Or you might notice someone else’s pupils are not the same size. Significant anisocoria will require further investigation into the possible cause, which may require treatment. Mechanical anisocoria can occur following a trauma to the eye that has caused damage to the iris or the structures around it. Pathologic anisocoria develops from an underlying disease or condition, often iritis. This information was developed collaboratively by the Patient Information Committee of the North American Neuro-Ophthalmology Society. This has been written by neuro-ophthalmologists and has been edited, updated, and peer-reviewed by multiple neuro-ophthalmologists.
The sooner you determine the cause of anisocoria, the sooner your eye doctor can advise the most appropriate treatment plan. Anisocoria may be diagnosed if one pupil is bigger or smaller than the other. In some cases, the pupils may continue to respond normally to light, while in other cases, their responses may differ from one another. The left pupil is smaller (solid arrow) and the left eyelid is droopy (dashed arrow). When you step into a brightly lit area, your pupils constrict to limit the light intake, protecting the sensitive retina at the back of your eye. If anisocoria is the first sign of a more serious condition, the treatment you’ll need depends on what’s causing it.
Different sized pupils could indicate a serious health issue requiring urgent medical care.
There are also near cards that have pupil sizes on them for comparison. While measuring the pupils, the patient should focus on a distant object. This is to avoid miosis (pupillary constriction) while the patient is accommodating at a near target. After the pupils have been measured, the practitioner should identify whether the anisocoria is greater in light or darker conditions.
The views expressed in this brochure are of the contributors and not their employers or other organizations. Please note we have made every effort to ensure the content of this is correct at time of publication, but remember that information about the condition and drugs may change. Anisocoria itself generally does not affect ocular health, and visual acuity usually is minimally affected. Anhidrosis is typically present in cases of central (1 order) or pre-ganglionic (2 order) lesions. Cleveland Clinic offers comprehensive ophthalmology services to help you do that. Experts estimate that around 15% of people experience anisocoria at some point in their lives.
Pathologic anisocoria
Every time you move your eyes or blink, your pupils “reset”, leading to small changes in their size over the course of a second or two. In their new paper, Mather and Cavanagh provide compelling evidence that these transient changes in pupil size are the underlying cause of the peripheral drift illusion. This is a benign condition that causes the pupils to differ in size, usually by up to one millimeter in diameter, without affecting the pupils’ response to light. This condition can be intermittent or constant, and may even go away on its own without medical intervention.
Head injuries can lead to increased intracranial pressure or other complications that may affect your vision and overall health. Being proactive about changes in your pupil size can help ensure that any potential issues are addressed early on, minimizing the risk of long-term complications. They examine whether the eyes move normally when the person follows a doctor’s finger moving up, down, left, right, and toward the eyes. Doctors examine the entire eye, usually using a slit lamp (an instrument that enables a doctor to examine the eye under high magnification).
- In some cases, unequal pupils may signal more serious conditions such as Horner’s syndrome or Adie’s pupil syndrome.
- The following information can help people decide when a doctor’s evaluation is needed and help them know what to expect during the evaluation.
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- Understanding the cause is crucial for determining whether treatment is necessary.
When you visit a healthcare provider for unequal pupils, they will likely conduct a thorough examination to determine the underlying cause. This may include a comprehensive eye exam where they assess your vision and check for any abnormalities in eye movement or response to light. They may also perform tests to evaluate how well your pupils react under different lighting conditions and whether they respond appropriately when focusing on near objects. Physiologic anisocoria is usually defined as a pupillary inequality of 0.4 mm, seldom greater than 0.8 mm, not due to a secondary cause. If the anisocoria is physiologic, the difference in pupil sizes should remain equal in dim and bright lights. This also should be something that patient has had for a long time and has not acutely changed.
The peripheral drift illusion is determined by pupil size changes.
The prognosis of anisocoria depends entirely on the causative factor. There is no difference in mortality from most causes anisocoria compared to the general population, with the exception of two causative conditions. Eye drops that cause activation of the dilator pupillae can cause mydriasis of the pupil. Because lots of conditions and injuries can cause anisocoria, there’s not one surefire way to prevent it. You might notice that your pupils are not the same size when you look in the mirror.
Other conditions to unequal pupils usually indicate ask about include uveitis, iris coloboma, corectopia, neovascularization of the iris, or iridocorneal endothelial (ICE) syndrome. Anisocoria is a condition characterized by unequal pupil size. The etiology of anisocoria is complex, ranging from benign to potentially life-threatening causes. Potential etiologies of anisocoria include systemic drug use, topical ophthalmic drug use, headaches, trauma, ophthalmologic diseases, and autonomic ganglion pathology.
Diagnostic Tests for Unequal Pupils
When your eyes are exposed to continuous motion in one direction for a long time, motion detectors in your visual system become adapted to this motion. This is why after staring at a waterfall (moving down) may lead you to perceive upward motion when you look at the non-moving landscape nearby. The pupil is the black circle at the centre of the iris that allows light to enter the eye so we are able to see. It appears black (sometimes red in photographs) but is actually clear.
What Unequal Pupils Reveal About Your Health
When it comes to the human eye, symmetry is usually the name of the game. That’s where anisocoria steps in—a condition characterized by unequal pupil sizes. Anisocoria can be a benign quirk or a sign of something more serious. Let’s dive into the world of uneven pupils, exploring causes, symptoms, diagnosis, and treatment. If you’re concerned about unequal pupils and are seeking related information, you might find it useful to explore other eye health topics such as complications after eye surgeries.
There are multiple pathways involved in determining pupillary size and reactivity. Pupillary size may be influenced by systemic drug use or topical ophthalmics. Anisocoria also may be present in a cluster headache with lacrimation and rhinorrhea. Additionally, some autonomic ganglion pathology may manifest as anisocoria.
Your doctor may order scans of your head and body, such as MRIs and/or CTs. If these tests find any serious problems, your doctor will refer you to the appropriate specialists for urgent treatment. In other cases, they may recommend treatments for your symptoms, which could involve eye drops or nothing at all.
In some cases, unequal pupils may signal more serious conditions such as Horner’s syndrome or Adie’s pupil syndrome. It’s important to recognize that pupil size can vary significantly from person to person and even from one moment to the next. Under normal circumstances, pupils may differ slightly in size due to natural asymmetry; this is often referred to as physiological anisocoria. In most cases, these variations are harmless and do not indicate any underlying health issues. The two entities causing anisocoria that are the most significant to the clinician and require prompt and accurate diagnosis are TNP and Horner syndrome.
People with Horner syndrome or third cranial nerve paralysis usually require magnetic resonance imaging (MRI) or computed tomography (CT). People who have Horner syndrome may also need a CT of the chest. Sometimes doctors examine an old photograph of the person (for example, on the person’s driver’s license) to see whether pupils were previously unequal or the eyelid(s) droopy. Discuss a plan of action with your healthcare provider if you have a chronic condition that can cause unequal pupils, such as MS or a ventricular shunt. The plan will include which symptoms you need to call about and who to call. You should see a healthcare provider immediately if you suddenly develop unequal pupils.
The difference in pupil size in physiologic anisocoria remains stable over time and is not a concern for an underlying medical condition. Normally, in dim light (such as at night), the pupil dilates (becomes larger) to let in more light to the eyes. In bright light (such as sunlight), the pupil constricts (becomes smaller), which decreases the amount of light getting into the eye. Problems affecting the muscles or nerves controlling the pupil cause abnormal pupil size. This could indicate a serious underlying condition that requires immediate medical evaluation. Additionally, if you have experienced trauma to the head or eyes and notice unequal pupils afterward, it is essential to seek medical care without delay.