Tag Archives: Visual Impairment

Truths about protecting our eyes

 

Fact: Eye exercises will not improve or preserve vision or reduce the need for glasses. Your vision depends on many factors, including the shape of your eyeball and the health of the eye tissues, neither of which can be significantly altered with eye exercises.
As the eyes age, problems with vision become more common. Learn how to recognize the risk factors and symptoms of specific eye diseases cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy — and what steps one can take to prevent or treat them before your vision deteriorates.

Myth: Reading in dim light will worsen our vision.

Fact: Dim lighting will not damage our eyesight. However, it will tire our eyes out more quickly. The best way to position a reading light is to have it shine directly onto the page, not over the shoulder. A desk lamp with an opaque shade pointing directly at the reading material is ideal.

Myth: Carrots are the best food for the eyes.

Fact: Carrots, which contain vitamin A, are indeed good for the eyes. But fresh fruits and dark green leafy vegetables, which contain more antioxidant vitamins such as C and E, are even better. Antioxidants may even help protect the eyes against cataracts and age-related macular degeneration. Just don’t expect them to prevent or correct basic vision problems such as nearsightedness or farsightedness.

Myth: It’s best not to wear glasses or contact lenses all the time. Taking a break from them allows our eyes to rest.

Fact: If we need glasses or contacts for distance vision or reading, we should use them. Not wearing glasses will strain our eyes and tire them out instead of resting them. However, it will not worsen our vision or lead to eye disease.

Myth: Staring at a computer screen all day is bad for the eyes.

Fact: Using a computer does not damage our eyes. However, staring at a computer screen all day can contribute to eyestrain or tired eyes. People who stare at a computer screen for long periods tend not to blink as often as usual, which can cause the eyes to feel dry and uncomfortable. To help prevent eyestrain, we should adjust the lighting so it doesn’t create a glare or harsh reflection on the screen, it is advised to rest the eyes briefly every 20 minutes, and make a conscious effort to blink regularly so that our eyes stay well lubricated.

It can be a frightening moment. When the doctor diagnoses an eye disease such as glaucoma, cataract, or AMD, we immediately worry about losing our sight or becoming seriously vision-impaired.

It’s important to know what to do not only when disease strikes, but what to do before and after. We should know the warning signs and how a diagnosis is made. And the best treatment options for that.

The good news is, with the proper treatment decisions, those eye diseases can be addressed and controlled and their potential to compromise our sight can be halted.

Our eyes do change as we get older. That’s a truth we can do little about. It’s the consequences we can change.
We we should learn all the facts about treating adult eye diseases.

Resources:
Harvard Health Publication
Harvard Medical School

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Macular Degeneration (AMD OR ARMD)

Definition:
Macular degeneration is a medical condition usually of older adults which results in a loss of vision in the center of the visual field (the macula) because of damage to the retina. It occurs in “dry” and “wet” forms. It is a major cause of blindness in the elderly (>50 years). Macular degeneration can make it difficult or impossible to read or recognize faces, although enough peripheral vision remains to allow other activities of daily life.

CLICK TO SEE THE PICTURES.>...(01)...…….(1).…………..(2).……..(3)………..(4)

Human eye cross section view

Macular degeneration doesn’t cause total blindness, but it worsens your quality of life by blurring or causing a blind spot in your central vision. Clear central vision is necessary for reading, driving, recognizing faces and doing detail work.

The deterioration occurs in the macula (MAK-u-luh), which is in the center of the retina — the layer of tissue on the inside back wall of your eyeball.

The inner layer of the eye is the retina, which contains nerves that communicate sight, and behind the retina is the choroid, which contains the blood supply to the retina. In the dry (nonexudative) form, cellular debris called drusen accumulate between the retina and the choroid, and the retina can become detached. In the wet (exudative) form, which is more severe, blood vessels grow up from the choroid behind the retina, and the retina can also become detached. It can be treated with laser coagulation, and with medication that stops and sometimes reverses the growth of blood vessels.

Although some macular dystrophies affecting younger individuals are sometimes referred to as macular degeneration, the term generally refers to age-related macular degeneration (AMD or ARMD).

Signs:
Drusen
Pigmentary alterations
Exudative changes: hemorrhages in the eye, hard exudates, subretinal/sub-RPE/intraretinal fluid
Atrophy: incipient and geographic
Visual acuity drastically decreasing (two levels or more) ex: 20/20 to 20/80.

Symptoms:
Dry macular degeneration usually develops gradually and painlessly. You may notice these vision changes:

* The need for increasingly bright light when reading or doing close work
* Increasing difficulty adapting to low light levels, such as when entering a dimly lit restaurant
* Increasing blurriness of printed words
* A decrease in the intensity or brightness of colors
* Difficulty recognizing faces
* Gradual increase in the haziness of your overall vision
* Blurred or blind spot in the center of your visual field combined with a profound drop in the sharpness (acuity) of your central vision
CLICK FOR PICTURE

Normal Vision.……………………………...Vision with AMD

Your vision may falter in one eye while the other eye remains fine for years. You may not notice any or much change because your good eye compensates for the weak one. Your vision and lifestyle begin to be dramatically affected when this condition develops in both eyes.

Hallucinations

Additionally, some people with macular degeneration may experience visual hallucinations as their vision loss becomes more severe. These hallucinations may include unusual patterns, geometric figures, animals or even faces. You might be afraid to discuss these symptoms with your doctors or friends and family for fear you’ll be considered crazy. However, such hallucinations aren’t a sign of mental illness. In fact, they’re so common that there’s a name for this phenomenon — Charles Bonnet syndrome.

