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Refraction eye exam: what is this test?

Eye Wellnes

Refraction eye exam: what is this test?

What is a refraction eye exam? It's a test to determine if there are any abnormalities in your vision by your optometrist or ophthalmologist and decide on your contact lens or eyeglasses prescription.

  • You will be seated in a chair with a phoropter or refractor connected to it.
  • Then you will read an eye chart from a standard 20-foot (6-meter) distance while looking through the phoropter. The instrument has several lenses that change how light refracts into the eye.
  • Tests are conducted on one eye at a time.
  • The doctor will ask for you to indicate when the details of the eye chart come into focus.
  • They will then begin shifting between lenses to get a more precise measurement of how the lens of your eye refracts light.
  • Then, the doctor will shine a specialized light into your eyes to calculate the refraction.

The cost of the eye exam depends on your insurance coverage, where you live, and your eye care provider. is based on your age and any predisposed hereditary conditions that may contribute to your eye health.

What is the refraction of the eye

What is refraction of the eye and what does refraction mean? Refraction is the measurement of how light rays bend when they enter the eye's lens. A refraction test measures the degree to which light bends as it passes through the cornea and lens, meaning, the refraction of light rays onto the back of the eye. Some physicians simply flash the specialized light into the patient’s eyes to measure the amount of light that reflects off the retina. Using this observation as a starting point, they construct the refractive score.

Refractive errors: the most common ones

If you need to wear lenses to see 20/20 (6/6) and receive a prescription, you have a refractive error. Wearing glasses or contact lenses should provide you with clear vision. The capabilities of the lenses you require to see clearly are indicated by a series of numbers that make up your prescription.

Even with lenses, if your final vision is less than 20/20 (6/6), there may likely be another underlying issue with your eyes.

The best-corrected visual acuity is the level of vision you attain during the refraction test (BCVA).

Causes of refractive errors

Unusual outcomes could be caused by:

  • Astigmatism (abnormally curved cornea causing blurred vision)
  • Hyperopia (farsightedness)
  • Myopia (nearsightedness)
  • Presbyopia (inability to focus on near objects that develop with age)

Other causes of refractive error can be:

  • ulcers and infections of the cornea
  • loss of vision clarity because of macular degeneration
  • separation of the retina's supporting layers from the light-sensitive membrane at the back of the eye is known as retinal detachment.
  • retinal vascular obstruction (blockage in a small artery that carries blood to the retina)
  • retinal pigmentation (an inherited disorder of the retina)

Treatment for refractive errors

Ordering prescription eyeglasses or contact lenses is the easiest way to correct refractive errors. Prescription lenses correct the specific degree of refractive error you have. Other means of treatment for refractive errors include corrective surgery, like Lasik or PRK, and should be discussed with your eye doctor for assessment.