Department of Ophthalmology, Katsushika Medical Center, The Jikei University School of Medicine, 6-41-2 Aoto, Katsushika-ku, Tokyo, 125-8506, Japan.
Department of Ophthalmology, The Jikei University School of Medicine, Tokyo, 105-8461, Japan.
Doc Ophthalmol. 2021 Oct;143(2):221-228. doi: 10.1007/s10633-021-09828-w. Epub 2021 Mar 18.
The purpose of this report was to describe the case of a 68-year-old male patient with stage IV colon cancer who exhibited electroretinographic abnormalities that are similar to those of KCNV2 retinopathy.
The patient presenting with photophobia, reduced visual acuity, and poor general conditions, the onset of which occurred ten days before presentation, was examined using fundoscopy, full-field electroretinography, blood tests, and abdominal computed tomography.
The patient's decimal best-corrected visual acuity (BCVA) was 0.4 in each eye. Fundoscopy showed bull's eye-like maculopathy in both eyes. Electroretinographic findings were similar to the characteristic findings of KCNV2 retinopathy: Rod electroretinogram showed delayed and preserved b-wave amplitudes; bright-flash electroretinogram showed double troughs of a-waves; b/a ratios shown by bright-flash electroretinogram were higher than those shown by standard-flash electroretinogram; and both cone and 30-Hz flicker electroretinograms showed extinguished responses. His serum potassium level increased to 6.2 mmol/L (normal range 3.6-4.8 mmol/L) owing to hydronephrosis resulting from disseminated carcinoma. After performing an emergency surgery to treat this condition, the serum potassium level immediately decreased to a normal range. Eleven days after presentation, rod and standard/bright-flash electroretinography showed improvement in the implicit time of the rod b-waves and the a-waves. Unexpectedly, the responses recorded by cone and 30-Hz flicker electroretinography became normal. The symptoms and maculopathy disappeared, and his BCVA improved to 1.2.
The abnormal electroretinographic findings might be associated with the transient increase in serum potassium level.
本报告旨在描述一例 68 岁男性 IV 期结肠癌患者，其表现出类似于 KCNV2 视网膜病变的视网膜电图异常。
患者以畏光、视力下降和一般状况不佳为主要表现，发病于就诊前 10 天，经眼底检查、全视野视网膜电图、血液检查和腹部 CT 检查。
患者的十进制最佳矫正视力（BCVA）在每只眼中均为 0.4。眼底检查显示双眼呈类牛眼样黄斑病变。视网膜电图结果与 KCNV2 视网膜病变的特征性发现相似：Rod 视网膜电图显示波潜伏期延长和 b 波幅度保存；闪光视网膜电图显示 a 波波谷双峰；闪光视网膜电图的 b/a 比值高于标准闪光视网膜电图；同时，锥体细胞和 30-Hz 闪烁视网膜电图均显示反应消失。由于播散性癌导致的肾盂积水，他的血清钾水平升高至 6.2mmol/L（正常范围 3.6-4.8mmol/L）。在紧急手术治疗该疾病后，血清钾水平立即降至正常范围。就诊后 11 天，Rod 和标准/闪光视网膜电图显示 Rod b 波和 a 波潜伏期改善。出乎意料的是，锥体细胞和 30-Hz 闪烁视网膜电图的反应变得正常。症状和黄斑病变消失，BCVA 提高至 1.2。
异常的视网膜电图发现可能与血清钾水平的短暂升高有关。
