causes of miosis
There are several reasons you might have small pupils, including the following: Miosis caused by opioids and other medications Some drugs will cause your pupils to become very small. Pinpoint pupils are a known result of taking opioids and barbiturates. Other drugs, such as myotic drugs like pilocarpine, make pupils small. Pilocarpine is a medicine used to treat glaucoma and dry mouth. Miosis caused by opioids is present in both eyes. Miosis caused by Horner’s syndrome Horner’s syndrome is a condition that affects your eyes and part of your face. It happens because of a disruption of the pathway of the sympathetic nerves that connect your brain stem to your eyes and face. The nerves control involuntary functions like dilation and constriction of the pupils of the eye. Oculosympathetic palsy or Bernard-Horner syndrome are other names for Horner’s syndrome. Miosis caused by Horner’s syndrome is monocular (one-sided). Miosis caused by poisoning You can develop miosis of the pupils because of poisoning. Poisons that cause miosis include organophosphates, benzodiazepines and clonidine. Miosis caused by uveitis Uveitis describes a group of diseases that cause pain in your eyes, redness and inflammation. The disease affects the middle part of the eye known as the uvea, along with the retina and the sclera. The sclera is the white part of your eye. The retina is the innermost part of the eye that senses colors and lights and sends images to the brain. Miosis caused by iritis Iritis is the medical term for inflammation (swelling) of the iris. The iris is the colored part of your eye. Muscles in your iris control your pupil. Miosis caused by an injury to your brain or eye, including a brainstem stroke If your eye is injured, it can swell and be painful. This can make it more difficult for the pupil to change sizes. Miosis can also happen after a stroke that happens in the pons area of the brainstem (a Pontine stroke) or bleeding in the skull or brain. Miosis caused by neurosyphilis (Argyll Robertson pupils) Argyll Robertson pupils are constricted pupils in someone who has late-stage syphilis. When syphilis goes untreated, the germ that causes it can enter the cerebral spinal fluid. Even though there is a treatment for syphilis, a sexually transmitted infection, a significant number of people don’t get treatment. Miosis caused by synechiae, or inflammatory adhesions between parts of the eye Sometimes, inflammation causes adhesions between parts of the eye that are located next to each other. Adhesions happen when tissues of two organs or parts stick together, usually because of scar tissue. Miosis caused by cluster headaches Cluster headaches get their name from how they affect you. They come on in clusters or groups before going away. Each headache may last about 30 minutes and you can have up to eight of these headaches within a period of 24 hours. Cluster headaches sometimes produce symptoms similar to Horner’s syndrome, meaning that miosis and drooping affect one side of your face.