Aniseikonia is the term for a difference in image size between your two eyes. Your brain works incredibly hard to reconcile these two differently-sized images, and that effort can be a significant drain on your energy. While you have a natural ability to deal with small image size differences, a more pronounced disparity can create significant challenges.

This often leads to a related condition called anisometropia. While anisometropia is not always an issue when you look straight ahead through the center of your glasses, it becomes a problem as you look through other parts of the lens. As you shift your gaze up, down, or to the side, the images move at different rates, causing discomfort. This is particularly noticeable on the vertical plane, such as when you’re looking up while driving and then down to read something.

The Invisible Symptoms of Visual Strain

The human brain is incredibly resilient, but this resilience comes at a cost. You might not consciously realize that your eyes are struggling to reconcile two different images. Instead, the symptoms often manifest in ways you wouldn't immediately associate with your vision. Common signs that your brain is expending too much energy include:

• Headaches: A frequent byproduct of the brain's struggle to fuse mismatched data.
• General Exhaustion: Feeling a systemic drain from constant visual processing.
• Afternoon Fatigue: Feeling unusually tired as the day progresses and the visual load accumulates.

Finding a Specialist

Most optometrists may not identify binocular vision as the source of these symptoms. To truly address aniseikonia, it’s important to consult with a binocular vision specialist. These experts look beyond a standard eye exam to consider how your eyes work together as a system. Organizations like OVDRA and NORA can help you find a qualified specialist in your area.

A Specialized Solution: The Shaw Lens

The best way to address the discomfort caused by aniseikonia and anisometropia is through freeform optics and specialized lens design.

A company called Shaw Lens designs lenses that take the prescription difference between your two eyes and use it to mathematically calculate and predict what the visual challenges will be. By considering the different positions in which you look through the lens, they can design a solution that is tailored to your specific needs. This ensures your brain doesn't have to work as hard to make your vision clear and comfortable.

At Chadwick, we’re the optical nerds who believe that your lenses should work with your brain, not against it.

Are you a low vision practitioner?

Get an Aniseikonia Size Lens Kit which helps you assess the magnification needed to correct size discrepancies in your aniseikonia patient's vision.

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