Eye Exams

If you’ve discovered you might need vision correction during your eye examination, it’s vital to determine just how “much” your eyes need to be corrected with lenses or contact lenses. This is called measuring your “refraction.

Autorefractors automatically measure this value during an eye examination.

While seated with your chin in a stabilizing chinrest, you’ll be asked to focus on an image or point of light. The autorefractor automatically determines the correction needed to place your “focus point” on top of the retina, the light-sensitive area at the back of the eye responsible for correctly processing images.

The measurement taken by an autorefractor can be translated into a prescription for eyeglasses.

In eye exams for small children, or for people with special needs who may have trouble sitting calmly during an extended exam, or verbally describing their vision problems—autorefractors give highly accurate measurements used to determine vision correction needs, automatically.

How do autorefractors work?

Autorefractors only take a few moments to determine each measurement for each eye. What’s more, autorefractors are quite reliable and are sometimes used in conjunction with a machine called a phoroptor to manually switch lenses in front of your eyes to provide ideal vision correction.

A truly comprehensive eye exam almost always includes eye dilation—the addition of special eye drops that “open up” the pupil at the front of the eyeball. This allows for a maximum amount of light to enter the eyeball, giving your eye doctor the best possible visibility during a variety of specific eye tests.

Eye dilation is common during an eye exam after preliminary testing of visual acuity, pressure testing, and any vision-correction measurements have been taken. Your eyes are dilated using special drops, by far the most effective way to examine the structures inside the eye, and the light-sensitive retina at the back of the eye.

Most eyecare professionals agree: eye dilation is a critical component of a comprehensive eye exam, and vital to the detection of symptoms of eye disease like macular degeneration, diabetic eye disease, glaucoma, cataracts and more.

Having your eyes dilated doesn’t hurt—it just feels a little strange. Your pupil at the front of your eye automatically adjusts to light intensity, closing when light is more intense, and opening in lower lighting conditions—much like an automatic camera adjusts to take photos indoors or outdoors.

The drops used to dilate your eyes don’t wear off immediately, that’s why it’s recommended you bring sunwear with you to a comprehensive eye exam. And if you’re driving, you may want to consider having a friend with you to help you drive home, or assist you if you feel slightly disoriented. (Remember, your eyes won’t automatically adjust to changing light conditions until the drops wear off.)

Can I have an eye exam without having my eyes dilated?

In short, yes. Most vision screenings done at a pediatrician’s office, health clinic or community health organizations don’t include eye dilation. But these basic vision tests cannot help you diagnose eye disease, and are certainly no substitute for a regular and thorough eye exam from a qualified eyecare professional.

Most eye doctors will tell you with very few exceptions, dilated eyes mean the best possible eye exam environment.

Glaucoma is the generalized name for a group of eye diseases that damage the optic nerve of the eye, preventing the eye from sending accurate visual information to the brain.

Glaucoma tests are designed to test your eyes for one of the key symptoms of the disease—increased eye pressure—however only a comprehensive eye exam can reveal whether or not you have glaucoma.

Increased pressure inside the eye is often a key indicator of glaucoma, though not exclusively so. Eye doctors can use a number of tests for eye pressure, but will, by default, check for signs of glaucoma as part of a detailed examination of the retina—the light sensitive area at the back of the eye responsible for processing images.

How Does Glaucoma Testing Work?

A glaucoma test is usually part of a routine eye exam. Both types of glaucoma tests measure internal pressure of the eye.

One glaucoma test involves measuring what happens when a puff of air is blown across the surface of the eye. (A puff test) Another test uses a special device (in conjunction with eye-numbing drops) to “touch” the surface of the eye to measure eye pressure.

While increased eye pressure is a key indicator of the disease, it does not necessarily mean you have a glaucoma diagnosis. In fact, the only way to detect glaucoma is to have a detailed, comprehensive eye exam that often includes dilation of the pupils.

So “true” glaucoma testing actually involves examining the retina and optic nerve at the back of the eye for signs of the disease.

Glaucoma can cause slight to severe vision loss, and is often discovered only after the disease is present—that’s why glaucoma testing is so important.