The Amsler Grid Test is one of the simplest and most effective methods for patients to monitor the health of the macula. The Amsler Grid is essentially a pattern of intersecting lines (identical to graph paper) with a black dot in the middle. The central black dot is used for fixation (a place for the eye to stare at). With normal vision, all lines surrounding the black dot will look straight and evenly spaced with no missing or odd looking areas when fixating on the grid’s central black dot. When there is disease affecting the macula, as in macular degeneration, the lines can look bent, distorted and/or missing. See a video on how to use an Amsler grid here:  and watch an animation showing the Amsler grid with macular degeneration here: .

Macular degeneration by itself will not lead to total blindness. For that matter, only a very small number of people with visual impairment are totally blind. In almost all cases, some vision remains. Other complicating conditions may possibly lead to such an acute condition (severe stroke or trauma, untreated glaucoma, etc.), but few macular degeneration patients experience total visual loss. The area of the macula comprises about 5% of the retina and is responsible for about 35% of the visual field. The remaining 65% (the peripheral field) remains unaffected by the disease

The loss of central vision profoundly affects visual functioning. It is not possible, for example, to read without central vision. Pictures which attempt to depict the central visual loss of macular degeneration with a black spot do not really do justice to the devastating nature of the visual loss. This can be demonstrated by printing letters 6 inches high on a piece of paper and attempting to identify them while looking straight ahead and holding the paper slightly to the side. Most people find this surprisingly difficult to do.

There is a loss off contrast sensitivity, so that contours, shadows and color vision are less vivid. The loss in contrast sensitivity can be quickly and easily measured by a contrast sensitivity test performed either at home or by an eye specialist.

Similar symptoms with a very different etiology and different treatment can be caused by Epiretinal membrane or macular pucker or leaking blood vessels in the eye..

When to see a doctor
See your eye doctor — particularly after age 50 — if:

* You notice changes in your central vision
* Your ability to see colors and fine detail becomes impaired

One way to monitor your eyes to determine if you may need to visit your eye doctor is to check your vision regularly using an Amsler grid. This simple test may help you detect changes in your sight that you otherwise may not notice.

Here’s how to perform the test:

* Hold the grid 14 inches (about 36 centimeters) in front of you in good light. Use your corrective glasses or reading glasses if you normally wear them.
* Cover one eye.
* Look directly at the center dot with your uncovered eye.
* While looking at this dot, determine whether all of the lines of the grid appear straight, uninterrupted and have the same contrast.
* Repeat the above steps with your other eye.
* If any part of the grid is missing or looks wavy, blurred or dark, contact your eye doctor immediately.

Causes:
The exact cause of dry macular degeneration is unknown, but the condition develops as the eye ages. The initial site of change is not in the light-sensitive cells of the macula, but in the retinal pigment epithelium (RPE), a single layer of cells located just behind the retina close to the back wall of your eye.

Your macula is an area about two-tenths of an inch (5 millimeters) in diameter at the center of your retina. This small part of your eye is responsible for clear vision, particularly in your direct line of sight.

The macula consists of millions of densely packed light-sensitive cells called cones and rods. Cones and rods have two segments: An inner segment controls cell functions and produces proteins responsive to light, and an outer segment stores and makes use of these proteins.

As they absorb light, outer segment proteins become degraded and eventually are shed as waste. Meanwhile, the inner segments continuously provide replacements for the outer segments. One function of the cells of the RPE is to remove the outer segments that are shed.

As the eye ages, cells in the RPE begin to deteriorate (atrophy) and lose their pigment. As a consequence, the RPE becomes less efficient in removing outer segment waste. When that happens, the normally uniform reddish color of the macula (as seen with an ophthalmoscope) takes on a mottled appearance. Drusen — yellow, fat-like deposits — begin to appear under the cones and rods. As the drusen and mottled pigmentation continue to develop, your vision gradually deteriorates.

Based on this progression, dry macular degeneration is categorized in three stages:

* Early stage. Several small drusen or a few medium-sized drusen are detected on the macula in one or both eyes. Generally, there’s no vision loss in the earliest stage.
* Intermediate stage. Many medium-sized drusen or one or more large drusen are detected in one or both eyes. At this stage, your central vision may start to blur and you may need extra light for reading or doing detail work.
* Advanced stage. Several large drusen, as well as extensive breakdown of light-sensitive cells in the macula, are detected. These features cause a well-defined spot of blurring in your central vision. The blurred area may become larger and more opaque over time.

Macular degeneration almost always starts out as the dry form. Dry macular degeneration may initially affect only one eye but, in most cases, both eyes eventually become involved.

