Your complete guide to eye exams: Visual acuity test, pupil dilation, and more!

Do you remember when your last eye exam was? If you can’t, that means you might be due for one. In this blog post, you’ll find all the information needed about eye exams, and how to keep your eye health in check.

How to tell if you’re due for an eye exam

Think it’s time for a check-up, but not quite sure if now’s the right time? Below are some questions you can ask yourself that may help you decide.

• Are your eyes very dry regularly?
• Do you notice eye floaters, spots, or other abnormal sensations?
• Do you have difficulties seeing at night? Are street signs difficult to make out at night?
• Do you experience eyestrain, headaches, and even blurry vision when performing routine tasks from up close distances (for example, using a computer)?
• Are you always holding reading material at arm’s length in order to see things clearly?

How often should I get an eye exam?

How often you should get an eye exam depends on your age.

• Children aged five and under: If you’re a parent with kids aged five and under, consider having your kid’s eyes examined as early as the age of three. At this age, it makes it easy for pediatricians to spot eye conditions—like amblyopia (lazy eye)—early on in children to avoid any future concerns.
• Children over five and teenagers: If your child or teen says they’re having a hard time seeing far distances it may mean it’s time to schedule an appointment. Sometimes, these routine check-ups can catch eye conditions before they worsen, helping your children better see.
• Adults: Depending on family history, or what visual symptoms you’re experiencing, visiting the clinic once-a-year is a safe bet. This is especially wise if you find your vision is often blurry, or if you have frequent headaches.

As is the case with any general health check-ups, regular exams are an excellent way to spot any potential problems with your vision before they worsen.

The tools used in an eye exam

During your eye exam, you will undergo several tests that are, for the majority of people, not painful. These tests will help eye care professionals understand your given eye condition, your prescription, and what next steps lie ahead.

Several tools, all of which will be administered by an eye care specialist, examine your eyes' health. Below are some of the devices that may be used to help you find out your specific eye condition.

• Snellen eye chart: If you’ve ever had an eye exam before, then you are no doubt familiar with the Snellen eye chart, a poster usually displayed on the wall of the examination room. On it, you’ll find several rows of text with letters randomly arranged. As your eye moves closer to the bottom, the letters get smaller and smaller. The Snellen eye chart allows the optometrist to measure your visual acuity (the way that your eye sees sharpness). If you can see small letters from a great distance, then you have strong visual acuity.
• Phoropters: A phoropter is a tool that the optometrist uses to measure refractive errors (like myopia, hyperopia, or astigmatism, for example). During this test, you’ll be asked to identify the clearer lens after looking through several different options. Oftentimes, the optometrist will ask you to choose between two to find your perfect lens fit. They’ll perform this test a few times over to ensure total accuracy.
• Ocular tonometry: Ocular tonometry measures the intraocular pressure inside the eye (IOP). This test is most commonly used to check for glaucoma, an eye disease that may put the individual at risk for blindness.

The difference between a LASIK screening and routine eye exam

A LASIK screening test differs slightly from a standard eye exam. For example, a LASIK candidacy test may look for conditions that would affect your potential eligibility for a vision correction procedure, such as dry eye syndrome. This is due to the fact that severe dry eye could have the potential to impair your eye’s healing process. Other eye conditions, such as keratoconus, may mean you aren’t a candidate for a LASIK procedure at all (however, the eye care professional performing the tests may find you are a suitable fit for a surgery like corneal collagen cross-linking instead). Other diseases like diabetes, herpes, or rosacea may all a part in your LASIK candidacy. Other tests, like a measuring of your eye’s topographic maps or a pupil dilation test may also be performed at a LASIK candidacy screening.

What is a pupil dilation exam?

A pupil dilation exam, a typical part of a LASIK screening test, dilates your pupils using eye drops (the pupil is the dark centre part of the iris, the coloured part of your eye).

• What does a dilated eye exam involve? A dilated eye exam is when the eye care professional uses eye drops to inspect the inside of the eye more closely. This can help spot eye disease (if any) and other conditions much earlier on.
   
• Why do I need to have my pupils dilated? While not always necessary, pupil dilation gives ophthalmologists the chance to do a more thorough exam of your retina.
   
• What results will a dilated pupil examination show? In undergoing a dilated eye exam, your optometrist will be able to detect different eye conditions, such as glaucoma, signs of age-related macular degeneration, or retinal tears or detachment. Dilated eye exams can also spot eye tumours.
   
• Is having a dilated eye exam necessary? Though not a necessary step, pupil dilation allows your optometrist to get a more in-depth look at your eyes—in cases with more severe symptoms, then pupil dilation will help find the root of the problem.
   
• Is pupil dilation safe? When your eyes experience pupil dilation, the first thing you’ll notice is that your vision will become blurry. This is normal. Eyes will also become sensitive to light so it is recommended to bring a pair of sunglasses along for your appointment. Effects of pupil dilation can last for a few hours but will eventually subside. Pupil dilation is generally quite safe, most doctors recommend avoiding driving until the effects have worn off so be sure to have someone drive you home after the appointment.

How thick your cornea is (and what that means for your LASIK candidacy)

Another major physical characteristic that a LASIK screening will examine is corneal thickness, a biological trait that lets your ophthalmologist decide which vision correction procedure is best-suited for your eyes. The cornea is the surface layer of the eye, sort of like a “window,” that allows light to enter into the eye.

In the same way that your eye’s shape differs from that of someone else’s, corneal thickness is a hereditary feature, so unfortunately, you have little control over its size.
Eye care professionals record this using a unit of measurement called a micron (one micron is the equivalent of 0.001 mm). In order to perform a LASIK procedure, a tiny flap is created on the cornea using a device called a microkeratome. The surgeon then places the flap back to allow the laser to enter the eye and reshape the cornea in order to improve your visual acuity. Because an incision is created on the surface of the cornea, the width has to be ample enough to support an incision.

Are you ready for your comprehensive eye exam?

As you’ve just learned, an eye exam can reveal a lot to you about your eye health. So now that you’re an expert on eye exams, isn’t it the right time for you to schedule one to see if you’re a LASIK candidate? Head over to our online form to get the ball rolling and start taking the steps that can help change your life.