Eye examinations are an important part of eye health. At Blue Sky Vision-Three Rivers, our doctors perform eye exams on patients of all ages.
What are Eye Examinations?
Eye exams are a way to measure and test your vision. They are also the only way to check for eye diseases.
Eye exams can only be performed by a qualified eye care professional. During an eye exam, your eye doctor will test your eyes using a variety of instruments.
They will also ask you to look through different kinds of lenses and they may shine bright lights in your eyes. If you have never had an eye exam before, there is nothing to be afraid of.
What Happens at an Eye Examination?
During a comprehensive eye exam, patients undergo several tests. The first is usually a visual acuity test to measure how sharp your vision is.
During a visual acuity test, you will sit in front of an eye chart that has numbers and letters on it. This measures your distance visual acuity and your near vision.
The next test you may complete is a color blindness test. This is a short test that tests your vision to see if you are color blind. It can also let your eye doctor know if you have other possible eye problems.
Another common test during an eye exam a cover test. This test is one of the easiest ways to see if your eyes work well together.
With the cover test, your eye doctor will ask you to focus on a small object that is across the room. They will then cover each of your eyes in succession while you stare at the small object.
To test your near vision, you will do the same thing while looking at an object that is up-close. While you look at the target objects, your eye doctor will pay attention to how your uncovered eye reacts.
If the uncovered eye needs to move to see the target you are looking at, this could be a sign of strabismus. Leaving this untreated could lead to eye strain or amblyopia, known as lazy eye.
Ocular Motility Testing
The next series of tests you may complete is ocular motility testing or eye movements. These tests help your eye doctor understand how your eyes follow a moving object.
They also help with seeing how the eyes can quickly move between and accurately look at two different things.
Smooth Eye Movements
You may also have your smooth eye movements, or pursuits, tested. You will hold your head still, and then follow your eye doctor’s movement of a hand-held light or another object with only your eyes.
If problems with eye movements are picked up on, it can cause eye strain. This can lead to trouble with reading ability and sports vision.
Another important test you may be given during an eye exam is a stereopsis test. This is how depth perception is tested for. One common way of testing for this is by wearing a pair of 3D glasses.
With the glasses on, you will look at a booklet filled with test patterns. Each pattern has four small circles inside of it.
The patient must point out which circle in each pattern looks closest to them. By identifying the closer circle in the patterns, it means the patient has normal depth perception.
For patients that wear glasses, this test might seem familiar. This test is often used to approximate an eyeglass prescription. During retinoscopy, the lights will be dimmed down.
You will then be asked to focus on a target, which is usually a large E on the eye chart. While you look at the E, your eye doctor will shine a light in your eye.
They might also flip lenses on a machine in front of you. The retinoscopy test helps determine which lens powers will correct your distance vision the best.
To determine the exact eyeglass prescription necessary, your eye doctor will use refraction. During refraction, an instrument called a phoropter will be put in front of your eyes.
Your eye doctor will then show several lens choices. After showing you the different lenses, they will ask you which lens in each of the choices was the clearest.
Based on your answers on what is the clearest, your eye doctor can come up with a precise eyeglass prescription with a fine-tuned lens power.
Slit Lamp Exam
To test for a wide variety of eye conditions like glaucoma, cataracts, and macular degeneration, your eye doctor may perform a slit lamp exam. This is performed with a binocular microscope or biomicroscope.
This biomicroscope allows your eye doctor to examine the structures of your eyes under high magnification. With a hand-held lens, they can also use it to see structures at the back of the eye like the retina or the optic nerve.
Testing for Glaucoma
One way of testing for glaucoma is non-contact tonometry or NCT. With NCT, you put your chin on the machine’s chin rest and look at a light inside the machine.
A small puff of air is then aimed at your open eye. There is no pain and the tonometer will not touch your eye.
Another way to test for glaucoma is with an instrument called an applanation tonometer. It is often mounted on a slit lamp.
For this test, your eye doctor puts yellow eye drops in your eyes to numb them. They are yellow because the drops glow under blue light, making it easier to see.
You will then stare straight ahead into the slit lamp. Your eye doctor will touch the surface of your eye with the tonometer to measure intraocular pressure. This is not painful and will take only seconds to complete.
During a comprehensive eye exam, you will likely have your pupils dilated. This can take about 20 to 30 minutes before it starts working.
Pupil dilation is important because it gives your eye doctor an excellent view of the eye’s internal structures. Without dilation, these internal structures are impossible to see.
Once your pupils have been dilated, you will may be more sensitive to light. You may also find it harder to focus on objects that are up close. This is temporary, but it can take several hours before the drops wear off.
What is the Difference Between an Eye Examination and a Vision Screening?
Some children receive vision screenings at school, but this is not the same thing as an eye exam. A vision screening is often performed by a primary care provider or in a school setting that looks for potential vision problems.
One of the biggest differences between a vision screening and an eye exam is a vision screening cannot diagnose a vision problem. If a vision problem is suspected or found during a vision screening, you will then be referred to an eye care specialist.
Who Needs Eye Examinations?
Everyone needs eye exams, though how often you need them depends on your age and if you have existing vision problems.
Infants should have their eyes checked for infections and other disorders and should be brought back in at six months old. At the age of 5 and older, children should have eye exams every year.
This should continue if children wear glasses or contacts and need prescriptions updated. If children do not have vision problems, they should have their vision checked every one to two years.
Adults without vision problems should get their eyes checked every two years. If you have vision problems, you should get eye exams every year or as recommended.
Adults who are 61 years old and older should have an eye exam every year or as recommended. This is the age when you are more likely to develop problems like cataracts, age-related macular degeneration, and glaucoma.