Eye Health Exams & Procedures Gallery of Eye Examination Equipment By Troy Bedinghaus, OD Troy Bedinghaus, OD LinkedIn Troy L. Bedinghaus, OD, board-certified optometric physician, owns Lakewood Family Eye Care in Florida. He is an active member of the American Optometric Association. Learn about our editorial process Updated on February 14, 2022 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Johnstone M. Kim, MD Medically reviewed by Johnstone M. Kim, MD Johnstone M. Kim, MD, is a board-certified ophthalmologist and a practicing physician at Midwest Retina in Dublin, Ohio. Learn about our Medical Expert Board Fact checked Verywell Health content is rigorously reviewed by a team of qualified and experienced fact checkers. Fact checkers review articles for factual accuracy, relevance, and timeliness. We rely on the most current and reputable sources, which are cited in the text and listed at the bottom of each article. Content is fact checked after it has been edited and before publication. Learn more. by Nick Blackmer Fact checked by Nick Blackmer LinkedIn Nick Blackmer is a librarian, fact-checker, and researcher with more than 20 years’ experience in consumer-oriented health and wellness content. Learn about our editorial process Print If you’ve never had a comprehensive eye examination, you may be surprised by the number of tests your eye doctor will perform. This type of exam involves the use of many pieces of equipment and several instruments. Knowing what to expect may help put you at ease. And it may prompt you to ask questions during the exam to round out your understanding of this important procedure. In this spirit, here are the pieces of equipment that you’re likely to see during your appointment. Exam Room Westend61 / Getty Images An examination room at an eye doctor’s office usually consists of an exam chair, a phoropter, an eye chart, a slit lamp, and a stool for the eye care practitioner. You’ll probably spend most of your time looking through the phoropter, the instrument fitted with various lenses, and judge whether they’re “good,” “better” or “the same.” Phoropter PaulVinten / Getty Images The phoropter is a rather imposing but ultimately friendly device that measures refraction, or how a lens should be curved and shaped to correct your vision. It determines eyeglass prescriptions, as well as if you have vision issues like nearsightedness, farsightedness, or astigmatism. Retinal Camera leezsnow / Getty Images A retinal camera is used to take a digital picture of the back of the eye, including the retina. It is used to document eye diseases. The camera produces a bright flash when the picture is taken. The Anatomy and Function of the Retina Binocular Indirect Ophthalmoscope U.S. Air Force photo / Staff Sgt. Victoria Sneed An ophthalmoscope is an instrument used for examining the interior structures of the eye, especially the retina. It consists of a mirror that reflects light into the eye and a central hole through which the eye is examined. Meanwhile, the eye doctor wears a binocular indirect ophthalmoscope (BIO) on their head to have the use of both hands to examine the patient’s eyes. Manual Keratometer Troy Bedinghaus A manual keratometer is used to determine how flat or steep the cornea is. It is often used to measure and diagnose conditions such as astigmatism, keratoconus, corneal scarring, and corneal distortion. A keratometer can be invaluable for finding an ideal fit for people who wear contact lenses. Anatomy and Function of the Cornea Autorefractor SerafinoMozzo / Getty Images An autorefractor is a machine used to measure a person’s refractive error and prescription for eyeglasses or contact lenses. This is achieved by measuring how light is changed as it enters a person’s eye. The automated refraction technique is quick, simple, and painless. The patient takes a seat and places their chin on a rest. One eye at a time, they look into the machine at a picture inside. The picture moves in and out of focus as the machine takes readings to determine when the image appears on the retina. Several readings are taken, which the machine averages to form a prescription. Slit Lamp Stefan Kiefer / Getty Images A slit lamp is a microscope with a light attached that allows the doctor to closely examine the eye. This instrument is used to view the structures of the eye, such as the cornea, iris, and lens. With special lenses, it is possible to examine the back of the eye as well. A slit lamp gives the eye practitioner an amazing view of the inside of the eyes. Tonometer Arthur Tilley / Getty Images A tonometer