Transient macular dysfunction determined by focal macular electroretinogram.

Case report A 75-year-old man complained of a sudden and painless decrease of vision in his left eye. He had undergone surgery for an unruptured intracranial aneurysm 20 years earlier and was taking 7 mg/day of systemic prednisolone for rheumatoid arthritis. He had also had diabetic mellitus without retinopathy for 5 years. He was being followed for a left hemianopsia and normal tension glaucoma for the previous 3 years. On examination, a left relative afferent papillary defect (RAPD) was observed, and visual acuity (VA) was 20/30 OD and 20/2000 OS. All of the ocular findings were normal except for enlarged disc cupping OU (fig 1). Fluorescein angiography showed a delay in the arm-to-retina circulation time of 20.0 s (fig 1). Neither retinal emboli nor localised filling delay were observed. Goldmann perimetry showed a left quadrantic homonymous hemianopsia and a small central scotoma with peripheral constriction. The alterations in the left eye were new (fig 1). Focal macular electroretinograms (FMERGs) were recorded 2 h after onset as described (see the supplemental figure available at http://bjo.bmj.com/ supplemental). 3 The FMERGs were decreased in the left eye (fig 2) indicating that the visual dysfunction was retinal in origin. Left VA improved to 20/ 250 spontaneously 3 h later. On the following day, VA had improved to 20/30, and the amplitudes of the FMERGs, full-field ERGs and pattern visual evoked response (VEP) were normal (fig 2). The visual field obtained 3 months later showed that the central scotoma was not present and an expansion of the peripheral visual fields. The fundus remained normal. Ultrasound echography revealed no stenosis of the carotid artery. Blood examination revealed rheumatoid factor and high HbA1c but was otherwise normal. We conclude that the acute visual loss and central scotoma with reduced FMERGs were consistent with transient macular ischaemia, and prophylactic anti-coagulation treatment was considered.