Esophoria

What is esophoria?

Esophoria is when covering one of your eyes makes it misalign and turn toward your nose. It’s a type of phoria, which is an eye misalignment that happens to an eye when you cover it. Larger phorias, including esophoria, are symptoms that fall under strabismus.

Nearly everyone has at least some amount of phoria, but it’s usually so small that you never notice it. Even when phorias are larger, they’re often much harder to detect because they only happen with one eye covered.

But if phorias get large enough, they can start causing unpleasant symptoms or worsen into misalignments that happen without covering an eye. And how much phoria a person can tolerate varies. A misalignment that doesn’t bother one person could be deeply unpleasant for another.

Why eye alignment matters

Your eye alignment is an important part of vision. When your eyes line up, your brain can “fuse” the input from both eyes into the single big-picture 3D view that you see. That’s called binocular vision (stereopsis).

When you have significant esophoria, your brain may struggle to fuse the two pictures. That can cause other, more disruptive symptoms like:

• Double vision (diplopia).
• Eye pain.
• Eye strain.
• Headaches.
• Dizziness or vertigo.

Horizontal (side-to-side) misalignments like esophoria and exophoria are more common than vertical (up-and-down) misalignments. Twisting misalignments (where your eyes rotate more diagonally than vertically or horizontally) are possible but uncommon.

What are the most common causes of esophoria?

Your brain uses what each eye sees to make subtle adjustments to align and focus them when you’re using both at the same time. So, when you cover one eye, that eye can’t use the same reference points as the uncovered eye. Without reference points, it drifts out of alignment. Small degrees of phoria like this are normal.

Esophoria can also be more likely to develop depending on a few factors, including:

• Your anatomy. People commonly have esophoria when they’re born or develop it during early childhood. Your head and face anatomy play a role in this. If your face isn’t symmetrical and your eyes aren’t the same distance from the center of your face, esophoria may be more likely to happen. It can also happen if you have weakness in muscles that control how your eyes move.
• Your eyesight. Having farsightedness (hyperopia) makes esophoria more likely to happen.
• How you use your eyes. Frequently relying on just one eye at a time for certain tasks can make you more prone to esophoria. Some examples of why you might use just one eye frequently include using a microscope or telescope, a transit level (a special scope that engineers or surveyors use), a magnifying glass or a jeweler’s loupe.
• Medical conditions. While it isn’t common, esophoria can happen with certain brain conditions like stroke. But they’re more common with concussions and traumatic brain injuries (TBIs).
• Sex. Some research studies show that women and people assigned female at birth (AFAB) are more likely to have esophoria. But more research is necessary to confirm if and why this is the case.

How is esophoria treated?

Like most phorias, esophoria usually doesn’t need treatment unless it is severe enough to cause other symptoms. Esophoria may also need treatment if it worsens over time and creates a risk for other eye alignment issues.

Some of the most common treatment options include:

• Vision correction. Prescription glasses or contact lenses may be enough to correct the esophoria.
• Vision therapy. This treatment helps strengthen your eye muscles the same way physical therapy helps strengthen muscles in your arms, legs and core. Specially trained vision therapists can guide you through specific eye exercises to help strengthen muscles that will keep your esophoria from worsening or even reverse its progress.
• Prism lenses. These can come as attachments for the lenses on your eyeglasses, or your eyeglass lenses can have prisms built in. Prisms bend and shift light as it travels through them on the way to your eye. That shift can make it easier for your eyes to align and keep esophoria from getting worse.
• OnabotulinumtoxinA (Botox®). This medication blocks nerve signals that control muscles. In small amounts, this medication can weaken muscles that control eye movement just enough to compensate for esophoria.
• Surgery. Certain procedures can intentionally weaken some of the muscles that rotate your eyes inward, reducing or eliminating esophoria. This isn’t reversible, so it’s usually a last option when other treatments aren’t effective.

What can I do at home to treat esophoria?

Esophoria isn’t something you can self-diagnose. It takes a trained eye care specialist to diagnose it. Because of that, you shouldn’t try to self-treat it. If you think you have it, an eye care specialist can diagnose you and guide you on how to manage esophoria.

What are the possible complications or risks of not treating it?

A small amount of esophoria is normal, and it usually doesn’t become an issue unless it’s more severe. When it’s more severe, there’s a risk it can also worsen over time. That’s known as “decompensated esotropia.” And if esophoria decompensates far enough, the misalignment can start happening without covering an eye. That’s known as esotropia, and it has the potential to be even more disruptive because it can happen frequently or even constantly.

Even when esophoria doesn’t decompensate, it can still be unpleasant. The misalignment forces your brain and eye muscles to put extra effort into realigning. That’s why esophoria can cause other symptoms like double vision, headaches and eye strain.

One way to think about it is like the rearview mirror in a car. If it isn’t lined up right, you need to adjust it. Now imagine having to readjust the mirror several or even dozens of times a day. The more you have to fix it, the more disruptive it becomes and the more tired your arm muscles will get.

When should an eye care specialist treat esophoria?

Most people who have esophoria don’t know they have it, so it’s rare for people to notice it on their own. Instead, other symptoms that happen because of esophoria are usually why people see a healthcare provider or eye care specialist about it, which leads to the provider seeing and diagnosing it. Esophoria is something that eye care specialists can see during routine eye exams, and that pediatricians can see during routine checkups and visits.

If you have frequent headaches, eye strain or fatigue, or notice changes in your vision, it’s a good idea to see an eye care specialist. They can check for esophoria or similar issues and offer treatment recommendations.

What’s the difference between esophoria and exotropia?

Esophoria is an inward-pointing eye misalignment that only happens to an eye when you cover it. Exotropia is when an eye misaligns away from your nose without covering it. They’re both types of eye misalignment, but the misalignments are in different directions and happen for different reasons.