Risk factors:
Contributing factors for development of macular degeneration include:

* Age. In the United States, macular degeneration is the leading cause of severe vision loss in people age 60 and older.
* Family history of macular degeneration. If someone in your family had macular degeneration, your odds of developing macular degeneration are higher. In recent years, researchers have identified some of the genes associated with macular degeneration. In the future, genetic screening tests may be helpful for assessing early risk of the disease.
* Race. Macular degeneration is more common in whites than it is in other groups, especially after age 75.
* Sex. Women are more likely than men to develop macular degeneration, and because they tend to live longer, women are more likely to experience the effects of severe vision loss from the disease.
* Cigarette smoking. Exposure to cigarette smoke doubles your risk of macular degeneration. Cigarette smoking is the single most preventable cause of macular degeneration.
*Stargardt’s disease (STGD, also known as Juvenile Macular Degeneration) is an autosomal recessive retinal disorder characterized by a juvenile-onset macular dystrophy, alterations of the peripheral retina, and subretinal deposition of lipofuscin-like material. A gene encoding an ATP-binding cassette (ABC) transporter was mapped to the 2-cM (centiMorgan) interval at 1p13-p21 previously shown by linkage analysis to harbor the STGD gene. This gene, ABCR, is expressed exclusively and at high levels in the retina, in rod but not cone photoreceptors, as detected by in situ hybridization. Mutational analysis of ABCR in STGD families revealed a total of 19 different mutations including homozygous mutations in two families with consanguineous parentage. These data indicate that ABCR is the causal gene of STGD/FFM.
*Drusen CMSD studies indicate that drusen are similar in molecular composition to plaques and deposits in other age-related diseases such as Alzheimer’s disease and atherosclerosis.
While there is a tendency for drusen to be blamed for the progressive loss of vision, drusen deposits can, however, be present in the retina without vision loss. Some patients with large deposits of drusen have normal visual acuity. If normal retinal reception and image transmission are sometimes possible in a retina when high concentrations of drusen are present, then even if drusen can be implicated in the loss of visual function, there must be at least one other factor that accounts for the loss of vision. Retinitis Pigmentosa (RP) is a genetically linked dysfunction of the retina and is related to mutation of the ATP Synthase Gene 63.
* Obesity. Being severely overweight increases the chance that early or intermediate macular degeneration will progress to the more severe form of the disease.
* Light-colored eyes. People with light-colored eyes appear to be at greater risk than do those with darker eyes.
* Exposure to sunlight. Although the retina is more sensitive to shorter wavelengths of light, including ultraviolet (UV) light, only a small percentage of ultraviolet light actually reaches the retina. Most ultraviolet light is filtered by the transparent outer surface of your eye (cornea) and the natural crystalline lens in your eye. Some experts believe that long-term exposure to ultraviolet light may increase your risk of developing macular degeneration, but this risk has not been proved and remains controversial.
* Low levels of nutrients. This includes low blood levels of minerals, such as zinc, and of antioxidant vitamins, such as A, C and E. Antioxidants may protect your cells from oxygen damage (oxidation), which may partially be responsible for the effects of aging and for the development of certain diseases such as macular degeneration.
* Cardiovascular diseases. These include high blood pressure, stroke, heart attack and coronary artery disease with chest pain (angina).
*High fat intake is associated with an increased risk of macular degeneration in both women and men. Fat provides about 42% of the food energy in the average American diet. A diet that derives closer to 20-25% of total food energy from fat is probably healthier. Reducing fat intake to this level means cutting down greatly on consumption of red meats and high-fat dairy products such as whole milk, cheese, and butter. Eating more cold-water fish (at least twice weekly), rather than red meats, and eating any type of nuts may help macular degeneration patients.
*Oxidative stress: It has been proposed that age related accumulation of low molecular weight, phototoxic, pro-oxidant melanin oligomers within lysosomes in the retinal pigment epithelium may be partly responsible for decreasing the digestive rate of photoreceptor outer rod segments (POS) by the RPE. A decrease in the digestive rate of POS has been shown to be associated with lipofuscin formation – a classic sign associated with macular degeneration.
*Fibulin-5 mutation Rare forms of the disease are caused by geneic defects in fibulin-5, in an autosomal dominant manner. In 2004 Stone et al. performed a screen on 402 AMD patients and revealed a statistically significant correlation between mutations in Fibulin-5 and incidence of the disease. Furthermore the point mutants were found in the Calcium binding sites of the cbEGF domains of the protein. there is no structural basis for the effects of the mutations.

Diagnosis:
Diagnostic tests for macular degeneration may include:

*An eye examination. One of the things your eye doctor looks for while examining the inside of your eye is the presence of drusen and mottled pigmentation in the macula. The eye examination includes a simple test of your central vision and may include testing with an Amsler grid. If you have macular degeneration, when you look at the grid some of the straight lines may seem faded, broken or distorted. By noting where the break or distortion occurs — usually on or near the center of the grid — your eye doctor can better determine the location and extent of your macular damage.

Regular screening examinations can detect early signs of macular degeneration before the disease leads to vision loss.
*Angiography. To evaluate the extent of the damage from macular degeneration, your eye doctor may use fluorescein angiography. In this procedure, fluorescein dye is injected into a vein in your arm and photographs are taken of the back of the eye as the dye passes through blood vessels in your retina and choroid. Your doctor then uses these photographs to detect changes in macular pigmentation or to identify small macular blood vessels.

Your doctor may also suggest a similar procedure called indocyanine green angiography. Instead of fluorescein, a dye called indocyanine green is used. This test provides information that complements the findings obtained through fluorescein angiography.
* Optical coherence tomography. This noninvasive imaging test helps identify and display areas of retinal thickening or thinning. Such changes are associated with macular degeneration. This test can also reveal the presence of abnormal fluid in and under the retina or the RPE. It’s often used to help monitor the response of the retina to macular degeneration treatments.

