The eyes have it—a glimpse into our body\’s overall health, that is. A myriad of health problems, from cancer to multiple sclerosis, can manifest themselves in symptoms affecting our eyes. Regular eye exams are crucial. This guide to eye-related health will clear up any confusion surrounding eye exams and ensure that your peepers get the protection they deserve.
You already know your eye care professional prescribes glasses and diagnoses eye diseases or disorders. But did you know a comprehensive eye exam can also reveal hidden health problems such as diabetes, hypertension, and cancer? Maybe now’s a good time to have your eyes checked.
Vision tests versus eye exams
The difference between vision tests and eye exams could impact your eyes and health.
This type of eye test, performed by optometrists and ophthalmologists, evaluates a range of factors affecting both vision and eye health. It includes
- reviewing case history—personal and family vision and medical issues
- analyzing visual needs for school/work environment and recreational activities
- conducting an external and internal eye exam. This may involve drops to dilate the pupils, giving a better view of the retina and the optic nerve to see problems such as leaking blood vessels and other medical conditions that show up in the eye.
- measuring vision qualities—acuity, sharpness, eye movements, coordination, focus, colour vision, depth perception
- performing a neurological assessment of pupil reaction, eye muscle reflexes and functions, and peripheral vision
- examining corneal or lens irregularities
- screening for glaucoma and other eye conditions
Many serious eye conditions and diseases, as well as non-vision problems and systemic diseases, are asymptomatic, or symptoms only appear after the condition is advanced, making treatment difficult or impossible. But with regular eye exams, an eye care practitioner can diagnose diseases early.
For Dr. Andrew Leung, a Toronto optometrist, the reason for regular eye exams is simple: “Most damage to the eye is non-reversible. It’s all about not letting it happen in the first place.”
Store sight test or school vision screening
Administered by nurses or technicians, these tests focus on eyesight correction rather than eye health. Based on computerized tests with no hands-on examination, these tests have a built-in bias because of instrument myopia—a tendency for eyes to over-focus when looking through a machine. This can lead to skewed test measurement and incorrect prescriptions. Plus, these tests cannot discover potential eye or health problems.
Hidden medical problems
Serious medical conditions can show up as eye or vision problems, or appear as retinal changes during an eye examination. As Leung reminds us, “We have to be proactive. Even though we see well, we have to check there’s no hidden problem.”
Some people with prediabetes or type 2 diabetes don’t experience early symptoms, so they remain undiagnosed. However, diabetes can manifest as damage to the small blood vessels in the retina (diabetic retinopathy), optic nerve damage (glaucoma), and the lens of the eye becoming opaque (early cataracts), which can all be caught through eye exams.
Untreated, diabetes can lead to vision loss, heart disease, stroke, nerve damage, kidney damage, hearing impairment, and possibly increased risk of Alzheimer’s disease.
Note: Exams by primary physicians, which don’t include eye dilation, are not adequate substitutes for comprehensive eye exams.
Like diabetes, hypertension (high blood pressure) may be asymptomatic. However, it can affect the eye’s blood vessels—presenting as headache, vision problems, or no symptoms in early stages—and shows up on a retinal scan as hypertensive retinopathy.
For asymptomatic patients, this may be their initial diagnosis of hypertension. The longer the hypertension goes undetected and uncontrolled, the more severe the damage for eyes, as well as heart and kidneys, is likely to be.
A number of systemic autoimmune diseases that attack various organs in the body can also show up in the eye. In some cases, it’s the first or most obvious sign of the disease. For example:
- Chronic red eye may indicate rheumatoid arthritis and lupus erythematosus.
- Yellowing of the whites of the eye may signal autoimmune hepatitis.
- Dry, burning, or itchy eyes; blurred vision; and light sensitivity can be signs of Sjögren’s syndrome (a condition most often affecting tear and saliva glands).
- Droopy eyelids or double vision could be symptoms of myasthenia gravis (weakening of skeletal muscles).
- Bulging eyeballs, light sensitivity, or blurred or double vision may be symptoms of hyperthyroidism.
Early diagnosis through eye exams can lead to treatment and improved outcomes.
