What is an eye test?
The vision of the eyes can be checked by means of eye tests. There are various methods for this. Which one is used depends on the goal of the test, i.e. what the test is supposed to determine. Opticians and ophthalmologists usually perform the eye test.
Eye test for visual acuity
To test visual acuity, people like to use vision charts with different sized characters. Most of the time, these characters are numbers or letters. Other symbols commonly used in eye testing are the E-hook and the Landolt ring.
- The Landolt ring consists of a circle with a small opening. It is also always shown on the eye chart in various rotated positions. The patient must then indicate where on the ring the opening is located.
Eye test for children
For preschool children (2 years and older) who are not yet able to express themselves well or read numbers and letters, there is the LEA test as an alternative. In this test, they are asked to recognize highly simplified symbols that they point to on a sheet of paper or for which they are allowed to choose a name. For example, the circle can be a ball or a sun, and the symbol curved on both sides can be a butterfly, apple or heart.
Vision test for central facial deficits
A simple eye test that anyone can easily perform at home is the Amsler grid test. It provides early indications of retinal diseases associated with facial field defects.
How exactly the test with the Amsler grid works and when it is used, you can read in the article Amsler grid.
Eye test for color recognition
How the Ishihara color chart works, what other test procedures there are for testing color perception and how they work, you can read in the article Color vision test.
Eye test to determine refraction
In order to determine the refraction or a possible refractive error (defective vision), adults are usually simply fitted with different lenses. They must then indicate which lenses they see best with.
Stereo eye test
New: The 3D eye test
Since 2014, another eye test procedure has been available: The 3D vision test is designed to conveniently and accurately determine vision. Instead of looking at alphabetic tables, the test person looks through 3D glasses at a monitor on which three-dimensional figures or landscapes appear.
When do you perform an eye test?
Whenever a visual impairment is suspected, an eye test is usually performed. The ophthalmologist or optician will advise this, for example, if a patient or customer reports that the letters are always somewhat blurred when reading (farsightedness) or that he or she can no longer see distant objects or faces clearly (nearsightedness). Here is an overview of diseases that can be detected with an eye test:
- Short-sightedness and long-sightedness
- Strabismus (crossed eyes)
- Night blindness
- Color vision deficiency (e.g. red-green deficiency)
- Retinal diseases (e.g. macular degeneration)
Preventive eye test for children
Many vision disorders such as astigmatism, nearsightedness or farsightedness should ideally be treated at an early stage so that they do not lead to permanent visual impairment. For this reason, an eye test is already performed during various preventive examinations in childhood, namely at:
- U7 at the age of two
- U8 at the age of four
- U9 at the age of 5
Eye test in occupational medicine
Opticians and other authorized bodies often carry out an eye test during preventive medical checkups in the field of occupational medicine. For certain occupational groups, good visual acuity is very important in order to avoid danger to oneself and others. This includes all professions with the following activities:
- Driving and steering activities (e.g. bus drivers, train drivers, pilots)
- Computer workstations (e.g. office work, security guard)
Eye test for the driver’s license
Driving licenses also require an eye test by an ophthalmologist. To find out what requirements are placed on the eyesight of applicants for a driver’s license and how long the completed eye test is valid, read the article Eye Test – Driver’s License.
What do you do during an eye test?
Vision test with eye charts
For the examination of near visual acuity, the doctor places the vision chart about 30 to 40 centimeters away from the patient. If, on the other hand, he is examining TV acuity, the distance between the patient and the chart should ideally be about five meters.
Eye test: refraction determination and skiascopy
In the subjective refraction determination, which is sufficient for adults, the doctor simply puts different glasses on the test person. The subject is then asked to say with which lenses he or she can best recognize the characters or figures depicted on an eye chart.
Long stereo test I and II
The physician holds the test card in front of the subject’s eyes at a distance of about 40 centimeters. The subject is then asked to describe the figures he sees (for example, an elephant or a car). Children who are not yet able to describe what they see in such detail can also point to the figures.
What are the risks of an eye test?
What do I have to observe after an eye test?
Since the eye test procedures are non-invasive and completely harmless examination methods, you do not need to observe any special precautions afterwards.
Depending on the results of your eye test, further test procedures are sometimes necessary for more precise diagnostics, which may, for example, make it necessary to dilate the pupils with special eye drops, thereby limiting your ability to drive for a short time.
