What is heterophoria?

Do you suffer from headaches or migraines and connect these issues with new display technology? Maybe you also see a connection between your pain and new LED lighting, hotly discussed blue light and changes in display technology in recent times?

You might have heterophoria.

Maybe you are familiar with this situation: you're working on a new computer, but after a while you are not able to focus, your eyes and head hurt, sometimes also your jaw, neck or even your whole body. Pain might both fade once you stop working and give your eyes a rest, or it might take the opposite direction and last longer and get even more intense.

In this case you might try to sleep on it, but in the morning you feel like you partied all night rather than feeling rested.

It may also happen, that after such work a migraine starts and makes everything described above even worse.

Naturally you will go to see an ophthalmologist (eye doctor) to get yourself checked. The doctor however says there is nothing wrong with you and might just try to change your glasses prescription a bit, or offer eye drops which don't really help to improve the situation.

If you're persistent and keep searching, you will be told the same at neurology and every other doctors appointment you might think of going to.

In the worst case you'll be sent home with diagnosis of migraine triggered by light. However there is no medicine or treatment for that at the moment, so youre advised to rest and avoid triggers. Or eventually find a job that doesnt require any type of computer work or prolonged staring into displays.

All this sounds very reasonable and nice, but what if you simply don't have such an option? Disregarding the fact that modern life and communication is almost impossible without using modern smartphones?

If all results from all the doctor's appointments you went to were negative, there were no findings on magnetic resonance in your brain and your friends start to think that you might be making all this up, maybe you have heterophoria.

So what is heterophoria?

Heterophoria is a binocular vision dysfunction. What this means is that your eyes don't cooperate the way they should. Another name for this condition is - hidden squint (hidden strabismus).

Most eye doctors don't test for this issue. It's therefore quite possible, that even if you visit many of them, they will find no problem with your eyes and may even discourage you from further examinations.

Your only option at discovering this issue and its scale is an optometrist. However you will likely not be advised to try this specialist, and the properly trained ones are unfortunately still very few.

The main problem at discovering that you have heterophoria is that, apart from all the issues and pain it can cause, it is not easily discoverable. Its name - hidden squint - points to the fact. At first sight, everything seems to be ok with you. It might happen that after all the previously described issues, one of your eyes might start to lose its place in some situations, but very few people will notice that. Proper examination of this issue by an optometrist and determination of the scale of it after all takes from 1-2 hours.

Sometimes this issue is found as early as in childhood. In this case, you have probably already been treated and this article is not for you. In adulthood, treating this problem is also possible, but it takes a lot more work and dedication.

So what exactly is heterophoria? It means that when your eyes are closed (calm state) and you don't gaze upon anything, either one or both eyes are more or less shifted. This shift is caused by an imbalance in muscles that move the eyes.

Types of heterophoria

Heterophoria has many types depending on how exactly the eye muscles are imbalanced. One or both eyes can turn towards or away from your nose (esophoria and exophoria, aka convergence insufficiency and convergence excess), one eye turned upwards more than the other (vertical heterophoria), or eyes turned on some direction around their own axis (cyclophoria). Ortophoria then means that both eyes are balanced and no issue is present.

The moment you open your eyes and gaze onto something, the eyes get fixated in the right position, the imbalance is compensated and nothing seems to be wrong. This compensation however comes at a price, which your system has to pay for keeping the eyes in a position that is not natural to you.

The price paid is for example a lowered ability to concentrate, early onset of tiredness, exhaustion and in case of a prolonged attempt aforementioned pains and ills.

To make it even more complicated, the issues are differentiated by whether you fixate your eyes on a near point (computer screen), or a far point in the distance.

Maybe you have noticed that to make the pain after such work better, it helps to gaze into the distance. The reason for that is simple - the eyes are at their most relaxed state when looking into the distance. Therefore it works as a form of therapy for the overworked eye muscles.

Another important part of this issue is eye accommodation. This is the ability of each eye to change the power of the eye lens - and therefore the sharpness of vision - depending on whether we are focusing on a near point, or in the distance. The same applies then - the most relaxed state for the eye lens is focusing in the distance.

The overall issue with heterophoria then lies in the imperfect combination of eye movement and accommodation. The plane where your eyes meet is not the same as the plane where they focus. Your eyes then get stuck in an endless cycle, where the attempt to correct one vision system (eye focus - accommodation) is met with a deviation in the other (where eyes meet - eye vergence). This keeps on going until you get tired and give up. If you are persistent or just unlucky, your body can give up on this effort by itself. For example by a form of migraine, which makes any further work impossible.

In most cases your body can handle this issue without a problem on its own and you may never realize that something is off. The problem begins, when your field of view is met with something, that doesn't enable eye fixation. Compensation is then nearly impossible and issues arise.

The longer you then try to fix your gaze onto something that does not allow proper eye fixation, the more severe the issue will be.

Symptoms of heterophoria

Every type of heterophoria has its specific symptoms and they may also differ from person to person, however generally they include:

• Dizziness
• Nausea
• Eye pain
• Reddening of eyes
• Inability to focus
• Headaches
• Migraines
• Feeling of loosing balance (while walking for example)
• Pain when moving the eyes in specific direction (usually directon that strains the eye muscles the most - against the form of deviation present)
• Anxiety
• Feelings of being overwhelmed by stimuli - disorientation due to the amount of visual stimuli
• Sensitivity to light, photophobia
• Pain in jaw and cracking of jaw muscles (the eye muscles get tense when you try to compensate this issue, this causes tension in many surrounding muscles. When released after such tension, the jaw may create cracking sounds)
• Neck pain
• Problems with orientation in space (hitting the door frame with a shoulder, missing items when trying to pick them up or knocking them off the table)
• In cases of near complete failure - double vision and inability to perceive a single visual image for a certain time. The pain you feel is the eye muscles trying to prevent that from happening.
  

So how exactly is this issue connected with the headaches, that you get from working on the computer or by spending time in rooms with modern lighting?

At this time it seems to be proven, that some forms of modern displays, the way the image is created on the display, blue light from LED lights and some forms of lighting in general disturb proper eye fixation.

Healthy people without any eye issues may not notice this problem. Or they notice it after a long time of being exposed and the issues are not as severe as to feel concerned. If you however suffer from heterophoria, the issues can arise very soon from when youre exposed (sometimes even minutes). Your ability to tolerate these technologies is then very small or not present at all.

You can read more about the possible technological triggers of heterophoria in the next article.

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