Due to the variability of causes associated with retinitis, there are a variety of tests available to diagnose the underlying cause. Genetic defects such as retinitis pigmentosa is primarily diagnosed with an electroretinogram.^[1] Other underlying causes may be distinguished using a variety of testing procedures. These procedures are usually directly associated with the hypothesized condition causing retinitis. Many of the underlying conditions may range from fungal to bacterial and thus are tested accordingly.^[2]

• Electroretinogram^[1]

• Polymerase chain reaction (PCR) testing in particular regions
• Usually detectable in blood and other bodily fluids^[2]

• Positive purified derivative skin testing
• Interferon-gamma release assay (QuantiFERON Gold TB Test)
• Isolation of acid-fast bacilli^[2]

• Testing methods for identification of a fungal infectious agent largely depend on microscopic examination of infected area.
• Localized infections may display hyphae and typically, easily identifiable lesions.^[2]

• Serological testing (ELISA)^[2]

• Serological testing
• Rapid plasma reagin (RPR) testing
• Fluorescent treponemal antibody absorbtion testing (FTA-ABS)^[2]