Silmäreaktiot

Silmäreaktiot, often translated as pupillary light reflex or pupillary reflex, refer to the involuntary constriction or dilation of the pupil in response to changes in light intensity. This reflex is a crucial mechanism for regulating the amount of light entering the eye, thereby optimizing vision and protecting the retina from damage.

When exposed to bright light, the iris muscles constrict the pupil, reducing the amount of light that reaches the retina. Conversely, in dim light conditions, the iris muscles relax, causing the pupil to dilate and allowing more light to enter. This reflex is mediated by a complex neural pathway involving the optic nerve, the pretectal nucleus in the midbrain, the Edinger-Westphal nucleus, and the oculomotor nerve, which innervates the iris sphincter muscle.

The pupillary light reflex can be tested by shining a light into each eye. A normally functioning reflex will cause both pupils to constrict, even if the light is only shone into one eye (a consensual response). Abnormalities in the pupillary light reflex can indicate damage to the optic nerve, the brainstem, or the oculomotor nerve, and can be a sign of various neurological conditions. It is a fundamental component of a neurological examination.