Uneven Pupils - Overview
Pupils are holes in the center of the iris. They normally change their size according to the light. If light is bright they will reduce in size and in the case of insufficient light, both of them will enlarge. This is a reflex and simply cannot be controlled. The problem occurs in case the size of pupils drastically differs. Namely, it is normal for pupils to be up to 1 mm different in size. However, if the difference is greater the problem has to be taken seriously. This unevenness of pupils is medically known as anisocoria.
There is no need to worry if a baby is born with uneven pupils, particularly if this has affected other members of the family. The cause is most probably genetic. Even if the problem occurs later in life and if the pupils temporarily differ in size but they eventually turn to normal there is no need for one to be worried. Only if the unevenness lasts longer and there are additional symptoms it is essential to search for the underlying cause as soon as possible.
Uneven Pupils - Causes
There are many illnesses associated with unevenness of the pupils. The problem may also arouse from intake of certain medications.
Uneven pupils are a characteristic of severe head injury. If a person has suffered a head injury and has uneven pupils this is a medical emergency and requires prompt treatment. Apart from trauma many conditions related to damage of the brain tissue lead to anisocoria. They include aneurysm or intracranial bleeding, brain tumors, brain abscesses, meningitis, encephalitis and any kind of damage to the cranial nerves.
Apart from the previously mentioned uneven pupils are a characteristic of Horner's syndrome. This syndrome features with uneven pupils and dropping of the upper eyelid. There is also an impression that the affected eye has sunk in. This syndrome may be related to many medical conditions and some of them are tumors of the apex of the lungs, thoracis aortic aneurysm, trauma of the base of the neck, multiple sclerosis, lateral medullary syndrome etc. Furthermore, uneven pupils also affect people suffering from Holmes-Adie's syndrome. This syndrome occurs due to viral or bacterial infections that cause inflammation and consequent damage to neurons in the cilliary ganglion or the spinal ganglion.
Anisocoria may be a side effect of some medications including several eye drops and drugs administered in case of allergies. Substances and drugs which predominantly affect the size of the pupils include pilocarpine, cocaine, tropicamide, and scopolamine.