Background: Pyrimethamine, an inhibitor of folate biosynthesis in bacteria and protozoa, is mainly used to treat toxoplasmosis outside of Japan. Here, we report on two patients with ocular toxoplasmosis treated with pyrimethamine.
Cases: Patient 1, a 58-year-old female, visited her local ophthalmologist upon noticing blurred vision in her left eye. She was referred to our department due to suspected toxoplasmosis of the left eye based on the white exudative retinal lesion observed in the left eye. The patient was diagnosed with ocular toxopla s mosis based on an increase in serum anti-toxoplasmosis IgM antibody titers. As oral treatment with acetylspiramycin was ineffective, oral treatment with pyrimethamine was initiated. The lesion shrunk and no subsequent recurrence of the eye lesion was observed thereafter.
Patient 2 was a 29-year-old female who presented with an exudative retinal lesion in the right eye. She was diagnosed with uveitis in the right eye by her local ophthalmologist and was treated with oral prednisolone. A subsequent diagnosis of ocular toxoplasmosis was given based on an increase in serum anti-toxoplasma IgM antibody titers. Despite initiating oral administration of acetylspiramycin, the disease worsened, and the onset of tractional retinal detachment was observed in the right eye. Thus, the patient was referred to our department. Intravitreal injections of clindamycin were administered to both eyes and vitreous surgery was performed for the tractional retinal detachment in the right eye. The lesion tended to shrink; however, there was residual disease. Oral administration of pyrimethamine was initiated, resulting in the shrinking of the lesion. However, the onset of drug-induced encephalopathy was observed 4 weeks after oral administration of pyrimethamine. Hence, its administration was discontinued.
Conclusion: Although treatment with pyrimethamine is effective in patients with persistent ocular toxoplasmosis, caution is required regarding the possibility of adverse reactions.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 125: 122-128, 2021.