.
Adjustable sutures have been used for decades, Dr. Mills pointed out, but the technique is gaining acceptance as a good approach to adults with complicated strabismus.
The patient is evaluated postoperatively, when he is awake and alert. If there is too much or too little correction, the suture knots can be adjusted at that time. “You get a chance to fine-tune the results without re-operating,” Dr. Mills explained.
Anesthesia. Unlike children, many adults can undergo surgery with local or regional anesthesia, the experts noted.
“I operate on most adult patients using topical anesthesia,” Dr. Coats said.
What About Botox?
In the hands of most surgeons, incisional surgery produces results that are more predictable and more permanent than are those seen with the use of botulinum toxin A. But Botox does have a role in managing strabismus, Dr. Mills said. “Botox may be useful when you anticipate changes over time, so you don’t want to do something permanent, or if the person is too reluctant or not healthy enough to go through with incisional surgery and anesthesia,” he explained.
Dr. Mills pointed out that in some cases, such as with sixth cranial nerve palsies, surgery and Botox are often used together to reduce postoperative risks and to produce a better result. “We use Botox to relax one of the muscles and to keep it from contracting for the first few weeks after surgery. When the Botox wears off, everything is healed,” he explained.
In a complicated strabismus surgery, you might inject some Botox into a very tight muscle (vs. taking the muscle off) to relieve the restriction, Dr. Donahue added. This may allow the eyes to straighten and stay straight after the surgery.
Using Botox as an adjunct in complicated strabismus surgery also limits the need to manipulate multiple muscles and decreases the risk of anterior segment ischemia, he said.
Dr. Donahue does not typically offer to inject Botox for unilateral sixth nerve palsies, “because they tend to do so well without anything, and most get better on their own.”
He does offer Botox to patients whose bilateral sixth nerve palsies are the result of trauma. “It allows them better eye movement and potentially decreases double vision during the healing period,” he said.
Getting the Word Out
“Strabismus surgery in adults is not simply cosmetic. It is reconstructive, and it has marked functional benefits, including the restoration of normal alignment and binocularity and the expansion of peripheral visual fields,” Dr. Donahue said.
The challenge is to get this information back to physicians and insurance companies, the experts agreed. Their take-home message? Strabismus treatment is not just for children.
1 Mills, M. D. et al. Ophthalmology 2004; 111:1255–1262.
Drs. Coats, Donahue and Mills have no related financial interests.