sentences:  Ocular drifts are altered by some neurologic conditions including Tourette syndrome and autism spectrum disorder
  
  Ocular microtremors (OMTs) are small, quick, and synchronized oscillations of the eyes occurring at frequencies in a range of 40 to 100 Hz, although they typically occur at around 90 Hz in the average healthy individual.They are characterized by their high frequency and minuscule amplitude of just a few arcseconds.Although the function of ocular microtremors is debatable and not fully known, they seem to play a role in processing of high spatial frequencies, which allows for perception of fine detail.