Eye doctors dislike the term “lazy eye” for lots of reasons. It makes kids feel awkward. It’s inaccurate: The eye does what the brain tells it to do, even when sent incorrect signals. And it’s a loose term for many conditions: eyes crossing inward (esotropia), wandering outward (exotropia), deviating upward or downward (hypertropia or hypotropia), or combinations of the four. Strabismus surgery can correct all of these conditions. Also, some use “lazy eye” to describe a condition when the vision in one or both eyes hasn’t developed properly.
“Lazy Eye” Problems: Strabismus and Amblyopia
Vision develops in children to about age 8. If vision in one or both eyes is blurry, it won’t develop properly. The word “strabismus” comes from the Greek strabismos, meaning “to squint.” (A patient who gets double vision from a misaligned eye can temporarily avoid it by shutting that eye.) Amblyopia is a condition where one or both eyes never develop good vision. It can be caused by strabismus but also happens if a child needs glasses at a young age and doesn’t get them.
Doctors first address the problem with a dilated eye examination, the only way to determine if a child needs glasses. A child with a lot of farsightedness may suffer from esotropia, with eyes crossing inward at distance, near, or both. Prescription glasses may not only clear up vision but sometimes the esotropia too. The same thing is true of eyes wandering outward related to underlying nearsightedness: Giving the child glasses may clear up vision and control the exotropia.
Children who develop amblyopia because of misaligned eyes won’t experience double vision. However, their brains will suppress the vision from one eye. If that happens, vision development gets delayed significantly, Amblyopia. The eye that sees better may have to be patched, usually starting at two hours per day, until the vision equalizes.
Strabismus Surgery for “Lazy Eye”
Extraocular muscles on each eye make our eyes move in, out, up, down, even rotationally. They’re attached to both sides of the eye, on top and below. And two small muscles wrap around the eye and attach obliquely above and below. We don’t see the muscles when we look at people, because a white blanket of tissue covers them.
The surgeon cuts through that blanket of tissue to identify muscles to be operated on, engaging them with small hooks. Extraocular muscles can be moved back to weaken them (a recession procedure) or shortened to give them a stronger effect (a resection procedure).
Recessions involve putting sutures where the muscle inserts on the eye. The muscle is then cut at its insertion and reattached to the eye further back. This weakens its ability to pull the eye.
Resections involve cutting out a certain segment of muscle, then suturing the remaining part back to its usual insertion point. The shortened muscle now exerts a stronger pull on the eye.
Doctors occasionally do other procedures with extraocular muscles, such as moving them over when a paralytic muscle gets weak. If the two small oblique muscles start over- or under-performing, operations can adjust them, too.
Risks and Benefits of Strabismus Surgery
Before operating, an ophthalmologist thoroughly examines eye movement and misalignment, looks for other vision abnormalities and does a post-dilation refraction to make sure no refractive error contributes to the misalignment.
Because surgery on extraocular muscles takes place outside the eye itself, loss of vision is extremely unlikely. On rare occasions, when eye muscles are sutured back in place, they become loose or come off; if so, surgery can retrieve the lost muscle. About 80 percent of patients get the proper result with one operation, though some require more surgery to achieve the desired alignment.
The benefits include improved appearance - both eyes look straight ahead when interacting with others, elimination of suppression by the brain (which can lead to amblyopia), treatment for double vision, better use of peripheral vision and potential improvement of higher-level visual functions, such as depth perception.
The Ins and Outs of Strabismus Surgery
The procedure takes 45 to 90 minutes, depending on the number of muscles involved. Some surgeons prefer to apply moderate sedation. Most use general anesthesia, especially with children. Patients go home the same day.
Adjustable sutures became popular in the 1990s, when doctors would reattach the muscle to the eye with a “half-knot” that allowed post-operative adjustment, if eyes remained misaligned. However, that second procedure could be uncomfortable for the patient and involve an extra charge, and a muscle could inadvertently slip back. Most pediatric ophthalmologists now generally tie the muscle down firmly in place during the primary surgery.
After the surgery, patients usually use an antibiotic/steroid combination eye drop or ointment three times a day for a week. Most resume their regular lives in three days but can’t go swimming for a week. The absorbable stitches dissolve during that time, so they don’t need to be removed by a doctor.
To schedule a consultation at Horizon Eye Care, call 704-365-0555 Monday-Thursday, 8 a.m. to 5 p.m., or Friday, 8 a.m. to 3 p.m.