During an eye exam sometimes you can't avoid having your eyes dilated. After all, dilating the eyes is an important part of the exam to check the overall health of the eyes. But what do you do about driving after eye dilation? Here are the most important things to think about before you get behind the wheel.
Dilation will cause extra brightness and glare in your vision
It's inevitable. Dilation makes your pupil bigger. Making your pupil will allow in more light. This extra light will make things appear brighter.
This may actually be quite nice at night. When it's dark, the eye naturally dilates to help us see. The more light we can use, the better night time vision we have. Night vision goggles work by magnifying the amount of light to artificially illuminate the surroundings for our eyes. Artificially dilating the eyes can help improve our night time vision in a similar way - by allowing us to absorb more light.
But if only all artificial dilation was near night time. Most dilation is in fact during the day when the clinic is open and when lights are the brightest. All that extra light in your vision can be uncomfortable. It can also make it harder to see as the overexposure to light causes glare in your vision.
This is especially the case while driving when light can reflect off of different surfaces and into your eyes. Shiny cars and signs are great at reflecting light back to you. You will definitely want to wear sunglasses to cut down on that extra light and glare from your vision.
Dilation can cause your vision to be more blurry
Most people can deal with some extra brightness and glare. The act of putting on sunglasses can help eliminate those issues to make driving feel more comfortable. Blurry vision is a different story.
Most people after dilation will have some blurry up close vision. Blurred up close vision isn't typically an issue while driving. Yes, you have to look at the dashboard but typically the dashboard isn't as blurred and easier to make out the essential details such as the speedometer. Blurred up close vision may actually be beneficial for driving if it prevents you from texting and using your phone.
Latent farsightedness (latent hyperopia)
But some people after dilation will experience unexpected blurred distance vision. On a normal day, these individuals can see just fine without glasses. But these individuals have some extra undetected farsighted prescription. This is called latent hyperopia or latent farsightedness.
Within the eye is a small muscle called the ciliary body. This muscle controls the focusing ability of our natural lens and allows us to see up close. But just as this can allow us to see up close, it can also allow us to focus through extra prescription. So, on a normal day, this ciliary body is focusing through the extra farsighted prescription of the individuals with latent hyperopia and allowing them to see off in the distance (although they may have some extra eye strain from this muscle working hard to focus all the time).
Commonly during dilation, this muscle is temporarily prevented from working. If this muscle can't work, then those individuals with undetected farsighted prescription will no longer be able to focus through that extra prescription. Their vision will become more blurry after dilation.
Note: This also happens to nearsighted people as well if they have extra unnecessary prescription in their eye glasses that their ciliary body is focusing through.
This blurry vision can be quite a bit and can actually prevent comfortable or safe driving. This can cause issues if you haven't been dilated before and aren't expecting this extra blurred vision. Sometimes a very light pair of reading glasses can correct the vision enough for driving but if that isn't an option you may have to call for a ride home.
Spherical aberration
While the individuals with latent hyperopia will experience a large increase in their blurred vision, all others will experience some blurred vision due to another cause: an increase in spherical aberration.
As the eye dilates and the pupil becomes larger, more of the natural lens becomes exposed. With a small pupil, all light passes through the center of the lens. With a large pupil, light passes through the center of the lens AND through the edges or periphery of the lens. Most lenses aren't perfect, our natural lens included, and light that passes through the edges of the lens will focus at a different spot on the retina in the back of our eye than light that passes through the center of the lens. This creates an effect called spherical aberration.
Spherical aberration will create additional halos in our vision. It will also create some extra blurred distortion in our vision. This is typically a small effect - things just won't appear as sharp as you are used to. But it can make a difference in more challenging driving situations - such as at night or in bad weather.
Cataracts
Cataracts are a clouding of the natural lens inside our eye. But different types of cataract exists and for some types of cataracts, dilation can make the vision much more worse. Some types of cataracts form directly in the center of the lens. But other types of cataracts form in the periphery of the lens. These types of cataracts are called cortical cataracts.
One of the defining features of these types of cataracts is that they cause extra difficulty driving at nighttime. For the most part, during daytime, the pupil covers up the cataract part of the lens. At night, the eye dilates and the cataract part becomes exposed. Light that hits the cataract is scattered into all different directions and the result is blurred vision.
So if natural dilation can cause blurred vision with these cataracts, you better believe that artificial dilation can do the same thing. These patients will experience more blurred vision after dilation. And unfortunately, unlike other causes there isn't a quick fix which can help improve these symptoms (other than trying sunglasses). But cataract surgery will be the answer in the long run.
See also Your Comprehensive Handbook To Learn What Are Cataracts
How to plan when your eyes are being dilated
The best way to deal with driving after eye dilation is to plan on bringing a driver. This is especially important when you haven't been dilated before or it's been a long time since you've been dilated. You may not know how dilation will affect your eyes.
If you've been dilated before and know how your eyes react to dilation, than you may feel perfectly fine driving after dilation. Be sure you are staying safe while driving. It may be helpful to stick with familiar routes and roads.
Avoiding being stranded with dilated eyes
But sometimes, you may be confronted with the plan to dilate your eyes without a plan ahead for a driver. Here's what you can do to avoid being stranded with blurry vision and no ride home.
- Some offices have ways to take pictures of the back of the eye without dilation. While this solution can't provide all the information an eye doctor may want during an eye exam, it may be a suitable option for many purposes.
- You can see if dilating only one eye is an option. While eye doctors frequently like to look at both eyes (even if only eye is giving you problems), they may be willing to only dilate the troublesome eye if you have concerns about driving home afterwards. Keeping one eye undilated can keep one eye good in case the dilation makes the other blurry.
- Lastly, you can always refuse the dilation (but the better way to word it is postpone the dilation). Not everything needs to be examined immediately. Many things can be postponed to a later time when you have more plans set in place. While probably not the best option if you are in an emergency room, this option can help if you didn't expect to be dilated at your clinic appointment and have concerns about driving home.
And lastly, you can always wait out the dilation. Not the best option, since it will take 4-6 hours for the dilation to wear off for most people. But perhaps there is a cafe a walk nearby that you've always wanted to visit. If you hang out long enough, your vision will return to normal.
Summary
Can you drive safely after having your eyes dilated? In most cases yes. It's just important to be aware of how dilation will affect your vision. And if you've never been dilated before or it's been a long time, it's best to take extra precautions such as having a driver as a backup just in case your vision becomes too blurry to see.
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