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A Complete Guide to Dominant Eye Test

People tend to have a preference for choosing one of their hands to do something. This is because one of their hands if often better at carrying out tasks than their other hand is. 90% of people prefer the use of their right hand for tasks. This means that the person is right hand dominant. A similar pattern to dominance can also be seen in eyes, this is called a dominant eye.

What is a Dominant Eye?

A dominant eye is one which functions better as a sensory organ. This is to say that it is better at providing input to the visual cortex (area of the brain that in concerned with incoming information from the eye).
There is a range of eye dominance. In most people, one eye is ‘better’ than the other eye only by a slight margin. There is very little difference between the input ability of both the eyes. In other cases, one eye might lead over the other eye by a very large degree. This means that there is a big difference between the input ability of both eyes.
For one eye to lead over another in a person with otherwise normal vision is a natural occurrence. However a dominant eye could also occur in a person that suffers from eye conditions like strabismus or amblyopia. In this case, the dominant eye is the one that functions normally and is without fault.

How to find out which eye is dominant?

Method 1: The dominant eye

This method makes use of ‘sighting tests’ where a ‘target’ is viewed through a ‘window’. Two different sighting tests have been described below:
Test 1:

  1. Assign an object, say a lamp or frame on the wall, away from you as the target.
  2. Hold your arms straight outstretched forward.
  3. Make a window by joining both your thumbs together at a 45 degree angle and then joining together the forefingers. This should make a triangle like shape.
  4. Position your window such that your target is in the center of it when viewed
  5. Close one of your eyes
  6. Use the other to look at the target through the window. Note its position. Is the target in the center or towards the side out of the window?
  7. Now repeat steps 5 and 6 with the opposite eye.

The dominant eye is the eye in which the target stays centered in the frame when the eye is used to view the target through the frame.
Test 2:

  1. Assign an object, say a lamp or frame on the wall, away from you as the target.
  2. Hold one of your arms straight outstretched forward.
  3. Make a ‘thumbs up’ sign with your hand. Your thumb should be stretched upwards.
  4. Position the thumb over your target such that it superimposes on top of it. At this point the thumb might appear as if it’s disappearing. This is okay.
  5. Close on of your eyes
  6. Use the other eye to look at your thumb. Note its position. Is the thumb directly in front of the target or to its side?
  7. Now repeat steps 5 and 6 with the opposite eye

The dominant eye is the eye in which thumb stays in front of the object when viewed when the other eye is closed.
The problem with sighting tests are that they can vary because of many different variables which can make the result inaccurate. The factors that can cause uncertainties in the sighting tests include the dominancy of the hand used for the test and other non-visual factors.

Method 2: The Non-Dominant Eye

This method makes use of specialized equipment specifically made to discern the non- dominant eye from the dominant one. During the procedure, both eyes have to open. First one eye is focused on a visual stimulus, and then the other eye is. The problem with this method is that it can only be done at a specialist office where both an expert and the required equipment are present to carry out the test.

So what happens if there is no dominant eye?

While highly unlikely, it does occur that there is no real difference in the sensory input of both eyes. Both the eyes are more or less equal to each other. In this case, there is no dominant eye. When there is no dominant eye, the result of Sighting Test 1 is that the target is not center positioned in the window when test is carried out for both eyes. Similarly the thumb is not positioned in front of the target for Sighting Test 2 of both eyes.
A lack of a strong degree of dominance is called a mixed dominance. This is when the one eye leads when it comes to certain tasks, while the other eye excels at other tasks. To understand how this happens one first needs to understand the signaling in the visual cortex.
Like all parts of the brain, the visual cortex too is made up of columns of interconnecting neurons. These columns respond differently to incoming signals from both eyes. This leads to the development of dominance of one eye over the other. There are connections between some of these columns and there are also columns that don’t interconnect. This can cause a wide spectrum of dominance from a strong degree between both eyes to there being barely any difference between both eyes.

The Role of Dominancy in Different Activities:

  • Sports: The position of your eye which is dominant will often need to be aligned to your dominant hand for full advantage.
  • Photography: The eye which is dominant needs to be used while taking a picture by looking through the view finder as it will help capture an image that is more authentic to the actual view.
  • Shooting: Cross dominance, where there the eye opposite to the hand is dominant, can cause problems. Knowledge of this can help with corrections being made for precision.