Post-operative vision loss after coronary artery bypass graft

CLINICAL SCENARIO A 61-year-old hypertensive gentleman with a prior history of coronary angioplasty, presented with triple vessel disease and a left ventricular ejection fraction of 50%. He underwent a coronary artery bypass graft (CABG) surgery, and was recovering well. On his 2nd post-operative day, once he regained consciousness, he complained of loss of vision in both his eyes. Visual acuity was only perception of light in both eyes. He was irritable and uncooperative for assessment—bed-side examination revealed a normal anterior segment with a central, circular, briskly reacting pupil, and fundus examination was unremarkable. Blood tests, cardiological and neurological evaluation, and magnetic resonance imaging (MRI) orbit were within normal limits. What would be your next step? Visual evoked potential (VEP)s Doppler study of carotid and cerebral vessels MRI brain with magnetic resonance angiography (MRA) carotid and cerebral vessels Fundus fluorescein angiography (FFA). Correct answer Choice C - MRI brain with MRA carotid and cerebral vessels MRI brain [Figure 1a-c] and MRA of carotid and cerebral vessels [Figure 1d] are depicted. A diagnosis of embolic stroke was made, and he was managed as per stroke protocol. A week later, his vision improved to counting fingers close to face. He refused any further investigations, and was discharged. Six months later, his vision improved to 6/60 in both eyes with few scotomata. Fundus examination remained normal [Figure 1e and f]. He was advised perimetry, but was unable to perform the test.Figure 1: MRI Brain showing multiple subacute infarcts (red arrows) involving the (a) right parieto-temporal lobe, (b) left parieto-occipital lobe, temporal lobe and (c) hippocampus. (d) MRA of carotid and cerebral vessels displaying focal severe (90%) narrowing of the P1 segment of posterior cerebral artery with attenuation of its cortical branch, and focal (60%–70%) luminal narrowing seen in the distal cavernous and clinoid parts of right intracranial internal carotid artery (red arrow). Normal fundus examination (e and f)Post-operative visual loss after cardiac surgical procedures has a reported incidence of 0.06%–1.3%. In the absence of any anterior or posterior segment findings, a cerebral infarction due to hypoperfusion or micro-emboli may be implicated in its pathogenesis.[1] Cortical blindness may ensue from damage to the primary visual cortex in the parieto-occipital lobe. Embolisms in CABG may develop because of handling of the heart and aorta, atrial fibrillation, hypercoagulability, or substance from the bypass pump. Risk factors include hypertension, diabetes mellitus, renal failure, smoking, Chronic obstructive pulmonary disease (COPD) and cardiac disease.[2] The prognosis is benign, with recovery of good visual function, in majority of the cases.[3] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.