Digoxin‐induced retinal toxicity after acute kidney injury in a patient with dilated cardiomyopathy: A case report

Abstract

Aims/Purpose: We would like to report a case of digoxin‐induced retinal toxicity.Methods: Observational case report. Clinical follow‐up was performed using optical coherence tomography and electroretinography.Results: A 50‐year‐old female patient was referred to our clinic with symptoms of blurred vision and a whitening of the central visual field. She had no prior ophthalmic history but had underlying diseases including hypertension, hyperlipidaemia, dilated cardiomyopathy, systemic lupus erythematosus and chronic kidney disease. She had been admitted to the department of nephrology due to acute renal impairment, presenting with flank pain and oliguria. At the initial examination, her best‐corrected visual acuity was 0.5 in the right eye and 0.4 in the left eye. The Ishihara colour vision test revealed 3/17 and 1/17 in the right and left eye, respectively. Optical coherence tomography showed blurring and thickening of the ellipsoid zone in both eyes. Electroretinography demonstrated decreased cone cell function. She had been taking digoxin 0.125 mg for dilated cardiomyopathy for the past 2 years. Following the onset of acute renal impairment, her serum digoxin level was found to be 2.95 ng/mL, more than twice the normal range [0.6–1.2]. Suspecting digoxin intoxication, we consulted with her cardiologist and decided to discontinue digoxin. 3 weeks after discontinuing the medication, she reported improvement in the whitening of central visual field. Her best‐corrected visual acuity improved to 0.7 in the right eye and 0.6 in the left eye, and the Ishihara colour vision test showed 16/17 in both eyes. OCT demonstrated normalization of the ellipsoid zone thickness, and ERG showed ongoing recovery of cone cell function.Conclusions: Digoxin toxicity is known to result in visual disturbances—including decreased visual acuity, blurry vision and central scotoma with altered colour perception—caused by direct dysfunction of photoreceptors. Symptoms are gradually recovered within days to months after discontinuation of the medication. When facing visual problems in a patient with comorbidities, it is important to elicit a complete history, with all drug and detailed complaints, and to include a drug adverse effect. If a drug intoxication was suspected, medical consultations should be obtained.