Pupillikoko

Pupillikoko refers to the size of the pupil, the dark circular opening in the center of the iris that allows light to enter the eye. Pupil size is controlled by two muscles within the iris: the sphincter pupillae, which constricts the pupil, and the dilator pupillae, which dilates it.

The primary function of pupil size changes is to regulate the amount of light reaching the retina. In bright light conditions, the sphincter pupillae muscle contracts, causing the pupil to become smaller (miosis) and reduce the amount of light entering the eye. This prevents overstimulation of the photoreceptors and improves visual acuity. In dim light conditions, the dilator pupillae muscle contracts, causing the pupil to enlarge (mydriasis) and allow more light to enter. This enhances vision in low-light environments.

Pupil size can also be influenced by non-visual factors. Emotional states, such as excitement, fear, or surprise, can lead to pupil dilation. Cognitive processes, like focused attention or mental effort, can also affect pupil size. Certain medications, drugs, and neurological conditions can also cause significant changes in pupil size, which can be an important diagnostic indicator for healthcare professionals. The measurement of pupil size is often referred to as pupillometry.