Digitalis-induced visual disturbances with therapeutic serum digitalis concentrations

Use of Visual Electrophysiology to Monitor Retinal and Optic Nerve Toxicity of Medications

It is important for clinicians to consider exposure to toxic substances and nutritional deficiencies when diagnosing and managing cases of vision loss. In these cases, physiologic damage can alter the function of key components of the visual pathway before morphologic changes can be detected by traditional imaging methods. Electrophysiologic tests can aid in the early detection of such functional changes to visual pathway components, including the retina or optic nerve. This review provides an overview of various electrophysiologic techniques, including multifocal electroretinogram (mfERG), full-field ERG (ffERG), electrooculogram (EOG), pattern electroretinogram (PERG), and visual evoked potential (VEP) in monitoring the retinal and optic nerve toxicities of alcohol, amiodarone, cefuroxime, cisplatin, deferoxamine, digoxin, ethambutol, hydroxychloroquine, isotretinoin, ocular siderosis, pentosane, PDE5 inhibitors, phenothiazines (chlorpromazine and thioridazine), quinine, tamoxifen, topiramate, vigabatrin, and vitamin A deficiency.

Xanthopsia Due to Digoxin Toxicity as a Cause of Traffic Accidents: A Case Report

Patient: Male, 76-year-old

Final Diagnosis: Digoxin toxicity • xanthopsia

Symptoms: Dyspnea • leg edema • xanthopsia

Medication:—

Clinical Procedure: Intravenous hydration

Specialty: Cardiology

Colored floaters as a manifestation of digoxin toxicity

PURPOSE

Since its report in one patient more than 70 years ago, digitalis-induced colored muscae volitantes have not surfaced again in the literature. We report here a case of digoxin induced colored floaters.

OBSERVATIONS

An 89-year-old man on 0.25 mg digoxin daily developed visual hallucinations and colored floaters. He had floaters in the past but now they were in various colors including yellow, green, blue and red, though predominantly in yellow. These "weirdly" shaped little particles wiggled around as if in a viscous solution and casted shadows in his vision. He also saw geometric shapes, spirals, and cross hatch patterns of various colors that moved and undulated, especially on wallpaper. Ophthalmic examination revealed reduced visual acuity, poor color vision especially in his left eye, along with central depression on Amsler grid and Humphrey visual field in his left eye. Discontinuation of digoxin resulted in complete resolution of his visual symptoms. On subsequent ophthalmic examination, the patient's visual acuity, field testing and color vision improved and he had normal Amsler grid test results.

CONCLUSIONS AND IMPORTANCE

Colored floaters may occur in patients taking cardiac glycosides but this association has not been explored. Unlike optical illusions and visual hallucinations, floaters are entoptic phenomena casting a physical shadow upon the retina and their coloring likely arise from retinal dysfunction. Colored floaters may be a more common visual phenomenon than realized.

The Role of Multifocal Electroretinography in the Assessment of Drug-Induced Retinopathy: A Review of the Literature

Multifocal electroretinography (mfERG) is an objective, noninvasive examination for the assessment of visual function. It enables the stimulation of multiple retinal areas simultaneously and recording of each response independently, providing a topographic measure of retinal electrophysiological activity in the central 40-50° of the retina. A clinical application of mfERG represents the assessment of retinal toxicity associated with systemic medications. Drug-induced retinopathy represents a disease that, although not common, requires early recognition: if not detected early, it may progress and cause irreversible retinal dysfunction with subsequent visual impairment. This review aims to evaluate the use of mfERG in the assessment of retinal dysfunction associated with various systemic pharmacological agents based on the currently available literature. The most commonly recognized systemic medications affecting retinal function are included, such as chloroquine and hydroxychloroquine, vigabatrin, deferoxamine, ethambutol, interferon-α, tamoxifen, digoxin, sildenafil, canthaxanthin, amiodarone and nefazodone. The role of mfERG in the early diagnosis of retinal toxicity and the evaluation of disease severity is reviewed, as well as its clinical value in monitoring disease progression or recovery after drug cessation.

Spectrum of digoxin-induced ocular toxicity: a case report and literature review

Background

Digoxin intoxication results in predominantly digestive, cardiac and neurological symptoms. This case is outstanding in that the intoxication occurred in a nonagenarian and induced severe, extensively documented visual symptoms as well as dysphagia and proprioceptive illusions. Moreover, it went undiagnosed for a whole month despite close medical follow-up, illustrating the difficulty in recognizing drug-induced effects in a polymorbid patient.