Treatment:
There’s no treatment available to reverse dry macular degeneration. But this doesn’t mean you’ll eventually lose all of your sight. Dry macular degeneration usually progresses slowly, and many people with the condition are able to live relatively normal, productive lives, especially if only one eye is affected. Dry macular degeneration can, however, develop into the more rapidly progressive wet type of macular degeneration at any time.

Taking a high-dose formulation of antioxidants and zinc may reduce progression of dry macular degeneration to advanced macular degeneration. The National Eye Institute-sponsored Age-Related Eye Disease Study (AREDS) showed that a daily supplement of 500 milligrams (mg) of vitamin C, 400 international units (IU) of vitamin E, 15 mg of beta carotene (often as vitamin A — up to 25,000 IU), 80 mg of zinc (as zinc oxide) and 2 mg of copper (as cupric oxide) reduced the risk of progressing to moderate or severe vision loss by up to 25 percent.

Life Style & Home Remedies:
Macular degeneration doesn’t affect your side (peripheral) vision and usually doesn’t cause total blindness. But it can rob you of your central vision — which is important for driving, reading and recognizing people’s faces. A low-vision center may be able to assess your visual capabilities and suggest certain optical and household devices that can be helpful for some near-vision tasks. Ask your eye doctor if there are any low-vision centers in your area.

There are ways to cope with impaired vision. Below are a few suggestions:

* Use caution when driving. First, check with your doctor to see if driving is still safe based on your current visual acuity. When you do drive, there are certain situations to avoid. For example, don’t drive at night, in heavy traffic or in bad weather.
* Seek help traveling. Use public transportation or ask family members to help, especially with night driving.
* Travel with others. Contact your local area agency on aging for a list of vans and shuttles, volunteer driving networks or ride shares.
* Get good glasses. Optimize the vision you have with the right glasses, and keep an extra pair in the car.
* Use magnifiers. Large-print books and magazines can help you read more easily.
* View with large type on the Internet. Look for Web sites that use large-sized type fonts, or change the font size on your display.
* Obtain specialized appliances. Some clocks, radios, telephones and other appliances have extra-large numbers.
* Have proper light in your home. This will help with reading and other activities.
* Remove home hazards. Eliminate throw rugs and other possible tripping hazards in your home.
* Ask friends and family members for help. Tell them about your vision problems so that they can help you perform certain tasks and help you recognize people.
* Don’t become socially isolated. A common frustration of people with macular degeneration is the inability to recognize other people and greet them by name. If this happens to you, try asking people you know to say hi and tell you their names when you meet them on the street or in other situations so that you can greet them back.
* Take advantage of online networks. The Internet is a good source for support groups and resources for people with macular degeneration.

Alternative Medicine:
Some people have turned to complementary or alternative therapies, such as bilberry, ginkgo and shark cartilage, in the belief that they can help prevent the progression of macular degeneration.

However, there’s no conclusive evidence that any of these products are effective for macular degeneration, and some may interact with other medications you’re taking. Check with your doctor before taking any dietary or herbal supplement.

Prevention
The Age-Related Eye Disease Study showed that a combination of high-dose beta-carotene, vitamin C, vitamin E, and zinc can reduce the risk of progressing from early to advanced AMD by about 25 percent.  Studies are underway with the goal of reducing lipofuscin accumulation.

Studies have found that Lutein and zeaxanthin (Carotenoid nutrients found in green vegetables such as Kale, Spinach, Collards, spices such as Saffron, and egg yolk) protect against and possibly reverse macular degeneration and Retinitis pigmentosa.  Studies found that antioxidants disrupt the link of two processes that cause macular degeneration and extend the lifetime of irreplaceable photoreceptors and other retinal cells (Lutein is known to have antioxidant properties).

Eating spinach or collard greens five times a week decreases the risk of AMD by 43%

Studies reported in the British Journal of Ophthalmology suggest that while beneficial for those in advanced stages, antioxidant supplements can be counterproductive for people with early stages of AMD as antioxidants can potentially negate the beneficial effects of Omega-3 fats. It has been found that Omega-3 fatty acids can prevent or even halt the progress of degeneration. However, moderation of oily fishes in patients’ diets is suggested as they can lead to a build up of pollutants such fishes may contain.

The following measures may help you avoid macular degeneration:
*Eat foods containing antioxidants.
*Take antioxidant and zinc supplements.
* Eat fish.
*Stop smoking.
*Manage your other diseases.
*Get regular eye exams.
*Screen your vision regularly.

If you have some vision loss because of macular degeneration, your eye doctor can prescribe optical devices called low-vision aids that will help you see better for close-up work. Or your doctor may refer you to a low-vision specialist. In addition, a wide variety of support services and rehabilitation programs are available that may help you adjust your lifestyle.
Impact:
Macular degeneration can advance to legal blindness and inability to drive. It can also result in difficulty or inability to read or see faces.

Adaptive devices can help people read. These include magnifying glasses, special eyeglass lenses, desktop and portable electronic devices, and computer screen readers such as JAWS for Windows.

Composer Josef Tal checks a manuscript (2006)Accessible publishing also aims to provide a variety of fonts and formats for published books to make reading easier. This includes much larger fonts for printed books, patterns to make tracking easier, audiobooks and DAISY books with both text and audio.

Because the peripheral vision is not affected, people with macular degeneration can learn to use their remaining vision to continue most activities. Assistance and resources are available in every country and every state in the U.S. Classes for “independent living” are given and some technology can be obtained from a state department of rehabilitation. You can also search for macular degeneration on the internet and contact one of the non-profit organizations for assistance.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.
Resources:
http://www.mayoclinic.com/health/macular-degeneration/DS00284
http://en.wikipedia.org/wiki/Macular_degeneration

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Scotoma

Definition:A scotoma (Greek: darkness; plural: “scotomas” or “scotomata”) is an area or island of loss or impairment of visual acuity surrounded by a field of normal or relatively well-preserved vision.
Every normal mammalian eye has a scotoma in its field of vision, usually termed its blind spot. This is a location with no photoreceptors, where the retinal ganglion cell axons that comprise the optic nerve exit the retina. This location is called the optic disc. The blindspot does not intrude into consciousness because the corresponding visual field locations of the optic discs in the two eyes differ: The visual signals that are absent in one eye are sent to the cortex by signals from the other eye.

click to see the picture

The presence of the scotoma can be demonstrated subjectively by covering one eye, carefully holding fixation with the open eye, and placing an object (such as your thumb) in the lateral and horizontal visual field, about 15 degrees from fixation (see the blind spot article). The size of the monocular scotoma is surprisingly large – 5×7 deg of visual angle.

It is a common type of vision loss post stroke or traumatic brain injury, a scotoma is an island of visual field loss (blindness) or impaired vision surrounded by relatively normal vision. The eyes of mammals naturally have a small scotoma (blind spot) that we normally don’t detect. However, a wide range of diseases and injuries can cause a pathological scotoma. For example, a scotoma can be a sign of optic nerve damage sustained during a stroke or brain injury. Previously considered untreatable, new research has led to exciting developments in treating scotoma.

Types of Scotoma: After a stroke or brain injury, a scotoma may occur in any shape or size, and it may affect any portion of the visual field. In some cases, a scotoma will include and enlarge the blind spot occurring naturally in a person’s eye. The main types of scotomas include:

* Central scotoma: an area of decreased or lost vision that interferes with central vision (likely to affect daily life)...CLICK & SEE
* Hemianopic scotoma: an area of decreased or lost vision that affects half of the central visual field….CLICK & SEE
* Peripheral scotoma: an area of decreased or lost vision toward the edge of the visual field (less likely to affect daily life)...CLICK & SEE

Symptoms: The main symptom of scotoma is one or more dark, light, or blurred areas in the field of vision. Those affected by visual field loss may also experience a need for greater illumination and contrast when reading, and may have difficulty perceiving certain colors.

click to see

Symptom-producing or pathological scotomata may be due to a wide range of disease processes, affecting either the retina (in particular its most sensitive portion, the macula) or the optic nerve itself. A pathological scotoma may involve any part of the visual field and may be of any shape or size. A scotoma may include and enlarge the normal blind spot. Even a small scotoma that happens to affect central or macular vision will produce a severe visual handicap, whereas a large scotoma in the more peripheral part of a visual field may go unnoticed by the bearer due to the normal reduced visual resolution in the peripheral visual field.

Causes:Common causes of scotomata include demyelinating disease such as multiple sclerosis (retrobulbar neuritis), toxic substances such as methyl alcohol, ethambutol and quinine, nutritional deficiencies, and vascular blockages either in the retina or in the optic nerve. Scintillating scotoma is a common visual aura in migraine.   Less common, but important because sometimes reversible or curable by surgery, are scotomata due to tumors such as those arising from the pituitary gland, which may compress the optic nerve or interfere with its blood supply.

Rarely, scotomata are bilateral. One important variety of bilateral scotoma may occur when a pituitary tumour begins to compress the optic chiasm (as distinct from a single optic nerve) and produces a bi-temporal hemicentral scotomatous hemianopia. This type of visual field defect tends to be very eloquent symptom-wise but often evades early objective diagnosis, as it is more difficult to detect by cursory clinical examination than the classical or text-book bi-temporal peripheral hemianopia and may even elude sophisticated electronic modes of visual field assessment.

In a pregnant woman, scotomata can present as a symptom of severe preeclampsia, a form of pregnancy-induced hypertension.

Click To learn about Detection:->

* Amsler grid…..CLICK & SEE
* Perimetry……..CLICK & SEE
* Visual field test….CLICK & SEE

Treatment: There is no treatment for scotomas.

When they are in the peripheral areas and are not large, they usually do not cause severe problems in general visual functioning. If the scotomas are large or numerous, mobility may be affected.

Central scotomas are another situation entirely. Functional acuity is severely affected and educational adjustments are indicated. Magnification or large print may be indicated. Higher levels of illumination and good contrast in reading materials may also be useful. Color perception may be affected.

Vision loss post stroke or brain injury, which may include scotoma, hemianopia / quadrantanopia, and diffuse field defect / low vision, can drastically impact a person’s quality of life. In the past, these vision defects were considered untreatable. However, cutting-edge research into neuroplasticity, the brain’s ability to grow and heal throughout adulthood, has led to effective methods of vision rehabilitation.

Developed by NovaVision, one such method of vision rehab, called Vision Restoration Therapy, works by stimulating the brain in precise, consistent ways. Studies show that 70 percent of patients who complete Vision Restoration Therapy experience significant improvements in their vision, which improves their quality of life. Today, the therapy is available at premier institutions and medical centers across the United States.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose

Resources:
http://www.helpforvisionloss.com/vision-loss/scotoma/#types
http://en.wikipedia.org/wiki/Scotoma
http://www.spedex.com/resource/documents/veb/scotoma.html

Blindness

Blindness is the condition of lacking visual perception due to physiological or neurological factors.