While an ophthalmoscope may seem similar to the retina scope, it has a different purpose. This is a handheld device that combines a light source with built-in mirrors and lenses so that your eye doctor can examine the interior structures of the eye. An ophthalmoscope is particularly useful for examining the structures of the retina—the light sensitive area at the back of the eye responsible for processing images.

Traditionally part of almost every eye exam, ophthalmoscopes can identify healthy structures within the eyeball, and easily help your eye doctor see symptoms or indicators of diseases of the eye.

In some instances, your eye doctor will use an indirect ophthalmoscope to gain a broader view of your eye’s internal structure, especially the retina.

With indirect ophthalmoscopes, your eye doctor wears a head visor (like a jeweler) that projects a bright light. By holding different handheld lenses in front of your eye, your doctor can better see, and magnify, the inside of your eye.

How does an ophthalmoscope it work?

Your eye doctor will dim the lights of the room and ask you to focus on a fixed point on a far wall. Using direct or indirect ophthalmoscopes, your eye doctor will examine the structures of your eye. Sometimes, special drops are used to “open up” (dilate) your pupils to aid your eye doctor in the exam.

Your eye doctor is looking for signs of a healthy retina, and also for indicators of any number of potential eye problems like cataracts or macular degeneration.

For many eyecare patients, having pupils dilated (opened up) using eye drops can be a bother. But as an integral part of a truly comprehensive eye exam, those drops are highly recommended. Dilation gives your eye doctor the widest view of the internal structures at the back of the eye—the optic nerve, retina, even blood vessels.

That’s where Optomap technology comes in. Using low-power laser technology, your eyecare professional can take a wide, instantly-viewable and detailed digital scan of your retina (the area responsible for processing images). All in real time. And in no time. Without the use of pupil-dilating eye drops.

How does Optomap work?

It’s very similar to sitting down in a type of photo booth and leaning forward to have your picture taken. Except in this instance, the picture being taken is a larger, wide-field image of the inside of your eyeball. Optomap takes around a minute.

Since retina scanning is so important in the early detection of cataracts, diabetic eye disease, glaucoma, age-related macular degeneration and more, it’s pretty easy to see why Optomap technology is so promising.

Optomap retinal exams are not available everywhere, however. And in some instances, these scans may not be covered by traditional insurance due to cuts in eye doctor reimbursements.

Check with your eyecare professional and ask if an Optomap eye exam is right for you.

As part of a comprehensive eye exam or vision screening, eye doctors almost always include a peripheral vision test. Your peripheral vision is the visual field at the “outside” of your vision. That means, while your eyes may be “focused” on an object directly in front of you, you should still have the ability to see and recognize objects to your left, right, up and down—not directly in your line of sight.

Since peripheral vision loss can be a sign of a number of eye diseases, including glaucoma and other optic nerve disorders, side vision must be tested regularly.

How does a peripheral vision test work?

A peripheral vision test takes little time and is usually incorporated into the early portion of the eye exam. The most common type of peripheral vision testing is “confrontational” peripheral vision testing, where your eye doctor asks you to focus on a target directly in front of you (the doctor’s eye, or an upraised finger, for example). With one eye covered, and your focus trained on the target, you’ll be asked to describe things you see in the “side” of your vision.

What’s important to remember is to keep focus on the main target and honestly describe what you see. You’ll then cover the other eye and repeat the procedure.

Peripheral vision loss indicates there may be an eye problem present, one that can then be tested for in greater detail during your eye examination.

There are additional types of peripheral vision testing using automated machines with a series of blinking lights in the outer visual field, or special cards with specific lines and patterns that create forced optical illusions.

No matter what the form of test, know that peripheral vision loss is a serious symptom that needs to be evaluated by a qualified eyecare professional.

If, during an eye examination, your doctor has discovered a vision problem like nearsightedness, farsightedness or astigmatism, it’s likely that one of the next steps you’ll take will involve a phoropter. A phoropter is special machine used to switch multiple lenses in front of your eyes to correct your vision.

Phoropters look imposing—like space-age visors—but are really an ingenious way to quickly determine the exact vision correction needed by your individual eyes.

By having you look through the phoropter at a visual reference, image, or the “Big E” chart (the Snellen chart), your eye doctor will help guide you toward lenses that correct your vision impairment by switching lenses within the machine on the fly.

How does a phoropter work?