Case presentation

Digoxin 0.25 mg qd for atrial fibrillation was prescribed to a 91-year-old woman with an estimated creatinine clearance of 18 ml/min. Over the following 2–3 weeks she developed nausea, vomiting and dysphagia, snowy and blurry vision, photopsia, dyschromatopsia, aggravated pre-existing formed visual hallucinations and proprioceptive illusions. She saw her family doctor twice and visited the eye clinic once until, 1 month after starting digoxin, she was admitted to the emergency room. Intoxication was confirmed by a serum digoxin level of 5.7 ng/ml (reference range 0.8–2 ng/ml). After stopping digoxin, general symptoms resolved in a few days, but visual complaints persisted. Examination by the ophthalmologist revealed decreased visual acuity in both eyes, 4/10 in the right eye (OD) and 5/10 in the left eye (OS), decreased color vision as demonstrated by a score of 1/13 in both eyes (OU) on Ishihara pseudoisochromatic plates, OS cataract, and dry age-related macular degeneration (ARMD). Computerized static perimetry showed non-specific diffuse alterations suggestive of either bilateral retinopathy or optic neuropathy. Full-field electroretinography (ERG) disclosed moderate diffuse rod and cone dysfunction and multifocal ERG revealed central loss of function OU. Visual symptoms progressively improved over the next 2 months, but multifocal ERG did not. The patient was finally discharged home after a 5 week hospital stay.

Conclusion

This case is a reminder of a complication of digoxin treatment to be considered by any treating physician. If digoxin is prescribed in a vulnerable patient, close monitoring is mandatory. In general, when facing a new health problem in a polymorbid patient, it is crucial to elicit a complete history, with all recent drug changes and detailed complaints, and to include a drug adverse reaction in the differential diagnosis.

Spatiotemporally varying visual hallucinations: II. Spectral classification and comparison with theory

In order to better understand the nature of visual hallucinations, and to test predictions of spatiotemporally oscillating hallucinations from a recent corticothalamic model of visual dynamics, clinical descriptions of hallucinations are used to establish boundaries on the spatiotemporal frequencies observed in various disorders. Detailed comparisons with hallucinations during migraine aura demonstrate that key features are consistent with corticothalamic origin and specific abnormalities, but underline the need for more detailed quantitative data to be obtained on temporally oscillating hallucinations more generally.

Pharmacology of antiarrhythmic drugs in elderly patients

Bradyarrhythmias and tachyarrhythmias are common in elderly patients as a result of aging and acquired cardiac disease. Antiarrhythmic drugs are effective in elderly patients for the management of supraventricular and ventricular arrhythmias; however, dosing of drugs must be performed with care because of age-related changes in drug pharmacokinetics, the presence of concomitant disease, and frequent drug-drug interactions. Despite the large number of antiarrhythmic drugs having different electrophysiologic actions, as described in this article, only the β-blockers have been shown to be effective in reducing mortality and to lack proarrhythmic actions.

Digoxin intoxication: An old enemy in modern era

Objectives

Although development of new treatment modalities limited digoxin usage, digoxin intoxication is still an important issue which could be easily overlooked. In this report, we analyzed a case series definitively diagnosed as digoxin intoxication in the modern era.

Methods

We analyzed 71 patients hospitalized with digoxin intoxication confirmed by history, complaints, clinical and electrocardiograph (ECG) findings, and serum digoxin levels > 2.0 ng/mL, during a five year period. The demographic and clinical data, indications for digoxin use, digoxin dosage, concurrent medications, laboratory data, hospital monitoring, and ECG findings were obtained from all patients.

Results

Thirty-eight of 71 patients (53.5%) had symptoms of heart failure during admission or later. Sixty-four percent of patients were older than 75 years. The percentage of females was 67%. Atrial fibrillation, hypertension and gastrointestinal complaints were more frequent in the females (64% in females, 30% in males, P = 0.007; 81% in female, 52% in males, P = 0.01; 50% in female, 17.3% in males, P = 0.008, respectively). The mortality rate during the hospital course was 7%.

Conclusions

This report demonstrated the reduced mortality rates in patients with digoxin intoxication over the study period. Gastrointestinal complaints are the most common symptoms in this population.

