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