Lyme disease is a tick-borne illness that can present with mild to moderate symptoms upon the initial infection. When a person seeks treatment promptly, their chances of destroying the bacteria completely are higher; however, if treatment is delayed, the bacteria can essentially “camp out” within the tissues of the body, causing chronic post-Lyme disease symptoms.
When someone develops post-Lyme disease syndrome, they can experience issues with various parts of the body – the bacteria doesn’t discriminate, and can attack several different organs and organ systems. In some cases, Lyme disease can attack the structures of the eye, such as the optic nerve. When this happens, the eye structures become inflamed, which affects vision and could bring on pain in the eyes. In some cases, other vision issues can develop, such as contrast sensitivity. But what is contrast sensitivity, exactly? And what is the evidence surrounding contrast sensitivity impairment in post-treatment Lyme disease?
What does contrast sensitivity mean?
Contrast sensitivity is a type of measurement used to distinguish how well the eye can see objects against specific backgrounds. To be more specific, it is the type of sight that allows people to see the fine contrast between different objects that are either light or dark.
Think of a monochrome color board. Typically, monochromatic colors are various shades of the same color. For example, there could be a board full of different shades of gray, ranging from light to dark; they are all the same color, but shaded in different contrasts.
What is impaired contrast sensitivity?
Good contrast sensitivity is marked by a person’s ability to easily distinguish between the lighter and darker shades of color on any given object. A person with good contrast sensitivity has no issues discerning between two shades that have different contrast; they are likely to be able to see even a slight difference between two contrasts.
When a person has impaired contrast sensitivity, however, their ability to see these different contrasts is compromised. A real-world scenario where impaired contrast sensitivity might come into play is driving a vehicle at night. The dark shades of the streets and possibly even pedestrians are difficult to distinguish because there is a lack of obvious contrast between the two.
Low or impaired contrast sensitivity can develop for a few reasons, including:
- Diabetic retinopathy
While Lyme disease isn’t always closely associated with contrast sensitivity deficits, new research has found that there are people with more severe Lyme disease cases who experience this as a particular consequence of the infection.
What do Lyme disease vision problems involve?
As mentioned above, Lyme disease treated early typically results in a full recovery. However, those who do not receive prompt treatment are at a greater risk of experiencing symptoms even after the initial infection has been treated. This is typically referred to as post-treatment Lyme disease syndrome (PTLDS).
Eye involvement isn’t always mutually exclusive with late Lyme disease infections; however, acute disease has also been shown to bring on eye infections such as pinkeye, as well as sensitivity to light. The symptoms that affect the eyes in early Lyme disease are different than those in PTLDS. One particular study looked at contrast sensitivity impairment as a symptom of post-treatment Lyme disease and found that in people with the chronic infection, this impairment can be used to help with diagnosis and identifying what effects the infection has had on the neurological system.
Lyme disease and contrast sensitivity
The study mentioned above recruited patients between 2015 and 2020 to participate in a vision test. Each patient had post-treatment Lyme disease. To participate in the study, each patient had to have undergone treatment for Lyme disease in the past and still be experiencing symptoms such as fatigue, chronic pain, or general cognitive dysfunction.
To help find out what was going on in terms of contrast sensitivity in post-treatment Lyme disease patients, the study used two sample populations. One had no history of Lyme disease, while those in the other had already recovered from an acute case of the infection. Each participant was put through visual testing to measure their contrast sensitivity. Tests were also conducted to help identify neurological and cognitive deficits in the same two groups of patients.
The results showed that people with post-treatment Lyme disease had a much higher rate of impaired contrast sensitivity than those in the control group. However, that isn’t all the results found. It turned out that patients with impaired contrast sensitivity were also more likely to experience issues with their neurological system. This shows that issues with contrast sensitivity may have a possible neurologic component.
People with cognitive issues because of Lyme disease were also more likely to have impaired contrast sensitivity; however, the connection may simply be because people with cognitive decline often experience brain fog, fatigue, and the inability to concentrate, which may make it more difficult to get through a contrast sensitivity test.
Cases of post-treatment Lyme disease continue to warrant more research to identify and address various issues that may develop, such as a decrease in contrast sensitivity.
Featured image by Paul Gilmore on Unsplash