Strabismus (Eye Turns)
Strabismus is a general term that describes an eye turn. The eye turn can be inward (esotropia), outward (exotropia), or upward (hypertropia). While some eye turns are constant and obvious, others can be intermittent and subtle.
This condition is often present from birth but can develop over time as well. It often occurs as a result of a high uncorrected glasses prescription. Although one eye is turned, patients rarely see double vision. That is because they suppress, or turn off the vision from that eye to the brain. With only one eye functioning, those with strabismus lack depth perception.
- Poor depth perception
- Poor hand-eye coordination
- Head turn or tilt
- Eye strain or headaches after prolonged near work
- May be a poor reader
- Clumsy, bumps into things around the house
Esotropia occurs when one eye fixates on a target, while the other eye points inward towards the nose. This can be very pronounced or subtle and may be constant or intermittent. It also may occur more frequently when looking up close versus far away or vice versa. Esotropia has a high correlation with uncorrected Hyperopia (far-sightedness), although some have no measurable prescription.
Exotropia occurs when on eye fixates on a target while the other eye points outward, towards another point in space. This is usually fairly pronounced, although it can be subtle. Exotropia is more often intermittent, occuring when the patient becomes tired but may be constant. Exotropia is often correlated with high amounts of prescription in one eye but not the other, such as high Myopia (near-sightedness) or Astigmatism.
Treatment of Esotropia
Treating Esotropia always begins with the correct glasses prescription, which often includes a bifocal to aid in eye alignment. Patching for a few hours a day may be recommended at first, but Vision Therapy is the preferred method for treating Esotropia. Vision Therapy for Esotropia involves teaching the turned eye how to point in the same direction as the fixating eye. This is accomplished through activites that give the patient feedback about where their eye is pointing.
Treatment of Exotropia
Treating Exotroia involves first identifying and correcting any refractive error through glasses or contacts. Vision Therapy is then started with the goal of teach binocular vision and improving eye alignment, teaming, and depth perception. This is accomplished by using activities and procedures that give the patient feedback about where their eyes are pointing, teaching them to identify when their eye is turned, and introducing patients to three-dimensional vision by using the latest technology.
Surgical Options in Strabismus
Surgery is commonly recommended as a treatment option for strabismus, but surgery has some major drawbacks.
Most importantly, surgery is cosmetic only. It does not restore binocular vision, which is what gives us depth perception and eyes that work in coordination when reading or tracking objects.
When the brain is only using one eye at a time, visually-guided tasks are still just as difficult after the surgery as before. And since surgery doesn’t address the underlying reason that the eye turned in the first place, the eye often turns again after surgery, requiring multiple surgeries. A recent study published in the American Journal of Ophthalmology (link HERE) found a failure rate of 77% when treating infantile esotropia with surgery.
Vision Therapy is a non-surgical option that can improve binocular vision, depth perception, and other visual skills in addition to cosmetic improvements. That makes Vision Therapy our first line of treatment in strabismus.
Clinical Research on Strabismus
Neurologist Sue Barry’s TEDx Talk about her journey with vision therapy as an adult with strabismus.
AOA Clinical Practice Guidelines: Strabismus (Beginning on Page 30).