Checkerboard visual field defect

A 63-year-old male presented with blurred vision in both eyes and an inability to distinguish between various colours for 1.5 months. He was being treated for diabetes mellitus, hypertension, vitamin B12 deficiency anaemia, and hyperhomocysteinemia. External and ocular examinations were normal, except for the colour vision test using the Ishihara chart. The patient read 1/21 plates in both eyes, improving to 19/21 in the right eye and 18/21 in the left eye with a red filter. Both eyes’ Humphrey visual field test (HVF) (30-2) depicted left superior quadrantanopia and right inferior quadrantanopia, resulting in the characteristic BMW sign or checkerboard visual field defect [Fig. 1a and 1b].Figure 1: (a). Humphrey visual field (30-2) of the right eye of a 63-year-old patient with a checkerboard visual field defect (BMW sign). (b). Humphrey visual field (30-2) of the left eye of the same 63-year-old patient with a checkerboard visual field defect (BMW sign)Computerized tomography (CT) and magnetic resonance imaging (MRI) brain scans revealed infarcts in the posterior circulation territories. Similarly, a 49-year-old hypertensive male with primary open-angle glaucoma in both eyes presented with blurred vision in both eyes. Colour vision test results using the Ishihara chart were 21/21 in the right eye and 18/21 for the left eye, with no further improvement with a red filter. Both eyes’ HVF (10–2) revealed a checkerboard field pattern [Fig. 2a and 2b]. MRI of the brain confirmed the suspected bilateral occipital lobe infarcts [Fig. 3].Figure 2: (a). Humphrey visual field (10-2) of the right eye of a 49-year-old patient with a checkerboard visual field defect (BMW sign). (b). Humphrey visual field (10-2) of the left eye of the same 49-year-old patient with a checkerboard visual field defect (BMW sign)Figure 3: MRI brain, axial T1 Fluid-attenuated inversion recovery (FLAIR) image of a 49-year-old patient depicting bilateral occipital lobe infarcts, marked by red arrowsDiscussion Kamal et al.[1] and Cross SA et al.[2] reported checkerboard field defects in patients with bilateral occipital lobe infarcts. This classical appearance is due to an infarct above the calcarine fissure in the occipital lobe and another below it in the contralateral hemisphere.[3] An uncommon cause is multiple sclerosis, which was reported by Tamhankar et al.[4] in a 43-year-old female due to lesions in the optic radiation bilaterally. Conclusion The checkerboard visual field defect is primarily caused by bilateral occipital lobe infarcts. Cerebrovascular accidents typically do not cause dyschromatopsia unless there is a bilateral occipital lobe lesion. Bilateral visual field testing is essential, even in patients with monocular complaints, to localize brain lesions. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship: Nil. Conflicts of interest: There are no conflicts of interest.