Why Eye Dilation Is Vital for Your Eye Exam | Cannon EyeCare
Many of our new patients 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.
What is Dilation?
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.
Why do Eye Doctors Dilate Your Eyes?
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 crystalline 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.
How Does it Feel?
The downside 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 be dangerous to drive while dilated, so we always encourage patients to bring a driver if they need or want to have their eyes dilated.
Optomap vs Dilation: Which Retinal Exam is Right for You?
Pupil dilation with eye drops remains the gold standard for comprehensive retinal exams, but advancements like Optomap retinal imaging offer alternatives. Let’s compare:
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Traditional Dilation: Uses medicated drops to widen pupils, allowing eye care professionals to examine the retina, optic nerve, and blood vessels for conditions like glaucoma, macular degeneration, or diabetes-related damage.
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Optomap Imaging: A non-invasive, wide-field retinal scan that captures up to 82% of the retina in a single image without requiring dilation. While convenient, it may miss peripheral retinal tears or detachments in some cases.
Eye care professionals often recommend dilation for high-risk patients (e.g., diabetics) or detailed diagnostics, while Optomap suits routine screenings. Always follow your clinic’s guidance based on your eye health history.
Understanding Pupil Dilation: Why It’s Done
Pupil dilation is a routine procedure in eye exams to temporarily enlarge the pupils using mydriatic drops. This allows clinicians to:
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Detect early signs of chronic diseases (e.g., diabetes, hypertension) through retinal changes.
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Evaluate optic nerve health for glaucoma risk.
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Diagnose retinal tears, detachments, or macular degeneration.
Dilation ensures a thorough view of the eye’s internal structures, which is critical for accurate diagnosis and preventing vision loss. Most adults should undergo dilated exams every 1–2 years, though frequency varies by age and risk factors.
Types of Eye Dilation Drops and How They Work
Common dilation drops include:
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Tropicamide: A fast-acting drop that dilates pupils for 4–6 hours, often used for standard exams.
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Phenylephrine: Enhances dilation and is sometimes combined with tropicamide for longer procedures.
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Cyclopentolate: Used for prolonged dilation (up to 24 hours), typically in children or patients with severe light sensitivity.
These drops temporarily paralyze the iris muscle to prevent pupil constriction. Side effects like light sensitivity or blurred vision are normal but consult your eye doctor if symptoms persist beyond 8 hours.
Dilated Eyes Pictures: How Imaging Supports Diagnosis
After dilation, clinics often capture retinal photographs to document eye health. These images:
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Provide a baseline to track changes over time.
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Highlight abnormalities like hemorrhages, drusen, or lesions.
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Enable remote consultations with specialists.
While Optomap can replace dilation for some imaging needs, traditional dilation remains essential for dynamic assessments (e.g., evaluating how pupils react to light).
Post-Dilation Care: Tips for Comfort and Safety
After dilation, manage side effects with these steps:
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Wear UV-protective sunglasses to reduce light sensitivity.
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Avoid driving until vision clears (typically 4–6 hours).
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Use lubricating eye drops if experiencing dryness from dilation drops.
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Skip contact lenses for 1–2 hours to prevent irritation.
Most symptoms resolve on their own, but notify your clinic if you experience severe pain or prolonged blurred vision.
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.
FAQs
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Wait at least 1–2 hours after dilation before reinserting contact lenses. Dilation drops can temporarily blur vision and dry out your eyes, which may cause discomfort with contacts. For safety, bring glasses to your appointment and ask your eye doctor for personalized advice.
