Eyepatch test for heterophoria

If you are looking for a more precise home method to test whether you have heterophoria or not, please look at this article. The method I will present here is very simple and requires almost no tools, but can still be very useful in determining whether your issues are of binocular nature or not.

All you need for this test is an eye patch that is ideally black and does not allow for any light to enter your eye. Make sure this condition is met, as even a little amount of light entering the eye can trigger binocular fusion. You can either use an eye patch or simply close your eye by the help of your hand. Don't just try to close it like if you are winking, as the facial muscles can get tired from doing this for a prolonged time and that would be counterproductive.

When you cover or close one of your eyes with no light getting in, it basically simulates monocular vision and therefore all binocular issues should be gone. Make sure that the eye you are using is not impaired in other common ways (nearsightedness, astigmatism etc.) and if it is, use your prescription glasses. We want to test for binocular vision dysfunction only.

Make sure that your eyes are rested before this test and are not aggravated by previous use of problematic devices or displays. In that case it would be difficult to discern whether any pain is just lingering from before, or actually being triggered during the test. This may be difficult, since some people may have lingering headaches and pains for hours or even days, but it's important to be as rested as possible.

The test

With one of your eyes closed or covered completely, try to look at a device or display that was previously causing issues (smartphone, computer display etc.) Do some reading, maybe look at some pictures, try what you would usually do but only with monocular vision. After some time (15-30 minutes) try covering the other eye and repeat the test. Make sure to never use both eyes to look at the device before, during and after this test, as that could trigger some pain and compromise the results. Few things might happen:

• You will feel no pain and will be surprised to be able to perceive the device as almost harmless
• You will feel some pain or burn but it will be a lot less than when looking at the device with both eyes
• It will be painful as usual

If the first option fits your experience, you can congratulate yourself, because the issue is 100% binocular vision dysfunction and therefore can be treated. The second option means that you might also have accommodation insufficiency (burning feeling) on top of some type of heterophoria (that was my case).

The third option is unlikely and could mean that your issue really is not heterophoria. However it could also mean that you were not properly rested from previous painful exposure, or that your experience of pain from these devices is memorized. This may sound weird, but it happened to me and some other people with this issue I have spoken to - you are so used to feeling pain when being exposed to the problematic devices, that it kicks in almost automatically now as a form of precaution. I therefore recommend trying this again later and a couple more times to make sure.

Using only one eye is not without problems. If you are used to using both eyes, using only one brings with it its own set of problems and difficulties. It may be more exhausting to read or do other activities, since the load that is separated between two eyes now rests on one eye only. However in case of heterophoria and the pain it brings, using only one eye in situations where it's triggered should bring a significant relief.

Before doing visual therapy and having prismatic glasses I have tested this method on some computer displays that triggered pain and felt that it didn't show much difference, which was very discouraging. However later at another time and fully rested, I gave it another shot with my digital camera display. I was amazed that for the first time I could look at the display as if no issue was present. This was a breakthrough and motivated me to do the visual therapy.

Variance in results and usability

Beware that this might not work with every display and not all the time. My guess is that some displays might trigger your accommodation issues more than others and some might flicker so bad that it can be nauseating even for monocular vision. But if you make sure that all the conditions are met and you try it a few times, you should notice a significant difference when using only one eye.

One of the people affected that I got to know through ledstrain.org and later met, has tried only this method and by alternating his eyes (and never using both eyes to view problematic devices for some time) he was actually able to get to a point where he can use binocular vision with these devices for hours where previously only minutes were possible. I am not sure this can be replicated by everyone, but it is an amazing result nonetheless. It is possible that by using one eye at a time accommodation was first trained in isolation, and then vergence had an easier time adjusting properly.

Maybe you wonder - wouldn't then just using one eye solve this problem? I don't recommend it. If you use only one eye all the time, you will further impair your binocular vision and that would not be beneficial in treating this issue long term. However as a testing tool, for relieving pain temporarily and as a form of training (or when training accommodation during visual therapy), it is of great help.

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If you would like to discuss this matter in person, feel free to book a consulting session with me. I will also be grateful for any donation to help me run this blog and my future research in this field.