The process of switching lenses in front of your eyes is less involved than it may look, given the imposing nature of the device. A phoropter is used to manually determine “refraction”—exactly how a lens must be shaped and curved to correct your vision to a normal state, nothing more.

Phoropters are subjective however, based on your visual perception and response to your eye doctor’s questions. Is your vision better, or worse? With this lens, or this lens? How about now?

There are other procedures and technologies available that automatically measure the refraction needed within your eye and produce a “prescription” measurement without your input. These are called autorefractors and aberrometers.

Most people who’ve had a comprehensive eye exam are familiar with the puffer test. A puffer test is what it sounds like: With your head resting in the chinrest of a diagnostic machine called a slit lamp, your eye doctor uses a puff of air across the surface of the eye to measure the intraocular pressure, “inside” pressure, of the eye.

High pressure is a key indicator of glaucoma, a series of eye diseases that attacks the optic nerve.

How does a puffer test work?

Puff tests are quick and largely without discomfort. You’ll look at a light inside the machine while your eye doctor blows a gentle puff of air across the surface of your open eye. A device called a tonometer measures the eye’s resistance to the air, and calculates your internal eye pressure.

This usually takes only a few moments, and while your eye might water slightly, the procedure is generally over before you know it!

A puffer test is a part of glaucoma testing, and is a routine part of a comprehensive eye exam. Glaucoma is a serious disease of the optic nerve, and often doesn’t present itself until vision becomes impaired—that’s why it’s so important to have a puffer test to measure your intraocular pressure.

A retina scope is a handheld device used by eyecare professionals to determine whether your eyes are “20/20,” or have difficulties in seeing things up close or far away. Technically speaking, retina scopes help eye doctors determine if you have “refractive errors” like nearsightedness or farsightedness.

By shining a light back and forth across your eye, eye doctors are able to determine (usually with great accuracy) if your vision needs corrective lenses by “dialing” the retina scope so that the light focuses properly at the back of the eye on the retina. The measurement taken by retina scopes is often the first step toward using other calibrated eye exam equipment (phoropters and slit lamps, for example).

A retina scope is particularly handy for examining younger children and people with special needs who might have problems accurately describing “what’s wrong” with their vision. In addition, retina scopes can be used to test how well your eyes work together.

How does a retina scope work?

Your eye doctor will dim the lights of the room and ask you to focus on a fixed point on a far wall. The eye doctor scans the light of the retina scope back and forth across your eyes as fine adjustments are made to the lenses in the retina scope’s light source.

This usually takes only a few moments, and while your eye might water or tear slightly, the procedure is generally over before you know it.

If your eye doctor discovers a potential vision problem, you’ll likely be asked to use other equipment to determine the exact prescription you need for corrective lenses, and look for general indicators of eye health, or potential eye problems.

Other high-tech equipment like autorefractors are becoming more common as well, as they take retinoscope measurements automatically in just a few seconds.

A retinoscope is a handheld device used by eyecare professionals to determine whether your eyes are “20/20,” or have difficulties in seeing things up close or far away.

By shining a light back and forth across your eye, eye doctors are able to determine (usually with great accuracy) if your vision needs corrective lenses by “dialing” the retinoscope so that the light focuses properly at the back of the eye on the retina. This simple procedure is called a retinoscopy.

During a retinoscopy, if light focuses in front of or behind your retina, you have what is called a “refractive error” of the eye. This means you may have difficulty seeing things up close (farsightedness) or difficulty seeing things in the distance (nearsightedness). And means you likely need prescription lenses or contact lenses.

Many times, your eye doctor can determine your exact prescription by using only a retinoscope, though other equipment during an eye exam will be used to completely study your eye health, and verify any refractive errors that require you to get glasses or contact lenses.

How does a retinoscope work during retinoscopy?

Retinoscopy is a relatively quick and pain-free procedure, though your eyes may water or tear up slightly when exposed to the light within the retinoscope.

Other high-tech equipment like autorefractors are becoming more common as well, as they take retinoscopy measurements automatically in just a few seconds.

The retinoscope is a handy examination tool that can automatically detect a possible vision problem. A retinoscopy can be especially good for young children or people with special needs who might have problems accurately describing “what’s wrong” with their vision.

If you’ve ever had a comprehensive eye examination, chances are you’ve had a slit lamp exam. Slit lamp tests are designed to help your eye doctor magnify and examine the eye from front to back.

