The Difference Between a Vision Screening and a Comprehensive Eye Examination



What Is a Vision Screening?
What Is a Comprehensive Dilated Eye Examination?
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What Is a Vision Screening?

A vision screening is a relatively short examination that can indicate the presence of a vision problem or a potential vision problem. A vision screening cannot diagnose exactly what is wrong with your eyes; instead, it can indicate that you should make an appointment with an ophthalmologist or optometrist for a more comprehensive dilated eye examination.

However, there is no clear evidence about the accurateness and effectiveness of a vision screening for open-angle glaucoma (U.S. Preventive Services Task Force, 2013). For glaucoma, a comprehensive dilated eye exam is the most effective detection method.

Tom McCarville, Co-Founder, E.A.R.S. for EYES Vision Rehabilitation Services

Tom McCarville head shot

Fifteen years ago, Tom McCarville was a photographer and lighting engineer, running his own company with his partner Martha Parisian. With combined experience in movie making, television, and commercial photography, Tom and Martha had a successful media business and were climbing their joint ladder of success.

Life changed when Tom decided to visit his eye doctor and purchase a more modern pair of eyeglass frames. He was given the news that he had permanently lost 20% of his peripheral vision through glaucoma. "The disease is out of control," he was told by his ophthalmologist. Learn more about the ways Tom coped with glaucoma, along with these facts about the importance of eye examinations:

What Is a Comprehensive Dilated Eye Examination?

A comprehensive dilated eye examination generally lasts between 30 and 60 minutes, and is performed by an ophthalmologist or optometrist. It should always include the following components:

1. A Health and Medication History

  • Your overall health and that of your immediate family
  • The medications you are taking (both prescription and over-the-counter)
  • Questions about high blood pressure (hypertension), diabetes, smoking, and sun exposure.

2. A Vision History

  • How well you can see at present, including any recent changes in your vision
  • Eye diseases that you or your family members have had, including macular degeneration and glaucoma
  • Previous eye treatments, surgeries, or injuries
  • The date of your last eye examination

As part of the vision history, the doctor may ask you the following questions:

  • Are you having any problems with your vision?
  • How long have you had these problems?
  • When do these problems occur?
  • When was your last eye examination?
  • Do you have any family history of eye problems?
  • How is your general health?
  • What medications are you taking?
  • Do you have any allergies?

This history of your own health and that of your family can give the doctor an indication of any issues that may be affecting, or could affect, your vision.

3. An Eye Health Evaluation

  • An examination of the external parts of your eyes: the whites of the eyes, the iris, pupil, eyelids, and eyelashes.
  • A dilated eye (or fundus) examination that can be achieved with the use of special lenses will allow your doctor to see inside your eye and examine the retina and optic nerve. Your doctor might choose to use eye drops to see the retina and optic nerve more clearly.
  • A test of the fluid pressure within your eyes to check for the possibility of glaucoma.

4. A Refraction, or Visual Acuity Testing

a phoropter

A refraction helps determine the sharpness or clarity of both your near (reading) and distance vision.

This includes testing your vision with different lenses (sometimes contained in a machine called a phoropter, pictured at right) to determine if your vision can be improved or corrected with regular glasses or contact lenses.

5. Visual Field Testing

Visual field testing helps determine how much side (or peripheral) vision you have and how much surrounding area you can see.

Humphrey Field Analyzer

The most common type of visual field test in a comprehensive eye exam is called a confrontation field test, in which the doctor briefly flashes several fingers in each of the four quadrants (above, below, right, and left) of your visual field while seated opposite you.

In some cases, your doctor may also want to perform a more precise visual field measurement, using a computerized visual field analyzer, such as the Humphrey Field Analyzer (pictured at left).

6. Your Examination Results

The doctor will be able to determine if the visual problems you are experiencing are normal age-related changes or are disease-related, and if additional testing, referral to another doctor or specialist, or treatments are needed.

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