What is Aniseikonia? Types | Causes | Symptoms | Treatment



The Greek word “aniseikonia” means unequal images. Anisyconia is a binocular condition where the image of one eye differs in size from the image of the other eye.

There are two different types of aniseikonia. They are:

  1. Static aniseikonia and
  2. Dynamic aniseikonia.

Static aniseikonia

This static anesthesia mainly occurs due to the spectacles that are made to correct anisometropia. When you use a different prescription for each eye to solve anisometropia, the monochromatic method induces anisyconia. As a result, the size of the image in each eye is seen differently. This creates problems for the wearer.

The brain has to work to fuse these different sized images together, creating two different sized images.

In dealing with the images that glasses create, the brain struggles to focus all the time. The brain tries to adapt by suppressing the image with one eye.

This often results in headaches, visual impairments or other problems. Many patients stop wearing glasses because of these problems.


Dynamic aniseikonia

Dynamic anisyconia is similar to static anisyconia. The main difference between them is the speed. There is motion in dynamic anisyconia, there is no motion in static anisyconia.

If the glasses are not made considering how the two eyes move together, the eyes are often forced to go vertically and permanently at different rates. It causes problems for contact lens wearers.


Causes of Aniseikonia:

There are some causes of aniseikonia. They are:

  • Asymmetric convergence
  • Anisometropia
  • Ocular surgery
  • Swelling in the macular area
  • Wearing of glasses of different magnifying power for the two eyes
  • Difference in size of dioptric images formed by the retina
  • Difference in the distribution of retinal elements
  • Cataract refractive surgery
  • Anatomical difference between the size of the eyes
  • Surgery to repair a partially detached retina

Symptoms of Aniseikonia:

Differences of up to 7% in the size of the image made with the eye are tolerated. If the magnification difference becomes excessive, problems can arise. In this case the following symptoms may occur.

  • Diplopia (motility)
  • Suppression
  • Disorientation
  • Eyestrain
  • Headache
  • Balance disorders
  • Photophobia
  • Reading difficulty
  • Nausea
  • Nervousness
  • Vertigo and dizziness
  • General fatigue
  • Distorted space perception

Although the difference in the size of the image created by the two eyes is less than 7%, there is a possibility of athenopic symptoms.


  1. Contact lenses are used generally for the treatment of refractive aniseikonia.
  2. Optical aniseikonia due to anisometropia can be corrected by these three ways:
  • Spectacles
  • Contact lenses
  • Refractive corneal surgeries
  1. Intraocular lens implantation: This treatment is used in case of aniseikonia due to uniocular aphakia.
  2. In case of refractive surgery, the optical image size difference reduces. So, to reduce the aniseikonia refractive surgery is used.
  3. The aniseikonia should be measured before the optics can be designed.



Is Anisometropia serious?

In case of anisometropia, the refraction of a person’s eye varies by more than 1 diopters (D). When the anisometropia is serious or severe, it shows some symptoms. They are:

  • Visual blurring
  • Alternating vision
  • Double vision
  • Amblyopia


Do lazy eyes affect vision?

Generally lazy eyes affect the vision of one eye. But in some cases, amblyopia can occur in both of the eyes. If you have this (lazy eyes) problem, you should be treated quickly without any delay.

In case of severe condition, you may face the permanent loss of vision of your affected eyes.

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