Divergence Excess – Binocular Vision Problem

We’re sure you’ve tried to go “cross-eyed” by watching your finger move closer to your nose. By making this silly face, your eyes are actually converging, or moving towards each other, which happens when you look at objects that are near you. Now if you move your finger away from your nose, did you consciously notice that your eyes moved away from each other? Your eyes are not just returning to their “normal” position; they diverge, or move out away from each other, when you look at objects in the distance. Some people actually experience an exaggerated amount of turning out by one or both eyes when looking far away. This is known as divergence excess – exotropia or high exophoria at distance (check out our blog post on tropias versus phorias!).

What is Divergence Excess?

Divergence excess is prevalent in 0.03% of the population and is found to be more common in women, making up 60-70% of cases. This eye turn when looking at far distances is a response to visual strain from looking at something near you due to convergence of the eyes and accommodation, or the ability of the lens to focus on objects at different distances. Consequently, when the eyes look into the distance and diverge, they relax and can wander off to the side. This is often noticeable in children less than 18 months of age, progressing throughout life if not treated. At first, parents may notice an eye that rarely turns outward, usually only when their child is tired or sick. Then the eyes start to spontaneously deviate outwards but straighten moments later. Eventually, the eye is constantly turned outward.

From the child’s perspective, divergence excess can cause blurriness and double vision when looking in the distance. He or she may also close an eye in bright sunlight or even suppress an eye, which occurs when the brain ignores the input from one eye. Because the eyes cannot focus on the same spot, depth perception can be lost at far distances as well. Fortunately, at near distances, the eyes can still perceive depth and have a normal near point of convergence. Furthermore, vision is typically normal in both eyes in that visual acuity should not be affected by divergence excess.

How do you Treat Divergence Excess?

It is not uncommon for an eye care professional to suggest patching one eye or even surgery to fix the eye turn. Unfortunately, patching presents risks for children especially 2 years old or younger since it is during this age that normal binocularity develops through the use of both eyes. Surgery can be especially scary for both parents and children. Usually the operation is done to shorten the medial rectus muscle of the eye, which is closest to the nose, to prevent the eye from turning outwards. However, there is no physiological support for mechanical causes of divergence excess, so surgery can lead to an eye that turns inward too much when looking near and thus double vision.  Not treating divergence excess also has its downfalls as the eye deviation can result in loss of depth perception and development of suppression of one eye. Glasses with special lenses that are over-minused or contain a prism can help, but must always be worn to prevent the outwards turn of the eye.

Can Vision Therapy Treat Divergence Excess?

Fortunately, there is another option that often goes unmentioned to parents and patients…vision therapy! Vision therapy, with eye exercises, has a success rate of 90%n or more for fixing divergence excess and can be completed at any age. Anatomically, the eye and the surrounding tissues and muscles are not altered in any way. Different exercises that work on skills like eye mobility and using both eyes together are performed including techniques using vectograms and a Brock string. Your eyes can be trained to focus on the same spot and your brain can be trained to properly process the visual input from both eyes. Once you complete vision therapy, your eyes should no longer experience divergence excess. At Insight Vision Center, we will come up with an individualized game plan of exercises to help anyone of any age fix their divergence excess, pain-free. If you’d like to learn more, please don’t hesitate to connect with us!

Where is Insight Vision Center Optometry?

Serving the communities of Costa Mesa, Irvine, Newport Beach, Tustin, Santa Ana, Huntington Beach, and Fountain Valley. Schedule a visit with Dr. Valerie Lam or Dr. Thanh Mai to learn more. Our optometry practice is located in Costa Mesa at 3151 Airway Ave. Suite J2, Costa Mesa, CA 92626.