Posterior Uveitis Due to Toxoplasmosis
Focal chorioretinal inflammation caused by infection.
This clinical syndrome is encountered frequently.
The pathogen,Toxoplasma gondii, is transmittedby ingestionof tissue cysts in raw or undercooked meat or by oocysts from cat feces. In con-genital toxoplasmosis, the child acquires the pathogen through transplacen-tal transmission.
As a general rule, a negativecomplement-fixation test does not exclude Toxoplasma infection where clas-sic clinical symptoms are present. Both forms of the disorder present with characteristic grayish white chorioretinal focal lesions surrounded by vitreousinfiltration and associated vasculitis (Fig. 12.34). Incongenital toxoplasmosis,the affected children have a macular scar that significantly impairs visual acu-ity. This often leads to secondary strabismus. Intracerebral involvement can also result in hydrocephalus and intracranial calcifications. In the acquiredform, visual acuity is impaired only where the macula is involved. This israrely the case.
Congenital toxoplasmosis results in a macular scar that significantly impairs visual acuity.
Chorioretinitis with tuberculosis, sarcoidosis, bor-reliosis (Lyme disease), or syphilis should be excluded by serologic studies.
The treatment of choice consists of a combination ofpyrimethamine, sulfonamide, folinic acid, and steroids in their respective standard doses.
Avoid raw meat and cat feces.
Posterior uveitis due to toxoplasmosis usu-ally heals without severe loss of visual acuity where the macula is not involved. However, it can recur at any time. There is no cure for the congenital form.