Have you ever wondered what sets a professional, comprehensive eye exam apart from a basic vision screening? A comprehensive exam includes many types of eye exams, all of which are important for maintaining eye health. Here we’ll walk you through the different types of eye exams and what they each test for.
Visual Acuity
Visual acuity is a test performed using the Snellen Eye Chart, which indicates whether you need corrective lenses. You can expect to sit or stand a few feet from a chart and read letters, numbers, or symbols that become progressively smaller. You’ve likely heard the metric for measuring these results--20/40, for example. If you have 20/40 vision, you need to stand 20 feet away to see what someone with perfect vision can see from 40 feet away.
Refraction
The refraction test determines your prescription for eyeglasses or contacts. During the test, your eye doctor will place an object called a phoropter between your eye and an image. Using a series of lenses, the doctor will ask you to indicate which lens image looks clearer. This test will help finetune a nearsighted vs. farsighted diagnosis to determine what your appropriate prescription should be. If your eye prescription is too strong, this test will help correct the prescription.
Retinoscopy
Sometimes used on children or patients who can’t easily answer questions, the retinoscopy test allows the physician to determine an approximation of the prescription. This test is usually performed before the refraction test. During the test, you will be asked to look at a single target image. As you do, your eye doctor will use a combination of light and lenses to determine (more generally) which corrective lenses to prescribe.
Autorefractors and Aberrometers
Autorefractors and aberrometers refer to another set of tests that help determine your prescription. An autorefractor is a machine that analyzes light reflex, and an aberrometer relies on “wavefront” technology to track rays of light as they move across your eye. Any imperfections in the measurements generated by this test could be due to a refractive error.
Eye Focusing and Eye Teaming Tests
Your eye doctor will want to be sure not to put too much emphasis on testing your eyes individually since your eyes always work together! With this test, you may be asked to follow an object or light with your eyes to determine how your eyes function as a duo.
Eye Health
The main reason to opt for a comprehensive exam is to assess the overall health of your eye. Some progressive eye diseases, such as keratoconus, may not show symptoms right away and require a medical diagnosis.
Slit Lamp Test
The slit lamp test is used to catch a variety of more serious eye problems or diseases, including macular degeneration, corneal ulcers, diabetic retinopathy, and cataracts. A “slit lamp” is a microscope with binoculars that allows eye doctors to magnify their view of your eyes. This allows them to take a closer look at all your eye structures, including your eyelids, cornea, conjunctiva, iris, lens, and even the retina and optic nerve.
Tonometry
Your eye doctor will also want to make sure to check for one of the most serious eye diagnoses—glaucoma. Also called the “puff-of-air” test, the non-contact tonometry test observes your intraocular pressure to determine whether you have high eye pressure. High eye pressure is what puts someone at risk for developing glaucoma.
Pupil Dilation
Sometimes your eye doctor may need to get a better look at the internal structures of your eye, and enlarging your pupils helps. He or she may use dilating drops to do this, which increases your light sensitivity for a few hours. Alternatively, some patients prefer a new technology called “optomap,” which uses a safe scanning laser that yields a digital image of the retina. There is some debate in the medical community around optomap vs. dilation tests. If you have any questions, ask your eye doctor during your comprehensive exam which test he or she suggests for you.