The optometrist told me my son is not seeing because of a scar in the back of the eye from toxoplasmosis. What is this?
Toxoplasmosis is a disease caused by a protozoa (a type of germ) called toxoplasma gondii. It is usually found primarily in cats, undercooked meat, or infected water.
Many people may have been infected and not know because a healthy person’s immune system usually keeps the parasite from causing illness. Pregnant women, children whose immune systems aren’t fully formed, and immuno-compromised persons like those infected with HIV, are more at risk since Toxoplasma infection could cause serious health problems.
Toxoplasmosis can be congenital – present at birth from an infection got from the mother while she was pregnant, or acquired as a child or adult. In fact, mostly this disease is congenital; the pregnant mother contracts it by coming into contact with an infected cat or its droppings, and may pass the infection on to the unborn child.
The infection is much worse if the mother contracts it during the first trimester and it can cause neurological as well as ocular problems.
In Guyana, because it is tropical, cats wander around yards at will.
Children who play in dirt or sand, and accidentally put into their mouths their fingers which may have encountered the parasite, can then become infected. Teach your children to always wash their hands after playing with cats, or after playing in dirt or sand.
How did it cause the scar?
The germ travels through the body and settles in the retina, which is the back layer of the eye, where it causes an infection. It is an unfortunate fact that congenital infection tends to involve the macula, the part of the eye we use for primary vision.
When the initial infection occurs, patients report seeing lots of fine spots in their central vision. These spots represent inflammatory cells. When the inflammation resolves, a scar remains. If the scar involves the macula, the vision can vary from mildly reduced to legal blindness in that eye. Toxoplasmosis can affect one or both eyes, and to differing degrees.
The first scar is at the macula and this patient will have very poor vision whereas the second scar is off in the periphery and this person will have very good vision.
Can it be treated? Removed? Can it get bigger?
Unfortunately, the scar is permanent. As well, the toxoplasma germ can stay dormant in the retina for many years and reactivate at any time and when it does this, a new infection can start.
Patients notice blurred vision and spots in the central vision. If you know you have retinal toxoplasmosis, as soon as you notice these symptoms, go to your eye care practitioner immediately, as the earlier the treatment is instituted the better, since this can decrease the length of the blurry vision and size of the scarring, and ultimately the amount of vision lost.
