Farsightedness, nearsightedness, astigmatism, and presbyopia are common vision issues. If you’re experiencing blurred or double vision, eyestrain, or headaches, you may need prescription glasses.

Glasses can help people see better, but you might not realize you need them. Your eyes can change over time, so even if you have perfect vision now, it’s not necessarily a given later on.

The Vision Council estimates that 166.5 million adults in the United States wear prescription glasses. It might not always be clear to you that you need glasses, so it’s a good idea to regularly see an eye doctor for a thorough exam.

Your vision changes as you age, and not all changes in vision are unusual. For instance, it’s expected to begin needing more light to see clearly or having trouble distinguishing black from blue. These issues don’t require glasses. But there are times when vision changes aren’t typical, and glasses may be warranted.

Some people who need glasses don’t have any symptoms, while others have very clear symptoms. Symptoms of needing glasses can vary depending on the kind of eye issue you’re having.

Common symptoms include:

  • blurred vision
  • double vision
  • fuzziness (when objects don’t have defined, clear lines and things seem a bit hazy)
  • headaches
  • squinting
  • “auras” or “halos” around objects when you look at them in bright light
  • eyestrain, or tiredness or irritation in your eyes
  • distorted vision
  • difficulty seeing and driving at night

This isn’t meant to be a comprehensive list. If you notice any changes from what’s typical for you, call an eye doctor. They can perform an eye exam to find out what might be going on and what you can do about it.

The National Eye Institute (NEI) states that refractive errors are the most common type of vision problem. This category includes:

Refraction is when the cornea and lens of your eye bend incoming light so that it’s concentrated on the retina, which is in the back of your eye. This allows you to see.

A refractive error happens when the light can’t be focused on the retina because of the shape of your eye. This can result from aging or changes in the shape of your eye or cornea.

Other vision problems include age-related macular degeneration, glaucoma, and cataracts, which cannot be treated with glasses.

Nearsightedness

If you have nearsightedness — also called myopia — you can see nearby objects clearly, but faraway objects get blurry. For example, you might have trouble clearly seeing people on a television screen, or a child might have difficulty reading the chalkboard in school.

This condition occurs if your eyeball is too long or your cornea is too curved. The American Optometric Association estimates that nearsightedness affects about 30% of people in the United States.

Farsightedness

With farsightedness, or hyperopia, objects far away are mostly clear, while objects nearby are blurry. This happens when your eyeball is too short, or your cornea is abnormally shaped.

According to the NEI, farsightedness affects about 5–10% of the U.S. population.

Astigmatism

In astigmatism, light isn’t evenly distributed onto your retina, so images can appear blurry or stretched. But not everyone with astigmatism has distorted vision.

This condition can happen at any age. While most people have some mild astigmatism, those with more significant astigmatism might need glasses to correct it.

Presbyopia

Presbyopia is a typical effect of aging and occurs in nearly everyone. According to the NEI, people usually start to develop presbyopia after 45 years of age.

As you age, your eyes lose some of their flexibility. When they can’t flex as well as before, focusing on nearby objects becomes more difficult. This is why many people need bifocals or reading glasses as they age.

Consult an eye doctor as soon as possible if you’re experiencing any unusual vision changes. Even if you don’t have any symptoms, it’s a good idea to get regular eye exams with dilation to ensure that you’re seeing clearly and keep tabs on your eye health.

Only an eye doctor can do a comprehensive eye exam to see whether you’d benefit from wearing glasses. If the results indicate that you need glasses, a doctor can speak with you about the kind of lenses that would be best for your condition, as well as any other treatment you might need.