Strabismus, commonly referred to as “crossed eyes,” is a condition in which the eyes are misaligned and point in different directions at the same time. While strabismus is a common pediatric eye condition, it can also present itself in adults.
To help you better understand strabismus, we spoke with Andrew T. Melson, MD, an ophthalmologist and assistant professor at the Dean McGee Eye Institute (DMEI)/University of Oklahoma Department of Ophthalmology, to answer common questions about the causes and surgical treatments available for people with crossed eyes. Dr. Melson specializes in adult strabismus treatment along with neuro-ophthalmology, comprehensive ophthalmology, and cataracts.
Strabismus vs. Lazy Eye: What’s the Difference?
It is easy for people to get crossed eyes (strabismus) and lazy eye (amblyopia) confused.
As Dr. Melson explains, strabismus is a specific term that refers to misalignment of the eyes and is typically due to abnormal control of one or both eyes together. Conversely, “lazy eye” can refer to a misaligned eye in patients with strabismus, or it is often used to refer to an eye that doesn’t see as well as the other since youth. Often, the “weak” or “lazy” eye loses vision due to amblyopia, a condition that reduces vision due to abnormal visual development in childhood.
When left untreated in childhood, strabismus can lead to amblyopia (lazy eye) in which the brain ignores visual signals from the turned eye, with long-term consequences for overall vision.
In other words, lazy eye can be a complication of crossed eyes. Children can also develop a lazy eye from an uncorrected refractive error, such as nearsightedness, farsightedness, or astigmatism. Other causes include cataracts or ptosis (drooping eyelid).
Causes of Strabismus in Adults
Research shows about 4% of adults will be diagnosed with adult-onset strabismus at some point in their life, according to Dr. Melson. However, that number is likely higher because many adults with this eye complication do not seek treatment.
Your eye has six muscles that control eye movement up and down, left to right, and at an angle. The brain controls these muscles and, in most adults, these muscles work in unison to produce single vision with good depth perception.
Strabismus occurs when there is an abnormality in the eye muscles or nerves associated with eye movement or in their connection to the brain. While it is not always possible to identify the origin of strabismus, there are several common causes of strabismus in adults.
“One large group of patients are those who sustain a neurological injury that damages the cranial nerves responsible for eye movements,” Dr. Melson says. “Some of the other common causes include thyroid eye disease, age-related changes to your eyes’ ability to converge on a near target, or decompensating ability to control long-standing eye misalignment.”
Once affected, adults typically have double vision (diplopia) and can see two different images superimposed onto each other.
“The simultaneous perception of two distinct images is often highly bothersome and can interfere heavily with activities of daily living such as driving and reading,” Dr. Melson says. “The associated loss of normal depth perception can lead to falls and motor vehicle collisions.”
Strabismus Surgery in Adults
Adults with strabismus may think there are not any options to treat their condition. However, this is a common misconception.
How to Fix Strabismus
Strabismus surgery can restore eye alignment and reduce or eliminate double vision. In this surgery, the muscles which turn the eyes are selectively weakened or strengthened depending on each patient’s individual needs.
“This is typically performed under general anesthesia and involves physically moving the muscles that attach to the sides of the eye,” Dr. Melson says. “Patients should be aware this is considered restorative surgery, not cosmetic surgery, and that it is routinely covered by medical insurance. Many adult patients are unaware that surgery is an option to help realign their eyes and may go years without pursuing surgical management.”
The surgery involves small incisions on the “whites” of the eyes, which are closed with absorbable sutures. The eye remains in the eye socket during surgery and no skin incisions are made.
Dr. Melson says most patients experience moderate itching and irritation for the first few weeks after surgery and are able to return to normal activities within days of surgery. Over-the-counter analgesics, such as acetaminophen, aspirin, ibuprofen, and naproxen, can help relieve pain. Narcotic pain medications are not typically needed. You may also experience eye redness in the first month after surgery, although that improves over time. Visible scarring is rare once your eye is fully healed.
Is Strabismus Surgery Worth It?
Many patients struggle with their self-image and confidence when their eyes are visibly misaligned. Studies have shown strabismus can negatively influence how others perceive the intelligence of someone with strabismus and can affect employability.
“One of the most rewarding aspects of what I do is getting to see the drastic change in confidence and overall happiness in my adult strabismus patients after surgery,” Dr. Melson says.
According to Dr. Melson, strabismus surgery is successful for a majority of patients and they are happy with the outcome.
“The exact likelihood of success for each individual varies based on the specific cause and degree of misalignment, with every surgery carrying some risk of under- or over-correction,” he says. “In these circumstances, residual strabismus can often be managed with prism glasses or further strabismus surgery. Some patients require multiple surgeries over time to achieve their best results.”
What Happens if Strabismus Goes Untreated?
In children, failing to correct strabismus can result in vision loss. However, this does not happen often in adults who have crossed eyes.
“The underlying cause of adult-onset strabismus has a higher likelihood of being associated with other neurologic or medical conditions which may require further evaluation and treatment to reduce potential medical harm,” Dr. Melson says. “In many cases of adult-onset strabismus, patients will find creative ways to avoid double vision through patching, abnormal head positioning, or avoidance of certain activities. In many of these cases, improved visual function is possible with surgical or prism management.”