A 60-year-old woman presented with fluctuating peripheral vision changes described as areas of her vision “going in and out” similar to “tunnel vision” and episodic superimposed fluctuating colored lights in her peripheral field. Past medical history was notable for poorly controlled diabetes mellitus complicated by nonproliferative diabetic retinopathy OU. On presentation, blood pressure was 180/100 and she was intermittently somnolent, with severe hyperglycemia >500mg/dl. Ophthalmologic examination had normal visual acuity and color vision, and funduscopic examination showed normal optic discs and mild background diabetic retinopathy. Humphrey visual field 24-2 showed exquisitely homonymous superior left and inferior right quadrantanopias. MRI brain showed subtle cortical enhancement in the right occipital lobe inferior to the calcarine fissure, and subtle cortical diffusion restriction in the left occipital lobe superior to the calcarine fissure. Continuous electroencephalography showed several brief electroclinical seizures in the posterior occipital lobes associated with episodes of flashing colored lights “like looking at a disco ball”. Treatment with levetiracetam improved her mental status and stopped the fluctuating colored lights in her peripheral vision. Her visual field deficits persisted for several days following adequate control of her seizures and treatment of her hyperglycemia, eventually resolving in 1 month.

This patient’s fluctuating mental status and positive visual phenomena were attributable to occipital lobe seizures. While postictal Todd’s paralysis of the visual cortex can cause brief homonymous hemianopic defects and even cortical blindness, the duration of our patient’s persistent visual field defects (1 month) were likely also a direct result of her hyperglycemia.