Título / Title

ETHAMBUTOL OPTIC NEUROPATHY

Introdução / Purpose

Ethambutol is a medication used as first line in tuberculosis treatment. Optic neuritis (EON) is its main adverse effect. Incidence ranges from 1% to 18% (15 and 35 mg/Kg/day respectively). EON has been classically described days to weeks after onset use.

Material e Método / Methods

41 year old woman, with a two week decrease of vision and photophobia. Under treatment for chronic renal failure, and lymph node tuberculosis in the last 4 months with RIPE scheme (rifampin, isoniazid, pyrazinamide, ethambutol) on dialysis days, and RI at the others. Best corrected visual acuity (BCVA) of 20/70 in right eye (RE) and 20/100 in left eye (LE). Unremarkable anterior slit lamp examination and intraocular pressure. Bilateral papilledema at fundus examination. At the time she was oriented to discontinue ethambutol treatment, seek her infectologist and we requested a Goldmann visual field. After 2 months the patient returned with worse vision (20/200 in RE and worst than 20/400 in LE). Evolved with optic nerve pallor and important field constriction in both eyes. After 4 months of vitamin replacement, the patient returned presenting BCVA of 20/40 in both eyes and important visual field gain, although maintained the atrophic appearance of the optic disc.

Resultados / Results

EON is a condition that has increased due to the number of new tuberculosis cases. Clinical presentation ranges from decreased visual acuity to dyschromatopsia and visual field changes. 30 to 60% of the patients show some improvement with prompt discontinuation of the drug. Risk factors for this condition include older age, higher dose, impaired renal function and duration of treatment. In our case, the patient has chronic renal failure, a condition that worsens the clinical picture.

Discussão e Conclusões / Conclusion

According to the clinical features and complementary exams our main diagnostic hypothesis was EON. We had a significant improvement with joint therapy, withdrawal of the medication associated with vitamin supplementation.

Palavras Chave

"Ethambutol optic neuropathy"
" chronic renal failure"