Patient Resources

The macula is the central most part of the retina, the inner layer at the back of the eye responsible for detailed central vision. It is used for reading, driving and recognizing people’s faces. Macular degeneration is a condition that causes the center of your vision to blur while the side or peripheral vision remains unaffected. It is generally related to the aging process, and is also commonly referred to as age-related macular degeneration (AMD). It is the leading cause of blindness in North America in adults over the age of 55.

Many children are affected by chronic allergies, which may become severe enough to affect their daily activities. However, children cannot always recognize what is wrong or explain their discomfort to family members or caregivers. The observation of specific behaviours and/or eye signs are useful in identifying eye allergies in children.

Seasonal allergies are caused by specific allergens such as ragweed, grass or tree pollen. When these allergens come in contact with your body, they are considered foreign particles. The allergens bind themselves to mast cells that are loaded with histamine. In response, your immune system starts to release large quantities of histamine and other chemicals from these mast cells to combat the allergens. It is the histamine action that produces the symptoms of sneezing, coughing, nasal congestion, red, itchy, and watery eyes. Seasonal allergic reactions can begin at any age. Areas that have poor air quality can result in more intense symptoms.

Amblyopia is described as weak vision or vision loss in one eye as a result of an uncorrected prescription during the early stages of development. If detected and treated before age six, it will often resolve completely. It is important to treat amblyopia early – with vision therapy, eyeglasses, contact lenses, or patching – as treatment becomes very difficult later on. Untreated amblyopia can lead to blindness in the affected eye. It is estimated that two to four per cent of children under the age of six have amblyopia.

Anterior uveitis is a common inflammation of the eye – more specifically, the iris. The iris is the coloured part of the eye. In Anterior uveitis, the iris becomes inflamed and the blood vessels within the iris leak white blood cells and protein into the anterior chamber (the cavity in the front of the eye). The ciliary body that is behind the iris may also become inflamed with Anterior uveitis. Anterior uveitis is not an infection and it is not contagious. The symptoms of Anterior uveitis include light sensitivity, throbbing eye pain, and blurred vision. The eye will look very red and inflamed and some patients need to wear sunglasses to help with the light sensitivity. The causes of red eye are virtually endless. The treatment required needs to be tailored for the particular cause of red eye. This stresses the importance for patients to seek the care of their Doctor of Optometry to be properly and thoroughly assessed for Anterior uveitis and other possible causes of red eye.

Astigmatism is a refractive error that occurs when the front surface of your eye (cornea) or the lens inside the eye is slightly irregular or cylindrical in shape, resulting in vision being blurred or distorted at all distances. Astigmatism is not a disease, but a common visual condition.

Blepharitis is a common condition that causes inflammation of the eyelids. It is a chronic external eye disorder resulting in red, burning, and irritated eyes.

When the normally clear lens within your eye becomes cloudy and opaque, it is called a cataract. Cataracts vary from extremely small areas of cloudiness to large opaque areas that cause a noticeable blurring of vision.

Colour deficiency occurs when your ability to distinguish colours and shades is different than normal. The term “colour blind” is often used, but usually incorrectly. Only a very small number of people are completely unable to identify any colours, a condition called achromatopsia. Colour deficiency is more common in males than females, with one in 10 males having a colour deficiency.

Conjunctivitis is an inflammation of the conjunctiva, the thin, transparent layer covering the surface of the inner eyelid and a portion of the front of the eye. Conjunctivitis has several causes and affects people of all ages.

Diabetes and its complications can affect many parts of the eye. Diabetes can cause changes in nearsightedness, farsightedness and premature presbyopia (the inability to focus on close objects). It can result in cataracts, glaucoma, paralysis of the nerves that control the eye muscles or pupil, and decreased corneal sensitivity. Visual symptoms of diabetes include fluctuating or blurring of vision, occasional double vision, loss of visual field, and flashes and floaters within the eyes. Sometimes these early signs of diabetes are first detected in a thorough examination performed by a Doctor of Optometry. The most serious eye problem associated with diabetes is diabetic retinopathy.

If you see two of whatever you are looking at, you may have a condition known as double vision, also referred to as diplopia. Double and blurred vision is often thought to be the same, but they do differ.

The tears your eyes normally produce are necessary for overall eye health and clear vision. Dry eye occurs when your eyes do not produce enough tears or produce tears that do not have the proper chemical composition.

Eye coordination is the ability of both eyes to work together as a team. Each of your eyes sees an ever so slightly different image and your brain, by a process called fusion, blends these two images into one three-dimensional picture. Good eye coordination keeps the eyes in proper alignment. A minor misalignment of your eyes can cause symptoms such as double vision, fatigue and headaches.

Floaters (often called floating spots) are small, semi-transparent cobwebs, specks or squiggles that appear in your field of vision. They are actually small particles within the gel inside the eye that become noticeable when they fall within the line of sight. They move when you move your eyes, but tend to drift or lag behind your eye movements. They may also appear along with flashes of light.

Glaucoma is an eye disease causing progressive damage to the optic nerve, which can lead to gradual vision loss and potential blindness if not detected and treated early.

