Michael Cole, OD, Child and Family Eye Care Center

dilated pupils

EYE CARE PROVIDERS are often asked about dilated eye exams. Is it important? What are the side effects? Can I drive home afterward? Does it cost extra? The short answer is that eye health examinations are just as important as glasses and contact lens prescriptions, if not more so. Dilations are the best way to check eye health, are part of a comprehensive eye exam, and do not affect driving ability. Short answers aside, let’s discuss why dilations are important:

Inside of the eye appears like a dark, round, cave-like room with the important structures to be examined lining the walls of the room. There is only one opening for light to enter the eye, which is through the pupil. As we try to examine the internal structures of the eye, we have only this tiny opening to look through, usually only a few millimeters across. This is much like peering through a keyhole in a door in order to view the decorations on the walls of a large room on the other side. You can imagine this is very difficult to do with such a small opening. When the muscles in the iris are affected with dilating drops, the pupil opens wider allowing for a much larger viewing window to look through, and a more thorough examination of the internal eye.

The main action of dilation drops is to dilate the pupil. There are, however, other effects of these drops on the eye, namely the loss of accommodation. Accommodation is the term we use to describe the eye’s ability to change focal lengths from one distance to another, allowing us to see both far away and up close. While dilated, the eye is no longer able to focus up close, causing near vision to be blurry. With age, we eventually lose this ability to accommodate, but the agents used in dilating drops temporarily relax the muscles involved in this process as well. Due to accommodation being less functional in older patients already, most hardly notice this effect at all, and still see well with multifocal lenses.

We often use this secondary effect of dilation drops called cycloplegia during refraction (the determination of one’s glasses prescription). In many cases, especially with children, accommodative systems may not be performing as intended, causing fluctuating vision and poor refractive results. With cycloplegia, we can relax all the muscles involved, and allow for refractive measurements in a completely relaxed state. In some cases, this is by far the best way to get accurate results.

While dilation allows examination of internal eye structures such as the optic nerve and macula, we also have a unique perspective of the overall health of a person by looking inside the eye. The only place in the entire body where it is possible to have an unobstructed view of blood vessels is inside the eye. It is important to have a dilated exam in order to monitor conditions that affect blood vessels such as diabetes, hypertension, and high cholesterol. If damage to the small vessels inside the eye exists, we know other areas in the body are likely affected as well. Anyone with systemic health conditions involving blood and blood vessels should have an eye exam annually regardless of the status of their eyesight due to our ability to closely monitor changes over time.

The list of potential problems that are detected and avoided with regular dilated eye exams is long, and the side effects of dilation are minor and shortlived. We only have one set of eyes, and it is important to take the best care of them possible