Myopia is a common refractive error that’s also known as nearsightedness. A myopic eye is too long in proportion to the curvature of the cornea, causing light to focus in front of the retina rather than directly onto the retina. This can cause distant objects to appear blurry.
Hyperopia is a refractive error that’s also known as farsightedness. A hyperopic eye is too short in proportion to the curvature of the cornea, causing light to focus behind the retina, rather than directly onto the retina. This causes close-up objects to appear blurry.
Astigmatism is a refractive error that causes vision to appear blurry to some degree, regardless of distance. The cornea on an astigmatic eye is uneven, preventing light from focusing at a single point on the retina.
Presbyopia is a refractive error that everyone develops with age. As you get older, your eye’s natural lens stiffens, reducing its ability to focus on objects up-close. This is why most adults over 45 need reading glasses.
Eye Alignment Issues
Amblyopia is a condition sometimes known as a “lazy eye.” When both eyes aren’t working together properly, the brain can’t merge the signals from both into a single image. Eventually, it starts ignoring one eye (usually the weaker eye) and relying solely on information from the other. Because the brain is no longer communicating with it, the unused eye tends to drift off in a separate direction from the eye that’s in use. This condition occurs from a young age, and if treated early (best before 7 years old) it can usually be resolved with something as simple as a pair of glasses. Amblyopia gets harder to treat as the child grows up, after the mid teens it is unlikely to be resolved and will be permanent.
Strabismus is an eye alignment issue that’s sometimes called being cross-eyed or wall-eyed. Strabismus is different from amblyopia in that it usually stems from a muscular problem. Typically, the muscles controlling one eye are either too tight or too weak to move the eye in uniformity with the other eye.
While diplopia (also known as double vision) isn’t necessarily an eye alignment issue, it is very often a symptom of an eye alignment issue. When the entire visual system functions properly, both eyes take in information, which your brain then merges into a single image. When the entire system isn’t functioning properly (due to eye alignment, refractive error, or other issues), the brain can’t merge the signals from both eyes into a single image, causing you to see things twice, usually overlapping.
Your body relies on tears to clean, protect, and lubricate your eyes. When your body doesn’t produce enough tears or produces tears without the right balance of oils, your eyes can feel dry, itchy, and tired. The chronic lack of tears or tears of insufficient quality is known as dry eye or dry eye disease.
Glaucoma is an eye disease that causes a progressive loss of peripheral vision. This damage usually occurs slowly over a long period, although one type of glaucoma can develop very suddenly. Glaucoma typically does not exhibit any noticeable symptoms, and in most cases, the resulting vision loss is so gradual that the patient doesn’t even notice until they’ve lost a significant portion of their sight.
The macula is a small light-sensitive group of cells in the middle of the retina. When the macula becomes displaced by deposits called drusen or fluid and scar tissue from damaged blood vessels, it can start to decay. Macular degeneration results in loss of central vision which is responsible for your ability to see details like people’s faces.
Cancer & Tumours of the Eye
Tumours and cancers occur when the body starts developing irregular or excess cells when it isn’t supposed to. There are two main types of eye cancers; the first are primary intraocular cancers. These are cancers that start in the eye. The second are secondary intraocular cancers which start elsewhere in the body and eventually spread to the eye.
Lumps, Bumps, & Growths
A Hordeolum (sometimes called a Stye) is a small bump that develops inside the eyelid or on the lashline as the result of localized infection. Hordeolums often resemble pimples, but it’s very important that you do not squeeze a hordeolum.
Pinguecula is a yellow-tinted raised area of the sclera or the white of the eye. These bumps are non-cancerous and can develop as a result of excessive UV radiation, or from untreated dry eye. They are often accompanied by dry eye symptoms. If left too long pinguecula will typically progress into a pterygium.
A pterygium is a triangle-shaped growth of tissue that grows from the sclera (or the white of the eye) over the cornea, toward the pupil. The growth almost looks as if the sclera is being stretched towards the centre of the eye. Scientists do not know exactly why pterygium develop, although they seem to be related to excessive exposure to sand, wind, dust, and UV rays, and chronic dry eye.
