- What to Expect During Your Eye Exam
- Your Eyes
- The Parts of the Eye
- Big as a Ping Pong Ball
- Iris Is The Colorful Part
- Light, Lens, Action
- A Muscle Makes It Work
- Rods and Cones Process Light
- Helping You See It All
- To the Brain!
- Have No Fear, You Have Tears
- PERRLA Eye Assessment: What It Stands for, Procedure, and Purpose
- Uneven size or shape
- Not reactive to light or accommodation
- 9 Things Doctors Can Tell About Your Health Just By Looking At Your Eyes
- NOW WATCH: Here's Why Paper Cuts Hurt So Much
- What Is a Slit-Lamp Examination?
- What Your Eyes Can Tell You About Your Health
- Multiple Sclerosis
- Hormonal changes
- Keep an eye out for these signs that your health is in trouble
- How Doctors Test Pupil Reflexes
What to Expect During Your Eye Exam
It depends in part on your age and also on your eyes and family.
If you’re younger than 40 and have no eye problems, your doctor might suggest you get routine tests every 2 years. Or he could tell you that you don’t need any tests. Ask what he thinks is best for you.
If you’re 40 or older, you should get your eyes checked every 1 to 2 years.
If you’ve had eye trouble in the past, or if you’re at risk for developing it (if someone in your family had it), you should see an eye doctor every year.
Why? You need to check to see if you have serious, sometimes “silent” problems that can affect your vision, :
- Age-related macular degeneration
- Diabetic retinopathy
If your child has no risk factors for eye problems, she should get her vision checked as a newborn and again at every regular health visit. By the time she’s 3, it will be easier for the doctor to assess her eyes. After the first grade, she should get eye tests every 1 to 2 years.
If you have a health condition high blood pressure, work in a job that requires you to use your eyes a lot, or take drugs that can affect eyesight, you may need more frequent exams.
If you have type 1 diabetes, get your eyes checked within 5 years of your diagnosis and every year after that.
You’ll need an exam ASAP if you’re diagnosed with type 2 diabetes. Have your eyes checked every year after that.
When you call to make an appointment for your exam, mention any vision problem you're having.
Before you go, list any questions you want to ask the doctor. Also be ready to update him or her on any medicines you take and your (and your family's) eye health history.
Bring your glasses and contact lenses along with the prescription with you. Also bring sunglasses for the trip home. The doctor might use eye drops to open up your pupils. This is called dilation. Your eyes will be sensitive to light afterward.
First, the eye doctor or an office staff member will ask you about your medical and vision history.
The exam may last from half an hour to several hours, depending on the equipment used. It will cover your vision and your eye health.
You'll probably have all or most of the following eye tests, and possibly some other ones, too:
Eye muscle movement test: This checks your eyes’ alignment. The doctor will watch your eyes move while you follow a target ( a finger tip or his pen) as it moves in different directions.
Cover test: This tells how well your eyes work together. You’ll stare at a small target some distance away. The doctor will cover and uncover each eye to observe how much your eyes move. Your doctor will also be watching for an eye that turns away from the target. This is a condition called strabismus. You may take the test again with a target close to you.
External exam and pupil reactions: The doctor will watch how your pupils adjust to light and objects close to you. At the same time, the whites of your eyes and the position of your eyelids will also be checked.
Visual acuity test: You'll sit in front of an eye chart, with letters that get smaller as you read down each line. You’ll cover each eye in turn and, using the other eye, read aloud, going down the chart, until you can't read the letters anymore.
Refraction testing: For your exact lens prescription, the doctor can use a computerized refractor. Your doctor may fine-tune the prescription by flipping the phoropter back and forth between lenses and asking you which is better. If you don't need corrective lenses, you won't have this test.
Slit lamp (biomicroscope): This device magnifies and lights up the front of your eye. The doctor uses it to check your cornea, iris, lens, and the back of your eye, looking for signs of certain eye conditions.
Retinal examination (ophthalmoscopy): Your doctor may dilate your pupils and use a tool called an ophthalmoscope and to see the back of your eyes — the retina, retinal blood vessels, fluid in your eyes (he may call this vitreous fluid), and the head of your optic nerve.
Glaucoma testing: This procedure checks to see if the fluid pressure inside your eyes is within a normal range. It's fast, painless, and can be done in a couple of ways:
- Tonometer: This is the most accurate. You’ll get drops to numb your eyes. The doctor will tell you to stare straight ahead and will barely touch the front surface of each eye with a tool called an applanation tonometer or Tonopen to measure the pressure.
- Puff of air or noncontact tonometer: You’ll stare at a target, and a machine will let out a small puff of air into each eye. How much your eye resists the puff indicates the pressure inside it.
