Miosis: If your pupil is abnormally small

If your pupil is abnormally small (less than 2mm) in diameter and unresponsive to light, it’s called a pinpoint pupil. This condition is also referred to as miosis or myosis. Miosis can affect one (unilateral) or both eyes (bilateral). Miosis is not a disease but may signal an underlying problem. Miosis of the eye is a condition characterized by the abnormal constriction of the pupil. This phenomenon involves a reduction in the size of the pupil. When your pupil shrinks (constricts), it's called miosis. If your pupils stay small even in dim light, it can be a sign that things in your eye aren't working the way they should. Miosis occurs naturally when doing close work or when stimulated by light. Note: also spelt myosis. See corneal reflex; pupil light reflex; baring of the blind spot; Horner's syndrome.