Why do I need glasses?

Why do I need glasses? Is there something I can do naturally to not need glasses? Is the need for glasses genetic? Will glasses make my eyes better? Will glasses make my eyes worse? As an eye doctor in Broken Arrow I get asked these questions daily. I am going to explain those questions and more in this article. This article will contain some math but I will do my best to keep it to a minimum. I am also going to ignore some diseases in this article that would make the explanations significantly more complicated. 

The anatomy of the eye. Simplified. 

The purpose of the eye is to allow us to see. The eyes job is to converge or move the  light into a single point on the back of the eye called the retina. If the light comes into focus in front of the retina the individual is near sighted. When the light comes into focus behind the retina the individual is far sighted. If the light has two points of focus the individual has an astigmatism. Here is a link to the article I wrote about astigmatism if you would like to learn more about astigmatism. The parts of the eye that converges the light include the tear film, the cornea, the aqueous, the lens, and the vitreous. The length of the eye will also play a major part. 

Index of refraction

The tear film, aqueous, and the vitreous do their job by having a different index of refraction or density then the surface in front or behind them. Think of a line of soldiers walking through short grass on a patrol. They are moving at a certain speed, but if they all of a sudden encounter a dense tall field of corn they will slow down and move closer together. That is similar to how density of the material converges light. Now the air to tear film has the largest change in density and is why the tear film does the majority of light converging. Think short grass to corn field. After that all the other densities are like changing from cornfield to forest to mountains. Still a change but not as drastic.  


The cornea has a curve to it. That steepness is what converges light. The steeper the curve the more it converges light. Now the cornea can also be shaped like a football(American) where one side is steeper than the other or a basketball where every side has the same curvature. If it is a football the person may have two points of light in the eye instead of one and that is where astigmatism can come from.  I am going to mention here that keratoconus and pellucid marginal degeneration along with hundreds of other corneal diseases can cause more than one point of focus in the eye. Light is converged by the lens that is curved. Again, if the curvatures aren’t the same it can cause astigmatism. 


The lens can also counteract the astigmatism created by the cornea. The lens will change in density as we develop cataracts and can cause our prescription to change. If all those factors work in perfect harmony then the individual has ametropia and probably doesn’t need glasses, but if one of those is off then the person will need glasses. 

Why do I need glasses?

Most of the factors around vision are not changeable. What I mean is aside from the lens you can’t really adjust the density of the materials. You can do orthokeratometry or surgery to adjust the curvature of the cornea. You can also do surgery to change all aspects of the lens.

Lastly, you can’t change the length of your eye. The only thing you can consciously change is the position and curvature of your lens by flexing the ciliary body or focusing. The loss of this focusing ability is why people need bifocals and lose their near vision. Do not hear from me that it is the ciliary body muscle becoming weak. That is what people thought years ago but technology proved that wrong a long time ago. So with that information, the most common reason people need glasses is the eye is too long/short or the cornea is too curved/flat. 

Are glasses genetic or inherited?

Yes and no. It is not a guarantee that if mom, dad, neither, or both needed glasses kid will. The reason why is fairly simple. Let’s assume mom needed glasses because her eyes are too long and dad needed glasses because his cornea are too curved. Both mom and dad are near sighted. However, kid got the cornea curvature from mom, which was perfect, and length of eye from dad, which was perfect. Thus, kid doesn’t need glasses. However, if kid got length from mom and curvature from then kid is blind as a bat. 

How do I know if I am near or far sighted?

As an eye doctor one of the first things done on every patient that comes in the door is check their visual acuity. I will check static visual acuity both for distance and near. It is static because neither the patient nor the target is moving. If either of those objects were moving it is dynamic visual acuity. When vision is blurry in the distance then you are near sighted. If vision is blurry at the reading distance then you are far sighted or presbyopic. I will cover presbyopia in a future article.

Will glasses make my eyes worse?

The short answer is no, but the long answer is maybe. It is challenging to get good research on this because very few people are willing to play guinea pig with their eyes. Also, what research we do have is easy to punch holes in. For instance, if glasses made the eyes worse why does the prescription rarely change from age 25 to 40? My opinion is that some people are susceptible to this and others aren’t due to genetics. This “old wives tale” came about because our brain is good at interpreting blurry objects. When given glasses for the first time the brain thinks the world is amazingly clear. However, when the glasses are taken off the brain no longer remembers how to interpret the old blurry world. So, the individual thinks it made their eyes worse.

Will glasses make my eyes better?

The short answer is no, but the long answer is yes for some people. If you have a condition called amblyopia the glasses will make the eyes better, but won’t change the glasses prescription. This better is not a change in prescription, but a change in neural wiring. I’ll dive deeper into amblyopia in a future post, but for now this is a resource.

Is there something I can do naturally to not need glasses?

I would love to have my vision clinic in Broken Arrow be the place that cures the need for glasses with a vitamin. Sadly there is no such vitamin. Currently surgery like lasik and PRK can get you to not need glasses, but nothing you can eat or drink. 

As always if there is a topic you would like me to talk about please mention it in the comments and if you liked this article share it with your friends to let me know these posts are beneficial. You can also like our FaceBook page to get notified of future posts.

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