Pachymetry: This test uses ultrasound to measure the thickness of your cornea. Thin corneas can lead to false low-pressure readings. Thick corneas can lead to false high-pressure readings. You may get this test just once to create a baseline for comparison with future readings. It can be used for people who need corneal surgery.
Pupil dilation (enlargement) (optional): With your pupils fully enlarged, the doctor will use tools and lights to check the insides of your eyes. The eye drops for this part of the exam take about 20-30 minutes to work.
They make your eyes more sensitive to light and blur your vision. These effects may last for several hours or longer. This is why you might need those sunglasses on your way home.
Newer machine can look in the far back of your retina without your pupils being dilated.
Visual field test (perimetry): Your visual field is the area you can see in front of you without moving your eyes. Using one of three tests, the eye doctor maps what you see at the edges (periphery) of your visual field and will use this map to diagnose eye conditions.
- Ask family or friends who they use.
- Ask your family doctor for a referral.
- Call the ophthalmology or optometry department of a nearby hospital and ask about doctors who practice there.
- Contact state and county academies, associations, or societies of optometrists and ophthalmologists, and ask if they can help you.
- Get a list from your health plan or health insurance company.
American Academy of Ophthalmology: “When to See an Eye M.D.”
FDA: “Saving Your Sight — Early Detection Is Critical.”
Prevent Blindness America: “Taking Your Child to the Eye Doctor.”
MayoClinic.com: “Eye Exams: What to Expect.”
All About Vision: “What to Expect From a Comprehensive Eye Exam.”
National Eye Institute: “Finding an Eye Care Professional.”
© 2019 WebMD, LLC. All rights reserved. Dilated Eyes
Which part of your body lets you read the back of a cereal box, check out a rainbow, and see a softball heading your way? Which part lets you cry when you're sad and makes tears to protect itself? Which part has muscles that adjust to let you focus on things that are close up or far away? If you guessed the eye, you're right!
Your eyes are at work from the moment you wake up to the moment you close them to go to sleep. They take in tons of information about the world around you — shapes, colors, movements, and more. Then they send the information to your brain for processing so the brain knows what's going on outside of your body.
You can see that the eye's pretty amazing. So, come on — let's take a tour of its many parts.
The Parts of the Eye
You can check out different parts of the eye by looking at your own eye in the mirror or by looking at (but not touching) a friend's eye. Some of the eye's parts are easy to see, so most friends will say OK. Most friends won't say OK if you ask to see their liver!
Big as a Ping Pong Ball
The eye is about as big as a ping-pong ball and sits in a little hollow area (the eye socket) in the skull. The eyelid protects the front part of the eye.
The lid helps keep the eye clean and moist by opening and shutting several times a minute.
This is called blinking, and it's both a voluntary and involuntary action, meaning you can blink whenever you want to, but it also happens without you even thinking about it.
The eyelid also has great reflexes, which are automatic body responses, that protect the eye. When you step into bright light, for example, the eyelids squeeze together tightly to protect your eyes until they can adjust to the light.
And if you flutter your fingers close (but not too close!) to your friend's eyes, you'll be sure to see your friend's eyes blink. Your friend's eyelids shut automatically to protect the eye from possible danger. And speaking of fluttering, don't forget eyelashes.
They work with the eyelids to keep dirt and other unwanted stuff your eyes.
The white part of the eyeball is called the sclera (say: SKLAIR-uh). The sclera is made of a tough material and has the important job of covering most of the eyeball.
Think of the sclera as your eyeball's outer coat. Look very closely at the white of the eye, and you'll see lines that look tiny pink threads.
These are blood vessels, the tiny tubes that deliver blood, to the sclera.
The cornea (say: KOR-nee-uh), a transparent dome, sits in front of the colored part of the eye. The cornea helps the eye focus as light makes its way through. It is a very important part of the eye, but you can hardly see it because it's made of clear tissue. clear glass, the cornea gives your eye a clear window to view the world through.
Iris Is The Colorful Part
Behind the cornea are the iris, the pupil, and the anterior chamber. The iris (say: EYE-riss) is the colorful part of the eye. When we say a person has blue eyes, we really mean the person has blue irises! The iris has muscles attached to it that change its shape. This allows the iris to control how much light goes through the pupil (say: PYOO-pul).
The pupil is the black circle in the center of the iris, which is really an opening in the iris, and it lets light enter the eye. To see how this works, use a small flashlight to see how your eyes or a friend's eyes respond to changes in brightness. The pupils will get smaller when the light shines near them and they'll open wider when the light is gone.
The anterior (say: AN-teer-ee-ur) chamber is the space between the cornea and the iris. This space is filled with a special transparent fluid that nourishes the eye and keeps it healthy.
