57 yo M with PMHx of uncontrolled DM and HTN who presents with 3 weeks of intermittent visual problems. Patient reports he sees visual distortion, characterized by flashes on both of his left sides of vision in both eyes. He is also unable to process 3D spacing and has trouble walking and reading due to vision problems. Episodes of symptoms tend to last 3-4 hours. Additionally patients complaints of mild R parietal headache that usually coincides with visual symptoms. Denies weakness or sensation deficits, dizziness, seizures or fever.
Physical examination in the ED is remarkable for absent vision on both left sides of his visual fields. Detailed eye and neurological exam reveal no additional abnormalities
Labs are only remarkable for hyperglycemia of 60 mg/dl, with no ketones or acidemia.
Management of hyperglycemia did not improve symptoms.
Brain CT and MRI were performed showing no abnormalities that could explain clinical picture.
What is the name of this patient’s deficit and where is anatomically located ?