Evolution of eye movement abnormalities in Huntington’s disease

Abstract

Huntington’s disease (HD) is an autosomal dominant neurodegenerative disorder. Eye movement abnormalities are characteristic manifestations of HD. The clinical manifestations and eye movement disturbances progress with the natural course of illness. Eye movement abnormalities evolve in HD from the premanifest stage to the early-manifest and late-manifest stages. In the premanifest stage, voluntary saccades, i.e., memory-guided saccades and anti-saccades are predominantly affected. There is an increase in latency and error rates of voluntary saccades. Early-manifest stage of HD is characterized by abnormality in reflexive saccades, with decrease in saccadic amplitude and velocity and slow broken pursuits. In the late-manifest stage, initiation of voluntary saccades in all directions is slow, leading to difficulty in initiating voluntary eye movements. The rate of progression of the saccades, pursuits, and other ocular movement correlate with the disease progression; monitoring this helps in early disease evaluation and in evaluating novel therapies to modify the disease. In this article, we systematically review the available literature on the patterns and progression of eye movement abnormalities, from the premanifest, to manifest, and advanced stages of HD.