A refraction test is a crucial part of a routine eye exam that determines your prescription for eyeglasses or contact lenses. It measures how well your eyes focus light onto your retina, the back of your eye. Normal vision requires that light focuses precisely on the retina; if it focuses in front of or behind the retina, you'll experience blurry vision.
Understanding Refraction Tests
This test helps your eye doctor diagnose refractive errors, such as:
- Myopia (nearsightedness): Light focuses in front of the retina.
- Hyperopia (farsightedness): Light focuses behind the retina.
- Astigmatism: The cornea (the front surface of your eye) is irregularly shaped, causing blurry vision at all distances.
The refraction test itself involves several steps, often including:
- Initial Vision Screening: Measuring your visual acuity with an eye chart.
- Subjective Refraction: The doctor uses different lenses to determine the clearest vision for you. This often involves asking you to choose between different lenses to find the best correction.
- Objective Refraction: Using specialized instruments (like an autorefractor) to automatically determine your refractive error. This method is often quicker and can help provide a starting point for the subjective part.
The results of the refraction test dictate the prescription strength and type of corrective lenses needed. This prescription specifies the lens power and any necessary corrections for astigmatism.
Several sources confirm this definition: Mount Sinai (https://www.mountsinai.org/health-library/tests/refraction-test), Healthline (https://www.healthline.com/health/refraction-test), and All About Vision (https://www.allaboutvision.com/eye-exam/what-is-a-refractive-eye-exam/) all describe a refraction test as a procedure to determine the necessary prescription for glasses or contact lenses. It's important to note that while Medicare may not cover refraction tests, many commercial insurance plans do (https://www.takleeye.com/what-is-a-refraction-test-and-will-medicare-cover-it/).
