A slit-lamp, which is a specialized magnifying microscope, is used to examine the structures of the eye (including the cornea, iris, vitreous, and retina). The slit-lamp is used to examine, treat (with a laser), and photograph (with a camera) the eye.

Human infection with the toxoplasma gondii protozoan results from ingesting contaminated raw meat or soil, or careless handling of the contents of an infected cat's litter box. An infected pregnant woman can transmit the infection to her fetus (congenital toxoplasmosis).

Antigens are large molecules (usually proteins) on the surface of cells, viruses, fungi, bacteria, and some non-living substances such as toxins, chemicals, drugs, and foreign particles. The immune system recognizes antigens and produces antibodies that destroy substances containing antigens.