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What happens during an eye exam or vision test?

Dr. Laura C. Fine, MD
Ophthalmologist (Eye Specialist)

External eye exam
When examining the external eye, the doctor checks the lids, lashes, and orbit—and looks for signs of any underlying problems, such as infections, styes, cysts, tumors, or lid muscle weakness. The doctor then checks your eyeball's appearance, including the sclera (white of the eye) and conjunctiva (transparent membrane lining the inner surface of the eyelids) and notes whether the pupil (the black hole in the center of your eye) reacts normally to light.

Checking the coordination of the six muscles in each eye is an important part of the exam. Tests vary, but the goal is to ensure that your eyes function properly together.

Internal eye exam
When examining the internal eye, the eye doctor uses a slit lamp, a diagnostic tool with a powerful microscope and a narrow slit of light, to explore different levels of the eye's transparent tissue and assess the inner workings of the eye. As you keep your head steady on a chin rest, a beam of light is projected onto your eye. The instrument's use of narrow light beams and high magnification provides a cross-sectional picture of eye tissue. This gives the doctor a close-up view of the cornea, anterior chamber, lens, vitreous humor, and retina.

The doctor will check for many things, including degeneration or the presence of foreign particles in the cornea (curved, transparent dome of tissue at the front of the eye), inflammation within the anterior chamber (space behind the cornea and in front of the iris that is filled with aqueous humor), cataract (clouding of the lens), floaters (seeing spots), tumors or abnormal blood vessels in the iris (colored part of the eye that controls how much light enters the eye), and circulatory or degenerative conditions of the retina (the film in the back of the eye).

A vision test or eye exam is a painless exam your optometrist or ophthalmologist will do to be sure your eyes and vision are healthy. It includes tests to check for general vision problems, such as nearsightedness or farsightedness, as well as more serious eye problems, such as glaucoma, cataracts or age-related macular degeneration. Guidelines for the frequency of exams vary, but are typcally based on age, condition of the eyes, and existing risk factors. Here are some general guidelines for when to get eye exams:

  • Children: every 1 to 2 years, starting in early childhood
  • Adults under 40: every 5 to 10 years
  • Adults 40 to 54: every 2 to 4 years
  • Adults 55 to 64: every 1 to 3 years
  • Adults 65 and older: every 1 to 2 years

Your eye doctor may suggest more or less frequent visits. If you wear contacts, or have an eye disorder or a health condition, ask your doctor if you need more frequent eye exams.

Your ophthalmologist and his or her assistants ask about your current symptoms and review your medical history. Eyedrops to dilate your eyes may or may not be used during the exam.

The examination typically evaluates:

  • Visual acuity
  • Need for eyeglasses or contact lenses (refraction)
  • Eyelid health and function
  • Coordination of eye muscles
  • Pupil response to light
  • Side (peripheral) vision
  • Intraocular pressure (pressure inside the eye)
  • The anterior segment in the eye (the area in front of the lens, including the cornea and iris)
  • The interior and back of the eye.

Our eyes need regular checkups from childhood through our senior years. During a comprehensive annual exam, people sit at two to four diagnostic machines while the doctor assesses several things.

Vision is measured to see if glasses, contact lenses or laser surgery is warranted. The eye doctor also screens for glaucoma, a fluid pressure build-up in the eye that damages the optic nerve and is a leading cause of blindness.

The eye doctor also checks the general health of the eye and surrounding tissues and looks for any physical abnormalities.

Dr. Mehmet Oz, MD
Cardiologist (Heart Specialist)

Watch this video to learn more from Dr. Mehmet Oz about an eye scan.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.