Light, Lens, Action
These next parts are really cool, but you can't see them with just your own eyes! Doctors use special microscopes to look at these inner parts of the eye, such as the lens.
After light enters the pupil, it hits the lens. The lens sits behind the iris and is clear and colorless.
The lens' job is to focus light rays on the back of the eyeball — a part called the retina (say: RET-i-nuh).
The lens works much the lens of a movie projector at the movies. Next time you sit in the dark theater, look behind you at the stream of light coming from the projection booth. This light goes through a powerful lens, which is focusing the images onto the screen, so you can see the movie clearly. In the eye's case, however, the film screen is your retina.
Your retina is in the very back of the eye. It holds millions of cells that are sensitive to light. The retina takes the light the eye receives and changes it into nerve signals so the brain can understand what the eye is seeing.
A Muscle Makes It Work
The lens is suspended in the eye by a bunch of fibers. These fibers are attached to a muscle called the ciliary (say: SIL-ee-air-ee) body. It has the amazing job of changing the shape of the lens.
That's right — the lens actually changes shape right inside your eye! Try looking away from your computer and focusing on something way across the room. Even though you didn't feel a thing, the shape of your lenses changed.
When you look at things up close, the lens becomes thicker to focus the correct image onto the retina. When you look at things far away, the lens becomes thinner.
The biggest part of the eye sits behind the lens and is called the vitreous (say: VIH-tree-us) body. The vitreous body forms two thirds of the eye's volume and gives the eye its shape.
It's filled with a clear, jelly- material called the vitreous humor. Ever touch toy eyeballs in a store? Sometimes they're kind of squishy — that's because they're made to feel they're filled with vitreous humor.
In a real eye, after light passes through the lens, it shines straight through the vitreous humor to the back of the eye.
Rods and Cones Process Light
The retina uses special cells called rods and cones to process light. Just how many rods and cones does your retina have? How about 120 million rods and 7 million cones — in each eye!
Rods see in black, white, and shades of gray and tell us the form or shape that something has. Rods can't tell the difference between colors, but they are super-sensitive, allowing us to see when it's very dark.
Cones sense color and they need more light than rods to work well. Cones are most helpful in normal or bright light. The retina has three types of cones. Each cone type is sensitive to one of three different colors — red, green, or blue — to help you see different ranges of color. Together, these cones can sense combinations of light waves that enable our eyes to see millions of colors.
Helping You See It All
Rods and cones process the light to give you the total picture. You're able to see that your friend has brown skin and is wearing a blue hat while he tosses an orange basketball.
Sometimes someone's eyeball shape makes it difficult for the cornea, lens, and retina to work perfectly as a team. When this happens, some of what the person sees will be focus.
To correct this fuzzy vision, many people, including many kids, wear glasses. Glasses help the eyes focus images correctly on the retina and allow someone to see clearly. As adults get older, their eyes lose the ability to focus well and they often need glasses to see things up close or far away. Most older people you know — your grandparents — probably wear glasses.
To the Brain!
Think of the optic nerve as the great messenger in the back of your eye. The rods and cones of the retina change the colors and shapes you see into millions of nerve messages. Then, the optic nerve carries those messages from the eye to the brain!
The optic nerve serves as a high-speed telephone line connecting the eye to the brain. When you see an image, your eye “telephones” your brain with a report on what you are seeing so the brain can translate that report into “cat,” “apple,” or “bicycle,” or whatever the case may be.
Have No Fear, You Have Tears
For crying out loud, the eye has its own special bathing system — tears! Above the outer corner of each eye are the lacrimal (say: LAK-ruh-mul) glands, which make tears. Every time you blink your eye, a tiny bit of tear fluid comes your upper eyelid. It helps wash away germs, dust, or other particles that don't belong in your eye.
Tears also keep your eye from drying out. Then the fluid drains your eye by going into the lacrimal duct (this is also called the tear duct). You can see the opening of your tear duct if you very gently pull down the inside corner of your eye. When you see a tiny little hole, you've found the tear duct.
Your eyes sometimes make more tear fluid than normal to protect themselves. This may have happened to you if you've been poked in the eye, if you've been in a dusty or smoking area, or if you've been near someone who's cutting onions.
And how about the last time you felt sad, scared, or upset? Your eyes got a message from your brain to make you cry, and the lacrimal glands made many, many tears.
Your eyes do some great things for you, so take these steps to protect them:
- Wear protective goggles in classes where debris or chemicals could go flying, such as wood shop, metal shop, science lab, or art.
- Wear eye protection when playing racquetball, hockey, skiing, or other sports that could injure your eyes.
