Abstract
Background
Digoxin related retinal toxicity causes blurred vision, photophobia, central scotoma, color vision abnormality, and electroretinography (ERG) abnormalities. Here, we report a case with transient abnormalities in vison, in which fundus autofluorescence (FAF), optical coherence tomography (OCT), and ERG findings resembled those in KCNV2 (potassium voltage-gated channel modifier subfamily V member 2)-associated retinopathy.
Case report
An 89-year-old woman presented with complaints of acute blurred vision, nyctalopia, photophobia, and color vision abnormality. She received digoxin for tachycardia induced by atrial fibrillation for a month. The fundi showed a faint white ring at the fovea, which showed hyperfluorescence in FAF. OCT showed a thickened EZ in the macula. A dark-adapted (DA)-30 ERG showed a reduced and “squaring (trough-flattened)” a-wave, and a delayed, supernormal b-wave, resulting in a high b/a-wave amplitude ratio. The digoxin dose was reduced following an elevation in serum levels. Five weeks later, her visual acuities improved, and abnormal hyperfluorescence on FAF disappeared. After 6 months, no visual symptoms were reported. The ellipsoid-zone thickening in OCT improved; however, the b/a-wave amplitude ratio on DA-30 ERG remained high. The b-wave in LA-long-flash ERG was initially reduced, which improved after correction of serum level of digoxin.
Conclusions
The patient’s clinical findings resembled those of patients with KCNV2-associated retinopathy or temporal hyperkalemia. These disorders appear to have a common pathogenesis, which may be related to abnormal extracellular potassium levels in the retina. The on-bipolar cells seemed to be more affected than the off-bipolar cells in digoxin related retinal toxicity.
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Acknowledgements
The authors would like to thank the patient for her kind consent for publishing her medical information on Documenta Ophthalmologica. The authors thank Dr. Junji Kato at Kato Cardiovascular Clinic, Sakai City, Japan, and Dr. Naoyuki Okamoto at Okamoto Eye Clinic, Sakai City, Japan, for their referral of the patient and providing their medical information to Kindai University Hospital. The authors also thank Dr. Hisao Ohde in Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan, for critical discussion.
Funding
A part of this research was supported by Grant 22K09825 from Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, to K.K.
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Nagae, Y., Kuniyoshi, K., Ishibashi, M. et al. Fundus autofluorescence, optical coherence tomography and electroretinography abnormalities in a patient with digoxin retinopathy that resemble those in KCNV2-associated retinopathy. Doc Ophthalmol 147, 131–137 (2023). https://doi.org/10.1007/s10633-023-09942-x
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DOI: https://doi.org/10.1007/s10633-023-09942-x