As far as I know, there is no permanent treatment for ocular toxoplasmosis. After treatment, it will become dormant. During this stage, it becomes a cyst. This cyst stage is very resistant to the host immune system, therefore it stays in the retina for the rest of your life. However, the disease can reactivate in the eye (usually at the edge of an old scar). The cyst ruptures and releases live organisms into the tissue. With further treatment, it becomes a cyst again. And the cycle can continue ad infinitum.
Toxoplasmosis is actually a protozoa, not a bacteria or virus. The good news is that, unless you are immunocompromised, the chance of reactivation is low.
Hope this helps