What does pupils dilating mean

Examining the retina and optic nerve is very important for diagnosing, preventing, and treating eye conditions such as glaucoma and macular degeneration; both of which could lead to vision loss if left untreated. When your pupils are not dilated the optometrist can still view the back of your eye, but his or her view is much more limited see diagram below and prevents them from thoroughly seeing your entire retina.

There are many different types of dilation drops that can be used, each varying in how long they last. This is a clear, colorless, and sterile topical ophthalmic solution that prevents the iris muscles colored part of the eye from constricting the pupil, thus causing dilation. When your pupils are dilated you can expect some light sensitivity, or photophobia, due to more light entering your eye.

You can also expect some blurred vision which is caused by the iris muscles being unable to constrict and contract to allow you to focus. Dilation drops affect everyone differently and according to the American Academy of Ophthalmology; can last from a few to several hours depending on the type of dilating eye drop used and how your specific eyes react.

To help with the effects of dilation, you can bring sunglasses to wear after your eye exam to help with the light sensitivity. If you are worried about having blurred vision and how long it may last, speak with your optometrist about your concerns and perhaps bring along someone who is willing to drive for you after your appointment. Overall, dilation is painless and is a very important diagnostic tool used by optometrists to help with diagnosing and treating eye conditions.

A dilated eye exam is recommended yearly. In one study of Americans ages 18 to 34 years, average pupil sizes in three different lighting conditions were found to be:.

A dilated pupil can sometimes still react to light — that is, get smaller in bright light or when a light is shined at the eye. A large pupil that is completely unresponsive to light is called a "fixed" dilated pupil. Dilated pupils aren't the same as anisocoria , a common condition where both pupils react normally to light but differ in size by about a half-millimeter or more. The following prescription and non-prescription medicines can cause your pupils to dilate and affect their ability to react to light:.

Atropine used for myopia control and other medical purposes. A serious, penetrating eye injury can damage your iris and cause the pupil to become dilated and irregular in shape. Sometimes, this sort of injury can occur during an eye surgery, such as a complicated cataract surgery or a corneal transplant.

A head injury , stroke or brain tumor can affect how your pupils react to light and cause dilated pupils. One or both eyes may be affected. This is why you see physicians checking an athlete's pupils with a penlight following head trauma sustained during sporting events, or when a patient arrives at a hospital emergency department with other possible stroke symptoms. Research has shown that alcohol and marijuana — separately or in combination — can reduce your eyes' ability to recover from exposure to a bright light source such as oncoming headlights at night and adapt to changing light conditions.

This effect can last two hours or longer after drug ingestion. A number of illegal drugs, however, do directly cause dilated pupils. This slows your eyes' ability to react to light. This is an unusual but harmless condition where a person experiences sporadic episodes of one pupil suddenly becoming dilated, often accompanied by blurry vision, headache and eye pain.

Young women who are prone to migraine appear to have the highest risk of benign episodic unilateral mydriasis. In one study, the median duration of the episodes was 12 hours some lasted much longer and the median frequency was two to three episodes per month. Also called Adie's tonic pupil or tonic pupil , this is a rare neurological disorder where one pupil is larger than normal and is slow to react to light. Sometimes, the pupil does not constrict at all. This pupil abnormality may be accompanied by poor or absent tendon reflexes.

When this occurs, the condition is called Adie's syndrome. Injuries that can damage your iris muscles and dilate your pupils include:. If the injury bruises your iris muscles, your pupils will likely be dilated temporarily, but if your iris muscles are torn or otherwise damaged, the change may be permanent. Benign episodic unilateral mydriasis BEUM is a condition in which the pupil in one of your eyes spontaneously dilates. It can stay dilated for just a few minutes or can go for days before returning to its normal size, Mackay says.

Usually, BEUM is nothing to worry about. There are many reasons your pupils may be dilated, and in many cases, there is nothing to worry about. But because there are some causes that are harmful, "a suddenly dilated pupil should be evaluated urgently, preferably by a qualified eye care provider," Mackay says. In particular, if one or both of your pupils are dilated and you have other symptoms like a drooping eyelid or double vision, you should get medical attention as soon as possible, Mackay advises.

World globe An icon of the world globe, indicating different international options. Get the Insider App. Click here to learn more. A leading-edge research firm focused on digital transformation. Women's Health. Primary Care. Mental Health. More Button Icon Circle with three vertical dots.