What is ophthalmic refraction?

Eye refraction is how the power of eyeglasses or contact lenses is calculated. This measurement is based on how much the lens of the eye has to bend light rays to process visual stimuli. This is expressed in a measurement of distance and clarity.

What is a refraction measurement?

The best way to measure your eyesight and health. For those who are new to eye exams, one of the most important measurements performed during your eye exam is the refraction measurement. Refraction refers to the bending of light as it passes from one transparent substance into another.

What is the purpose of refraction?

Everyone needs a refraction test They’re a routine part of an eye doctor visit and require no preparation on your part. They can help your doctor diagnose and treat conditions such as glaucoma and determine the need for corrective lenses, among other things.

How does a refraction test work?

This can be done by shining a light into your eyes or with computerized technology (phoropter). In nearsighted eyes, light refracts in front of your retina, causing blurry distance vision. In farsighted eyes, light refracts behind the retina, causing blurry up-close vision.

Why is refraction important in the eye exam?

Refraction is done when the ophthalmologist wants to know if your vision can be improved, for example, after a cataract operation when your glasses are likely to need changing. A refraction can also help the ophthalmologist decide whether or not to operate.

What is normal refraction?

Normal Results If your uncorrected vision (without glasses or contact lenses) is normal, then the refractive error is zero (plano) and your vision should be 20/20 (or 1.0). A value of 20/20 (1.0) is normal vision. This means you can read 3/8-inch (1 centimeter) letters at 20 feet (6 meters).

What parts of the eye are involved in refraction?

Cornea: the transparent part at the front of the eye that refracts light entering the eye onto the lens. Lens: a transparent structure behind the pupil that refracts incoming light and focuses it onto the retina. The lens is able to change shape in order to improve the focus.

Are eyes dilated for refraction?

1 A dilated eye exam allows the doctor to measure the degree of light refraction. Another aspect of dilation is that it may help determine your true refractive error because it stops your eye from focusing, This can be helpful for your corrective lens prescription.