Various scales have been developed to describe the extent of vision loss and define “blindness.” Total blindness is the complete lack of form and light perception and is clinically recorded as “NLP,” an abbreviation for “no light perception.” Blindness is frequently used to describe severe visual impairment with residual vision. Those described as having only “light perception” can see no more than the ability to tell light from dark. A person with only “light projection” can tell the general direction of a light source.

CLICK & SEE

In order to determine which people may need special assistance because of their visual disabilities, various governmental jurisdictions have formulated more complex definitions referred to as legal blindness.[2] In North America and most of Europe, legal blindness is defined as visual acuity (vision) of 20/200 (6/60) or less in the better eye with best correction possible. This means that a legally blind individual would have to stand 20 feet (6 m) from an object to see it with the same degree of clarity as a normally sighted person could from 200 feet (60 m). In many areas, people with average acuity who nonetheless have a visual field of less than 20 degrees (the norm being 180 degrees) are also classified as being legally blind. Approximately ten percent of those deemed legally blind, by any measure, have no vision. The rest have some vision, from light perception alone to relatively good acuity. Low vision is sometimes used to describe visual acuities from 20/70 to 20/200.

By the 10th Revision of the WHO International Statistical Classification of Diseases, Injuries and Causes of Death, low vision is defined as visual acuity of less than 6/18, but equal to or better than 3/60, or corresponding visual field loss to less than 20 degrees, in the better eye with best possible correction. Blindness is defined as visual acuity of less than 3/60, or corresponding visual field loss to less than 10 degrees, in the better eye with best possible correction.

Legal blindness:
In 1934, the American Medical Association adopted the following definition of blindness:

“Central visual acuity of 20/200 or less in the better eye with corrective glasses or central visual acuity of more than 20/200 if there is a visual field defect in which the peripheral field is contracted to such an extent that the widest diameter of the visual field subtends an angular distance no greater than 20 degrees in the better eye.” The United States Congress included this definition as part of the Aid to the Blind program in the Social Security Act passed in 1935. In 1972, the Aid to the Blind program and two others combined under Title XVI of the Social Security Act to form the Supplemental Security Income program[4] which currently states:

“An individual shall be considered to be blind for purposes of this title if he has central visual acuity of 20/200 or less in the better eye with the use of a correcting lens. An eye which is accompanied by a limitation in the fields of vision such that the widest diameter of the visual field subtends an angle no greater than 20 degrees shall be considered for purposes of the first sentence of this subsection as having a central visual acuity of 20/200 or less. An individual shall also be considered to be blind for purposes of this title if he is blind as defined under a State plan approved under title X or XVI as in effect for October 1972 and received aid under such plan (on the basis of blindness) for December 1973, so long as he is continuously blind as so defined.”
Kuwait is one of many nations that share the same criteria for legal blindness.

Epidemiology:
In 1987, it was estimated that 598,000 people in the United States met the legal definition of blindness. Of this number, 58% were over the age of 65. In 1994-1995, 107.3 million Americans reported legal blindness.

In November 2004 article Magnitude and causes of visual impairment, the WHO estimated that in 2002 there were 161 million (about 2.6% of the world population) visually impaired people in the world, of whom 124 million (about 2%) had low vision and 37 million (about 0.6%) were blind.

Causes of blindness:

Serious visual impairment has a variety of causes:

Diseases

Most visual impairment is caused by disease and malnutrition. According to WHO estimates in 2002, the most common causes of blindness around the world are:

click to see
………………. Artist’s depiction of blind people

People in developing countries are significantly more likely to experience visual impairment as a consequence of treatable or preventable conditions than are their counterparts in the developed world. While vision impairment is most common in people over age 60 across all regions, children in poorer communities are more likely to be affected by blinding diseases than are their more affluent peers.

The link between poverty and treatable visual impairment is most obvious when conducting regional comparisons of cause. Most adult visual impairment in North America and Western Europe is related to age-related macular degeneration and diabetic retinopathy. While both of these conditions are subject to treatment, neither can be cured. Another common cause is retinopathy of prematurity.

In developing countries, wherein people have shorter life expectancies, cataracts and water-borne parasites—both of which can be treated effectively—are most often the culprits. Of the estimated 40 million blind people located around the world, 70–80% can have some or all of their sight restored through treatment.

In developed countries where parasitic diseases are less common and cataract surgery is more available, age-related macular degeneration, glaucoma, and diabetic retinopathy are usually the leading causes of blindness.

Abnormalities and injuries:
Eye injuries, most often occurring in people under 30, are the leading cause of monocular blindness (vision loss in one eye) throughout the United States. Injuries and cataracts affect the eye itself, while abnormalities such as optic nerve hypoplasia affect the nerve bundle that sends signals from the eye to the back of the brain, which can lead to decreased visual acuity.

People with injuries to the occipital lobe of the brain can, despite having undamaged eyes and optic nerves, still be legally or totally blind.

Genetic defects:
People with albinism often suffer from visual impairment to the extent that many are legally blind, though few of them actually cannot see. Leber’s congenital amaurosis can cause total blindness or severe sight loss from birth or early childhood.

Recent advances in mapping the human genome have identified other genetic causes of low vision or blindness. One such example is Bardet-Biedl syndrome.