- Wear sunglasses. Too much light can damage your eyes and cause vision problems later in life. For instance, a lens could get cloudy, causing a cataract. A cataract prevents light from reaching the retina and makes it difficult to see.
The eyes you have will be yours forever — treat them right and they'll never be sight!
Reviewed by: KidsHealth Medical Experts
PERRLA Eye Assessment: What It Stands for, Procedure, and Purpose
Your eyes, besides allowing you to see the world, provide important information about your health. That’s why doctors use a variety of techniques to examine your eyes.
You may have heard your eye doctor mention “PERRLA” when discussing testing your pupils. PERRLA is an acronym used to document a common pupillary response test. This test is used to check the appearance and function of your pupils. The information can help your doctor diagnose several conditions, from glaucoma to neurological diseases.
PERRLA is an acronym that helps doctors remember what to check for when examining your pupils. It stands for:
- Pupils. The pupils are in the center of the iris, which is the colored part of your eye. They control how much light enters the eye by shrinking and widening.
- Equal. Your pupils should be the same size. If one is larger than the other, your doctor will want to do some additional testing to figure out why.
- Round. Pupils should also be perfectly round, so your doctor will check them for any unusual shapes or uneven borders.
- Reactive to. Your pupils react to your surroundings to control how much light enters your eyes. This step reminds your doctor to check your pupils’ reactions to the next two items in the acronym.
- Light. When your doctor shines a light in your eyes, your pupils should get smaller. If they don’t, there could be a problem affecting your eyes.
- Accommodation. Accommodation refers to your eyes’ ability to see things that are both close up and far away. If your pupils are nonreactive to accommodation, it means they don’t adjust when you try to shift your focus to an object in the distance or near your face.
You can also think of PERRLA as a sentence. Pupils are equal, round, and reactive to light and accommodation.
To perform a pupillary exam, your doctor will have you sit in a dimly lit room. They’ll start by simply looking at your pupils, noting anything unusual about their size or shape.
Next, they’ll do a swinging eye test. This involves moving a small, hand-held flashlight back and forth between your eyes every two seconds while you look in the distance. They’ll do this several times to see how your pupils react to the light, including whether they react at the same time.
Finally, your doctor will ask you to focus on a pen or their index finger. They’ll move it toward you, away from you, and from side to side. The purpose of this is to check whether your pupils can properly focus. They should shrink when watching an object that’s shifting perspectives.
The results of a pupil exam can indicate many conditions, depending on which part of the test was unusual.
Uneven size or shape
If your pupils have a difference of more than 1 millimeter in size (called anisocoria), or aren’t perfectly round, you may have an underlying condition affecting your brain, blood vessels, or nerves. However, one five people with no eye health problems have pupils that are normally different sizes.
Some examples of conditions that cause differently sized pupils include:
Not reactive to light or accommodation
If your pupils aren’t responding to light or moving objects, it could indicate:
- optic neuritis
- optic nerve damage
- optic nerve tumor
- retinal infection
- ischemic optic neuropathy
- an overactive ciliary muscle, located in the middle layer of your eye
Keep in mind that the results of a pupil exam usually aren’t enough to diagnose any condition. Instead, they give your doctor a better idea of what other tests they can use to help narrow down what might be causing your symptoms.
Pupil eye exams are quick, noninvasive tests that doctors can use to check the health of your eyes and nervous system. PERRLA is the acronym they use to remember exactly what to check when examining your pupils.
If you look in the mirror and notice that your pupils look unusual, make an appointment with your doctor. Seek immediate medical treatment if you also start to notice severe head pain, confusion, or dizziness.
9 Things Doctors Can Tell About Your Health Just By Looking At Your Eyes
When you look into your eyes, you may be trying to steel yourself for an interview. Or maybe you're just checking to see if they are red and bloodshot, irritated by allergies or perhaps a long night out.
But when doctors look into your eyes, they can see a lot more. The eyes might be the proverbial window to the soul, but they are also a clear window to your health, and the amount of information they can reveal is astounding.
Many conditions cause symptoms throughout the body — some show up in the skin, others in the mouth, and some even in fingernails — but the eye is one spot that reveals a particularly large percentage of health issues.
“Looking in an eye really is a fabulous experience,” says Dr. Charles P. Wilkinson, a retina specialist and clinical spokesman for the American Academy of Ophthalmology. “It's the only place you can see blood vessels bouncing along their merry way, you can see the optic nerve, which is part of the brain.”
With so much visible, more than 30 conditions show symptoms in the eyes. That's why eye doctors — ophthalmologists — and optometrists are frequently among the first to spot certain problems.
e_monk/flickr An internal study of 120,000 patients by the insurance company VSP Vision Care found that an eye exam was the first indicator of 34% of diabetes cases, 39% of cases of high blood pressure, and a shocking 62% of cases of high cholesterol.
