Macular Degeneration

1) WHAT IS AGE-RELATED MACULAR DEGENERATION (AMD)?

 

Age-related Macular Degeneration (AMD) is a very common eye disease. It is the leading cause of blindness in the Western World and it affects more people than either cataracts or glaucoma.  More than 100 million people worldwide suffer from AMD.  AMD is a disease associated with age: over 25% of Americans 65+ have the disease; and this increases to over 30% among those who are 70+. 

 

AMD affects the center-most region of the retina, called the macula. This part of the eye is responsible for discrimination of fine detail, reading, and color.​

  • AMD is the leading cause of blindness in the Western World, and (prior to the Amerivision therapy), there has been no therapy that can restore or improve eyesight to patients blinded or visually impaired by AMD.  

  • Approximately 10MM Americans, 1.2MM Canadians, 1.5 MM Australians, 16MM Europeans, and 40MM Chinese have this disease.

  • AMD Causes $184 Billion in lost productivity each year

  • 90% is the “Dry Form” and 10% the “Wet” Form.

 

There are two forms of AMD: “Dry” AMD and “Wet” AMD. 90 percent of people with AMD have the Dry or “atrophic” form, which is due to a progressive loss of support cells and build up of waste material. Underlying causes are generally believed to be an impairment in the circulation and a process called “oxidative stress”, which results in the buildup of waste materials. Wet or “exudative” AMD is caused by leakage and bleeding from abnormal blood vessels building up under and within the retina.  The wet form is less common, affecting 10 percent of people with AMD, but causes the most rapid loss of vision.

 

(2) WHAT CAUSES AMD?

 

Age-related Macular Degeneration (AMD) can occur when there is an impairment in blood circulation to the center part of the retina. With circulation impaired, AMD results in the deterioration of various tissues in the region of the macula, the central, most sensitive light sensing area of the retina responsible for detailed central vision.  First, poor circulation can cause a gradual loss of the retinal pigment epithelium (RPE) The retinal pigment epithelium (RPE) is the support cell complex for the photosensitive rod and cone cells which make up the light-sensing retina. These cells photochemically process images that send signals to the parts of the brain responsible for sight. The RPE is the first to be affected by the circulation impairment.

 

Second, once affected by poor circulation, the RPE cannot efficiently assist the rods and cones in removing the metabolic and photochemical response by-products, which are common during cellular function. Yellowish-colored subretinal deposits called “drusen” form when extracellular by-products are not carried away by blood circulating through the eye. As a result, the photoreceptor cells in the macula enter a dormant, toxic state and do not respond to light.  If normal retinal cellular metabolism is not restored, the cells eventually die and visual acuity is permanently lost. Further, this excess waste material building up (drusen) can also cause the macula to become distorted and separated from the retinal wall, causing vision distortion. And, finally the neural pathway from the optic nerve to the brain which carries the light signal that gets converted into an image is also impaired. Together, this can devastate vision.

(3) WHAT ARE THE EFFECTS OF AMD?
 

The progressive damage from AMD can cause a gradual loss in vision, visual distortion, and a loss of color vision. In the early stages it may only affect the ability to read small print. As it progresses, vision may reduce to a level which affects the ability to drive, read larger print, discriminate color and recognize faces. Depending on the type of AMD, there may also be distortion of images and more rapid loss of central vision. Over time, the damage caused by AMD may lead to partial or even total loss of central vision.

 

(4) WHAT IS THE DIFFERENCE BETWEEN DRY AND WET AMD?

 

Dry AMD, called “atrophic” macular degeneration, represents about 90% of the total cases of macular degeneration.  Dry AMD occurs when the light-sensitive cells in the macula slowly break down, due to a lack of blood flow, gradually blurring central vision in the affected eye. As dry AMD gets worse, patients may see a blurred spot in their center field of vision. Over time, as less and less of the macula functions, central vision is gradually lost in the affected eye.

The most common symptom of dry AMD is blurred vision. Patients may have difficulty recognizing faces; and patients may need more light for reading and other tasks. Dry AMD generally affects both eyes, but vision can be lost in one eye while the other eye seems unaffected. Patients will often notice a dark spot in the central vision. Dry AMD will often progress to intermediate AMD; then progress to advanced AMD. In the most extreme cases, the patient may progress to “Wet AMD”.  Progression time varies by patient.

 

Wet AMD, called “exudative” AMD, is found in about 10% of all AMD patients and is a progression from the Dry stages.  (Wet AMD can follow in some patients after they have experienced Dry macular degeneration.) Wet AMD occurs when new abnormal blood vessels behind the retina start to grow under the macula, to replace the atrophied blood vessels that are no longer properly serving the retina. These new blood vessels tend to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its normal place at the back of the eye. Damage to the macula can then occur rapidly. Vision becomes distorted, colors fade, and dark spots occur in the central vision area and sometimes other parts of the field of vision.

 

An early symptom of wet AMD is that straight lines appear wavy. If a patient notices this condition or other changes to their vision, they should contact their eye care professional at once. They will need a comprehensive dilated eye exam.  Waiting to take therapeutic measure until after the Dry stages is not recommended.  Early therapy may halt the diseases progression from Dry to Wet.

With wet AMD, loss of central vision can occur quickly. Wet AMD is also known as advanced AMD. It does not have stages like dry AMD. Wet AMD is not considered reversible, although, with drugs or laser it can be stabilized in some patients.

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