Phoropter is an ophthalmic diagnostic instrument used to determine a patient’s refractive error and establish the appropriate prescription for eyeglasses or contact lenses. It contains multiple lenses and optical components that allow eye-care professionals to quickly change lens powers while assessing visual acuity and refractive needs. Commonly used during eye examinations, a phoropter helps provide accurate and efficient vision testing for conditions such as myopia, hyperopia, and astigmatism.