VSP president Jim McGrann says that these findings showed that for many of these patients, “if people hadn't gone to see their eye doctor, they'd be walking around with time bomb diseases.”
Here are irregularities that show up in your eyes — and sometimes mean that something more serious is at stake.
1. Red spots, caused by dots of blood in the eye, can be a sign of diabetes — a terrible disease that the CDC predicts 40% of Americans will develop in their lives.
If blood sugar builds up too high, blood vessels begin to get blocked and to swell up. This can burst the tiny blood vessels in the retina, causing bleeding.
If it's not treated, this can potentially lead to impaired vision or even blindness.
Conditions that cause bleeding in the eye range from benign, that shown here, to the quite serious. Andy Aldridge/flickr 2. But bloodshot eyes can be caused by many other conditions, too — ranging from an intense cough to pinkeye to a fungal infection.
3. Itchy, swollen, red eyes are common giveaways that a patient is suffering from allergies, frequently triggered by pollen, dust, or pet dander. Eyedrops can help, especially if they include an antihistamine, though be careful of oral antihistamines, as some can cause eyes to dry out, worsening the problem.
4. Dry eyes are a side effect of both computer usage and many medications, sleeping pills, pain relievers, or anti-anxiety medications. Autoimmune diseases can cause dry eyes as well, especially one called Sjögren's syndrome, which destroys moisture-producing glands and mostly affects older women.
5. Most people lose the ability to focus on close-up things the print on restaurant menus as they age, but certain medications — antidepressants, antihistamines, and diuretics — can cause this condition, called presbyopia, to happen prematurely.
6. Blurry vision can be caused by a long list of eye conditions, but for those already at risk of high blood pressure, it can be a sign that someone needs to get to the doctor immediately. Once a person's sight is obscured by side effects of hypertension, that person needs treatment quickly, as vision and more is at stake.
A torn retina can cause the retina to detach, this one — though this was caused by an illness. National Eye Institute/National Institutes of Health 7. Suddenly seeing specks or flashes of light can be a sign of a torn retina.
Some people experience these symptoms with migraines or simply as they grow older. But a sudden increase in the size and number of specks or flashes of light you see can be caused by a torn retina, which needs to be treated.
That's especially the case if the flashes or spots are accompanied by a shadow or loss of peripheral vision, which very ly indicates a detached retina.
8. Eye doctors can be the first ones to detect some cancers. An eye doctor can check for ocular melanoma, a rare form of melanoma but one that usually can't be detected by looking in the mirror. If other causes of pressure or pain in the eye are ruled out, Wilkinson says, an eye doctor may check to see if a brain tumor is a possibility.
9. High cholesterol can frequently cause white rings to develop around the eyes, and can also cause yellowish bumps to appear in the eyelids. Older patients are ly to also develop similar white rings, but in any case, it can be a sign that cholesterol needs to be checked by a doctor.
McGrann says the large number of diseases that cause symptoms in the eye should convince people that an annual eye exam is worthwhile. An annual exam is especially necessary for anyone over 40, Wilkinson says — though he notes that many of these health conditions are frequently detected first during routine medical screening.
At that point, changes in the eye and body mean that eye doctors have important conditions to monitor, even if vision is stable. And new problems can surface at any time. Many can be treated before they cause a problem — but only if a doctor has a chance to examine the eye in the first place.
NOW WATCH: Here's Why Paper Cuts Hurt So Much
What Is a Slit-Lamp Examination?
When you visit your eye doctor, she’s not just checking to see if you can read the third line on the eye chart clearly. She’s also making sure your eyes are healthy.
To do this, many doctors use a “slit lamp.” It’s a special microscope and light that lets your doctor see your eyes in 3-D, both inside and out. She’ll use it along with an ophthalmoscope to look at the back of your eye.
A slit-lamp exam is usually done during a regular checkup with your eye doctor.
The slit lamp is several pieces of equipment combined into one device. It includes a binocular microscope on a base that moves in an arc, an adjustable light source, and a frame to rest your head on and hold it steady during the exam.
Your doctor has a lot of flexibility with the light. She can narrow and widen it, increase its brightness, and filter it with colors. By doing this, your doctor can focus on particular parts of your eyes and face.
If you drive to your appointment, you may want to bring someone along to take you home. Some eye exams include dilating your pupils. Until they return to normal size, the outside world may seem overly and even uncomfortably bright for a few hours. Your vision may be a bit blurry too.
