Many of our new patients at Cannon EyeCare seem surprised when we bring up dilation at their routine eye exams. Often they have never had their eyes dilated in the past, or it has been a very long time. This blog post will let you know what it means to get your eyes dilated, and why it is important for all patients to do so.
Dilation means putting in special eye drops that make your pupils huge (see photo above, where the left eye only is dilated). Typically both eyes would be dilated with pharmaceutical drops that cause the pupil to open as the iris retracts. Without dilation your eye doctor’s view of the back of your eye is limited; as they shine light in, the pupil constricts. This limits the doctor’s view of the intra-ocular lens where cataracts occur, as well as the retina. The retina (also called the fundus) is the light sensitive nerve tissue in the back of the eye of course.
In most patients the doctor can see about 10-20% of the retina without dilating, which means they aren’t able to assess the health of ~85% of the retina without dilation or special imaging tools. When your optometrist performs a dilated eye exam, your eye doctor can see the remaining ~85% of your retina. They also get a better look at the crystallin lens (where cataracts occur) and the vitreous (where floaters are located). So in the end you get a more thorough health exam for your eyes. At Cannon EyeCare in Seattle, we try to incorporate dilation into a patient’s annual exam. When we can accomplish this, patients get a more thorough eye health exam for the same money. That is the good part.
The down side to having your eyes dilated is that your exam takes longer, there are some bright lights that are uncomfortable, and then there are the side effects. When you get your eyes dilated, the typical side effects include blurry vision that is typically worse up close than far away, in addition to light sensitivity. Both of these side effects can last from 3-6 hours, so getting dilated and then going back to work may not be the best plan. It can also dangerous to drive while dilated, so we always encourage patients to bring a driver if they need or want to have their eyes dilated.
At Cannon EyeCare we are very thorough, but most of our patients do not need a dilation every year. Most healthy, normal patients are dilated every two to four years. Those with risk factors for vision loss like diabetes, glaucoma, or macular degeneration are dilated more often. If you have trauma to an eye or experience new floaters or flashes of light, you should go see your eye doctor and ask to be dilated right away. New floaters and flashes of light can sometimes be due to a retinal tear or detachment. So if you are diabetic and are due for dilation or have had a recent onset of flashes and/or floaters, call your eye doctor today to make sure your retina is OK.
Sincerely, Dr. Mark J Cannon, optometrist @ Cannon EyeCare (at Market Optical) in Seattle, Washington
P.S. If you are in the Seattle metro area, think you’re having an ocular emergency (like retinal detatchment) and can’t get in to see us or your regular eye doctor, go to the UW medical center or Harborview Hospital.