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How Do Glasses Work?


Approximately 75% of adults use some sort of vision correction. Of these, about 64% wear eyeglasses to help them read, play sports, work effectively on a digital screen, and keep their surroundings in view.

Understanding how glasses work begins with an understanding of how the eye functions.

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How The Eye Focuses Light

The eye is composed of several parts, each with its own distinct function:

  • The pupil - The opening through which light enters the eye.
  • The retina - The nerve layer that focuses light at the back of the eye.
  • The cornea - The first and strongest focusing layer of the eye that’s a transparent opening at the front of the eye.
  • The lens - The second focusing mechanism, capable of fine-tuning and adjusting the focusing light depending on the object's size.

When all of these parts are shaped correctly and working properly, the result is clear 20/20 vision. One of the eyes’ most important functions is to bend light rays entering the eyes, so they focus directly on the retina. The direct focus of light enables the retina to capture a sharp image, which is then sent to the brain so that the brain can correctly perceive the image in clear, sharp detail.

When the eyeball is misshapen it doesn’t focus light directly on the retina and causes refractive errors. Myopia (nearsightedness) occurs when light is focused in front of the retina, while hyperopia (farsightedness) occurs when the light is focused behind the retina.

How Do Lenses Correct Vision Problems?

High-quality plastic or glass eyeglass lenses work by ensuring the light is focused directly on the retina. This corrects the eye’s refractive errors.

There are two main types of lenses:

  • The plus/convex (+) lens corrects farsightedness by bending the light and moving the focal point forward to properly focus on the retina.
  • The minus/concave (-) lens corrects nearsightedness by shifting the light's focal point backwards to properly focus on the retina.

Glasses compensate for your eyes’ refractive errors, making it possible for you to work, drive and play sports, and countless other activities.

If you'd like to learn more about how glasses work or think it might be time for a new pair of glasses, please contact James Tracey Eye Care in Midtown to set up an appointment.

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Q&A

How often should I get a new pair of glasses?

You should get a new pair of glasses any time your prescription changes. See your eye doctor annually or every two years to keep seeing clearly.

Why should I go to the eye doctor when I can easily buy an inexpensive pair of eyeglasses online or at a drugstore?

In addition to keeping track of refractive errors, your eye doctor will assess whether you have eye diseases, like glaucoma, and treat them to prevent or minimize vision loss. Some sight-threatening eye diseases display no symptoms in their early stages, so eye exams are crucial. .

If you need reading glasses, one-size-fits-all reading glasses don't work well for people who have astigmatism, a different prescription in each eye, or eyes that are closer together or farther apart than average. In these cases, pre-made reading glasses can cause headaches and eye strain.