Before the exam starts, you’ll be asked to remove your glasses or contact lenses. You’ll put your chin and forehead against rests to keep your head steady. Your doctor may also put a few drops of dye in your eyes to highlight things she wants to look at. She’ll then turn out the room lights and turn on the slit lamp.
During the exam, your doctor will look through the microscope, adjusting the light from the slit lamp to view certain parts of your eyes. Things she’ll look at:
The skin around the eye. Your doctor can check the area for skin diseases and abrasions.
Your eyelids and eyelashes. Styes (oil gland infections), folliculitis (hair follicle infections), and tumors are some of the conditions your doctor will look for.
The surface of the eye. This includes the tissue under your eyelids and over the whites of your eyes. These areas can be swollen or infected. This can be caused by sexually transmitted diseases, allergies, or viruses
The sclera. This is the protective outer layer of the eyeball. Next to the sclera is the episclera, which helps keep it healthy. These areas can get diseases related to allergies, autoimmune disorders (where the body attacks itself), and gout (a type of arthritis).
The cornea. This is the layer of the eye that helps focus your vision. A slit-lamp exam may show your cornea isn’t as clear as it used to be. A number of things can cause your vision to blur.
The iris. This is the colored disc that surrounds the pupil and changes to allow more or less light into your eye. It can be affected by a variety of diseases and conditions, including freckles or melanoma of the iris.
The lens. Cataracts (a clouding of the lens) are diagnosed by examining this part of the eye. It’s located behind the pupil.
In addition, when the slit lamp is coupled with a special magnifying lens, your doctor will be able to view the retina and the optic nerve located in the back of your eye. Before doing this exam, he’ll dilate your pupils with eye drops.
Looking at the retina and optic nerve can help your doctor figure out if you have glaucoma or if diabetes is affecting your eyes. The examination may also show tumors, blood clots, and hardening of the arteries caused by high blood pressure.
Though eye exams make some people squeamish, the procedures should be pain-free.
Your doctor should tell you what she learned during your eye exam immediately.
If your exam reveals you may have a disease affecting other parts of your body, your eye doctor may recommend you see your regular doctor. If you have a specific eye condition, she may give you a prescription or suggest further testing.
Mayo Clinic: “Eye exam,” “Slit-lamp examination.”
Ophthalmic Photographers’ Society: “Slit Lamp Biomicrography.”
Weill Cornell Brain and Spine Center, “Orbital Tumors.”
University of Ottawa, “Primary Care Ophthalmology: Slit Lamp: Anterior Segment Exam,” “Primary Care Ophthalmology: Slit Lamp: Part and Functions,” “Primary Care Ophthalmology: Slit Lamp: Preparing the Patient.”
American Academy of Ophthalmology, “Conjunctiva,” “Slit-Lamp Biomicroscopy,” “What to Expect When Your Eyes Are Dilated.”
Palo Alto Medical Foundation, “Eye Health Department: Frequently Asked Questions.”
MedRounds.org, “What is the structure of the sclera, episclera and Tenons capsule?”
National Eye Institute, “Facts About the Cornea and Corneal Disease.”
VisionAware.org (American Foundation for the Blind), “Eye Health: Anatomy of the Eye.”
National Eye Institute, “Facts About Cataract.”
Stanford Medicine, “Fundoscopic / Ophthalmoscopic Exam.”
© 2019 WebMD, LLC. All rights reserved. Eye Pressure Test
What Your Eyes Can Tell You About Your Health
Liz Rodovich was at work last December when she noticed a shimmering, crescent-shaped aura on the periphery of her left eye. She assumed it was caused by eye fatigue, from spending too much time on the computer.
But when the shimmering episodes became more frequent, and then she awoke one night with a stabbing pain at the junction of her head and neck, the registered nurse wondered if she was getting a migraine preceded by visual aura or, worse, a detached retina.
“I knew that something was wrong,” recalls Rodovich, 59. “My vision didn’t seem right the next morning.”
She sought help at the Ottawa General Hospital Eye Institute, where she failed a visual field test, a standard eye test that measures central and peripheral vision.
A subsequent CT scan revealed that Rodovich had suffered an embolic stroke in her occipital lobe – the brain’s visual processing centre. A clot had lodged in one of the arteries that supply blood to the eyes, affecting her vision.
Though she has a background as an ER nurse, the news stunned Rodovich.
“The presentation of the stroke was something I never would have guessed,” she says. “Generally you think that if you have vision problems, there must be something wrong with your eyes.” Though symptoms such as blurry vision or foreign body sensation can signal a variety of ocular conditions, your peepers also provide a portal into your whole-body health.
