Pupillrörelserna

Pupillrörelserna refers to the movements of the pupils of the eye, a key component of the neurological examination. They are assessed to determine neurological function, detect asymmetries, and evaluate ocular reflexes.

The pupil is a circular opening in the iris that regulates light entry. Its size and reaction to light are controlled by the autonomic nervous system. The sphincter pupillae muscle, innervated by the parasympathetic pathway via the oculomotor nerve, constricts the pupil. The dilator pupillae muscle, driven by the sympathetic pathway via the radial nerve, dilates it. Any disruption in these pathways can result in abnormal pupil size or reactivity.

During assessment, an examiner observes for equal pupil size, shape, and response to bright and dim light, known as the pupil light reflex. The near response, where pupils constrict when focusing on a near object, is also tested. Movement of the eyeball in all directions should be smooth and coordinated, indicating intact extraocular muscles and cranial nerves III, IV, and VI.

Clinical significance is considerable. Unilateral pupil dilation (mydriasis) can indicate increased intracranial pressure, third nerve palsy, or pharmacologic blockade. Conversely, fixation of a pupil (nonreactive) can signal brainstem injury. Anisocoria, a difference in pupil size, may be benign or symptomatic, warranting further evaluation.

Common disorders associated with pupillrörelserna include anisocoria, Horner’s syndrome, Adie's tonic pupil, and the Marcus Gunn pupil. Accurate interpretation of these signs guides diagnosis of neurological or ocular pathology.