Myambutol^®(Ethambutol) bedingte Retinoneuritis

Abstract

A retinoneuritis due to ethambutol (Myambutol) occurs with Myambutol doses of over 20 mg/kg per day after 3 weeks to 15 months. Visual acuity can deteriorate within the following 6 months even after immediate discontinuation of treatment with Myambutol. It may recover 2 months (though in some cases only 16 months) after the onset of the deterioration; in cases of optic atrophy a more severe loss of vision usually remains. If there was loss of vision to 1/10 or less there was in most cases no change in the visual acuity. On the other hand, a primary loss of vision to only 0.3 or 0.4 usually ended with recovery of full vision. The occasionally observed clinical picture of a reddish optic disk, retinal hemorrhages, a very fine granular pigment alteration of the macular region, and loss of vision for more than a year without optic disk pallor suggests a toxic retinitis or retinoneuritis rather than neuritis. This is confirmed by electrophysiological observations.

Recovery after severe ethambutol intoxication - psychophysical and electrophysiological correlations

“…The observation that a decline of the visual acuity below a value of 1/10 worsens the prognosis tremendously was made by Pau [14] in a similar manner and is illustrated in Fig. lc. Trusiewicz [6] stresses the importance of the Farnsworth-Munsell 100-Hue Test in detection of early changes in the optic nerve of ethambutol patients and the value of the test for following the clinical course of ethambutol intoxication.…”

“…Most studies come to the conclusion that visual acuity returns to normal with cessation of the drug [1,5,10,13]. The prognosis after severe ethambutol intoxication, however, is still difficult to assess since cases with permanent visual impairment are reported [5,10,14]. Atrophies of the optic nerve seem to occur only sporadically [9].…”