Spatiotemporal dynamics of pattern formation in the primary visual cortex and hallucinations

The existence of visual hallucinations with prominent temporal oscillations is well documented in conditions such as Charles Bonnett Syndrome. To explore these phenomena, a continuum model of cortical activity that includes additional physiological features of axonal propagation and synapto-dendritic time constants, is used to study the generation of hallucinations featuring both temporal and spatial oscillations. A detailed comparison of the physiological features of this model with those of two others used previously in the modeling of hallucinations is made, and differences, particularly regarding temporal dynamics, relevant to pattern formation are analyzed. Linear analysis and numerical calculation are then employed to examine the pattern forming behavior of this new model for two different forms of spatiotemporal coupling between neurons. Numerical calculations reveal an oscillating mode whose frequency depends on synaptic, dendritic, and axonal time constants not previously simultaneously included in such analyses. Its properties are qualitatively consistent with descriptions of a number of physiological disorders and conditions with temporal dynamics, but the analysis implies that corticothalamic effects will need to be incorporated to treat the consequences quantitatively.

Cardiovascular drug therapy in the elderly

Pharmacokinetic considerations in the elderly include absorption, bioavailablility, drug distribution, half-life, drug metabolism, and drug excretion. There are numerous physiologic changes with aging that affect pharmacodynamics with alterations in end-organ responsiveness. This article discusses use of cardiovascular drugs in the elderly including digoxin, diuretics, beta-adrenergic blockers, angiotensin-converting enzyme inhibitors, angiotensin-II receptor blockers, nitrates, calcium channel blockers, alpha-adrenergic blockers, antiarrhythmic drugs, lipid-lowering drugs, and anticoagulants. This article also discusses the adverse effects of cardiovascular drugs in the elderly, medications best to avoid in the elderly, and the prudent use of medications in the elderly.

Olfactory and gustatory disturbances caused by digitalism: A case report

It is known that an overdose of digoxin causes visual disturbance, but the effect on the senses of smell and taste is not known. A case of olfactory and gustatory disturbance caused by digitalism is reported. In a 62-year-old male patient suffering from chronic digitalism, the serum digoxin level rose to 6.0 ng/ml. The patient was diagnosed not only with visual disturbance but also hyposmia and hypogeusia. The patient recovered from visual and chemosensory disturbances after the serum digoxin concentration returned to normal. Because the similarity of intracellular signal transduction between photoreceptor cells and olfactory and/or taste receptor cells is known, it is suspected that the influence of digoxin to chemosensory organs was caused by intermediation of sodium-potassium-adenosine triphosphatase (Na-K-ATPase) of the chemosensory receptor cells.

Photopsia as a manifestation of digitalis toxicity

CASE REPORT

To present a case of photopsia resulting from digoxin intoxication brought about by dehydration in a 72-year-old woman.

COMMENTS

Ophthalmologists may be the first clinicians to notice the symptoms of digitalis intoxication, which is potentially a life-threatening condition.

Detection of cone dysfunction induced by digoxin in dogs by multicolor electroretinography

It is difficult to detect discrete cone function with the present conventional electroretinography (ERG) examination. In this study, we developed contact electrodes with a built-in color (red (644 nm), green (525 nm), or blue (470 nm)) light source (color LED-electrode), and evaluated an experimental model of digoxin in the dog. First, 17 normal Beagle dogs were used to determine which electrode works well for color ERG measurement on dogs. Then, color ERG was performed on seven normal Beagle dogs at various points during a 14-day period of digoxin administration. A single daily dose of 0.0125 mg/kg/day, which is within the recommended oral maintenance dosage range for dogs, was administered orally for 2 weeks. Ophthalmic examination, measurement of plasma concentration of digoxin, and color ERG examination were performed. On first examination, amplitudes of all responses were significantly (P < 0.01) lower with the red, than with the blue and green electrodes during ERG recording. In ERG using the red electrode, the standard deviation was large. According to these preliminary results, the red electrode was not used in the experimental dog model with digoxin. In the digoxin administrated animals, no significant change was observed in the ophthalmic examination findings. The digoxin level increased steadily throughout the dosing period but was always within the therapeutic range for dogs. In rod ERG, no abnormalities were detected with any electrode. In standard combined ERG, decreased amplitude of the a-wave was detected with every electrode. In single flash cone ERG, prolongation of implicit time was detected by color ERG with the blue and green electrodes. In 30-Hz flicker ERG, decreased amplitude was detected only by color ERG with the blue electrode. The decreased amplitude and prolonged implicit time recovered after termination of digoxin administration. Cone dysfunction induced by digoxin in the dog was revealed by multicolor ERG using blue and green LED-electrodes. Multi-color ERG was useful for detecting cone type-specific dysfunction in the dog.

