During an examination, blurry vision is usually the biggest complaint a patient has. Patients do not realize that they are seeing two images at the same time since there is often an overlap between the two images, so they report blurry vision. Or they may not even talk about their symptoms as a symptom of vision, but rather how it impacts their function. So instead of saying they have diplopia (double vision) or even blurry vision, they may say that they are experiencing difficulty focusing when they read. 

Examining the Patients Visual Function

When we do a neuro optometric eye exam we are discussing with the patient their visual function. Most people will not know how to explain the symptom divorced from function. For example, students who have suffered a concussion may not realize that they have suffered a concussive injury that can lead to post-traumatic vision syndrome. They will complain that they can't concentrate, that their brain feels foggy. They may share that their reading comprehension has fallen dramatically since they had a concussion. They may explain that it is impossible for them to read for long periods of time, forcing them to give up on what they are reading after a short while.

What are some of the vision conditions from a concussion and their functional challenges?

• Exophoria - One of the conditions that may result from a brain injury is exophoria, in which one of the eyes tends to move outward while looking at an object up close. As a result, it is difficult to do close-up tasks such as reading a book or using a computer since the eyes do not work together as a team. Sometimes this will be explained as “reading makes me tired” or “I have trouble remembering what I read”.
• Exotropia - It is an extreme form of exophoria in which the eyes move outward more frequently and more prominently. When it is not treated with glasses or convergence exercises, it further worsens and the angle of deviation increases. A person with exotropia may have difficulty with bright lights, headaches, blurred vision, and eye fatigue. They may express this as “the sun bothers me” or “my eyes feel tired”.
• Esophoria - One of the eyes tends to move inward when focusing on near tasks, such as reading the newspaper, a condition known as esophoria. Typically, this condition occurs only when both eyes are not concentrating on a single image. Functionally the patient may express that reading or computer use “makes me tired” or “I have a hard time concentrating when I read”.
• Esotropia - When left untreated, esophoria often becomes esotropia, where one eye looks constantly inward while the other eye remains in its normal position. A patient with esotropia looks at their left using their right eye, and at their right using their left eye. Esotropia makes certain tasks like reading, driving, playing sports, and using the computer more difficult. A patient may share their functional symptoms as “I find it harder to drive” or “I make mistakes when copying from the board”.

Convergence insufficiency

Convergence insufficiency affects the ability of your eyes to work together when looking at nearby objects. This may result in blurry or double vision when you see things up close, like a book or smartphone screen.
There is a difference between convergence insufficiency and exotropia, which is a subtype of strabismus (eye misalignment). Individuals with convergence insufficiency only experience eye drifts when focusing up close and generally have good vision.
Functional complaints include “I lose my place when reading” or “I have difficulty concentrating on schoolwork”.

Neuro Optometric Rehabilitation

The treatment approach for most patients is to use lenses and prisms, sometimes with selective occlusion or tensor filters to alleviate some symptoms while trying to restore balance in the patient's system. In many cases the patient will use prism lenses in conjunction with in-office vision therapy.  Vision therapy is a series of exercises that retrain the visual pathways that were impacted by their head injury. Because of neuroplasticity our brain is able to recreate these visual connections and relearn how to properly control eye movements, align the eyes, and process visual information.