With your head resting in a machine called a slit lamp, your eye doctor can use a combination of bright light and different magnifying lenses to view your eye’s structure. A slit lamp examination helps your eye doctor see the entire physical structure of your eye from the inside.

A slit lamp test is designed to have your eyes tell a story that might indicate the presence of many types of eye diseases and potential vision problems.

How does a slit lamp exam work?

A slit lamp examination is relatively quick and largely without discomfort, though your eye may tear or water and you’ll have to resist the urge to blink frequently.

With your head resting in the chin rest of the slit lamp, you’ll look at a light inside the machine while your eye doctor performs a meticulous scan of your eyes using different lenses, much like on a microscope. Slit lamp tests are ways to magnify what’s happening on the surface of your eye, at the front of the eye, inside the eye, and at the all-important retina at the back of the eye.

A slit lamp test is one of the most common procedures in a comprehensive eye exam because it tells your eye doctor so much about the state of your eye health, and can be used to spot indicators of a wide variety of diseases and conditions including cataracts, glaucoma, diabetic eye disease, age-related macular degeneration, even blood disorders and certain cancers.

Hopefully by now, we’ve all seen one. The projected or wall-mounted Snellen eye chart, usually topped by the big letter “E”, is a common visual acuity test used to measure your sharpness of vision at multiple distances.

Arranged as a pyramid of sorts, the letters in the Snellen chart are specifically chosen and arranged to test your sharpness and clarity of vision at a baseline distance of 20 feet. During a visual acuity test, the Snellen eye chart is viewed as a projection, or mounted on a wall. Handheld versions of Snellen charts are used for testing near vision as well.

By viewing or reading each line from top to bottom (with one eye covered at a time), your eye doctor can gain a general approximation of the quality of your visual acuity, or sharpness. Where a line of characters begin to become difficult to see is the approximate measurement of your vision. The Snellen chart serves as a beginning—not an end—to a comprehensive eye examination.

What does “20/20” vision mean?

Snellen charts help to determine a baseline for your vision in each eye—a baseline typically measured against “20/20” vision. This means when you are 20 feet away from an object, you can comfortably see details that most people with normal vision can also see at 20 feet distance.

If you have 20/30 vision, that means what you see comfortably at 20 feet, can be seen by a person with “normal” vision at 30 feet. Your vision is weaker, in other words.

Conversely? In the rare instances where vision may test better than normal on a Snellen chart, a value of 20/10 vision means that you can see clearly from a distance of 20 feet, what a person with normal vision sees well at a distance of 10 feet. Make sense?

In fact, if you look closely at a Snellen eye chart, you’ll see the vision values associated with measuring your vision on the right or left side of each line of characters.

What’s the difference between a vision test and a vision screening? If you consider the vision test as the “goal” of having a comprehensive eye exam at regular intervals throughout your life, then a vision screening is one way to reach that goal. Vision screening sometimes determines an immediate need for vision testing.

It’s important to not confuse the two. A vision screening is not a substitute for a vision test or comprehensive eye exam performed by an eyecare professional. But it can play an important role in helping numerous groups get the vision testing they need.

What is vision screening?

A set of simple eye tests to help identify people who may have certain eye problems. Often performed by pediatricians, school nurses, assisted living caregivers and other healthcare professionals and volunteers, vision screening usually includes a vision test for your ability to see clearly at distances using the “Big E” chart (Snellen chart).

A vision screening may also include testing of your eye’s reaction to light, muscle coordination, or by viewing simple images and graphs that could reveal colorblindness or other hidden problems. The vision test you take to get your driver’s license is an example of a vision screening.

Community health organizations, public schools, wellness clinics, and assisted living facilities often offer vision screening as part of their services. Given at important intervals in life, such as early childhood, pre-teen years, and as you age, vision screening can help monitor the quality of your vision, and possibly identify common vision problems. But they’re not a substitute for a complete vision test given by an eyecare professional.

What is vision testing?

A comprehensive set of eye tests performed by an eyecare professional in a controlled office setting with equipment that goes far beyond what’s available at a vision screening.

