The findings may change the way surgeons treat certain cases of the eye alignment problem to prevent the development of amblyopia (or “lazy eye”).

What is accommodative esotropia?

Esotropia is an inward misalignment of one or both eyes to create a “crossed eyes” (or “cross-eyed”) condition.

Accommodative esotropia is a special type of crossed eyes caused by excessive focusing demands (accommodation) required of eyes with uncorrected farsightedness. Because it is caused by a refractive condition, accommodative esotropia sometimes is also called “refractive accommodative esotropia.”

Accommodative esotropia usually can be successfully treated non-surgically with eyeglasses and contact lenses (often with an accompanying program of vision therapy). Other types of esotropia, such as non-refractive congenital esotropia, require strabismus surgery to realign the eyes.

Esotropia differs from a less severe binocular vision problem called esophoria. Whereas a person with esotropia has crossed eyes and essentially monocular (one-eyed) vision, a person with esophoria typically has normal binocular vision and straight eyes, but their eyes have a tendency to drift inward when the eyes are in a totally relaxed, unfocused state (such as during sleep).

A person with mild esophoria generally will have no visual symptoms. However, moderate or severe esophoria may cause headaches, eyestrain and/or intermittent blurred vision, especially during prolonged visual tasks such as reading or computer work.

Why refractive surgery for accommodative esotropia?

Though accommodative esotropia can be corrected with contact lenses or eyeglasses, in some cases a person with the condition may not be able to successfully wear contact lenses or may object to wearing eyeglasses that may have thick lenses to correct hyperopia. In these cases, laser vision correction may be an option.

The purpose of this study was to determine if LASIK and PRK are safe and effective for the treatment of accommodative esotropia among young healthy patients.

LASIK and PRK for accommodative esotropia: Study design

Researchers at the University of Napoli Department of Ophthalmology performed bilateral laser vision correction on a total of 20 patients with fully refractive accommodative esotropia. Seventeen patients (34 eyes) were treated with LASIK and three patients (six eyes) were treated with PRK.

In all cases, the surgical procedures were performed in the tradition manner of using only local anesthesia.

The age of the patients at the time of surgery ranged from 14 to 24 years, with a mean age of 18.8 years.

Visual acuity, eye alignment and stereopsis (depth perception) measurements were taken before and after surgery, with a mean follow-up period of 30.2 months.

Esotropia and esophoria both are measured in units called prism diopters (pd). The mean degrees of accommodative esotropia without corrective lenses prior to surgery among participants in this study were 13.7 pd for distance vision and 18.1 pd for near vision.

Results and conclusions

Following LASIK and PRK surgery, accommodative esotropia was successfully treated in all patients, resulting in binocular vision and proper eye alignment.

Post-operative measurements yielded the following results:

• No patients had esotropia.
• Mean esophoria measurements were 2.5 pd for distance vision and 4.0 pd for near vision.
• Eight patients (40 percent) had no esophoria at distance or near.
• Two patients (10 percent) had esophoria at near only.
• Ten patients (50 percent) had some esophoria at both distance and near.

Thirty-nine of 40 eyes (97.5 percent) had no more than 1.00 diopter (D) of residual refractive error and no eyes lost a significant degree of best-corrected visual acuity compared with pre-operative levels. No PRK or LASIK complications occurred during or after surgery.

The researchers concluded that LASIK and PRK and safe and effective for the treatment of accommodative esotropia among healthy young individuals.

If you are considering refractive eye surgery, such as LASIK, PRK, PresbyLASIK or Epi LASIK eye surgery, conduct thorough research before deciding to go forth with treatment. Explore the other pages of this portal to learn about the benefits and risks of various procedures, and to familiarize yourself with laser eye surgery cost.

SOURCE:  Excimer laser treatment of fully accommodative esotropia safe. EyeWorld. April 2009.