Scientists from Nagoya University have found that the cause of blindness in ocular toxoplasmosis is the accumulation of iron in the retina. A drug that reduces iron concentrations mitigates the disease in mice. The study was published in the journal Redox Biology.

Toxoplasma is a parasite that infects approximately a third of humanity. When Toxoplasma affects the eyes, 25% of patients experience vision loss. This is partly because the PCR test used to diagnose the disease is unreliable, with an accuracy rate of only 30%.

In a new study, scientists suggested checking iron levels in patients’ eyes instead of testing for the parasite. They found increased concentrations of iron in the retinas of mice with toxoplasmosis. In addition, people with ocular toxoplasmosis had decreased vitreous iron concentrations compared to patients with other eye diseases, which may indicate migration into the retina. The sensitivity and specificity of the test based on the analysis of iron levels exceeded 80%. Further research showed that iron accumulation caused retinal cell loss, which may be a cause of blindness. Administration of the iron-binding drug deferiprone reduced retinal inflammation in mice.