Ocular tremor in Parkinson's disease: the debate is not over

Recent evidence tends to suggest that ocular tremor can be present in patients with Parkinson's disease (PD). This ocular tremor may have frequency characteristics similar to those of PD limb tremor. This fact was recently challenged in an article demonstrating that ocular tremor could simply be the consequence of vestibulo-ocular reflex activity induced by head movement. Although this hypothesis can be valid in some circumstances, we previously presented evidence that, in fact, these ocular may exist. Here, we address the shortcomings of previous studies describing the possible origins of these ocular tremors and propose solutions to circumvent those shortcomings.