What Your Eyes Can Tell You About Your Health

Your eyes hold valuable clues to your overall health.

What your eyes can tell you about your health

This is why doctors look in your eyes with a light.

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 based on 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.

Related: What Canadians Need to Know About Organ Donation

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 based on 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.

Multiple Sclerosis

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.

Hormonal changes

“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).

Related: 10 Questions You Need to Ask Your Doctor

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.

Related: 11 Things Your Doctor Can Tell Just by Looking at You