A chalazion is a small bump that develops inside the eyelid. Chalazia (pleural for chalazion) typically develop as the result of hordeolums that have not been properly treated. The infection is no longer there, but now the oils created by the glands are not able to exit the glands and begin blowing them up like a balloon. In some cases, a chalazion may resolve on its own, though if left untreated some will become encapsulated and may need to be surgically removed.
Eye Conditions and Disorders
Ptosis is a condition that causes the upper eyelid to droop. The severity of ptosis varies from case to case; a slight ptosis may not impact the patient’s life whatsoever, while a more dramatic ptosis may obscure the pupil and impede the patient’s vision.
Proptosis is a condition that causes the eyeball to bulge or protrude. This condition can develop as the result of a variety of underlying eye issues, including hypo- or hyperthyroidism and tumours. Proptosis may increase intraocular pressure which can lead to glaucoma, and can cause double vision.
Keratoconus is a condition that affects the shape of the cornea. While a normal cornea is round, a cornea afflicted with keratoconus is more cone-shaped, growing progressively outward towards a point. This condition causes irregular astigmatism and can result in visual distortion, that is not resolved by glasses. In most moderate to advanced cases custom rigid contact lenses provide the best vision.
There are many different types of cataracts, one type everyone develops with time secondary to UV exposure, and can be worsened by exposure to radiation. Other types of cataracts can develop secondary to systemic conditions such as diabetes, Muscular Dystrophy, and Down’s syndrome. Most types of cataract grow slowly, progressively making the vision more blurry, opaque and decreasing colour vision.
Lagophthalmos is a condition that prevents patients from fully closing their eyelid, either to blink or simply rest their eyes. As a result, the eyes can become dry, and may end up vulnerable to injury and infection. A form called Nocturnal Lagopthalmos is common with people who have sleep apnea.
Flashes are the apparently random flashes of light that appear in your vision, which occur when the retina is tugged, touched, or jostled. The jelly ball inside of your eye is called the vitreous, and it tends to shrink as you get older. As the vitreous shrinks away from the retina, it tugs on it, which sends an impulse that the brain interprets as a flash of light. Though it is rare, if the vitreous tugs on the retina too hard it can cause a retinal tear or hole that can then progress into a retinal detachment. Therefore, it is recommended if you see any flashing lights to get a thorough retinal exam done.
The term “floaters” refers to the mysterious shapes that seem to float in the margins of your vision from time to time. When you are born, the vitreous is a jelly-like substance. As you age, it becomes more and more of a liquid. The shapes floating in your vision are reflections of the pieces of your vitreous that have not yet dissolved. In some cases, floaters can be a sign of retinal damage or sickness and a thorough retinal examination should be completed to rule out there uncommon causes.
The retina is a crucial part of your visual system. If the retina becomes loose inside the eye, it will most likely result in vision loss. While retinal detachments can be surgically repaired, the repairs must be made immediately. The longer the detachment goes untreated, the less likely the patient is to recover their vision. Symptoms of a retinal detachment include: 1. New floaters 2. Flashes of light lasting less than a second 3. Curtains or veils (blackness coming in from the top bottom or sides of your vision 4. Peripheral vision moving when it shouldn’t. If you experience any of these symptoms see your eye care practitioner as soon as possible.
Posterior Vitreous Detachment
Posterior vitreous detachment is a natural process that occurs due to age. As the vitreous shrinks, it pulls away from the retina, eventually detaching. Assuming the vitreous detaches slowly and evenly, this should not have any ill effects on your vision. However, in some case, posterior vitreous detachment can cause a retinal tear, or macular hole.
An epiretinal membrane is a small layer of tissue that can develop on the retina as you age. In some cases, the tissue can start to shrink pulling on the retina causing it to pucker, wrinkle, or fold, which can affect the health of the macula, impacting your central vision.
General Health Conditions
Diabetes can cause unusually high blood-sugar levels, which may eventually damage retinal blood vessels. When the damaged blood vessels start to leak or develop scar tissue, it can damage the macula. This is called diabetic eye disease.
Lupus & Autoimmune Diseases
Lupus and other autoimmune diseases can trick the body into attacking its own healthy tissues. One of the areas that autoimmune diseases can attack is the visual system. Patients with autoimmune diseases often suffer from uveitis (which causes inflammation inside the eye leading to light sensitivity and pain) scleritis (which causes the white part of the eye to become painfully inflamed), optic neuritis (which can result in vision loss), retinal vasculitis (which causes scar tissue, damaging the macula), dry eye, and more.