A small area of redness and pain or a bump on the margin of your eyelid may indicate that you have a stye, known in medical terms as an external hordeolum. A stye is a blocked gland at the edge of the lid that has become infected by bacteria, usually Staphylococcus aureus.

Farsightedness, or hyperopia, as it is medically termed, is a visual condition in which distant objects are easier to see than near objects.

Keratoconus is a progressive disease affecting the front window of the eye, the cornea, and results in poor vision that cannot be corrected fully with glasses. Keratoconus usually begins in the late teenage years. However, it can start in the 20s or early 30s. Keratoconus causes the “clear window” at the front of the eye to become thin and bow outwards. It is this irregular distortion of the cornea that makes vision correction with glasses less than optimal. For this reason, other means of correcting vision are often necessary.

Nearsightedness, or myopia, as it is medically termed, is a visual condition in which near objects are seen clearly, but distant objects do not come into proper focus.

Presbyopia is a normal aging change in which the crystalline lens of your eye loses its elasticity and flexibility. This results in an inability to focus on close objects.

A pterygium is a benign, triangular-shaped growth of the conjunctiva that grows onto the cornea. The conjunctiva is the thin clear layer of tissue that lies over the white of the eyeball. A pterygium is made up of collagen and fibrovascular tissue that grows from the conjunctiva and eventually advances onto the cornea (the clear outer covering of the eyeball). Pterygia are more commonly located on the inner or medial portion of the eye.

The cornea is the clear, dome-shaped covering of the eye. RCE occurs when the outer layer of the cornea, known as the epithelium, loosens or peels off. Normally the epithelium is tightly adhered to the layer of the cornea beneath it. The eye becomes very painful with RCE since the cornea is very sensitive to any disruption of cells. The pain frequently is worse upon awakening. When the eyelids are closed during sleep, the reduced oxygen supply causes mild swelling of the epithelium. This swelling can cause the epithelium to become stuck to the under surface of the eyelid. Upon awakening, this loose tissue peels off when opening the eyelids, resulting in severe pain. The pain may last for a couple of hours or up to several days, with a recurrence rate of several times per year. Frequently, if they resolve quickly, the symptoms of a RCE are often ignored. A Doctor of Optometry should be consulted to properly diagnose and treat a recurrent corneal erosion to minimize the discomfort experienced and provide solutions to prevent recurrence.

The retina is a thin layer of tissue that lines the inner posterior portion of the eye. It consists of fine cells called photoreceptors, or rods and cones. These cells transmit light from the eye to the brain where it is perceived as vision. During a retinal detachment, the retina partially or completely peels away from the back of the eye. Once it is detached, the retina stops working and light signals cannot get back to the brain to be processed. To the patient, some degree of vision loss occurs. Depending on the severity of the detachment, vision loss can be severe and permanent.

Retinoblastoma is a rare cancer of the eye that typically affects children between birth and five years of age. The incidence of RB is one in 15,000 live births, with about 23 children being affected in Canada each year. The retinoblastoma tumor(s) originate in the retina, the light sensitive layer of the eye that enables the eye to see. When the tumors are present in one eye, it is referred to as unilateral retinoblastoma, and when it occurs in both eyes it is referred to as bilateral retinoblastoma.

Shingles is a viral infection that affects many parts of the body. The particular virus is called the herpes varicella-zoster virus. The varicella portion of the virus causes chickenpox. After the chickenpox has cleared, the virus becomes dormant in specific nerve roots of the brain. If the virus is reactivated later in life, the virus results in shingles. A reduction in one’s immunity can cause the reactivation. Such things that can cause a reduction in your immunity include aging, UV exposure, stress, organ transplantation, etc. Shingles is only contagious to people who have never had chickenpox.

A crossed eye or out-turned eye is referred to clinically as strabismus. It is a muscle condition in which your eyes are not properly aligned with each other, resulting in double vision or the suppression of the image from the affected eye. For a variety of reasons, one or both of your eyes may turn in, out, up or down.

The most common cause of temporary vision loss is known as a transient ischemic attack. It is more commonly known as a TIA, or a “mini-stroke,” and tends to occur most often in seniors. A TIA may only last a matter of minutes but it should not be ignored since roughly fifteen per cent of patients who survive their first TIA or mini-stroke will suffer another one within one year.

The term trichiasis describes the condition in which one’s eyelashes turn inwards. The eyelids normally have a single row of eyelashes on the upper and lower lids. The lashes typically point outwards, away from the eye. Sometimes the lid margin can turn inwards causing one or more lashes to scratch the cornea (clear covering of the eye) or the conjunctiva (thin layer of clear tissue that covers the white of the eye). This will result in eye pain ranging from mild to moderate, redness, and excessive tearing. Most patients who suffer from this condition will experience several attacks per year.

The vitreous is a semi-solid to liquid material that occupies up to 75 per cent of the eyeball volume. It is contained within a thin sac that is tightly adhered to the retina, or the inner layer of the eye. One role of the vitreous is to keep the eyeball inflated much like air in a soccer ball. However, the vitreous sac can pull away from the retina and shrink as we age.