Dynamic Visual acuity is used to refer to the clarity of the vision that is experienced by a person. In simple terms, it is a way of measuring how “well” a person can see. There are a number of factors that influence visual acuity such as:
- The health of the retina and how sharp it can focus within the eye.
- The sensitivity of the interpretative process of the brain.
Whereas static visual acuity refers to the ability of a person to see objects which are stationary, dynamic visual acuity measures the sharpness and clarity of vision when it comes to situations where either the object or the observer is moving.
In this blog, we’re going to understand what is dynamic visual acuity and learn about the tests that are used most commonly these days.
Dynamic Visual Acuity (DVA)
Vision is one of the most important of all our senses and we use it to guide almost every action of our lives. Visual acuity refers to a person’s ability to see things. While static visual acuity refers to our ability to see things that are not moving, DVA refers to the ability to see things that are in motion.
Most people think of a static visual acuity test like a Snellen chart when they think of a visual acuity test. Snellen charts are very commonly used as most people have to get a static visual acuity test at some point in their lives.
However, not a lot of people know about DVA or the tests that are used to measure it because not a lot of people experience loss of their dynamic visual acuity which is often caused by health problems such as Benign Paroxysmal Positional Vertigo (BPPV), particularly during its acute onset.
The term dynamic visual acuity was first used in 1949 by researchers to describe a person’s ability to “visually resolve subtle spatial details of an object” when the object or the observer is in motion. A DVA test is usually performed using specialized equipment that can detect it but there are very few instruments with proven reliability and validity and there has been a lack of research on-going in this field.
A DVA diagnosis test or an eng test is often undertaken by patients suffering from BPPV as part of their diagnosis and treatment.
How does our vision work?
Even though our eyes are really important for vision, they do not solve the problem of translating light into “vision” and just allow the light to enter the eye. There are a lot of different neural mechanisms that handle the process of visual perception in human beings.
The optic nerve is used to route information to the central cortex via the thalamus. This is where visual perception takes place. However, the nerve is also used to carry information for two important sites in the brainstem. These two sites are called pretectum and superior colliculus.
The pretectum controls the pupillary size in response to the intensity of the light and the superior colliculus is concerned with moving the eyes in quick bursts, which are called saccades. These saccades allow our brain to detect motion by “stitching” a series of relatively still pictures together.
This explains the low correlation between static visual acuity and DVA in patients as they are handled by different neural mechanisms.
Dynamic Visual Acuity Test
Dynamic visual acuity is used to evaluate the vestibulo-ocular reflex (VOR). VOR is used in dynamic motion and is used to create smooth a vision of the objects we see when we move our heads or when the object moves or when there is any kind of motion involved.
VOR has to be tested in all patients suffering from vertigo and it one of the most common symptoms of vertigo that causes people to seek treatment. The test is usually computerized and is pretty much like an eye test used by an optometrist to test the vision of a patient.
While non-computerized tests were common, these days most tests are computerized and use the latest technology. Our DVA testing equipment use advance features like precise head motion tracking and other computing
Computerized Dynamic Visual Acuity
Computerized Dynamic Visual Acuity is a computerized test that can be used for the screening of vestibular impairment. The test is used for the following reasons when it comes to vertigo treatment:
- Early detection of vestibulotoxicity
- Detection of bilateral peripheral vestibulopathy
- Rehabilitation tool
- Determining the output of rehabilitation
DVA asses the function of VOR i.e maintaining the image on the fovea of the retina during head movement. As mentioned earlier, defective VOR results in blurry dynamic vision which is a symptom of vertigo.
Our DVA test is computerized and uses motion sensors that detect head movement and provide precise data for head velocity and angulation which makes the testing of the VOR much more reliable and provides a lot of support in the treatment of the underlying conditions.
The VOR (vestibulo-ocular reflex) gain is most helpful when it comes to diagnosing ototoxicity and other bilateral vestibulopathy.
The dynamic visual acuity test is used to precisely measure the VOR and is critical when it comes to the treatment of vertigo in people. A computerized dynamic visual acuity test can detect VOR more precisely.
We manufacture the latest DVA testing equipment with the latest technology and strive to create solutions that make vertigo treatment better and easier. A video electronystagmography test is often used in the DVA test.