Macular Degeneration (AMD)
Macular degeneration causes damage to the macula of the eye. The macula is the central part of the retina at the back of the eye that allows us to see fine details clearly. Macular degeneration makes close work like threading a needle or reading a book difficult or impossible. When the macula does not function correctly, we experience blurriness or darkness in the center of our vision. Although macular degeneration reduces vision in the central part of the retina, it does not affect peripheral vision. For example, you could see a clock but not be able to tell what time it is. Macular degeneration alone does not result in total blindness. Most people continue to have some useful vision and are able to live independently.
There are two stages of macular degeneration:
- The Dry Stage. This is the more common form. In this type of macular degeneration, the delicate tissues of the macula become thinned and slowly lose function.
- The Wet Stage. This is less common, but is typically more damaging. The wet type of macular degeneration is caused by the growth of abnormal blood vessels behind the macula. The abnormal blood vessels tend to hemorrhage or leak, resulting in the formation of scar tissue if left untreated. In some instances, the dry stage of macular degeneration can turn into the wet stage. Macular degeneration develops differently in each person. Because it will affect regions of the macula differently from person to person, the symptoms tend to vary. Macular degeneration causes a progressive loss of central sight, however, it does not cause total blindness. Peripheral vision is unaffected, allowing a certain amount of mobility in normal surroundings. If left untreated, the wet type of macular degeneration may progress rapidly. Symptoms
- Blurry vision
- Distorted vision
- Straight lines appear wavy
- Objects may appear as the wrong shape or size
- The loss of clear, correct colors
- Difficulty reading
- A dark, empty area in the center of vision
The symptoms described above may not necessarily mean that you have age-related macular degeneration. However, if you experience one or more of these symptoms, contact your eye doctor for a complete exam.
AMD is the leading cause of vision loss in the western world for individuals older than 50. Approximately, 2 million Canadians and 13 million Americans are affected. In the US and Canada, at least 30% of individuals over 75 years of age have some degree of macular degeneration.
Currently, there is no known cure for macular degeneration. There are, however, new therapies emerging. For individuals with macular degeneration, it is highly recommended that a regular schedule of eye examinations be maintained. During these examinations, detailed documentation with photographs and fluorescein angiography may be performed. With this information, your eye doctor is better able to monitor the condition, note any changes that may occur, and determine the most appropriate therapy.
Treatment for Dry Macular Degeneration
Supplementation with specific anti-oxidant vitamins and minerals has been shown to significantly slow the progression of Dry AMD. For details on the dosage and side-effects, please see your ophthalmologist.
Treatment for Wet Macular Degeneration
The newest treatment for wet AMD is Lucentis, a drug that was approved by the FDA in 2006. This drug inhibits the growth and leakage of abnormal blood vessels and it is the first treatment that has been shown to improve vision in some eyes rather than simply slowing the rate of vision loss. Lucentis is delivered through tiny injections in the eye, once a month for three months, with additional, less frequent injections, as needed, for one year or more. A similar drug, Avastin, is also commonly used for the treatment of wet AMD.
Other treatments include laser treatments and photodynamic therapy. These treatments are designed to seal the leaking blood vessels, halting the damage they can inflict upon the retina. These treatments are effective in slowing the progression of wet macular degeneration and are sometimes used in combination with Lucentis or Avastin. Research is underway to find new and more effective treatments for this condition. Low vision aids are very successful in helping to maximize distance and near vision through the use of specialized telescopic/binocular spectacles, high powered reading glasses, glare controlling spectacles, illuminated magnifiers, portable digital magnifiers, and other electronic viewing devices.
Glaucoma is a group of eye diseases causing optic nerve damage. The optic nerve carries images from the retina, which is the specialized light sensing tissue, to the brain so we can see. In glaucoma, eye pressure plays a role in damaging the delicate nerve fibres of the optic nerve. When a significant number of nerve fibres are damaged, blind spots develop in the field of vision. Once nerve damage and visual loss occur, it is permanent. Most people don’t notice these blind areas until much of the optic nerve damage has already occurred. If the entire nerve is destroyed, then blindness results.
Glaucoma is the second leading cause of blindness according to the World Health Organization. Over 4 million Americans and 350,000 Canadians have glaucoma, but only half of them know they have it. Early detection and treatment by your eye care professional (optometrist or ophthalmologist) are the keys to preventing optic nerve damage and vision loss from glaucoma.
The treatment for glaucoma depends upon the nature and severity of each case. In general, glaucoma cannot be cured, but it can be controlled. Eye drops, pills, laser procedures, and surgical operations are used to prevent or slow further damage from occurring. Treatment may include one or a combination of these. With any type of glaucoma, regular eye examinations are very important to detect progression and to prevent vision loss. Because glaucoma can worsen without your being aware of it, your treatment will likely need to be changed over time to achieve a lower “target eye pressure.”
Diabetes can affect sight by causing cataracts, glaucoma, and most importantly, damage to blood vessels inside the eye, a condition known as “diabetic retinopathy”. Diabetic retinopathy is a complication of diabetes that is caused by changes in the blood vessels of the retina. When blood vessels in the retina are damaged, they may leak blood and grow fragile, brush-like branches and scar tissue. This can blur or distort the vision images that the retina sends to the brain. Diabetic eye disease is a leading cause of blindness among adults aged 20-74 yrs old in the United States and Canada. People with untreated diabetes are said to be 25 times more at risk for blindness than the general population. The longer a person has had diabetes, the higher the risk of developing diabetic retinopathy. Fortunately, with regular, proper eye care and treatment when necessary, the incidence of severe vision loss has been greatly reduced. If you have diabetes, your eye care professional (optometrist or ophthalmologist) can help to prevent serious vision problems.
In mild cases, treatment for diabetic retinopathy is not necessary. Regular eye exams are critical, though, to monitor any progression. Strict control of blood sugar and blood pressure levels can greatly reduce or prevent diabetic retinopathy. In more advanced cases, treatment is recommended to stop the damage of diabetic retinopathy and prevent vision loss.
Specialized distance and near viewing spectacles, as well as conventional and digital magnifiers are very beneficial depending on the degree of vision loss. Glare controlling lenses also help to enhance vision.
Retinitis Pigmentosa (RP) refers to a group of diseases which cause a slow but progressive vision loss. In each of them there is a gradual loss of the light-sensitive retinal cells called rods and cones.
An estimated 200,000 people in the United States have some form of RP. Most forms of RP are inherited or genetic, though its signs do not necessarily appear in every generation. Learning more about your family history may help you and your doctor to make informed decisions about treatment and eventually a cure for RP.
In some cases, RP may be associated with other health problems, such as hearing loss. People with RP may also develop other treatable eye diseases, such as glaucoma and cataract.
- Night blindness
- Loss of peripheral vision
(Symptoms usually start during young adulthood, although RP may be seen at any age.) The symptoms described above may not necessarily mean that you have retinitis pigmentosa. However, if you experience one or more of these symptoms, contact your eye doctor for a complete exam.
Currently, very few treatments exist for persons with RP. Occasionally, the degeneration can be slowed to preserve vision for a longer time. Genetic studies of RP are a significant factor in finding a cure or prevention for this disease. In the meantime, low vision aids that focus on glare controlling and distance and near viewing tasks have been very beneficial in maximizing the remaining vision.
Albinism is a rare disorder found in fewer than five people per 100,000 in the United States and Europe. Other parts of the world have a much higher rate; for example, albinism is found in about 20 out of every 100,000 people in southern Nigeria. There are 10 types of the most common form of the condition, known as “oculocutaneous albinism,” which affects the eyes, hair, and skin. In its most severe form, hair and skin remain pure white throughout life. People with a less severe form are born with white hair and skin, which turn slightly darker as they age. Everyone with oculocutaneous albinism experiences abnormal flickering eye movements (nystagmus) and sensitivity to bright light. There may be other eye problems as well, including poor vision and crossed or “lazy” eyes (strabismus).
The second most common type of the condition is known as “ocular” albinism, in which only the eyes lack color; skin and hair are normal. There are five forms of ocular albinism; some types cause more problems-especially eye problems-than others.
There is no treatment that can replace the lack of melanin that causes the symptoms of albinism. Doctors can only treat, not cure, the eye problems that often accompany the lack of skin color. Glasses are usually needed. Tints that help reduce glare and improve contrast as well as secondary sunglasses that minimize bright sunlight are very useful. There is no cure for involuntary eye movements (nystagmus). Low vision aids are beneficial in helping maximize distance and near vision.
Stargardt’s Macular Degneration
Stargardts disease is the most common form of juvenile macular degeneration(JMD). The changes in vision are usually noticed before the age of 20. This genetic form of macular dystrophy results in a dying of the photoreceptor cells in the macula which provide us with our detailed and central vision. It is the result of both parents carrying the recessive gene - which often means that the parents do not know that they are carriers and that the parents do not have the disease themselves. The responsible gene, ABCR, has recently been identified which will be useful for future gene therapy. There also is a form of Stargardt’s that is inherited from a dominant gene.
Initially, the child will complain of some vision loss, but JMD may not be detected during an eye exam and the macula may appear normal. This often causes delayed diagnosis or a lack of validation of the child’s complaints of vision problems. Later, as Stargardts progresses, and it will, a fluorescein angiogram will show changes in the choroid layer, a layer of blood vessels that feeds the macula. Eventually small yellowish-white flecks (fundus flavimaculatus) appear in the peripheral retina.
According to conventional medicine, there currently is no treatment for macular degeneration. Low vision aids that focus on glare control, near and distance viewing tasks are very successful.