Related: 3 Cancers On The Rise And What You Can Do To Protect Yourself
Everything from allergies to autoimmune diseases can present with ocular symptoms first. And while red eyes, discharge, itching, light sensitivity or visual changes can be uncomfortable enough to bring patients in to see their optometrists, some symptoms, such as optic nerve or vascular changes, take place inside the eye and can go unnoticed.
This is why it’s important for adults to have an eye exam every two years. “There are so many conditions we can find that don’t have symptoms, so coming in every couple of years allows us to look for trends or changes,” explains Craig Meckelborg, an optometrist with FYidoctors in Calgary. Eye symptoms combined with a patient’s medical history will alert doctors to possible systemic diseases.
For example, Rodovich was a smoker who had previously experienced a “hypertensive episode” – a spike in blood pressure – two risk factors for stroke. (She quit smoking after her stroke.
) What’s more, women are more susceptible to certain conditions that can present in the eyes, such as multiple sclerosis (MS) and thyroid dysfunction, says Setareh Ziai, an assistant professor of ophthalmology at the University of Ottawa Eye Institute.
Here are five whole-body conditions that can be revealed by looking at this special organ.
A stroke is the sudden loss of brain function caused by an interruption of blood flow due to either a clot (ischemic stroke) or the rupture of blood vessels (hemorrhagic stroke).
Rodovich experienced an ischemic stroke that temporarily compromised her eye function.
Another type of stroke with ocular symptoms is a transient ischemic attack (TIA), which is a mini-stroke caused by a blood clot that travels to the eye.
What the doctor sees: Often an eye doctor won’t actually see the clot because vision loss associated with a TIA doesn’t last very long – by the time the patient comes in, the clot has cleared and vision has been restored. The doctor can make the diagnosis symptoms and medical history.
What the patient experiences: A sudden, painless loss or partial loss of vision in one eye that lasts for minutes or hours.
What happens next: The patient is sent to a stroke clinic for a full workup. “The risk of stroke is so much higher in these patients because essentially they’ve already had a little stroke. Hopefully we can prevent something bigger from happening by referring them for appropriate testing and systemic management and lifestyle modifications,” says Ziai.
Also known as high blood pressure, this condition puts extra strain on the vascular system. If left unchecked, it can lead to heart attack or stroke, among other systemic ailments.
What the doctor sees: Changes within the blood vessels at the back of the eye in the retina, such as leakages or hemorrhages, and alterations in the appearance of the vessels. ‘With chronic hypertension, often we see a narrowing of the arteries in the back of the eye.
We can see tortuosity of the vessels. If the arteries are really thickened, they can push on the veins to the point where they cross and actually cause indentations in the veins.
And the arteries can change colour “they can start looking silvery or coppery rather than the red colour of normal vessels,” says Ziai.
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What the patient experiences: There are seldom any symptoms. In extreme cases, a patient might experience a sudden loss or blurring of vision caused by a sudden spike in blood pressure.
What happens next: An optometrist can measure a patient’s blood pressure during an exam and report back to the family doctor. “We interact with who we need to – a lot of time it’s the family physician,” says Meckelborg, adding that optometrists sometimes end up being advocates for general health their findings.
The most common cause of blindness in North America in patients aged 20 to 65 is diabetic retinopathy, a condition caused by damage to the blood vessels in the retina.
Diagnosed diabetics visit an eye doctor yearly to monitor the disease’s ocular impact, but sometimes patients come in because of blurry vision or for a routine exam and the eye care professional is the first to suspect diabetes, says Ziai.
“In Type 2 diabetes, many adults are unknowingly walking around with higher than normal blood sugar levels. If you don’t go to your doctor for annual examinations and have the blood work done, you could have diabetes for years and not know it.”
What the doctor sees: Damage to tiny blood vessels in the retina, such as bleeding and exudation, due to chronic high blood sugar levels. New, fragile vessels can form, which can leak a yellowish, fatty substance beneath the retina. Additionally, patients can have swelling or blood in and around the macula, which is the part of the retina associated with central vision.
What the patient experiences: In the early stages, there may be no eye symptoms whatsoever, or the patient might have blurry vision that seems to come and go (the fluctuations are due to blood sugar changes). “Even over the course of a day, their blood sugar levels can fluctuate,” says Ziai.
What happens next: The patient is referred back to the family doctor or to an ophthalmologist, either of whom can order blood work to confirm. “My job is to monitor the condition or triage it to the right person, depending on the severity,” says Meckelborg.
MS is a chronic autoimmune disorder affecting vision, sensation, balance, strength, coordination and other bodily functions. “Some patients can present ocular symptoms first before they’ve had a formal diagnosis of MS,” says Ziai.
