Microsaccades and Ocular Drift in Ophthalmic and Neurologic Disease

Clinical disorders can have a significant impact on the quality of our vision, resulting in detectable abnormalities in eye movement patterns and downstream effects on perception. These abnormalities often include impairments in fixational movements that are often not consciously perceived by the patient, but which can be objectively measured via eye tracking. Neurologic and ophthalmic disease can produce specific fixational eye movement patterns with distinct characteristics. As a result, objectively assessing these small eye movements can aid in our understanding of pathologies that impair fixation and can provide insight into the nature and extent of visual impairments. These objective characterizations can also provide a means of early and differential diagnostics, as well as a means of evaluating ongoing treatment by quantifying progression and the response to medical intervention (in terms of the normalization of fixational eye movement dynamics). Methods—We conducted an exhaustive literature search of articles describing efforts to characterize fixational eye movement dynamics in common neurologic and ophthalmological conditions. We selected articles through extensive key word searches and searches of the references of retrieved articles. Results—Relatively few studies address fixational eye movement impairments in patient populations. However, this topic is a growing area of inquiry. We will present an overview summary of recent findings, with a particular focus on studies that have been published in the last five years. Conclusion—Recent discoveries point to some key research areas that may facilitate the translation of fixational eye movement measures into clinical practice. We discuss these discoveries and their implications. We also call for interested researchers to join the International Society for Clinical Eye Tracking (ISCET), which is a recently established community effort to provide guidance and protocols for conducting and analyzing eye tracking tasks in clinical settings.