Hyper & Hypo Thyroidism
Thyroid eye disease (also called Graves Disease) is another disease that causes inflammation of the muscles that sits behind the eyes. This inflammation pushes the eyes outward, causing them to bulge, and occasionally creating eye alignment issues, double vision and dry eye.
High Blood Pressure
High blood pressure puts unnecessary strain on your circulatory system. This strain can be particularly damaging to the small blood vessels within your retina, which can eventually start to leak from the damage. Leakage can lead to scar tissue, which may cause irrevocable harm to your macular health.
Cholesterol build-up in the body’s circulatory system can lead to multiple issues such as strokes, and heart attacks. The mechanism that causes these conditions can also happen in the eye, Leading to a loss of blood flow to the whole or part of the retina. This retinal tissue that does not get any new oxygen can then become irreversibly damaged, and vision can be lost.
Low Blood Pressure
Blood carries oxygen to your body’s various systems. When blood pressure is too low, it can starve your eyes of the oxygen they need to function. Research indicates that a link exists between low blood pressure and glaucoma, which can result in blindness if left untreated.
Multiple sclerosis is a disease that, in addition to the brain and spinal cord, can have a profound impact on your vision. Common optical symptoms of multiple sclerosis can include swelling of the optic nerve (which can cause peripheral vision loss, blurring, and dulling of colour vision,) double visions, and nystagmus (causing uncontrolled eye movements that interfere with depth perception.) It’s quite common for the first signs of MS to be found during a routine eye exam.
Sarcoidosis is a condition that causes small clumps of tissue to develop on or in various organs, including the lungs, lymph nodes, and liver. Patients with sarcoidosis often experience eye irritation, excessive tears, burning, and redness, and may develop small, yellow-tinted bumps on their eyes.
Inflammation & Infections
Conjunctivitis (sometimes called pink eye) is an inflammation of the conjunctiva; the mucous membrane covering the surface of the eye and inside of the eyelid. This condition can stem from a variety of sources, including viral infections, bacterial infections, allergies and dry eye. The treatment of conjunctivitis varies based on what caused the inflammation.
Blepharitis is a condition that is closely associated with dry eye. Multiple factors such as environment, bacteria, blinking habits, and plaque build up (just like on your teeth) cause inflammation and/or infection of the oil producing glands in the eyelids. The oil component of the tears is then insufficient leading to increased evaporation and dry eye. Funnily enough excessive tearing is a very common side effect of blepharitis and dry eye.
Keratitis is a general term describing the inflammation of the cornea. Although keratitis can develop a variety of ways, in some cases, it is the result of an infection. It’s important that you seek medical attention to determine the cause of your keratitis and receive the appropriate treatment.
Corneal edema is when the cornea begins to swell due to a buildup of fluid within the cornea which can cause vision to become blurry. This condition can develop as the result of injury, infection, and other elements. Without treatment, corneal edema can cause scarring that causes a permanent reduction in vision.
Medications With Eye Health Implications
Plaquenil (Hydroxychloroquine) & Arafen (Chloroquine)
Plaquenil and closely related Arafen are medications used for malaria prevention, as well as the treatment of arthritis, lupus, and other conditions. Although there are relatively few side effects, studies indicate that high cumulative doses may cause retinal toxicity, which could result in the destruction of the macula. Macular destruction would result in a total loss of central vision. With current dosages this risk is quite minimized, but anyone who is taking these medications should be monitored yearly including optical coherence tomography, fundus autofluorescence, colour vision and central visual field testing.
Tamoxifen is a cancer treatment drug most commonly used to treat metastatic breast cancer. This drug can have a significant impact on the patient’s eye health, potentially resulting in dry eye, retinal hemorrhaging (retinopathy), and cataracts.
Ethambutol is an antibiotic that is used to treat and prevent tuberculosis. There is evidence to suggest that this drug can result in vision loss, which starts with visual distortion, blurring, and discolouration.
Amiodarone is a medication typically prescribed to help with irregular heart beats. Amiodarone can be deposited into the cornea causing Vortex Keratopathy. These corneal deposits rarely cause vision loss but can lead to haloes and glare around lights.