Often performed with eyedrops that help the pupil “open up” (dilation), vision tests commonly include testing of vision at multiple distances, peripheral vision testing, and a series of procedures designed to check the structures of the eye for evidence of eye disease or eye problems like age-related macular degeneration, glaucoma, cataracts or diabetes.

A vision test from a qualified eyecare professional is important because many of the things hidden or unknowable at a vision screening, reveal themselves under closer professional observation.

And just as importantly, only an eyecare professional can direct you to the treatment necessary to improve your vision or protect your eyes—a prescription for corrective lenses, medications to treat common eye problems, or a wide variety of surgical options now available to people with eye problems.

How often should you have a vision test?

As a general rule of thumb, it’s a good idea to have a comprehensive eye exam and vision test at least every two years. This especially includes children below the age of 5, who may not fully understand that they’re even having a vision problem until they undergo a professional vision test.

Vision can change rapidly throughout childhood. Regular vision testing is a quick and smart way to keep up with those changes.

In many instances, more frequent vision testing is recommended. If you have diabetes, for example, you are at higher risk for developing glaucoma, cataracts and diabetic retinopathy–damage to the blood vessels in the retina. After age 35, the risks increase for a host of age-related eye problems or diseases such as presbyopia, macular degeneration, and cataracts.

A comprehensive eye exam every year is not unheard of. Vision tests are convenient and protect your eyes in the short term, and long term.

Vision testing at the eye doctor is as individual as you are. When it comes to vision testing, no two eye exams are alike, because no two people are alike. In fact, it’s those differences that often determine what types of vision testing—and vision testing equipment—are used during any given examination.

Types of vision testing

• Visual acuity testing: The Snellen Chart (the chart with the big E at the top) is used to test each eye for visual acuity or “sharpness” at a distance. A smaller, hand-held chart is used to test near vision.

• Visual field testing: Manual and automatic testing designed to measure the quality of your side vision (peripheral vision). This type of test usually involves covering one eye and focusing the other on a fixed point in front of you, while describing what you can see on the “periphery” of your vision.

• Cover testing: By having you focus on a distant object within a room, and then alternately covering each eye, your eyecare professional can see if your eyes work together, or must refocus slightly.

• Color-blind testing: Using a series of multi-colored dots arranged within a circle, color-blind vision testing “hides” numbers within the overall pattern of dots. These numbers will appear as easy-to-see colored numbers to everyone except those few people who suffer from various degrees of color-blindness—the inability to perceive certain colors or color combinations.

• Refraction testing: Refraction errors like nearsightedness and farsightedness are the most common eye problems. Vision testing is used to determine how strong your prescription glasses must be to see clearly, based on how your eyes react while using the vision testing equipment.

Phoropters are machines that allow your eye doctor to “switch” lenses during your exam to see if your focus is better, or worse. Autorefractors are machines that automatically check the lens power needed to clearly focus images on your retina for the best possible vision.

• Slit lamp testing: This piece of vision testing equipment combines a simple chin rest with a light source that produces a “slit” of light that’s used scan your eye. Your eye doctor (with the help of special viewing lenses) can look into the internal structure of your eye to potentially diagnose a host of eye problems and diseases.

• Tonometry (Glaucoma) Testing: There are two types of glaucoma vision testing, each with the goal of measuring the internal pressure of the eye. Increased eye pressure is a warning sign for glaucoma, a series of eye diseases that damages the optic nerve of the eye, limiting and sometimes eliminating vision.

• The “Puffer” Test: A light is beamed into your eye while a gentle puff of air is blown across the eye’s surface. A special machine measures the resistance of the eye to the puff of air, and then calculates internal eye pressure.

• The Touch Test: Using a machine called an applanation tonometer, a special probe makes gentle contact with the eye’s surface to measure internal eye pressure. Your eye doctor may numb your eye in advance.

• Dilation testing: Sometimes, your eye doctor will use special drops to “open up” your pupil (dilate it) so that as much light as possible can enter the eye. Using special magnifying lenses and other vision testing equipment, your eye doctor can diagnose a host of eye problems and see internal structures that indicate the presence of eye diseases.

Vision testing is both thorough and painless, though there may be some discomfort from direct beams of light momentarily. In addition, the drops used to dilate pupils may take a little time to wear off, so you will be sensitive to bright light, and may need assistance driving after vision testing that includes pupil dilation.