

Reasons
Many cases of so-called mild anisocoria are normal and have no pathology or history of trauma. Generally, these cases where one pupil is 1.0 mm larger than the other for no reason are called simple anisocoria, benign or physiological anisocoria. Research shows that as many as 20% of the general population have mild, benign anisocoria. However, for a more serious type of anisocoria there can be a number of reasons, and some may be medical problems.
- Eye trauma: e.g. David Bowie (below)
- Certain eye medications: for example, pilocarpine – eye drops used to treat glaucoma can cause the pupil of one eye to be smaller than the other.
- Inflammation of the iris: Iritis (anterior uveitis) can cause anisocoria which is accompanied by pain in the eye.
- Adie’s tonic pupil: This benign anisocoria (also called Adie’s pupil, tonic pupil, or Adie’s syndrome) typically causes one pupil to be drastically larger than the other. The larger pupil also does not respond to light. In most cases, the causes of this condition are not known, but it can be caused by trauma to the eye (eg, trauma caused by complicated cataract surgery), lack of blood flow (ischemia), or infection.
- Neurological disorders. Many conditions that damage the nerves in the brain or spinal cord can cause anisocoria. One of the most significant is Horner syndrome (below). People with nervous system disorders that lead to anisocoria often have drooping eyelids, double vision, and / or strabismus. Anisocoria-related brain disorders include strokes, haemorrhage / bleeding of the eye (spontaneous or due to head injury) and, less commonly, certain tumors or infections.
Horner Syndrome (or Horner Syndrome)
The three classic symptoms are:- Ptosis (lowering of the eyelid)
- Miosis (narrowing of one pupil, anisocoria)
- Facial anhydrosis (sweating of the face around the eyes)
The eyes of David Bowie

What should the patient do when he has anisocoria?
When a patient has one pupil larger than the other, it is necessary to visit an ophthalmologist, especially if they have the following symptoms:- Ptosis (lowering of the eyelid)
- Duplicate pictures
- Loss of vision
- Headache or neck pain
- Eye pain
- Current head or eye injury
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Anisocoria means that the patient has an uneven pupil size. One pupil may be larger than normal, i.e. dilated, or one pupil may be smaller than normal, i.e. narrow, leading to their uneven appearance.
Reasons
Many cases of so-called mild anisocoria are normal and have no pathology or history of trauma. Generally, these cases where one pupil is 1.0 mm larger than the other for no reason are called simple anisocoria, benign or physiological anisocoria.
Research shows that as many as 20% of the general population have mild, benign anisocoria. However, for a more serious type of anisocoria there can be a number of reasons, and some may be medical problems.

- Eye trauma: e.g. David Bowie (below)
- Certain eye medications: for example, pilocarpine – eye drops used to treat glaucoma can cause the pupil of one eye to be smaller than the other.
- Inflammation of the iris: Iritis (anterior uveitis) can cause anisocoria which is accompanied by pain in the eye.
- Adie’s tonic pupil: This benign anisocoria (also called Adie’s pupil, tonic pupil, or Adie’s syndrome) typically causes one pupil to be drastically larger than the other. The larger pupil also does not respond to light. In most cases, the causes of this condition are not known, but it can be caused by trauma to the eye (eg, trauma caused by complicated cataract surgery), lack of blood flow (ischemia), or infection.
- Neurological disorders. Many conditions that damage the nerves in the brain or spinal cord can cause anisocoria. One of the most significant is Horner syndrome (below). People with nervous system disorders that lead to anisocoria often have drooping eyelids, double vision, and / or strabismus. Anisocoria-related brain disorders include strokes, haemorrhage / bleeding of the eye (spontaneous or due to head injury) and, less commonly, certain tumors or infections.
Horner Syndrome (or Horner Syndrome)
The three classic symptoms are:
- Ptosis (lowering of the eyelid)
- Miosis (narrowing of one pupil, anisocoria)
- Facial anhydrosis (sweating of the face around the eyes)
Horner syndrome differs from simple (benign) anisocoria in how quickly the pupils dilate in low light or in a dark room. Normal pupils dilate within 5 seconds. Whereas, in the case of Horner syndrome, the pupil takes 10 to 20 seconds. Horner syndrome is most often caused by a health problem, such as a stroke, tumor, or spinal cord injury. In some cases the real reason cannot be found. There is no specific treatment for this syndrome, but if it is associated with an identified medical problem, treatment of this condition may resolve Horner’s symptoms, including anisocoria.
The eyes of David Bowie

One of the most prominent physical characteristics of the late singer, songwriter and producer David Bowie was his eyes. Many people believe that he had two eyes of different colors – a condition called heterochromia. However, the real reason David Bowie’s eyes are so striking is anisocoria. Bowie was born with blue eyes, but a fight with a friend when he was a teenager caused one of his eyes to widen permanently, giving the eye a much darker look.
What should the patient do when he has anisocoria?
When a patient has one pupil larger than the other, it is necessary to visit an ophthalmologist, especially if they have the following symptoms:
- Ptosis (lowering of the eyelid)
- Duplicate pictures
- Loss of vision
- Headache or neck pain
- Eye pain
- Current head or eye injury
It is basically incurable. If it is accompanied by another disease, the disease from which it is caused is treated. If the patient has benign anisocoria, the ophthalmologist may prescribe photochromic glasses. These glasses are dimmed automatically in daylight to reduce light sensitivity (photophobia). Photochromic glasses will also protect the eyes from harmful UV rays and blue light – especially the eye that has a larger pupil and does not respond normally to light. It is basically incurable. If it is accompanied by another disease, the disease from which it is caused is treated. If the patient has benign anisocoria, the ophthalmologist may prescribe photochromic glasses. These glasses are dimmed automatically in daylight to reduce light sensitivity (photophobia). Photochromic glasses will also protect the eyes from harmful UV rays and blue light – especially the eye that has a larger pupil and does not respond normally to light.