Pupil dilation refers to the widening of the black center of your eye, known as the pupil. The size of your pupils is controlled by tiny muscles within the iris, the colored part of your eye. This adjustment helps regulate the amount of light entering the eye, similar to an aperture on a camera. While pupil size changes naturally, various factors can also cause them to dilate.
Why Pupils Dilate
Pupils naturally expand in dim environments to allow more light to enter the eye, enhancing vision in low-light conditions. Conversely, they constrict in bright light to prevent too much light from reaching the retina. Beyond light, strong emotions such as excitement, fear, or even physical attraction can trigger pupil dilation due to autonomic nervous system responses.
Medical interventions, such as dilating eye drops used during eye exams, frequently cause temporary dilation for a clearer view of the retina and optic nerve. Certain prescription and non-prescription medications, including antihistamines, decongestants, tricyclic antidepressants, and Parkinson’s drugs, can also cause pupil widening. Recreational substances like amphetamines, cocaine, LSD, and MDMA also cause dilated pupils.
Physical trauma, such as a head or direct eye injury, can affect pupil-controlling muscles or neurological pathways, causing dilation. Various medical conditions, including stroke, brain tumors, aneurysms, certain migraines, or rare neurological disorders like Adie’s tonic pupil, can also cause pupil dilation.
Can You Make Your Pupils Undilate?
Directly forcing your pupils to undilate on command is generally not possible. Pupil size is largely regulated by the autonomic nervous system, which controls involuntary bodily functions. This means you cannot consciously command your pupils to shrink, much like you cannot consciously control your heart rate or digestion.
Pupil dilation resolves on its own once the underlying cause diminishes or is removed. For instance, dilation from eye drops used during an exam will wear off over several hours as the medication’s effects fade. Emotionally induced dilation returns to normal once the emotional state subsides.
What to Do While Your Pupils Are Dilated
Since direct undilation is not feasible, managing the effects of dilated pupils involves addressing common symptoms. Light sensitivity and blurred vision are frequent experiences, particularly when focusing on close objects. Headaches or general eye discomfort may also occur.
To alleviate discomfort, wearing sunglasses, especially polarized ones, can significantly reduce the amount of light entering your eyes. Avoid bright lights and limit activities requiring clear vision, such as driving or operating machinery, until your vision returns to normal. Resting your eyes and ensuring adequate hydration can also help minimize strain and promote recovery.
When to Consult a Doctor
While temporary pupil dilation is often harmless, certain symptoms warrant immediate medical attention. If you experience sudden dilation in only one eye, or if dilation persists without an obvious cause, seek professional evaluation.
Consult a doctor if dilated pupils are accompanied by severe headaches, eye pain, vision loss, dizziness, confusion, nausea, or vomiting. These could indicate a more serious underlying medical condition, such as a head injury, stroke, or other neurological issues.