Vision test With an eye test, vision is tested. Learn more about the procedure and reasons for eye tests.
What is an eye test?
An eye test is used to check vision. Depending on what is to be tested, different examination methods allow an eye test to be performed. Opticians and ophthalmologists are, in most cases, the ones who perform an eye test.
Visual acuity eye test (visual acuity)
Visual acuity indicates how far two points must be for the retina to perceive them as separate points. Therefore, eye charts are used to check visual acuity, on which figures of different sizes are represented. Most objects on the panels are numbers or letters. Other symbols commonly used in the eye test are the E-hook and the Landolt ring.
The E-hook looks like an exaggerated E and is displayed on an eye chart in different positions: sometimes E is “on the back”, sometimes it is inverted in the mirror. The patient should report to the doctor who positions the e-hook.
The Landolt ring consists of a circle with a small opening. It is always shown in the eye chart in different rotated positions. The patient must then indicate where the ring is located on the ring.
Eye test for central facial defects
A simple eye test that the patient can perform well at home is the Amsler grid test, which can provide early evidence of retinal disease.
More information: Amsler grid
What is the Amsler grid and how to use it to test your eyesight, read in the Amsler grid.
Eye test for color detection
Although most eye testing procedures primarily check visual acuity, it is just as important for the ophthalmologist to test eye color perception. For example, he may recognize the red-green weakness. Examination methods for color vision differ in structure from examination of visual acuity. In Germany, the so-called Ishihara color chart is used, a simple and inexpensive method.
Additional information: Color visibility test
What test methods are used in the color visibility test and how they are performed, read the article Color Vision Test.
Eye test to determine refraction
The refraction of the eye denotes the state of refraction and depends on the relationship between the power of refraction and the axial length of the eye. This means that the power of refraction is changed so that the seen image is focused either slightly in front of or just behind the retina. If the eyeball is too short in relation to the power of refraction, diarrhea occurs; if it is too long, the patient is nearsighted.
Determination of refraction in adults usually takes place simply by putting on different lenses of glasses; The patient indicates which glasses he sees best. In infants, young children, and patients who are unable to express themselves due to language problems, dementia, or other illnesses, the doctor uses so-called skiascopy (shadow sample).
Eye test in children
Children usually have excellent memory and can quickly memorize images. As beautiful as this skill is, it makes the eye test so difficult. Children are often able to disguise poor eyesight by guessing the pictures on the diagrams. Therefore, eye charts with typical pictures for children, such as animals, cars or clothing, are not suitable for eye testing in children. It is better to have an eye test with the so-called e-hooks or Landolt rings that represent more abstract shapes. They are not easy to remember and are harder to guess. Only then can the doctor get an objective result in the children’s eye test and discover a visual disturbance.
Many eye tests require covering one eye so that the eyes can be examined separately. Children often try to look at the tablets with both eyes with their fingers. Then, a unilateral visual impairment is compensated by the healthy eye and remains undetected. To avoid this, the doctor often asks parents to cover one of their child’s eyes with their hands. It is even safer to mask an eye with an eye patch.
stereo vision screening
The ability of the eyes to obtain a spatial visual impression is called stereo vision. There are several methods of testing and examination: Long stereo tests I and II are used specifically. They each consist of a test book on which many randomly distributed black dots form three-dimensional images. The patient can only discover them with intact stereoscopic vision. The only difference between the stereo test I and II is that the images on the latter are a little finer.
New: 3D eye test
Recently, a new eye test procedure has become available: a 3D eye test promises a more comfortable and accurate vision assessment. Instead of looking at letters, the patient looks at patients through a pair of 3D glasses on a monitor, on which three-dimensional figures or landscapes are now displayed. For example, this test is intended to provide benefits to people who need a pair of progressive lenses in order to better determine the vision needed in various simulated situations during the test. However, the 3D testing system is not yet installed by many opticians or ophthalmologists.
When do you have an eye test?
Whenever there is a suspicion of poor eyesight, usually do an eye test. Ophthalmologists or opticians, for example, hear from a patient that the letters are always a little blurry when they read or that they no longer clearly recognize distant objects or faces. When diagnosing the following diseases, an eye test can provide valuable information:
- Short and long
- Color deficiencies (eg red-green weakness)
- Retinal diseases (eg macular degeneration)
Eye test in children
Many visual disturbances, such as astigmatism, short or long vision, should ideally be treated early so as not to lead to permanent visual impairment. Therefore, an eye test is already performed in childhood exams. The eye test at the pediatrician is part of the following checks:
- U7 at the age of two
- U7a at the age of three
- U8 at the age of four
- U9 at the age of 5 years
Eye test in occupational medicine
An eye test at an optometrist or other authorized locations is also commonly used in preventive occupational health examinations. For certain occupational groups, good visual acuity is important to avoid dangers to themselves and others. This includes all professions with the following activities:
- Driving and charging (bus drivers, train drivers, pilots)
- Surveillance activities (operation of power plants or furnaces)
- Computer workstations (office, security)
The license for individuals also requires an eye test at the ophthalmologist.
Additional information: Eye test: driving license
What requirements do you have in mind when purchasing a driver’s license, read in the article Eye Tests – driving license.
For these diseases, an examination is important
- macular degeneration
- Retinitis pigmentosa
- Red-green color blindness
What do you do in an eye test?
The different eye tests procedures differ in their order. However, with the exception of the stereoscopic test, they all have in common that each eye is examined individually. Only in this way can the doctor reliably detect unilateral visual impairment. Examinations are usually performed by an optician or ophthalmologist.
Eye test with eye charts
For the examination of Nahsehschärfe, the doctor places the eye chart about 30 to 40 centimeters from the patient. On the other hand, if you examine the clarity of the TV, the distance between the patient and the tablet should be around five meters. First, the doctor asks the patient to cover his eye with his hand. Then the patient should name the figures displayed on the eye map, starting with the large images. Following the eye tests for the other eye follows the same principle.
Eye test: refraction determination and skiascopy
In determining the subjective refraction, which is sufficient in adults, the doctor simply puts the patient in different glasses. The patient should then say with which eye lenses he can recognize the best figures represented on an eye chart.
For patients who cannot express themselves or for children, the doctor uses the skiascope, also known as the shadow test. The doctor sheds light on the patient’s student with a special device, the skiascopy. If the doctor turns the ski-goal into a patient with a distance view, his students move in the direction of rotation. In a moving person, students move in opposite directions to the direction of movement of the skiascopye. The doctor then sets different lenses in front of the patient’s eye, until the student no longer moves with the ski rotation.
A long stereo test I and II
The doctor holds the test card at a distance of about 40 centimeters from the patient’s eyes. He asks the patient to describe the numbers he sees (for example, an elephant or a car). Children who cannot describe what they saw such details should best indicate the figures.
More about symptoms
- blurry vision
What are the risks of an eye test?
The eye tests is not invasive, the patient should read only the numbers or figures. Therefore, the patient should not expect risks or side effects. Worst case, it can cause some eye tests, in which the doctor must rely on patient statements coming from inadequate staff to incorrect results. Then, a visual disturbance may not be detected. Therefore, it is very important that the patient is honest with the doctor and himself during the eye tests.
What should I think about after an eye test?
Because eye testing methods are non-invasive and completely harmless examination methods, it is not necessary to take special precautions. Depending on the outcome of your eye tests for a more accurate diagnosis, sometimes more testing methods are needed, which make a dilation of the pupils with special eye drops as needed, thus limiting the ability to drive in the short term.
Your doctor should be at your vision test. If he has noticed a problem with his vision, he will inform you of your treatment options and plan your further care by consulting with you.