The term “refraction” describes the manner in which waves of light are bent as they pass through the cornea and lens of your eye. The refraction assessment test helps your provider determine the prescription of the corrective lens that will help you see best. This test is used only for patients who require glasses or contact lenses.
Your provider may use an automated refractor to measure your eyes and determine the prescription needed to correct your refractive error. Another technique used to evaluate refractive errors is called retinoscopy. In this procedure, your provider will shine a light into your eye and measure the refractive error by evaluating the movement of the light that is reflected by your retina.
In many cases, your provider will continue the refraction assessment by asking you to look through a device called a phoroptor. This is a mask-like device that contains many different lenses mounted on a wheel. Your provider will try a variety of lenses as he fine-tunes your prescription, determining which lens gives you the sharpest vision. By repeating this step several times, your doctor finds the lenses that give you the greatest possible acuity.