Related Experiment Video
Updated: Jun 1, 2026
16:49
Multifocal Electroretinograms
Published on: December 4, 2011
Bitemporal visual field defects in ethambutol-induced optic neuropathy.
Richard C Kho1, Majed Al-Obailan, Anthony C Arnold
1UCLA Department of Ophthalmology, Jules Stein Eye Institute, Los Angeles, California 90095, USA.
Summary
Bitemporal visual field defects are a common finding in ethambutol-induced optic neuropathy, potentially mimicking chiasmal compression. Neuroimaging is crucial for diagnosis and understanding the toxicity affecting optic nerve fibers.
Area of Science:
- Neuro-ophthalmology
- Optic Neuropathy
- Visual Field Defects
Background:
- Ethambutol-induced optic neuropathy is a known condition.
- It typically presents with central or cecocentral visual field defects.
- This study focuses on patients with bitemporal visual field defects.
Purpose of the Study:
- To characterize patients with ethambutol-induced optic neuropathy exhibiting bitemporal visual field defects.
- To investigate the clinical features and outcomes of this specific presentation.
- To differentiate this pattern from other causes of visual field loss.
Main Methods:
- Retrospective review of patients diagnosed with ethambutol-induced optic neuropathy.
- Tabulation of clinical data including ethambutol dosage, duration, visual acuity, and visual fields.
- Assessment of bitemporal defects and visual recovery after ethambutol discontinuation.
Main Results:
- Nineteen cases of ethambutol-induced optic neuropathy were identified.
- Bitemporal defects were observed, often with vertical midline margination.
- Significant visual improvement occurred in 50% of eyes by Snellen lines and 79% by automated perimetry.
Conclusions:
- Bitemporal visual field defects are a notable presentation of ethambutol-induced optic neuropathy.
- This pattern can resemble chiasmal compression, necessitating neuroimaging.
- The findings suggest susceptibility of chiasmal crossing fibers to ethambutol toxicity.
Related Concept Videos
01:27Diabetic Retinopathy
DefinitionDiabetic retinopathy is a microvascular complication of diabetes affecting the retinal blood vessels.Risk FactorsDiabetic retinopathy is present in almost all individuals with type 1 diabetes and more than 60% of those with type 2 diabetes after two decades of disease.The risk increases with poor glycemic control, hypertension, dyslipidemia, smoking, pregnancy, and puberty.Although cataracts and glaucoma are also more frequent in people with diabetes, retinopathy remains the leading...
01:22Photoreceptors and Visual Pathways
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...