Wednesday, January 23, 2013

Non-surgical treatment alternatives to strabismus surgery - the risk of a single childhood exposure to anesthesia

The risks of strabismus surgery and exposure to anesthesia during surgery

We previously wrote about the new scientific evidence that repeat exposure to anesthesia at a young age is associated with the development of learning disabilities and ADHD later on in life.  As eye doctors, we care about this because strabismus (cross eyes, eye turn, esotropia, exotropia) is often treated in very young children with surgery using general anesthesia.  The safety of exposing children to anesthesia has been questioned in light of the recent research.  And with strabismus surgery there is a very high risk of repeat surgeries being performed on the same patient (click here to learn about all the risks of strabismus surgery) which means more potentially harmful anesthesia exposure.

The risks of surgery pose a problem because vision therapy is a safe and effective non-surgical treatment for most types of strabismus, which makes most people think twice about surgery as a first choice treatment.

A famous case of vision therapy treatment for strabismus was the subject of the book Fixing My Gaze, an inspirational book by neuroscientist, Susan Barry, who was born with strabismus and had lived all her life without stereo vision, meaning that she could not see in three dimensions.

Even a single exposure to anesthesia during surgery is associated with developmental problems in children: new study

There is now new evidence that even a single exposure to anesthesia can be dangerous for a child.  A study published in December 2012 in the journal Evidence Based Medicine  found that children exposed to anaesthesia for surgery under 3 years of age were found to be at significantly increased risk for developing disabilities in receptive language, expressive language, total language and abstract reasoning at age 10.

The study authors commented that:

This study was the first to report the effects of anaesthetic exposure early in life on neuropsychological outcome using individually administered neurocognitive tests. Perhaps due to the greater sensitivity of these tests, Ing and colleagues observed disability even following a single exposure in early childhood, while several previous reports, utilising group-administered tests, had only detected learning abnormalities following multiple exposures.

This is the latest of 250 studies that have linked anesthesia exposure at a young age to brain development disorders.  The previous studies found a link between anesthesia and learning disabilities in children who had two more more exposures to anesthesia, while the new study found a link in children with just one exposure.  In the study's own words:

Thus far, more than 250 studies in immature animals have demonstrated that exposure to commonly used anaesthetics produces neuronal cell death, alters brain development and may lead to neurocognitive impairment. Similarly, in humans, an association between learning disabilities and two or more anaesthetic exposures has been observed in some studies, as most recently reported in children under 2 years of age.
According to Cyber-Sight, a program of ORBIS International, a non-profit organization that prevents and treats blindness by providing quality eye care, "most immature patients (younger than mid-teens) require general anesthesia for extraocular muscle surgery." Click here to read more about anesthesia use in strabismus surgery.

Repeat strabismus surgeries are common

Children who have strabismus surgery are risk of repeat surgeries, all of which carry the same risk. Eye surgeons often lament the need for repeat eye surgeries for strabismus patients. Surgeon, John W. Simon, notes that "patients must regularly contend with the unfortunate reality that even the most accurately planned and carefully executed surgery may not totally eliminate the deviation [i.e. the misalignment of the eyes] or completely normalize rotations. In addition, strabismus tends to recur over time." This limitation of surgery often results in the the patient being subjected to repeated surgeries - all of which may be unsuccessful. It is not uncommon for a patient to have had two or three or more surgeries and still have a noticeable misalignment or poor binocular vision together with depth perception problems or all three. For this reason, the surgeon's view is that "strabismus is less a problem to be cured than a problem to be controlled, with the minimum number of surgeries": Simon, John W. Complications of Strabismus Surgery. Current Opinion in Ophthalmology. 2010. 21: 361-366.

One study found that only 45% of children had successful alignment of the eyes at an eight-year follow up to their strabismus surgery. And while the low percentage was disappointing enough, 20% of the children had to undergo repeat strabismus surgeries which were ultimately unsuccessful: Awadein A, Sharma M, Bazemore MG, et al. Adjustable suture strabismus surgery in infants and children. J AAPOS 2008; 12:585–590.

Parents need to get the right information and ask the right questions

Parents of children with strabismus need to carefully evaluate the available treatment options.  They should see a developmental optometrist like Dr. M.K. Randhawa  to talk about whether vision therapy is effective for the type of strabismus that the child has.   Parents contemplating surgery need to ask their surgeons about the risk of anesthesia exposure during surgery as well as all the other risks of strabismus surgery (ranging from death - a mortality rate of 1.1 per 10,000 cases is reported - scars, repeat surgeries, infections, lost muscles, vision loss, lack of depth perception). 

Parents should consider vision therapy if their developmental optometrist thinks that vision therapy is appropriate for the type of strabismus that the child has. At our clinic, we have successfully treated dozens of strabismus patients, achieving straight eyes as well as functional binocular vision and depth perception and other developmental optometrists likely have similar results. 

Here is a TED talk on vision therapy by neuroscientist, Dr. Susan Barry, author of Fixing my Gaze: