Vision Library

The Brockville Optometric Centre is pleased to offer this important library of topics related to vision for our patients. Our Vision Library provides information and resources related to many issues in eye care. Feel free to browse the categories to learn more about specific areas of interest or concern. Your doctor is always the best source of information related to your individual eye care and new developments, so be sure to raise any questions or concerns with your doctor during your appointment.

Legal Disclaimer
All content is provided solely for information and education purposes and should not be considered a substitute for the advice of an Optometrist. The Brockville Optometric Centre assumes no responsibility or liability arising from any errors or omission or from the use of any information contained herein. 

Eye Diseases

Visual Conditions

Eye Diseases

Cataracts
Cataracts are a clouding of the eye's crystalline lens that usually develops slowly over time. It commonly affects people over 60 years of age but can occur in younger individuals or newborns.  Symptoms include blurred vision, glare around lights, and colours appearing less brilliant.  The treatment for cataracts is the surgical replacement of the clouded lens with an implant.  Following surgery, it is normal to require a change in glasses.

Diabetic Retinopathy 
Diabetic retinopathy, a complication of diabetes, is the damage to the retina due to leakage from the fine retinal blood vessels. The majority of these changes are symptomless until extreme stages.  Keeping you blood sugar levels under control will help decrease the risk of complications.  When retinal changes become sight threatening, laser treatment or surgical intervention may be necessary.  
Diabetics should be followed by an optometrist or ophthalmologist annually or sooner if recommended.  More information is available at the Canadian Diabetes Association website.

Dry Eyes
Dry eye is caused by a lack of tear production or poorly formed tears that do not adhere to the surface of the eye.  It can be caused by aging, medications, hormone changes and environmental conditions.  Symptoms include itchy, watery, red, burning eyes or the feeling of something in the eye.  Treatment includes artificial tear drops or ointments and plugging of the tear drainage canals of the eye.  Nutritional supplements such as Omega-3 and flaxseed have been shown to be effective in the treatment of dry eyes.

Glaucoma
Glaucoma is a condition in which the intraocular pressure of the eye can become elevated damaging the optic nerve and leading to peripheral vision loss.  It affects 2-4% of people over 40 years of age and can be hereditary. Often there are no symptoms of this disease.  Once diagnosed, glaucoma treatments are highly effective. Prescription eye drops, oral medications, laser treatment or even surgery may be required. If untreated, glaucoma can cause irreversible vision loss.  More information is available at the Glaucoma Research Society.

Macular Degeneration
Macular degeneration is a hereditary condition in which the macula (the part of the retina responsible for sharp reading vision) fails to function efficiently. It is a common cause of impaired reading or detailed vision is the leading cause of blindness worldwide.  Macular degeneration is generally age-related.  There are two forms of the condition; the less sight threatening dry form to the more sight threatening wet form.  Initial signs include blurred reading vision, a weakening of colour vision, distortion or loss of central vision (e.g., a dark spot in the middle of your field of vision), and distortion of lines (appear squiggly). 

            Treatment of dry form
Although there is no cure, nutritional supplements and lifestyle changes can decrease the risk of progression.  Vitamins based on the Age Related Eye Disease Study (AREDS)http://www.cnib.ca/en/your-eyes/nutrition/AREDS/default.aspx http://www.nei.nih.gov/amd/lutein/zeaxanthin, and omega 3 fish oil have been shown to decrease the risk of progression by 30%.  Lifestyle changes such as not smoking, controlling weight and decreasing exposure to UV light will also decrease the risk of progression of the disease.

            Treatment of wet form
The most recent treatment for this form of AMD requires the injection of a drug, anti Vascular Endothelial Growth Factor (VEGF), into the eye which seals the leaking blood vessels and stops the leakage of blood and fluid into the retina. The treatment is repeated every 4 to 5 weeks until diagnostic tests indicate that the blood vessels are sealed.  This treatment has been shown to halt the deterioration of vision in the majority of patients, and to have improved the vision in some.  The vision will not be restored to normal.  It is possible that leakage will begin again, and then another cycle of treatments will be required.

Macular Degeneration Society and CNIB   (http://www.amdsupport.ca/)

Retinal Detachment
Retinal detachment is the separation of the retina from the attachment to the underlying tissues of the eye.  Most detachments are due to a retinal tear, break, or hole.  There is a higher rate of incidence in the highly myopic patient.  Symptoms include flashing lights, increase in spots or floaters, or vision loss often described as a shadow or curtain affecting any part of the vision.  If a retinal detachment has occurred, time can be critical, therefore the patient should see a specialist as soon as possible.  The sooner the retina is reattached, the better the chance of recovering vision.

Spots & Floaters 
Spots and floaters are tiny flecks or threads, which seem to float in front of your eyes. They are experienced by most people. They are often caused by particles of protein trapped in the fluid inside the eye, or by the deterioration of the fluid due to advancing age. 
Occasionally they are the result of certain eye diseases or injuries, or they may signal the development of more serious conditions such as retinal detachment. They are usually harmless, but those experiencing a sudden change or increase in spots and floaters or flashes of light should consult their eye doctor.

Post Vitreous Detachment (PVD)
A PVD is due to the separation of the vitreous gel from the retina.  Symptoms are flashes of light and floaters.  When a patient has experienced a PVD, they are at a higher risk of a retinal detachment, therefore a thorough dilated fundus exam is recommended to rule out any retinal involvement.

Styes
A stye is a red tender bump on the eyelid that is caused by an acute infection of the glands of the eyelid. Its appearance can vary somewhat, but it is harmless to your vision. Symptoms include a noticeable swelling with some discomfort and tenderness in the affected area. 
Most styes heal without treatment, although the application of hot compresses can help. Unlike a pimple, however, styes cannot be manually ruptured and drained. Antibiotic ointments are available for recurring cases

Visual Conditions

Amblyopia (Lazy eye)
Amblyopia or lazy eye is the failure of the vision to develop in one eye and is not due to a health problem of the eye.  The vision cannot be fully corrected with glasses or contacts. Treatment typically includes vision therapy, eyeglasses, contact lenses, or a patch. Surgery will not treat amblyopia.   The sooner treatment is initiated, the greater the rate of success.

Astigmatism 
Astigmatism affects vision at both distance and near.  The front surface of the eye(cornea) or the lens inside the eye is irregular in shape causing the light rays entering the eye to come to focus at two different points and result in blurred vision.  It is a common refractive error, just like nearsightedness and farsightedness.  Eyeglasses and contact lenses are used to correct for astigmatism.

Hyperopia (Farsightedness)
Light rays entering the eye focus beyond the retina and cause objects to be blurred at near.  If there is a substantial amount of hyperopia, objects in the distance can be blurred as well. Farsightedness is very common among elementary school-age children and a frequent cause of reading and learning difficulties.  It is often associated with headaches when reading or working on a computer. Hyperopia is commonly corrected by eyeglasses or contact lenses

Myopia (Nearsightedness) 
Light rays entering the eye focus in front of the retina and cause objects in the distance to be blurred while near vision is usually clear.  Myopia is corrected by eyeglasses or contact lenses.

Presbyopia 
Presbyopia is a condition in which the eye can no longer accommodate or focus objects up close to the point where near vision becomes blurred.  Presbyopia usually occurs to people between the ages of 38 and 45.  People with presbyopia will hold print further away, tilt the paper or increase the light in order to read better.  Presbyopia is treated by reading glasses, bifocals or contacts.

Strabismus
Strabismus or "crossed eyes" is a condition in which the eyes are not properly aligned with each other. One or both eyes may turn in (esotropia), out (exotropia), up (hypertropia) or down (hypotropia). Treatment may include the use of eyeglasses, prisms and/or vision therapy. In extreme cases, surgery may be needed.

Glossary

Colour deficiency: Commonly called colour blindness is a lack of ability to distinguish certain colours. The most common form is the inability to distinguish shades of red and green.
Cornea: Transparent tissue covering the front of the eye that lets light travel through.
Fovea: Located in the center of the macula and contains only cone receptors. It allows us to see things sharply.
Iris: A ring of muscles in the colored part of the eye that controls the size of the pupil.
Lens: Located directly behind the pupil, it focuses light rays onto the retina.
Macula: The part of the retina responsible for sharp, central vision needed to read or drive.
Ocular Disorder: A disorder of the eye.
Optic Nerve: A bundle of nerve fibers that carries messages from the eyes to the brain.
Photophobia: Also called light sensitivity is a condition that can have many underlying causes and can be prompted by many medications. Protection from UV radiation is critical for anyone with this condition.
Pterygium: This is a raised growth on the eye that is most often directly related to over-exposure to the sun. Dry, dusty conditions may also be a factor. Protecting your eyes from UV radiation is a preventive measure.
Pupil: An opening in the center of the iris that changes size to control how much light is entering the eye.
Retina: Part of the eye that changes light that enters into nerve signals.
Rods and cones: Special receptors in the eye used by the retina to process light.
Sclera: The white part of the eye that is composed of fibrous tissue that protects the inner workings of the eye.
Snellen chart: The chart topped by a large letter is used in eye examinations which measures your eye's visual acuity, or the ability to see sharp detail clearly.
Ultraviolet radiation (UVR): Commonly referred to as UV Rays consist of both UVA and UVB rays from the sun. Without proper protection, UV rays can contribute to various eye conditions.