Dilated drugs are specialized eye drops administered during a comprehensive eye examination. They work by widening the pupil, the black opening in the center of the iris. Normally, the iris adjusts pupil size to control light and focus. By temporarily enlarging the pupil, these drops prepare the eye for a thorough internal inspection.
Purpose of Eye Dilation
Eye dilation provides the eye care professional with an unobstructed and detailed view of the eye’s internal structures. When the pupil is undilated, the view of the back of the eye, including the retina, optic nerve, and blood vessels, is limited. Dilating the pupil allows for a wider “window” into the eye, enabling a comprehensive assessment.
This expanded view is particularly helpful for detecting and diagnosing various eye conditions, often before symptoms become noticeable. These include:
- Glaucoma, a condition affecting the optic nerve.
- Macular degeneration, which impacts central vision.
- Diabetic retinopathy, a complication of diabetes affecting retinal blood vessels.
- Retinal tears or detachments.
In children, dilating drops are also used to accurately determine refractive errors, which helps in prescribing the correct eyeglasses.
How Dilating Drops Work and Their Effects
Dilating eye drops generally contain two types of medication: mydriatics and cycloplegics. Mydriatics, such as phenylephrine, work by stimulating the iris dilator muscle, which causes the pupil to widen. Cycloplegics, like cyclopentolate or tropicamide, relax the muscles responsible for constricting the pupil and, importantly, also temporarily paralyze the eye’s focusing muscles. These two types of drops are often used together to achieve sufficient dilation and relaxation of focusing.
After the drops are administered, patients experience several temporary effects. A common sensation is a mild stinging upon application, which usually subsides within a few seconds. Vision will become blurry, especially for close-up tasks, because the eye’s ability to focus up close is impaired. Patients will also notice increased sensitivity to light, known as photophobia, as more light enters the dilated pupil. This occurs because the pupil is temporarily unable to constrict and regulate light intake.
Duration of Dilation and Aftercare
The effects of dilating eye drops last between 4 to 24 hours, though this duration can vary. Factors influencing how long the dilation lasts include the specific type and strength of the drops used, as well as individual patient characteristics. For example, people with lighter-colored eyes may experience longer-lasting dilation compared to those with darker eyes due to differences in iris pigment. Children often require stronger dilating drops, which can result in their eyes remaining dilated for a longer period, sometimes even exceeding 24 hours.
After the eye exam, it is advisable to take certain precautions to manage the temporary effects. Wearing sunglasses outdoors is strongly recommended to alleviate light sensitivity and glare. Driving immediately after dilation is generally not advised due to blurry vision and impaired depth perception. It is best to arrange for someone else to drive or wait until vision returns to normal.
Patients should also postpone tasks that require sharp near vision, such as reading or computer work, until the effects of the drops have worn off. If unexpected or severe symptoms, such as persistent irritation or unusually prolonged blurry vision, occur, contacting an eye care professional is recommended.