Poisoning:
A small portion of all cases of blindness are caused by the intake of certain chemicals. A well-known example is methanol , found in methylated spirits, which are sometimes used by alcoholics as a cheap substitute for regular alcoholic beverages.

Willful actions:
Blinding has been used as an act of vengeance and torture in some instances, to deprive a person of a major sense by which they can navigate or interact within the world, act fully independently, and be aware of events surrounding them. An example from the classical realm is Oedipus, who gouges out his own eyes after realizing that he fulfilled the awful prophecy spoken of him.

Blindness prevention:
There exist a number of organizations, such as International Agency for the Prevention of Blindness, ORBIS International, and Seva Foundation, who have developed programs aimed at preventing blindness.

On September 10, 2007, in a 6-year study, researchers, led by John Paul SanGiovanni of the National Eye Institute, Maryland found that Lutein and zeaxanthin (nutrients in eggs, spinach and other green vegetables) protect against blindness (macular degeneration), affecting 1.2 million Americans, mostly after age 65. Lutein and zeaxanthin reduce the risk of AMD (journal Archives of Ophthalmology). Foods considered good sources of the nutrients also include kale, turnip greens, collard greens, romaine lettuce, broccoli, zucchini, corn, garden peas and Brussels sprouts.

Adaptive techniques:

Visually impaired and blind people have devised a number of techniques that allow them to complete daily activities using their remaining senses. These might include the following:

click & see
.A tactile feature on a Canadian banknote.

  • Adaptive computer software that allows people with visual impairments to interact with their computer via audio or screen magnifiers.
  • Adaptive mobile phones that allows people with visual impairments to interact with their phones via audio or screen magnifiers. These mobile phones uses software called Mobile Speak a screen reader from Code Factoryhttp://www.codefactory.es. It provides audio feedback to every functionality on the phone.
  • Adaptations of banknotes so that the value can be determined by touch. For example:
    • In some currencies, such as the euro, and pound sterling,the size of a note increases with its value.
    • Many blanknotes from around the world have a tactile feature to indicate denomination in the upper right corner. This tactile feature is a series of raised dots, but it is not standardBraille
    • It is also possible to fold notes in different ways to assist recognition.
  • Labeling and tagging clothing and other personal items
  • Placing different types of food at different positions on a dinner plate
  • Marking controls of household appliances

Most people, once they have been visually impaired for long enough, devise their own adaptive strategies in all areas of personal and professional management.

For corrective surgery of blindness, see acquired vision.

Tools:
Designers, both visually impaired and sighted, have developed a number of tools for use by blind people.

Mobility:
Many people with serious visual impairments can travel independently assisted by tactile paving and/or using a white cane with a red tip – the international symbol of blindness.

A long cane is used to extend the user’s range of touch sensation, swung in a low sweeping motion across the intended path of travel to detect obstacles. However, some visually impaired persons do not carry these kinds of canes, opting instead for the shorter, lighter identification (ID) cane. Still others require a support cane. The choice depends on the individual’s vision, motivation, and other factors.

……………………………..click & see
………………………...Watch for the blind

Each of these is painted white for maximum visibility, and to denote visual impairment on the part of the user. In addition to making rules about who can and cannot use a cane, some governments mandate the right-of-way be given to users of white canes or guide dogs.

A small number of people employ guide dogs. Although the dogs can be trained to navigate various obstacles, they are not capable of interpreting street signs. The human half of the guide dog team does the directing, based upon skills acquired through previous mobility training. The handler might be likened to an aircraft’s navigator, who must know how to get from one place to another, and the dog is the pilot, who gets them there safely.

Orientation and Mobility Specialist are professionals who are specifically trained to teach people with visual impairments how to travel safely, confidently, and independently in the home and the community.

Reading and magnification:
Most blind and visually impaired people read print, either of a regular size or enlarged through the use of magnification devices. A variety of magnifying glasses, some of which are handheld, and some of which rest on desktops, can make reading easier for those with decreased visual acuity.

The rest read Braille (or the infrequently used Moon type), or rely on talking books and readers or reading machines. They use computers with special hardware such as scanners and refreshable Braille displays as well as software written specifically for the blind, like optical character recognition applications and screen reading software.

Some people access these materials through agencies for the blind, such as the National Library Service for the Blind and Physically Handicapped in the United States, the National Library for the Blind or the RNIB in the United Kingdom.

Closed-circuit televisions, equipment that enlarges and contrasts textual items, are a more high-tech alternative to traditional magnification devices. So too are modern web browsers, which can increase the size of text on some web pages through browser controls or through user-controlled style sheets.
Computers:
Access technology such as Freedom Scientific’s JAWS for Windows screen reading software enable the blind to use mainstream computer applications. Most legally blind people (70% of them across all ages, according to the Seattle Lighthouse for the Blind) do not use computers. Only a small fraction of this population, when compared to the sighted community, have Internet access. This bleak outlook is changing, however, as availability of assistive technology increases, accompanied by concerted efforts to ensure the accessibility of information technology to all potential users, including the blind. Linux distributions (as Live CDs) for the blind include Oralux and Adriane Knoppix, the latter developed in part by Adriane Knopper who has a visual impairment. The Macintosh OS also comes with a built-in screen reader, called VoiceOver. Later versions of Microsoft Windows include an Accessibility Wizard & Magnifier for those with partial vision.

The movement towards greater web accessibility is opening a far wider number of websites to adaptive technology, making the web a more inviting place for visually impaired surfers.

