Ethambutol Ocular Toxicity in Treatment Regimens for Mycobacterium avium Complex Lung Disease

Abstract

Ethambutol (EMB) is an important component of multidrug treatment regimens for Mycobacterium avium complex lung disease. Ocular toxicity is the most important potential EMB toxicity, especially in the elderly population with M. avium complex lung disease. Two hundred twenty-nine patients with M. avium complex lung disease, 55% women and 53% with nodular/bronchiectatic disease, received a mean of 16.1 +/- 10.8 months of multidrug therapy that included EMB. Fifty patients (22%) were known to have preexisting ocular disease. While on EMB, 97 (42%) patients consulted an opthalmologist and 24 (10%) stopped EMB at least temporarily. Eight of 139 patients (6%) on daily therapy were diagnosed with EMB ocular toxicity, whereas 0 of 90 patients on intermittent therapy had EMB ocular toxicity (p = 0.05). All patients with EMB ocular toxicity developed symptoms between outpatient clinic appointments; none were diagnosed with routine visual acuity and color vision testing. All patients with EMB ocular disease returned to baseline ocular status after discontinuation of EMB. Intermittent EBM administration was associated with less ocular toxicity than daily EMB administration in this patient population.

Antimicrobial Susceptibility Testing, Drug Resistance Mechanisms, and Therapy of Infections with Nontuberculous Mycobacteria

“…Multiple studies have shown the importance of ethambutol as a component of the treatment regimen for pulmonary MAC infection (130,132,139,345). The primary and most serious adverse effect associated with ethambutol is ocular toxicity.…”

“…Patients on a high dose of drug (usually 25 mg/kg of body weight daily) present with blurred vision; decreased acuity; central scotomas; and, often, a loss of red-green color discrimination, and optic or retrobulbar neuritis may occur in one or both eyes. Sometimes, the central fiber of the optic nerve is affected, but more often, peripheral constriction of the visual fields occurs (139).…”

To evaluate the role of pentoxifylline in optic atrophy induced by tuberculosis

“…5 The most serious potential adverse effect of Ethambutol toxicity is optic or retrobulbar neuritis, which may affect one or both eyes. 6 Pentoxifylline is a alkyl xanthine derivative 3,7-dimethyl 1-5 oxohexylaxtheme. 3 It was first synthesized in 1965.…”

Spectrum and Clinical Course of Visual Field Abnormalities in Ethambutol Toxicity

“…However, MAC also represents a significant pathogen in certain populations, including the immune-compromised and particularly the elderly where non-tuberculous mycobacterial infection prevalence has risen to 30 of every 100,000 people older than 70 years of age, 11 or approximately 8350 persons based on 2010 Census data. Because many patients with MAC are also treated with ethambutol, and the medication's potential for visual toxicity, 12 we report a series of six patients who developed vision loss due to this treatment. These patients presented with bitemporal hemianopsias that mimic the clinical features for compressive optic neuropathy.…”