is used to measure the pressure of the eye. The test is used to help detect glaucoma. Numbing drops are used for the type of tonometer that actually touches the eye. Some doctors use an air-puff tonometer, for which no numbing drops are needed. A tonometer measures the production of aqueous humor, the liquid found inside the eye, and the rate at which it drains into the tissue surrounding the cornea. Lensometer Ohio Air National Guard/Staff Sgt. John Wilkes A lensometer measures the power of an existing lens. An optician uses a lensometer to determine the prescription of a patient’s current eyeglasses. Sometimes, it can serve as a good baseline for a new prescription. It can also be used to show how much a prescription has changed since the last doctor’s visit. Retinoscope and Direct Ophthalmoscope photo by ARZTSAMUI / Getty Images A retinoscope is used to shine light into a patient’s eye for an eye doctor to observe the reflection off the retina. The doctor moves the light back and forth across the pupil. A retinoscope is especially useful in prescribing corrective lenses for patients who are unable to give oral feedback to the eye doctor. It is also useful for determining how well the eyes work together to see clearly. A direct ophthalmoscope is a hand-held instrument used for examining the interior structures of the eye, especially the retina. It consists of a mirror that reflects light into the eye and a central hole through which the eye is examined. Be a Wise Patient There are no hard and fast rules, but many eye care professionals agree that their adult patients (ages 40 and up) should get their eyes examined once a year. Younger adults can probably go once every two years. But there are exceptions. You should see your eye doctor if you experience: Eye painBulging eyeDecreased vision, even if temporaryDouble visionVision blocked by partially or entirely by dark or blurred shapesLoss of peripheral visionUnusual or persistent rednessUnusual pupil size or shapeBlood in the eyeExcess tearingInjury to an eye, including a blow to the eye or chemicals splashed in the eye These warning signs fall under the category of an emergency. You should contact your eye doctor if there has been a significant change in your eyes or your ability to see. Excessive tearing, itching, and intermittent blurred vision fall into the “change” category, as does any new difficulty you have seeing or focusing on objects, nearby or far away, Stabilizing your vision could prevent it from getting any worse. Frequently Asked Questions What is the machine that puffs air during an eye test? An air-puff tonometer is a type of tonometer that measures the pressure inside your eye. The results of the air pressure reading can help your doctor tell whether you have glaucoma, a disease that damages the optic nerve. Learn More: Symptoms of Glaucoma Why does the eye doctor dilate your eyes during an exam? Your doctor may put drops in your eyes that will dilate (open) your pupils. This lets more light into the eyes and makes it easier to examine areas in the back of the eye, including the optic nerve, blood vessels, and the macula. Learn More: What Is the Macula How is a refraction test for eyes done? An eye doctor attaches a special device to you. This is a phoropter or refractor. As you look through the lenses in this device, you can see a chart. A number of lenses of different strengths are loaded into the machine. The doctor will switch the lenses you’re looking through until you find a strength that makes it easy to read the chart. This tells the doctor what prescription glasses or contacts you need. Learn More: What Does Your Eye Glass Prescription Mean? Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 6 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. American Optometric Association. Comprehensive adult eye and vision examination. Amirsolaimani B, Peyman G, Schwiegerling J, Bablumyan A, Peyghambarian N. A new low-cost, compact, auto-phoropter for refractive assessment in developing countries. Sci Rep. 2017;7(1):13990. doi:10.1038/s41598-017-14507-5 American Academy of Ophthalmology. Signs you may need an eye exam right away. Lee SY, Bae HW, Kwon HJ, Seong GJ, Kim CY. Utility of Goldmann applanation tonometry for monitoring intraocular pressure in glaucoma patients with a history of laser refractory surgery. PLoS One. 2018;13(2):e0192344. doi:10.1371/journal.pone.0192344 Brown K, Sewell JM, Trempe C, Peto T, Travison TD. Comparison of image-assisted versus traditional fundus examination. Eye Brain. 2013;5:1-8. doi:10.2147/eb.s37646 MedlinePlus. Refraction.