Why do I need to get my eyes dilated?

When a doctor physically examines your eyes, they are looking not just at the outer surface, but at the inside health of the eye too. They do this by looking through the pupil, which is like a keyhole into the 'room' where the retina is. When the light shines into the eye, the pupil naturally shrinks smaller to protect the eye from what it perceives to be bright sunlight. By putting special eye drops into the eye, the doctor can make the pupil open wide, just as it does when we enter a darkened room. The doctor can see much more clearly to examine our inner eye through this wide opening, making the examination far more effective and thorough. Although having the pupils dilated is a time-consuming inconvenience, it is a necessary part of your preventative eyecare.

Application of the Eye Drops
As part of a regular eye examination the optometrist will apply eye drops into your eye to dilate and open the pupils. The drops take approximately 15-20 minutes to work. Side affects of this drop is sensitivity to light and difficulty focusing up close, such as reading a book, for a few hours. For this reason you should allow plenty of time for the examination itself, for both the preparation time and the recovery time afterwards. Dilating drops work on one of two principles: they either stimulate the iris muscle that opens the pupil (the dilator), or prevent action of the iris muscle that closes the pupil (the sphincter).

What Does the Optometrist See?
Once the pupil is fully dilated, which takes around thirty minutes after the eyedrops have been applied, the optometrist can then see all the way into the back of the eye.

Why do I need to get my eyes dilated?

During a normal eye examination, the doctor uses a light and a lens to look right into the eye and inspect the health of the cornea, the iris and the lens of the eye. They can check the optic nerve and the important blood vessels to make sure there are no signs of disease or cataract. Pupil dilation can also reveal other health problems such as hypertension (high blood pressure), diabetes, eye conditions like glaucoma and cataracts. Dilated exams can also detect thinning areas of the retina, or tears and holes which can lead to a retinal detachment and blindness. Once the eye examination has been completed, the pupils will remain dilated for a while, so it is a good idea to wear dark sunglasses to protect your eyes from the bright daylight which may hurt your eyes. Some optometrists supply disposable sunglasses if you have forgotten to bring any. Having your eyes dilated may make you feel slightly disoriented for a while afterwards. You should sit for awhile before driving, or take someone with you to drive you home.

To Summarize Eye Dilation:

  1. Allow plenty of time for your appointment and recovery time after pupil dilation
  2. Bring a pair of dark glasses to wear after the examination
  3. Arrange alternative transport home as you may not be able to drive
  4. Bring a book with large print to pass the time after the drops begin to work

Related Questions



I don't like my eyes getting

I don't like my eyes getting dilated. I get a weird headache after the dilation. Anyone know why this happens?

Headache after pupil dilation

I don't know why it happens but it always happens to me. I was told that lighter colored eyes take longer to return to normal but I have dark brown eyes and my eyes take more than 12 hours to be normal again. Luckily for me, the headache is less intense after the first couple hours. My regular eye doctor uses the lowest strength available to achieve dilation.

Picture of eye vs eye dilatation

I recently had an eye exam and I was told by the eye doctor that taking a picture of the eye now replaces dilation. Any eye care professionals willing to comment?

Hi, I am an optometrist.

Hi, I am an optometrist. In my mind taking a picture of the eye will never replace dilation. Retinal photography is great as medical documentation of your retina and is very useful to monitor for change over time. It does have a number of limitations however. The main one's being that it generally only shows a small portion of the retina and has no stereopsis (can't see in 3d). Also Retinal photography only shows the retina. Dilation is also useful for diagnosing cataracts, predisposing conditions for glaucoma, as well as a myriad of other conditions. It is a great adjunct to dilation, and having both performed is probably the ideal, but if I had to choose between the two, I would chose to dilate every time.

Lens of eye

What happens to the eye lens when the eye is dilated? Here is why I ask: I had my eyes dilated 10 days ago. My left eye was slow to recover from this. I had bleary eyesight until last night when I was trying to read and all of a sudden I had what looked like a line go across my eyes from the upper left to lower left. And, now I have no bleary eyesight there!
I have very blue eyes and I hate getting my eyes dilated. I am diabetic so they always do it. I really feel it does damage to my eyes and am tired of it and this was by far the worse experience yet.