Behaviour of disc oedema during and after amiodarone optic neuropathy: case report

Low-dose Amiodarone Is Safe: A Systematic Review and Meta-analysis

Amiodarone is commonly used for a variety of arrhythmias and, in some parts of the world, is the only available antiarrhythmic drug (AAD). Yet, amiodarone is known to have a wide range of potential side effects, many of which are dose- and duration-dependent. We sought to study the incidence of side effects leading to the discontinuation of low-dose amiodarone, arbitrarily defined as 200 mg/day or less, and very-low-dose amiodarone, defined as 100 mg/day or less. In this study, literature databases were searched through June 2019. Studies that reported the incidence or prevalence of side effects of amiodarone were included. Effect estimates from individual studies were extracted and combined using the random-effects generic inverse variance method of DerSimonian and Laird. A total of 10 observational cohort studies involving 901 patients were included in the analysis. The pooled estimated incidence of overall side effects for low-dose amiodarone was 0.17 [95% confidence interval (CI): 0.12–0.22]. In addition, the pooled estimated incidence of side effects requiring medication discontinuation was 0.06 (95% CI: 0.03–0.11). As compared with 200 mg/day of amiodarone, the pooled estimated incidence of overall side effects was 0.11 (95% CI: 0.04–0.27), while the incidence of side effects requiring medication discontinuation was 0.02 (95% CI: 0.01–0.06) for the dose of 100 mg/day. In conclusion, very-low-dose amiodarone displays a low incidence of significant side effects requiring medication discontinuation.

The role of Optical Coherence Tomography in optic neuropathies

Optical neuropathies are neuro-ophthalmologic disorders, the main symptoms of which are the decrease of visual acuity and the alteration of the color vision. Optical coherence tomography has been one of the most important innovations in ophthalmology, which offered the possibility to analyze specific structures of the retina. Optical coherence tomography performs in vivo, real-time, noncontact scanning and provides cross-sectional and volumetric images with a resolution approaching that of histology. Optical coherence tomography offers the opportunity to study neurological diseases in an objective and non-invasive manner. The measurements of retinal nerve fiber layer can be an objective measurement of nerve swelling or nerve atrophy. By analyzing the ganglion cell complex, optical coherence tomography can help detect early axonal damage and may predict the visual outcome. It can be useful for diagnosis and follow-up of optic nerve and chiasmal compressive diseases. Furthermore, optical coherence tomography is useful in patients with multiple sclerosis in distinguishing macular disease from optic neuritis and in monitoring the treatment. Multiple studies and clinical observations support the importance of optical coherence tomography in the diagnosis, treatment, and follow-up of optic neuropathies.

ABBREVIATIONS

OCT = optical coherence tomography, VA = visual acuity, RNFL = retinal nerve fiber layer, GCL = ganglion cells layer, MS = multiple sclerosis, ON = optic neuropathy, NAION = non-arteritic ischemic anterior optic neuropathy, LHON = Leber hereditary optic neuropathy, RE = right eye, LE = left eye.

Amiodarone-Induced Retinal Neuronal Cell Apoptosis Attenuated by IGF-1 via Counter Regulation of the PI3k/Akt/FoxO3a Pathway

Amiodarone (AM) is the most effective antiarrhythmic agent currently available. However, clinical application of AM is limited by its serious toxic adverse effects including optic neuropathy. The purpose of this study was to explore the effects of AM and to assess if insulin-like growth factor-1 (IGF-1) could protect retinal neuronal cells from AM-induced apoptosis, and to determine the molecular mechanisms underlying the effects. Accordingly, the phosphorylation/activation of Akt and FoxO3a were analyzed by Western blot while the possible pathways involved in the protection of IGF-1 were investigated by application of various pathway inhibitors. The full electroretinogram (FERG) was used to evaluate in vivo effect of AM and IGF-1 on rat retinal physiological functions. Our results showed that AM concentration dependently caused an apoptosis of RGC-5 cells, while IGF-1 protected RGC-5 cells against this effect by AM. The protective effect of IGF-1 was reversed by PI3K inhibitors LY294002 and wortmannin as well as the Akt inhibitor VIII. AM decreased p-Akt and p-FoxO3a while increased the nuclear localization of FoxO3a in the RGC-5 cells. IGF-1 reversed the effect of AM on the p-Akt and p-FoxO3a and the nuclear translocation of FoxO3a. Similar results were obtained in primary cultured retinal ganglia cells. Furthermore, FERG in vivo recording in rats showed that AM decreased a-wave and b-wave of FERG while IGF-1 reversed the effects of AM. These data show that AM induced apoptosis of retinal neuronal cells via inhibiting the PI3K/Akt/FoxO3a pathway while IGF-1 protected RGC-5 cells against AM-induced cell apoptosis by stimulating this pathway.