If you see that your child’s eye has become crossed, or he or she complains of having double vision, you may be struggling to find clear answers about what caused this to happen and the best way to get your child’s eyes working together again.
When the sudden onset of an inward-turning crossed eye doesn’t respond to glasses and isn’t associated with other systemic or structural disease, it’s known as acute comitant esotropia. This condition is quite rare and usually requires prompt surgical intervention.
Until recently, the only treatment for acute comitant esotropia has been traditional strabismus (misaligned eye) surgery.
But more recently, injection of medical-grade botulinum toxin (Botox) has been used to correct esotropia.
So, how do you know if Botox injection is appropriate for correcting your child’s esotropia? Dr. David Hunter, Ophthalmologist-in-Chief at Boston Children’s Hospital, answers questions about the differences between strabismus surgery and Botox injection.
How soon can each procedure be performed?
When a child’s eye suddenly becomes crossed, time is of the essence. Without fast correction, a child is more likely to have permanent reduction of stereopsis (depth perception) and an increased risk of amblyopia (lazy eye). Lazy eye, aside from the obvious cosmetic impact, can eventually lead to vision loss.
Even knowing these risks, many surgeons prefer to wait for three to six months before performing traditional strabismus surgery. The waiting period enables them to see if the esotropia will spontaneously improve itself. That’s preferable — although rare to actually occur — because strabismus surgery permanently alters the position of the muscle relative to the eye.
On the other hand, Botox injection does not disturb the anatomy of the eye muscle. Therefore, surgeons familiar with using Botox to treat a crossed eye will rarely hesitate to perform the procedure.
What are typical outcomes of each procedure?
Both treatment options target the affected eye’s medial rectus muscle, which controls inward-turning movement and position.
In traditional strabismus surgery, the surgeon separates the affected muscle from the eye and sutures it to a new location, which decreases tension on the eye and reduces the deviated gaze. Inevitably, some scarring and bleeding occurs. However, there is immediate improvement in eye alignment.
With Botox, the medical-grade toxin is injected into the eye muscle, weakening it. There can be some soreness for a day or two after the injection. It usually takes about a week to see the benefit (although some patients have regained proper alignment by the next day). Peak results typically appear within two weeks.
Although Botox’s muscle-weakening effect gradually wears off within three months, the temporarily-relaxed medial rectus muscle allows the lateral rectus (outward pulling) muscle to strengthen itself. At the same time, the brain has a chance to regain control of binocular vision and eye alignment.
As a result, the corrected alignment from Botox can remain indefinitely. Botox injection is considered at least as effective as traditional strabismus surgery, according to ten years of retrospective data analysis — by Hunter and his surgical team — in a recent study from the American Journal of Ophthalmology.
How do the potential side effects compare?
With strabismus surgery, aside from inherent scarring and bleeding previously mentioned, there also are some small risks of having infection, a slipped muscle or more severe scarring. The procedure usually requires at least an hour under general anesthesia and a day or two of rest and recovery.
Botox injection has two potential side effects: (ptosis) droopy eyelids and (exotropia) outward-turning eyes, which can result from overcorrection. These effects usually wear off completely after a few weeks. There have also been rare reports of prolonged pupil dilation following injection. Botox injection only takes about five minutes under general anesthesia, and the child can go home after less than an hour of recovery.
Does either treatment option require a follow-up procedure?
According to the data analysis in Hunter’s recent study, the two types of treatment do not see significantly different patient outcomes at six or 18 months post-procedure.
In both groups, re-operation or repeat injection is necessary in about 20 percent of cases. Sometimes if the Botox fails, surgery is recommended, or vice versa.
Will Botox work in all patients with a crossed eye?
“Some children aren’t likely to respond well to Botox, in which case I will confidently recommend standard surgery,” says Hunter. “And in other cases, such as babies with infantile esotropia who were referred to my care too late to prevent the eye from becoming severely crossed, I combine Botox injections with standard surgery to best restore proper eye alignment.”
Hunter stresses that each child’s case is nuanced and requires the expertise of an ophthalmologist who has extensive experience working with children.
Learn more about Ophthalmology at Boston Children’s.