Online eye tests are convenient but should never replace your eye doctor.
Online eye tests can be a convenient way to get a prescription to replace lost or broken glasses, but online vision tests should never completely replace visits to your eye doctor for comprehensive eye exams and refraction.
The online eye tests are refraction tests, which is an eye exam that measures refractive errors. If you do not have 20/20 vision then you have a refractive error.
A refractive error means that light, as it travels through your cornea and lens, is not bending at an angle that will directly focus light on your retinas.
Glasses or contact lenses are prescribed based on the degree of refractive error. In nearsighted eyes, light converges in front rather than directly on your retinas, causing blurry distance vision. In farsighted eyes, light converges behind the retina and this causes blurry close-up vision. In eyes with an astigmatism, an imperfection in the curvature of your cornea or lens, light is scattered which causes overall blurry vision.
It is good to remember that these online tests can measure the power of your eyeglass prescription, but they can’t detect eye diseases. For that you have to have a comprehensive eye exam.
Difference between online eye tests and comprehensive eye exams
A comprehensive eye exam uses a series of tests and evaluations that assess the overall health of your eyes, muscles, blood vessels, connective tissue, cornea, retina, macula, and your optic nerve. A variety of microscopes, lenses, and digital technology are used to view the eye and the surrounding tissues and the optic nerve.
Dilating eye drops are used to temporarily widen the pupil for better views of the structures inside your eyes. The pressure inside your eyes is measured to screen you for glaucoma.
Your eyes will be assessed for how well they move and work together. Each eye has six muscles and a comprehensive eye exam assesses if those muscles are working properly and that checks for any misalignments.
A comprehensive eye exam also offers an indication of your overall health because a comprehensive eye exam can detect many other health issues, such as diabetes, heart disease, high blood pressure, some cancers, vascular disease, retinal detachments, and many others.
Whenever a comprehensive eye exam uncovers other health conditions your ophthalmologist will recommend further testing by a specialist or your primary care provider.
Convenience can be a good thing and online eye tests can be a convenient way to update an eyeglass prescription or replace a lost or broken pair, but don’t let that convenience replace in-person comprehensive eye exams because only a comprehensive eye exam can evaluate your overall eye health and detect eye problems at their earliest stage.