March 15, 2022 | Basecamp

The Reasons Behind Eyesight Getting Worse in 20s

By Barrett Eubanks, M.D.

The Reasons Behind Eyesight Getting Worse in 20s

No matter what you do, it seems your vision is just getting worse. Is there something you are doing wrong? And what can you do about it?

The biggest reason why your eyesight can get worse during your 20s is due to a change in the prescription of your eye. The eye has become more nearsighted. This won’t affect everyone, however those that are in their schooling years are at a greater risk.

Anyone may actually have insignificant small changes in their prescription, however, for some, these changes become large enough to be noticeable. There are also some medical reasons why your vision will get worse in your 20s, but those reasons apply to a small group of individuals.

Is It Blue Light Damaging My Eyesight?

There are many myths about what can actually damage the eyes or eyesight. The harm of blue light and the need for blue light blocking glasses is just one of the most recent ones.

  • Blue light from our screen is damaging our eyes - MYTH! We encounter much much more blue light when we are outside without any damage than we get sitting in front of a screen. Blue light CAN affect your ability to sleep.
  • Looking at a bright screen in a dark room will damage the eyes - MYTH! This may cause some eye strain but will not lead to any damage to the eyes.
  • Wearing glasses will make you more dependent on the glasses - MYTH! Your need for glasses will be the same regardless of whether you wear the glasses or not. The glasses will just improve your vision.
  • Reading in dim light will damage the eyes - MYTH! This won’t hurt the eyes, it will just be harder to actually read without adequate lighting.
  • Wearing the wrong glasses prescription will hurt the eyes - MYTH! The wrong prescription of glasses just won’t allow you to see very well and can potentially cause you to have a little more eye strain.
  • Eating carrots will improve your eyesight - MYTH! Carrots contain high amounts of vitamin A. Vitamin A is essential to maintain the health of your eyes. But more than likely you get more than enough vitamin A from your diet already. But carrots are tasty!

These myths aren’t causing the issue with your eyesight (but some of them can cause you extra eye strain).

Becoming More Nearsighted

The prescription of your eye is largely based upon the length of your eyeball. If the eyeball is too long, light doesn’t focus onto the retina.

Nearsighted eye

This is where glasses come into play to correct vision and allow light to focus properly:

Correcting a nearsighted eye
Correcting a nearsighted eye, graphics by Gumenyuk I.S., CC BY-SA 3.0, via Wikimedia Commons / cropped from original

When you are a child and into your teenage years, your prescription changes. This is mostly due to the fact that the eyeball gets larger and longer. As the eyeball gets longer, you become more nearsighted. Most of this occurs between the ages of 8 and 15.

Risk Factors For Nearsightedness

The biggest risk factor for becoming nearsighted is having parents that are nearsighted. Can’t escape genetics on this one. If both of your parents are nearsighted, this makes you 6x more likely to become nearsighted! While there are no single inherited gene which will cause the nearsightedness, the hereditary link is very very strong.

But nearsightedness is also influenced by the environment: up close activities and reading have a very important role in the development of nearsightedness. The more time you spend doing up close activities, the greater the risk of developing nearsightedness (which is a problem in today’s device driven world).

Thus the myth of sitting too close to the TV - while it won’t cause any short-term damage, it may actually contribute to the development of more nearsightedness!

But Eventually The Prescription Stabilizes

But as we get through our teenage years, our prescription mostly stabilizes. For most, this occurs around the age of 15. And by the age of 18, there isn’t a whole lot of change to the prescription.

For most individuals...

When Can Prescription Continue To Change?

Some individuals can continue to have changes in their prescription in their 20s. Who are these individuals?

Looking at the risk factors for nearsightedness provides some clues: individuals with increase near vision demands are at a greater risk of continuing to develop nearsightedness.

This includes: professional or graduate students

There is good evidence that nearsightedness progresses at a greater rate for those that are still in school. This is especially the case for disciplines with a high amount of intense up-close book-work or study (think engineers, lawyers, doctors, etc.). These individuals become more nearsighted at a rate 2-3x more than the average person!

Once you get out of school, are you safe? Well, not necessarily.

Individuals who work on computers for long periods of time may also be at risk of having increased nearsightedness.

While the evidence for working at a computer isn’t quite as strong, there is still some evidence to suggest that working on a computer for more than 40 hours a week can increase the risk of becoming more nearsighted over time.

Medical Reasons for Worsening Eyesight in 20s

While most of the change people can notice in their 20s is due to the prescription getting worse and becoming more nearsighted, there are a few medical conditions to be aware of. The most important one being a condition called keratoconus.

Keratoconus is a condition where the cornea becomes progressively weaker over time. As the cornea becomes weaker, it changes shape. Initially this causes your prescription to change and develop more astigmatism. But if left untreated, this condition can cause you to lose vision.

Thus, if you notice your eyesight getting worse, it is always a good idea to visit your eye doctor for a full eye examination.


During your 20s, you can become more nearsighted. This can cause your eyesight to get worse. This is especially the case if you spend a lot of time performing up close activities such as reading textbooks during your university years and potentially by spending lots of time on computers. So take a break from your books and screens every now and then. Your eyes may just thank you.

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