Reduced full-field electroretinogram (ERG) in a patient treated with methotrexate

To examine retinal function in a patient with decreased vision possibly due to treatment with methotrexate.

Ophthalmological examination included testing of visual acuity (VA), fundus inspection, fundus photography, and kinetic perimetry. Retinal function was tested objectively with three electrophysiological methods: full-field electroretinography (ERG), multifocal electroretinography (mfERg) and also electro-oculography (EOG).

A 13-year-old boy with psoriasis arthritis had been treated with methotrexate on a weekly basis for 8.5 years. After terminating treatment, his VA, which was reduced to 0.3 in both eyes initially, improved during the following 3 years but did not return to normal. No visual field defects were found with kinetic perimetry. The rod and cone responses in the full-field ERG were markedly reduced in b-wave amplitude initially, but grew slowly to nearly normal values 3 years later. After withdrawal of the drug, the mfERG demonstrated normal responses in the macular region. The Arden index in the EOG was normal.

Chronic treatment with methotrexate may affect VA, and mat reversible reduce rod and cone function. In patients who use systemic medication and who vision is reduced, objective evaluation of retinal function with electrophysiological methods is recommended.