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Medicinal Optic Neuropathies
Last reviewed: 18.10.2021
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Medicinal optical neuropathy caused by ethambutol
Etambutol in combination with isoniazid and rifampicin is used to treat tuberculosis. Toxicity depends on the dose and duration of treatment and is 6% with a daily dose of 25 mg / kg (a dose of 15 mg / kg is rarely toxic). Toxicity may occur after 2 months of treatment (an average of 7 months).
Isoniazid can also cause toxic optical neuropathy, especially in combination with ethambutol.
It is manifested by symmetrical gradual deterioration of vision and dyschromatopsia,
Symptoms: normal or slightly swollen disc with dashed hemorrhage.
Defects of the field of vision: central or centrocecal scotoma, can also be a bitotral or peripheral narrowing.
The prognosis after treatment is good, but recovery can take up to 12 months. In a small number of patients, a persistent decrease in vision is associated with the development of atrophy of the optic nerve.
Screening should be carried out at intervals of 3 months if the daily vine exceeds 15 mg / kg. If symptoms of optical neuropathy appear, the medication should be stopped immediately.
Medicinal optical neuropathy caused by amiodarone
Amiodarone is used to treat cardiac arrhythmias. Vortex keratopathy, which is harmless, occurs in almost all, Optical neuropathy develops only in 1-2% of patients regardless of the dose.
It is manifested by gradual unilateral or bilateral deterioration of vision.
Symptoms: bilateral edema of the optic nerve disc, persisting for several months after drug discontinuation.
Defects of the field of vision can be small and reversible or large and persistent.
The forecast is difficult, because cancellation of the drug may not cause improvement.
Screening is not carried out, because it does not contribute to the identification of risk. Nevertheless, patients should be warned about the possible risk of manifesting the toxicity of the drug and report any changes in vision,
Medicinal optical neuropathy caused by vigabatrin
Vigabatrin is an antiepileptic agent used as a second-line drug, with the exception of cases of infantile spasm (Wesl syndrome). Many patients with a total dose of 1500 g or more develops dyschromatopsia and narrowing of the vision fields. Defects develop from 1 month to several years from the start of treatment and often persist despite the withdrawal of the drug. Investigation of the field of vision is recommended to be carried out at intervals of 6 months.