There is an ongoing investigation towards developing measurement techniques and equipment for measuring eye movement. Various ophthalmologic, vestibular and neurologic tests exists which involves observing eye movements. Tests may comprise a patient being asked to visually follow an object, or movement of the patients head either voluntarily or by the clinician forcing the movement. For example, the head impulse test has previously been performed using subjective assessment by the clinician.
Tests may comprise measuring fast eye movements, e.g. eye saccades, lasting approximately between 20-200 ms and involving angular speed up to 900 deg/s. Such fast movements may be visual to the clinician, but may be difficult to quantify consistently.
It is desirable to circumvent subjective measurements and provide a possible standardized test, which is independent of the clinician or other person performing the test. Furthermore, in some environments, such as in pre hospital settings, it may be problematic, if not impossible, to accurately perform the test when relying on subjective measurements.
Previously, it has been tried to perform the head impulse test objectively using scleral search coils. However, scleral search coils are uncomfortable, complex, bulky and expensive, and therefore alternative solutions are continuously sought.