A 40-year-old Caucasian female was first seen 20 years ago for a routine ocular screening in relation to hydroxychloroquine treatment for systemic lupus erythematosus. Her daily dose was 600 mg (or 12 mg/kg of body weight/day) of hydroxychloroquine. Three years later, she complained of mild visual loss in the right eye. Her best-corrected visual acuity was 0.9 in the right (RE) and 1.0 in the left eye (LE). In addition, she had a central scotoma (RE > LE) on automated visual field analysis (Humphrey central 30 degrees ). On fundoscopy and fluorescein angiography, the first signs of a bilateral bull's eye maculopathy were detected. A decreased Arden ratio on EOG (<1.50) was found with an accompanying decreased amplitude of the scotopic b-wave on full-field electroretinography in both eyes. Consequently, the treatment was immediately stopped. During the following years, the patient was retested regularly. After more than 18 years after cessation of the drug, most tests showed a further deterioration, including best-corrected visual acuity (RE: 0.1; LE: 0.7). On visual field testing, a progressive evolution to a total and absolute central scotoma in the RE (central 10 degrees ) and an annular scotoma in the LE became apparent. In contrast, a partial recovery of the Arden ratio of the EOG to 1.8 in both eyes was seen. In addition, a partial recovery of the scotopic b-wave full-field ERG was noted 19 years after cessation of treatment. At retest visits respectively 18, 19 and 20 years after cessation of hydroxychloroquine, a multifocal electroretinogram was performed in combination with colour vision tests and contrast sensitivity measurements.