To dilate or not to dilate, that is the question

By Jen Hanten, Tammy Menning, Erin Eckerman and Erin Averkamp, Opthalmic Assistants at The Eye Center at Southwest Health.

If you’ve ever had an eye exam you’ve probably been asked if you would mind having your eyes dilated. Sometimes the uncertainty of the situation gives us pause and we may hesitate to say “yes.” The good news is it’s not that bad. It doesn’t hurt. It’s only temporary, and there are no lasting side effects. In fact, our eyes naturally dilate on their own throughout the day as they adjust to changing light, stimulation, and even our changing emotions. Having them medically dilated simply helps us re-create what your body does on its own.

What are dilating eye drops?

Dilating eye drops (called mydriatics) contain medication to enlarge or dilate the pupil. According to the American Academy of Ophthalmology, the drops work in one of three ways:

• By temporarily and gently paralyzing the muscle that makes the pupil smaller;
• By stimulating the muscle that makes the iris (the colored part of the eye) widen; or
• By preventing the pupil from adjusting for focus (called accommodation).

Once the drops are put into your eyes it usually takes 20 to 30 minutes for your eyes to fully dilate. People with light colored (blue, green, hazel) eyes will dilate faster than people with darker (brown) eyes.

Why is dilation necessary?

A large pupil allows the doctor to examine the inside of the eye in order to diagnose and treat eye diseases. However, it is not always necessary to dilate more than once every one to two years unless instructed by your doctor.

“I always tell my patients that trying to assess their ocular health through an un-dilated pupil is like looking through a keyhole into a room, while looking though a dilated pupil is like looking through a wide open door,” Says Nicole Klein, OD at The Eye Center at Southwest Health. “We are much better able to assess for retinal disease such as choroidal melanoma or retinal holes and tears, which may be asymptomatic in early stages.”

Some types of eye surgeries also require dilating drops to help your surgeon see inside to your retina and optic nerves. After surgery, the drops can be used to keep your eyes “relaxed” and the pupil wide so that scar tissue doesn’t form. Your optometrist will also use the drops to help measure for your correct prescription as well.

How long do dilating drops last?

Dilating eye drops usually last from four to six hours depending on the strength of the drop and the patient, dilation tends to last longer in people with lighter color eyes. At times a stronger dilation is used on children to help gently paralyze the tiny muscles that focus the eyes to help determine the correct prescription. Finally, dilating drops are sometimes used to treat eye diseases such as amblyopia (lazy eye) and inflammation. These may have a longer duration of action, even up to two weeks. Despite the longer duration, daily administration of the drop may be necessary for treatment to help with painful contractions of the pupil.

What are the side effects?

Light sensitivity and blurred vision (especially for near tasks) may be noticed but both gradually disappear. It’s always a good idea to bring a pair of sunglasses to your appointment if there is potential for dilation. These will help minimize glare and light sensitivity while your eyes return to normal. Children may return to school, and their teachers should be made aware that they may experience temporarily blurred vision while reading as their eyes are readjusting. It’s also a good idea to arrange for transportation after your visit as driving may be difficult immediately after your appointment.

For questions about the dilating process or to schedule your yearly eye exam, call The Eye Center at Southwest Health at 608-342-2020.