Monocular vertical oscillations of amblyopia. The Heimann-Bielschowsky phenomenon

The Heimann-Bielschowsky phenomenon is an unusual ocular motility pattern which may develop years following uniocular visual loss and may be mistaken as a neuro-ophthalmologic sign pointing to a posterior fossa or brain stem lesion. It consists of strictly monocular coarse, pendular vertical oscillations occurring only in the amblyopic eye. It is noted primarily with distance fixation and is inhibited by convergence or fixation. The oscillations vary between 1-5 cycles/second, and amplitude, often only 2-5 degrees, may be quite large, up to 20-30 degrees (40-60 prism diopters). A faden operation improved the disorder in one patient. The importance of recognizing this characteristic motility pattern is emphasized to ophthalmologists and neurologists.