Nearsighted In One Eye: Is It Normal or Should You Worry?

Just like many other body parts of your biology, having two of the same doesn’t mean they’re equal. With that said, being slightly nearsighted in one eye is no reason to be concerned. But at what point does the difference in both eyes become problematic? In this article, we’ll go over everything we know about unilateral high myopia.

Is Being Nearsighted In One Eye Normal?

Yes, but not too much.

Ocular dominance occurs naturally. Even though we don’t have a clear reason for its purpose, we can probably safely agree that it’s part of the biological design and it’s normal. Here’s why:

The two eyes don’t affect the visual consciousness with equal force. One eye leads the other, and this leading eye is called the dominant eye. The dominant eye is the eye that performs the major function of seeing. The less dominant fellow eye assists it.

Just as the two hands are unequal in the way you move and feel them, so are the eyes. It’s the same thing with a person being right-handed or left-handed, they can also be right-eyed or left-eyed.

With that said, it is not normal when the difference in diopters between eyes starts getting very significant.

High unilateral myopia is when one eye is able to naturally see clearly and the fellow eye has a large amount of myopic refractive error.

What Causes It?

Currently, there is conflicting research as to what can cause unilateral high myopia. How is it that two eyes with the same genetic and environmental influences develop in such a different way?

Some studies suggest that the problem is solely due to differences in the structure of the two eyes, such as differences in the ability of the lens of the eye to absorb and dissipate energy, in the thickness of the ciliary body (responsible for shaping the lens of the eye), or even in the fluid pressure inside the eye.

Other studies focus on external factors. This study says that using stronger lenses than needed in one eye only can increase that eye’s length (which is the cause for myopia).

According to the study, the non-dominant eye may benefit reduction in its length if exposed to defocus. This suggests that a prescription with different diopters for each eye may be what turns an initial slight natural difference into a serious imbalance. Similar to going to the gym and lifting lighter weights with your weaker arm. It’s only going to make the imbalance worse.

What Can You Do?

It’s necessary to perform a complete evaluation of your ocular and medical history in order to identify potential causes for being very nearsighted in one eye only. Please refer to your eye doctor.

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Hugo Moreira

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Every single article in Myopia Daily is fact-checked to ensure the information is high-quality, medically accurate, and meets industry standards.

I have extremely strict sourcing guidelines and only cite from the most respected sources, including recent scientific research, peer-reviewed medical journals, government agencies, scholarly articles, certified optometry websites, and up-to-date textbooks.

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My passion for promoting eye health in communities around the world fuels me to create content that is factually reviewed not only by the most up-to-date scientific research but also by everyday expertise from my personal experience with being nearsighted since I was a child.