Human eyes are constantly moving, even if they appear to be focused on an object. These constant oscillations are called fixational eye movements, and they include ocular microtremor, microsaccades, and drift.<unk>  is the smallest of these movements, and it often overlaps with drift. This makes it the most difficult fixational eye movement to measure. Due to these difficulties in measurement, fewer studies have been performed on ocular microtremor, leading to the phenomenon of<unk>  not being well-understood. Researchers are not entirely sure of the cause of ocular microtremor. It may be a result from the firing of motor neurons at different times. It has also been suggested that<unk>  is a result of the eye being balanced between opposing muscles.
Ocular tremor
Ocular dysmetria
Pendular nystagmus
Nephroptosis
Mydriasis
Nystagmus
Lagophthalmos
Exophthalmos