Experimental approaches in sensory substitution are beginning to provide access to arbitrary live views from a camera.

Other aids
People may use talking thermometers, enlarged or marked oven dials, talking watches, talking clocks, talking scales, talking calculators, talking compasses and other talking equipment.

Social attitudes towards blindness:
The story of the Blind Men and an Elephant uses blindness as a symbol of limited perception and perspective. Stories such as The Cricket on the Hearth by Charles Dickens provided yet another view of blindness, wherein those affected by it were ignorant of their surroundings and easily deceived. H. G. Wells’ story The Country of the Blind explores what would happen if a sighted man found himself trapped in a country of blind people to emphasise societies atttitude to blind people by turning the situation on its head.

The authors of modern educational materials (see: blindness and education for further reading on that subject), as well as those treating blindness in literature, have worked to paint a different picture of blind people as three-dimensional individuals with a range of abilities, talents, and even character flaws.

The Moche people of ancient Peru depicted the blind in their ceramics.

Young mammals:
Statements that this or that species of mammals are “born blind” refers to them being born with their eyes closed and their eyelids fused together; the eyes open later. One example is the rabbit.

In humans the eyelids are fused for a while before birth, but open again before the normal birth time, but very premature babies are sometimes born with their eyes fused shut, and opening later.

Source: http://en.wikipedia.org/wiki/Blindness

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Glaucoma

normal tension glaucom is a serious eye condition that involves an elevation in pressure inside the eye. Increased pressure results from a buildup of excess fluid in the eye. Glaucoma is a dangerous eye condition because it frequently progresses without obvious symptoms. This is why it is frequently referred to as “the sneak thief of sight.”

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Types of Glaucoma
There are several types of glaucoma, for example, congenital, primary, secondary, and normal tension glaucoma. Congenital glaucoma appears in young people; secondary glaucoma is the result of injury or trauma. There are two types of primary glaucoma most frequently associated with aging: acute or closed angle glaucoma, and chronic or open angle glaucoma. The Reference Section at the end of this Fact Sheet provides resources for learning more about each of the types of glaucoma.

Regardless of the type, glaucoma can impair vision by creating pressure that damages the optic nerve, The “cable” of nerve fibers that transmits messages about what we see from the eye to the brain.

It is important to recall the structure of the eye and how it works to understand the dangers posed by glaucoma. Glaucoma can cause damage when the aqueous humor, a fluid that inflates the front of the eye and circulates in a chamber called the anterior chamber, enters the eye but cannot drain properly from the eye. Elevated pressure inside the eye, in turn, can cause damage to the optic nerve or the blood vessels in the eye that nourish the optic nerve. The Human Eye, Its Functions, and Visual Impairment explains how the eye works. When glaucoma begins to affect a person’s vision, the first problems are with peripheral vision, or what can be seen at the sides of the visual field, rather than in the center. If glaucoma progresses, it can destroy all peripheral vision, then impair central vision, and lead to total blindness. Treatments for glaucoma are aimed at bringing down the pressure in the eye to a level that is low enough to prevent harm to the optic nerve. Once the optic nerve is damaged from glaucoma, lowering the pressure in the eye only prevents further damage to the nerve. Damage already done to the optic nerve cannot be reversed.

Diagnosing Glaucoma
When a person receives a diagnosis of glaucoma, it means a diagnosis of a life-long condition. However, early detection of glaucoma, appropriate and ongoing treatment, and the availability of specialized low vision and vision rehabilitation services if vision should become impaired, means that people who have glaucoma can live productive and satisfying lives.

A pressure check for glaucoma should be a routine part of every eye examination at least by the age of 35. A visual field test can also detect glaucoma by indicating the loss of peripheral vision.

How Common Is Glaucoma?
According to the Glaucoma Research Foundation glaucoma affects more than 3 million Americans. It is also reported that glaucoma is the third leading cause of legal blindness in Caucasians, and the leading cause of blindness in African Americans. Although anyone can get glaucoma, some people are at higher risk. Those at risk include:

1.People over the age of 60.

2.African Americans over the age of 40.

3.People with a family history of glaucoma.

Treatment:
Untreated glaucoma can lead to blindness. Eye drops or tablets may be prescribed to reduce fluid production and consequently reduce pressure in the eye.

Laser or surgical treatment may be used when medical treatment isn’t sufficiently effective.

Screening:
People over the age of 40 are advised to have their eyes tested every two years to check for signs of glaucoma. If glaucoma is identified early enough, treatment can be given to prevent further damage and reduce the risk of blindness.

These tests are available at your local optician and should include:

•examination of the optic disc
•measurement of the pressure in the eye
•checking of peripheral vision (by looking for a sequence of spots of light on a screen).
Retaining Independence
People who have experienced vision loss from glaucoma can retain their independence, productivity, and quality of life by learning to use specialized devices and techniques to carry out their daily activities. These may include using special lenses that can help those who have remaining sight make the best use of available vision, and using specialized techniques that enable people to manage home and work responsibilities, travel using mass transportation, and carry out a host of other activities.

Click to learn more about Acute Glaucoma  and its Ayurvedic Remedy

Click to see->:6 Sure-Fire Tips to Prevent Glaucoma Naturally

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:

http://www.bbc.co.uk/health/physical_health/conditions/glaucoma1.shtml

:www.afb.org

http://www.dwueye.com/glaucoma-eye-care.html

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