Pupil dilation: What you need to know

The article was professionally consulted by Specialist Doctor I Nguyen Thi Bich Nhi - Ophthalmologist - General Surgery Department - Vinmec Nha Trang International General Hospital.

The pupil is a black hole located in the center of the iris. They focus light and carry it to the retina to form an image.
Mydriasis is the dilation of the pupil, stimulation of the radial fibers of the iris increases the pupillary aperture. Mydriasis may be a physiological response to the pupil or be due to some other cause.
Normally, the pupil dilates in the dark and restricts light to improve the vividness of the image at night, protecting the retina from the harmful effects of sunlight during the day. Pupil dilation can also be natural dilation in low light or due to sympathetic stimulation. When the pupil dilates, the eye becomes more sensitive to light, making the vision blurry.

There are many causes of pupil dilation such as:
Medications: Some drugs make the eyes sensitive to light such as antihistamines, motion sickness drugs, nausea drugs, tricyclic antidepressants, anti-inflammatory drugs. parkinsonian treatment, antiepileptic drugs,... Eye trauma: Some serious eye injuries lead to damage to the iris and cause the pupil to dilate or deform. In addition, eye trauma may occur during surgery such as corneal transplant, cataract surgery. Brain diseases: A stroke, brain tumor, or head injury can affect the eye's sensitivity to light, causing the pupils in one or both eyes to become dilated. Pressure that builds up inside the brain after these conditions can damage the muscles in the iris that help the pupil dilate. Addictive drugs: People who use narcotics will cause their eyes to react slowly to light and dilated pupils. In addition, detox drugs can also dilate the pupils.

Congenital iris defects: Congenital iris defects are partial or complete defects in the iris, causing the pupil to be very dilated. Iris defects usually affect both eyes and are associated with serious problems such as: congenital cataracts, retinal and optic nerve failure to develop, glaucoma, nystagmus demand and vision loss.

To diagnose dilated pupils, your doctor will rely on your medical history and current medications, along with your symptoms. The hallmark symptom of dilated pupils is that the pupils do not dilate in response to ambient light. The eyes become more sensitive to light as the pupils dilate. At this point, the patient may have blurred vision, and a feeling of constriction around the eyes and forehead. Headache, dizziness, trouble sleeping, and eye irritation can also be among the symptoms of dilated pupils.
Patient will have vision tested through visual acuity and eye movement test to evaluate the muscles of the eye. In addition, the doctor may order other types of tests to rule out other health conditions.

Treatment of dilated pupils should be based on the cause of the disease. The doctor will recommend appropriate treatment methods for each patient.
If the patient is using a pupil dilator, it is necessary to pay attention to the effect of the drug and replace it with another drug. In cases of eye and brain injury, surgery may be required if there is damage to the nerves or structures of the eye.
In addition, the doctor may also prescribe the use of low-dose glaucoma medication to narrow the pupil.
For patients with dilated pupils, often very sensitive to light. Therefore, the best way is to wear sunglasses outside and avoid places with bright lights.
In summary, mydriasis may be due to normal physiological reflexes under the influence of the environment. However, it can also be a sign of an injury, neurological disease, or a side effect of medication. Therefore, when seeing blurred vision, sensitive to light, sometimes accompanied by headache, dizziness, the patient should immediately go to a medical facility for examination and appropriate interventions.
Doctor CKI Nguyen Thi Bich Nhi has nearly 10 years of experience in the eye field. Treatment of medical eye diseases as well as eye surgery such as: pterygium, entropion, milia, glaucoma and cataract surgery by Phaco method. Besides, it also treats diabetic retinopathy by intraocular Anti-VEGF injection and ophthalmic surgery. Currently, the doctor is an Eye Doctor in the Department of Medical Examination - Internal Medicine, Vinmec International General Hospital Nha Trang
Vinmec International General Hospital is one of the hospitals that not only ensures professional quality with a team of medical professionals. leading doctors, a system of modern equipment and technology, but also outstanding with comprehensive and professional medical examination, consultation and treatment services; civilized, polite, safe and sterile medical examination and treatment space.