Eyes dilate for many reasons. They mainly dilate to control the amount of light that enters the eye. Pupils become smaller when the light is bright, and larger in the dark. Eye doctors dilate eyes to check for signs of disease. Eyes can also dilate as a result of an illness, or another condition or emotion.
The circular and radial muscle of the iris control eye dilation. The radial muscle responds to dim light and will cause your pupil to become larger. The circular muscle reacts to bright light and causes the pupil to grow smaller. These muscles respond to the signals sent by the nervous system. The iris moves to change the dilation of the eye.
Eyes may dilate for as a result of physiological stimuli such as fear or being attracted to someone. Generally, these reactions are minimal and the pupil will become slightly more dilated. The dilation may happen when you switch focus between objects suddenly, and again it is only temporary. It usually corrects itself immediately. Drugs can also affect the dilation of the eye, particularly muscle relaxants. Some illegal drugs also cause the eyes to dilate.
Dilated eyes may be a sign of a head injury or another serious health condition. This condition is called mydriasis. If your eyes are unnaturally dilated and do not respond to light, you should seek medical attention immediately. A concussion can cause poor response to light and dilation, but usually the eyes recover as the concussion goes away. Epilepsy and stroke can also cause your pupils to dilate when they would not normally do this. This symptom will usually dissipate after a period of time, but it does signal something serious.
Eye doctors can dilate eyes during an exam with eye drops. Doctors will use mydiatric drops during the exam. The eye doctors will be looking for signs of damage on the back of the eye. They can also spot early signs of multiple sclerosis, kidney disease, and high blood pressure. If they see any abnormal signs, they may recommend that you see your regular doctor for a physical. Doctors also dilate young children’s eyes so that they can more accurately write a prescription to correct their vision.
If you have had your eyes dilated for an exam, you must be careful when going outside. You should wear sunglasses outside until your eyes have returned to normal. Your doctor can provide you with a pair of free sunglasses if you do not have any. Your vision may also be affected, and you should be sure that you have planned your day to allow your eyes time to adjust after the exam. Your eyes will usually adjust back to normal within a few hours’ time. Children’s eyes tend to stay dilated longer, and they still may be dilated the next morning after an exam. If you have light colored eyes, dilation may last longer as well. If you have any questions about this, be sure to ask the doctor before you leave.