Drug-induced toxic reactions in the eye: an overview

Every drug can produce untoward consequences, even when used according to standard or recommended methods of administration. Adverse drug reactions can involve every organ and system of the body, even the eye, and frequently are mistaken for signs of underlying disease. Reactions in the eye may involve the eyelids, periorbital tissues, lacrimal apparatus, conjunctiva, cornea, lens, iris, ciliary body, intraocular pressure, retina, optic nerve, and ocular movement. In addition, fetal abnormalities can be caused by the use of eye drugs during pregnancy. Topical ophthalmic therapies or the use of ophthalmic dyes may cause systemic reactions. This article reviews drugs used systemically or topically that may cause adverse effects in the eye and related structures. Adverse ocular reactions to medications create an important health problem, and nursing professionals in close contact with patients inside and outside the hospital must assume a role in detecting them early, identifying them, educating the patient about them, and treating them.

Visual hallucinations

Neurologists and ophthalmologists should be familiar with the causes and treatment of visual hallucinations so that they are able to reassure patients and minimize the anguish associated with untreated visual hallucinations. Hallucinations are under-reported by patients because of the perceived psychiatric implication or because of poor insight into the unreal nature of the hallucinations. In the appropriate setting, physicians should specifically inquire about hallucinations as well as initiate medical treatment. Visual hallucinations have many etiologies and are associated with a variety of disorders. Identification of the associated disorder or cause is necessary to determine the appropriate treatment. Causes and associated disorders include ocular phenomena, migraine, seizures, visual loss (ie, release hallucinations), neurodegenerative disorders, midbrain injury, alcohol and drug effects, narcolepsy, post-traumatic stress disorder, and psychosis. Therapeutic treatment should be directed at the associated disorder or etiology. For instance, antiepileptic drugs may be appropriate for patients with irritative phenomena such as seizures and visual aura of migraine. Depending on the cause, other agents are available and include neuroleptics, cholinesterase inhibitors, and acetazolamide. Well-designed, randomized, controlled clinical trials regarding treatment of visual hallucinations associated with various disorders are lacking. Although complete resolution of visual hallucinations can be difficult, even minimal improvement may be symptomatically beneficial.

Acquired colour vision deficiency in patients receiving digoxin maintenance therapy

BACKGROUND/AIMS

Disturbances of colour vision are a frequently reported sign of digoxin toxicity. The aim of this study was to investigate the incidence of acquired colour vision deficiency in elderly hospitalised patients receiving maintenance digoxin therapy.

METHODS

30 patients (mean age 81.3 (SD 6.1) years) receiving digoxin were tested using a battery of colour vision tests (Ishihara, AO Hardy Rand Rittler plates, City tritan test, Lanthony tritan album, and the Farnsworth D15). These were compared to an age matched control group. Serum digoxin concentrations were determined from venous blood samples.

RESULTS

Slight to moderate red-green impairment was found in approximately 20-30% of patients taking digitalis, and approximately 20% showed a severe tritan deficiency. There was no correlation between colour vision impairment and serum digoxin level.

CONCLUSIONS

Formal colour vision testing of elderly patients taking digitalis showed a high incidence of colour deficiency, suggesting that impairment of retinal function can occur even at therapeutic drug levels. As a result, colour vision testing in this population would have limited value for the detection of drug toxicity.

Digoxin visual toxicity with therapeutic blood levels of digoxin

PURPOSE

To report two cases of digoxin-related visual disturbances associated with therapeutic blood levels of digoxin.

METHODS

Case reports. One patient reported shimmering lights in the field of vision of both eyes; the second patient had a corrected visual acuity of BE, 20/40 and generalized visual field depression in both eyes. Both patients experienced these symptoms while receiving digoxin.

RESULTS

Both patients had digoxin blood levels in the therapeutic range (1.7 and 1.0 ng/ml, respectively). Therapeutic levels are 0.5 to 2.0 ng/ml. After discontinuing digoxin, the first patient noted that the shimmering light symptoms resolved, and the second patient had improved visual acuity and visual fields.

CONCLUSIONS

Digoxin-related visual toxicity may be associated with therapeutic blood levels of digoxin. Recognition of this entity may avoid unnecessary testing and frustration.