Neuro-ophthalmological Methods for the Clinical Analysis of Double Vision

Abstract

The first task at the bedside, regardless of whether that patient is unconscious or of intact consciousness, is to establish whether the palpebral fissures are identical. It is assessed if there is incomplete or complete ptosis, if eye opening is unilateral or bilateral, and if there is abnormal contraction of the eyelid (blepharospasm). The second step is to observe the primary position, i.e., if the two eyes looking straight ahead are parallel or they are misaligned in the horizontal or vertical plane. Is any type of nystagmus visible already when looking straight ahead? State of the pupils before the reflex tests: whether they are identical in size (isocoria), and whether one or both are constricted–dilated are important information, and eye drops that affect pupillary function must never be used, especially in case of an altered level of consciousness. Evoking and accurately recording the pupillomotor functions, i.e., the direct and indirect pupillary reflexes are among the most important parts of neurointensive care and the first neurological examination. Unilateral pupil dilation with decreased indirect reaction (anisocoria) can be decisive already at the bedside, since it may be the leading and first symptom of higher intracranial pressure (HIP), even without papilledema or other symptoms. In conscious patients: the examination of smooth pursuit and saccadic eye movements, and the optokinetic reflex test (OKN) are of differential diagnostic value in the distinction between the dysfunctions of the slow pursuit supranuclear oculomotor system.