What the doctor sees: A condition called optic neuritis, which is inflammation and swelling of the optic nerve. “If we’re seeing an episode of optic neuritis, one of the things we think of is MS, but it’s not necessarily a slam-dunk diagnosis. You have to look at the whole body and whether there are other symptoms, such as tingling of the fingers,” says Meckelborg.
What the patient experiences: A variety of symptoms that can include one or more of the following: dimming of vision, changes in colour sensitivity, pain with eye movements and alterations in visual field perception.
What happens next: The patient is referred to the family physician or to a neurologist, depending on the symptoms. A detailed patient history and an MRI can help confirm the diagnosis.
“Hormones, among many other factors, play an important role in the health of the tear film and ocular surface,” says
What the doctor sees: Ocular redness, ocular surface inflammation, mucus and dryness on the surface of the eye. What the patient experiences: Blurry vision, burning and irritation, foreign body sensation and difficulty working on the computer (people blink about 30 percent less when looking at screens).
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What happens next: An eye doctor can prescribe lubricating drops, ointments or warm compresses, lid hygiene or a range of other products, such as omega-3 supplements, to help ease the discomfort.
Keep an eye out for these signs that your health is in trouble
Watch for these additional symptoms and talk to your doctor if you have any concerns:
1. Bulging eyes can be a sign of thyroid eye disease, a condition related to autoimmune thyroid disease that is marked by swelling of the muscles and tissues of the eye and orbit.
2. Pupil abnormalities – where one pupil is larger than the other or where one pupil reacts inappropriately when exposed to light – could signify an underlying medical problem.
3. Yellow eyes can signal liver disease. Both hepatitis and cirrhosis can turn the whites of the eyes yellow.
4. Redness, pain and inflammation of the ocular coats, a condition called scleritis, can be a symptom of a number of autoimmune diseases, including lupus, rheumatoid arthritis and thyroid disease.
5. Eye spasms, or annoying eye twitches, are caused by contractions of the eyelid muscles due to irritation of the muscle fibres. The underlying cause is almost always completely benign and can occasionally be precipitated by stress, fatigue or caffeine.
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How Doctors Test Pupil Reflexes
Your pupils control the amount of light that enters your eyes. Testing the pupils is an important part of a comprehensive eye exam. Because you do not have voluntary control of your pupils, pupil testing may uncover possible problems with your autonomic nervous system as well as other problems in the rest of your body.
The pupil is the round black circle in the center of the iris, the colored part of your eye. The pupil is actually a hole through which light passes to the retina, the light-sensitive layer in the back part of the eye. The pupil is similar to a camera aperture that you control when you want more or less light into your camera.
The pupil can expand to be become larger (dilate) or contract to become smaller (constrict). Your iris contains muscles that respond to outside stimuli to control the amount of light that reaches your retina. In bright light, the pupil constricts to reduce the amount of light entering the eye. In dark or dim light, the pupil dilates to allow more light into the eye to improve vision.
When your doctor examines your pupils, he or she will first look for anisocoria. Anisocoria is a condition in which your pupil sizes are unequal. Twenty percent of the general population has normal anisocoria and does not signal anything abnormal. In some cases, however, unequal pupil sizes can be a symptom of disease.
Your doctor is also looking at the size and shape of the pupil in both bright light and dim light. The speed and quality of pupillary response to stimuli will also be noted. Your doctor may also test your pupillary reaction to near stimuli such as small print.
The pupil is controlled by a very long nerve pathway in the body.
The nerve that controls the pupil starts in the brain, then travels down the spinal cord, up over the top of the lung, under the subclavian artery, up the neck and through extensions of the brain, and finally travels close to the optic nerve and then to the pupil. Any interruption along this pathway could possibly affect this nerve and cause changes in pupillary reaction.
Eye doctors use three procedures to test pupil reflexes.
Peter A. Kemmer/Getty Images
The light response pupil test assesses the reflex that controls the size of the pupil in response to light. Your doctor will first dim the lights, then ask you to look at an object in the distance.
A light will be shone into your eyes from each side.
Your doctor will watch your pupils closely to determine whether or not your pupils constrict in response to the light, making note of the size and shape of your pupils.
The swinging flashlight pupil test is used to compare your pupils' response to light. The lights in the room will be dimmed, and you will again be asked to look at a distant object.
Your doctor will “swing” the light rhythmically from one eye to the other, noting the response of each pupil. Your pupils should constrict or stay the same size when the light is shone on them.
Dilating pupils may alert your doctor to a possible optic nerve problem.
The near response pupil test measures the pupil's response to a near target. This test will be performed in a room with normal lighting.
Your doctor will ask you to look at a distant object, then move a small object or card in front of your eyes.
As you fixate your eyes on the near object, your doctor will watch your pupils closely to make sure they constrict quickly as your fixation changes from far to near.