Online Vision Test: ZEISS Online Vision Screening

This is certainly the most important. All eyeglass wearers are familiar with this test. The eye doctor asks you to read letters or symbols and to identify the direction of the opening in special rings (Landolt rings) – each with a different size on a projection surface. The eye doctor checks the size of the various elements you can identify them without difficulty. A process known as subjective refraction is also performed after this by the eye doctor. After various lenses with different powers have been inserted in a device known as a trial frame, we indicate whether we see better or worse with each lens. The eye doctor begins to optimize the lens first for one eye, and then for the other. It is then important to check the interaction of the eyes by using a binocular test. Other tests can also be used to identify a condition known as associated heterophoria, which can then be corrected and, in some cases, treated.

In  Part 1  of our free online assessment we simulate the testing of your visual performance on the screen. This is not intended as a replacement for the tests conducted by your eye doctor. However, you will receive an initial impression of the quality of your vision.

During eye examination, the refractive power required to correct defective vision is determined without accommodation (the eye's automatic adaptation to various distances).

Initially, you may think that this test is not really important. However, contrast vision is of major significance for comfortable vision. If we cannot distinguish differences in contrast, eye fatigue may be the result. We all know what it's like when the contrast isn't properly set on our computer screen, or if we try to read in poor light.

Checking contrast vision is important to identify any changes that have occurred to our vision. Changes in contrast sensitivity may, for example, be an indication of glaucoma.

In  Part 2  our online screening assessment we simulate contrast vision. The test may provide you with an initial indication that your contrast vision is not as good as it could be. Your eye doctor will be pleased to look into this in more detail.

What we all know as "color blindness" affects many more men than women. This is a genetic variation that affects as many as 180 million people worldwide. Various types of lenses are available for this condition.

1. People with this condition have only a limited ability to recognize certain colors. All the sensory cells – the red, green and blue cones – are present within the retina, but some of them do not function correctly. The most common form of the condition is red/green blindness.
2. Partial color blindness: In this form of the disorder some of the sensory cells are not present at all or are not functioning. The people affected have only two types of still functioning receptors. The result: color vision is significantly impaired. This can sometimes be dangerous especially for red-weak and red-blind car drivers. In fog, for example, they see only black instead of the red rear light of a vehicle in front of them.
   
3. Total color blindness: The disorder known as achromatopsia is very rare. People with this condition cannot perceive any nuances in color at all.

To diagnose the condition, the eye care professional uses three different tests: pseudoisochromatic plates, the Farnsworth test and Nagel's anomaloscope.

In  Part 3  of our free online check you can test your color vision with color charts.

Astigmatism is a type of refractive error of the human eye in which the focal point is not evenly distributed along the meridians. As with other refractive errors, astigmatism can change gradually with age. Symptoms with  astigmatism can include eyestrain, headaches or trouble driving at night. Astigmatism can be corrected  with properly fitted glasses or contacts.

In  Part 4  you can check your eyes for Astigmatism.

The check provides a symbol which contains differently orientated groups of black lines. These lines are designed to appear in different shades of gray if your eyes have some astigmatism. Your task is to indicate whether you see the sharp/black differently, which is a first sign for astigmatism.