Melanoma of the eye is another disease that is often symptomless in its early stages. When it does present symptoms, they may include
- blurred vision or loss of vision
- a growing dark spot on the iris
- change in size or shape of the pupil
- change in position or movement of the eyeball
- bulging eye
Because many of these symptoms are also caused by aging or less serious conditions, it takes a professional to make the correct diagnosis.
One of Leung’s patients, a woman in her late thirties, came in for a regular checkup. During eye dilation, he discovered a large tumour inside her eye. Because no pain receptors were affected, she wasn’t aware of it. Leung referred her for treatment, and she’s fine now.
Inflammation of the optic nerve is a common effect of multiple sclerosis and can affect both how people see the world and how their eyes move. For some MS patients, it’s the first sign of this disease. That makes eye care professionals important for diagnosis and management of visual MS symptoms, which may include
- partial or complete loss of vision (usually in one eye at a time)
- eye discomfort or pain, especially during eye movement
- double vision or blurring of vision
- rapid and uncontrolled eye movement
A study compared MRIs for brain scans to optical coherence tomography (OCT) for optic nerve scans. Findings suggest OCT may be increasingly used to monitor MS because OCT is significantly faster and cheaper and can be used to monitor the disease in earlier stages. Using the optic nerve to gain insight into other neurological disorders, such as Parkinson’s disease, ALS, and Alzheimer’s disease, is becoming more common.
Eye care professionals
Differences between eye care professionals are a function of training and licensing, which dictate their roles in treating eye problems, prescribing aids, and performing surgery.
Optometrists are considered primary care providers for eye-related health. They complete a four-year doctor of optometry degree program. They specialize in examination, diagnosis, treatment, management, and prevention of eye disease and disorders, as well as diagnosis of systemic conditions that show up in the eye.
Optometrists can recommend glasses, contact lenses, exercises, and vision therapy. Depending on the province, they may be able to prescribe medicine for some eye conditions.
Surgical cases or patients with more serious eye conditions are referred to ophthalmologists; patients with non-vision problems or systemic conditions are referred to appropriate specialists.
Ophthalmologists are physicians with additional specialized training in eye and vision care. While optometrists are front-line eye care practitioners, ophthalmologists deal with more serious eye diseases and are trained to perform surgical and laser techniques to correct problems.
Opticians are licensed professionals who design, fit, and dispense eyeglasses, contact lenses, low vision aids, and prosthetic eye devices based on prescriptions from ophthalmologists and optometrists.
Eye exam frequency
How frequently we should get our eyes checked depends on age and underlying medical conditions, according to Doctors of Optometry Canada.
Frequency of eye exams
|Infants||A complete eye exam between six and nine months of age. Up to six months, infants’ eyes often appear slightly crossed or out of alignment. If this continues, it can indicate strabismus (crossed eyes) or lead to amblyopia (lazy eye). Without early treatment, vision damage can be permanent.|
|Children||At least one eye exam between the ages of two and five; annually after starting school. Common symptoms of eye problems are
|Adults (19-64)||An eye exam every one to two years. People with rheumatic diseases or diabetes; of African or Hispanic descent; or who have a family history of or existing eye disease need frequent visits. So do contact lens wearers, as poorly fitting lenses can chafe, scar, and cause infections.|
|Seniors||An exam annually. Seniors are more prone to vision and medical problems and more likely to have low or limited sight.|
Note: Lost or decreased vision, changes in vision (including colour vision), physical changes to the eye, or symptoms of infection require immediate attention.
Best supplements for eye health
According to Leung, up to 25 percent of children fail their eye test. With 60 to 80 percent of learning coming through vision, these children struggle in school and may act up.
Researchers are studying supplements, alone and in combination, to help prevent or treat eye conditions and diseases. Promising ones are
- systemic and topical omega-3 and omega-6 for dry eye syndrome
- dietary intake of omega-3 for decreased risk of age-related macular degeneration (AMD) (decreasing central vision)
- an antioxidant supplement combining vitamins C and E, lutein and zeaxanthin, omega-3, and zinc (with cupric oxide) to reduce the risk of advanced AMD in those at intermediate or high risk
- a general daily multivitamin to decrease risk of cataracts
- a combination of dietary folate and supplemental folic acid for a possibly lower risk of exfoliation glaucoma
Other supplements being studied include
- vitamin B
- Ginkgo biloba
- berry anthocyanins