Eye Tests: What Are They and What do They Measure?

It's common to think that your vision is fine if you do not have any symptoms of an eye problem. However, it is essential to understand that many types of eye diseases do not cause symptoms in their early stages. 
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Eye exams or tests are vital for diagnosing various types of eye diseases. The specific eye tests performed by an eye specialist may vary depending on your age, underlying medical condition, and any eye symptoms present. Eye exams can detect problems with eye pressure, blood vessels, and retinal issues. 

Continue reading for an overview of various types of eye tests, their purposes, and what they measure.

Visual Acuity Test: A visual acuity test is an eye exam you may be familiar with. It measures how well you can see, including the clarity and sharpness of your vision. Usually, a visual acuity test involves reading symbols or letters on an eye chart from a certain distance. A visual acuity test cannot determine the cause of poor vision, but it can provide an indication that your vision is normal or that it requires additional testing.

Refraction Test: Your eye specialist will do a refraction test if it appears that you need eyeglasses. The doctor uses a device called a phoropter. You are asked to compare visual clarity while looking at an eye chart through a series of lenses of different strengths. This helps determine your eyeglass prescription. 

Slit-lamp Examination: This exam provides a view of the structures in the front of your eye, including the iris, lens, and cornea. It can help determine any abnormalities and diagnose various eye diseases, such as cataracts. To perform the exam, your eye care professional uses a special microscope with a focused beam of light to view the structures.

Eye Muscle Movement Test: An eye movement test can help detect abnormal eye muscle function, including crossed or lazy eyes. Your eye specialist may ask you to follow an object, such as a light, with your eyes as it moves in different directions. This allows the doctor to evaluate how well your eyes track the object, which helps determine the functioning of the eye muscles.

Intraocular Pressure (IOP) Measurement: The eye specialist will likely use a special device called a tonometer to measure the pressure in the eye. Increased intraocular eye pressure may require further testing to monitor for glaucoma.
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Retinal Examination: A retinal exam helps visualize the back of the eye, including the optic nerve, retina, and surrounding blood vessels. It is often performed using a special instrument to examine dilated eyes. Digital imaging can also be used for a detailed analysis of the retina.

The type of eye tests recommended may depend on your family history of eye diseases, medical conditions present, and any visual symptoms you may be having. 

​When should you have eye exams?

A comprehensive eye exam will often include some or all of the tests listed above. According to the American Academy of Ophthalmology, most people should have a comprehensive eye exam by age 40. However, some people may need an eye exam sooner. Consider seeing an eye specialist earlier than age 40 in the following situations:

• You have a family history of glaucoma
• You are diagnosed with diabetes
• You develop visual symptoms, such as double vision, decreased vision, or pain in your eyes

Remember, eye tests play a vital role in monitoring the function and health of your eyes. If you develop any visual symptoms, do not delay seeing a specialist. Early diagnosis and treatment of certain eye diseases may reduce your risk of vision loss.

If you would like to ask whether an appointment with one of our eye doctors would be appropriate at this time, call our office at 508-746-8600.
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