In the eye, the most minute focus of inflammation due to congenital toxoplasmosis is recorded permanently as a pigmented chorioretinal scar. Typically, each macula is attacked with disastrous effect on vision. Serologic examinations are most important. If either the patient or his mother shows no serologic evidence of past infection, a diagnosis of congenital toxoplasmosis should be disregarded. The inexperienced examiner must be warned against the many other pigmented and central retinal conditions with which chorioretinitis may be confused. The greatest help that can be obtained in the matter is wide dilation of the pupils. Only increased awareness will lead to an accurate determination of the incidence of the disease.
Fair JR. CONGENITAL TOXOPLASMOSIS—DIAGNOSTIC IMPORTANCE OF CHORIORETINITIS. JAMA. 1958;168(3):250-253. doi:10.1001/jama.1958.03000030022005