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Macular degeneration affects your central vision, but not your peripheral vision. It does not cause total blindness. In spite of everything, the loss of clear central vision will affect your reading, driving, recognizing people's faces and doing detail work.  As you, get older the condition tends develops and worsen as age progresses.  Macular degeneration is the main cause of severe vision loss in people age 60 and older.

The damage caused by macular degeneration can't be reversed, but early detection and treatment may help reduce the degree of vision loss.

Macular degeneration occurs in two types:

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Dry macular degeneration -
Most people with macular degeneration have the dry form. In fact, macular degeneration usually starts out as the dry form. The dry form may initially affect only one eye but, in most cases, both eyes eventually become involved. Dry macular degeneration occurs when the RPE cells begin to atrophy and lose their pigment. The normally uniform reddish color of the macula takes on a mottled appearance because of the patchy loss of pigment. Drusen, which look like yellow dots, are fatty-like deposits that appear under the light-sensing cells in the retina.

Dry macular degeneration is the result of a deterioration of the RPE brought on by aging. You may notice little or no change in your vision. Many people who have received a diagnosis of early-stage dry macular degeneration may not be bothered with symptoms, such as blurred eyesight, unless they live to a very old age. However, as the drusen and mottled pigmentation continue to develop, your vision may deteriorate. Thinning of the RPE may progress to a point where this protective layer of the retina disappears. This affects the overlying cones and rods and may result in complete loss of your central vision.

Wet macular degeneration -
The wet form accounts for about 15 percent of all cases, but it is responsible for most of the severe vision loss that people with macular degeneration experience. If you develop wet macular degeneration in one eye, your odds of getting it in the other eye increase greatly. Almost everyone with the wet form of the disease started out with the dry form.

Wet macular degeneration develops when new blood vessels grow from the choroid underneath the macular portion of the retina. These new vessels are called choroidal neovascularizations (CNVs). These vessels leak fluid or blood, which is why it's called wet macular degeneration. This causes your central vision to blur. Eyes with the wet form of macular degeneration usually show signs of the dry form, that is, drusen and mottled pigmentation of the retina. In addition, what should be straight lines in your sight become wavy or crooked, and blank spots appear in your field of vision.

Much like the dry form of macular degeneration, a breakdown in the waste removal system may be what is causing the abnormal growth of blood vessels. When the waste from the cones and rods is not disposed of and begins to accumulate, sufficient flow of nutrients to the macula is interrupted. The abnormal growth of blood vessels may be a response to this interruption in the flow of nutrients. The mechanism that triggers the development of new blood vessels is unclear, and it remains the subject of scientific study. Whatever the cause of the abnormal growth, the result is a disruption in the nutrition of the macula, and without enough nutrients, healthy tissue in the macula begins to deteriorate.

With the wet form of macular degeneration, sight loss is usually rapid and severe, often deteriorating to 20/200 vision or worse, which is considered legally blind. This means that what someone with normal vision can see from 200 feet away, a person with 20/200 vision can see only from 20 feet away.

Another form of wet macular degeneration, is called retinal pigment epithelial detachment

This occurs when fluid leaks from the choroid under the RPE even though it appears that no abnormal blood vessels have started to grow. The fluid collects under the retinal pigment epithelium, causing what looks like a blister or a bump under the macula.

This kind of macular degeneration causes similar symptoms to typical wet macular degeneration, but your vision can remain relatively stable for many months or even years before it deteriorates. Eventually, however, this form of macular degeneration usually progresses to the more common wet form of macular degeneration that includes newly growing abnormal blood vessels.

Symptoms

Macular degeneration usually develops gradually and painlessly. The symptoms of the disease may differ, depending on which of the two types of macular degeneration you have: dry or wet.

Dry macular degeneration

The symptoms include:

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The need for bright light when reading or doing close work

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Difficulty adapting to low levels of light

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Blurriness of printed words

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A decrease in the intensity or brightness of colors

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Encountering problem recognizing faces

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Slow increase in the lack of clarity of your overall vision

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Blurred or blind spot in the center of your visual area combined with a intense drop in your central vision acuity

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Symptoms Include:

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Visual distortions, such as straight lines appearing wavy or crooked

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Objects appearing smaller or farther away than they should

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A decline in or loss of central vision

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Central blurry spot

In either form of macular degeneration, your vision may falter in one eye while the other has no problem 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
some people with macular degeneration may experience visual hallucinations, as their vision loss gets worse.
These hallucinations may include:

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Unusual patterns

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Geometric figures

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Animals

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Grotesque-appearing faces

While these hallucinations may be frightening, they are not a sign of mental illness. These hallucinations are so common that there is a name for this occurrence called, “The Charles Bonnet syndrome.”

Causes

Researchers do not know the exact causes of macular degeneration, but they have identified some contributing factors,
including:

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Age

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Family history of macular degeneration

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Race:
Macular degeneration is more common in whites than it is in other groups, especially after age 75.

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Sex:
Women are more likely than men are to develop macular degeneration.  

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Cigarette smoking:
Exposure to cigarette smoke doubles your risk of macular degeneration. Cigarette smoking is the most preventable cause of macular degeneration.

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Obesity

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Light-colored eyes:
People with light-colored eyes appear to be at greater risk than do those with darker eyes.

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Exposure to sunlight:
It is possible 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.

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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.

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Cardiovascular diseases:
These include high blood pressure, stroke, heart attack and coronary artery disease with chest pain (angina).

Diagnosis

To determine whether you have macular degeneration, you will undergo a thorough 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.

Other diagnostic tests may include:

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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 the existence of abnormal blood vessels in your macula that may not be visible or recognizable during a standard examination.

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Indocyanine green angiography:
Instead of fluorescein, a dye called indocyanine green (ICG) is used. This test provides information that complements the findings obtained through fluorescein angiography.

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Optical coherence tomography (OCT):
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.

Genetic screening

Even though genetic abnormalities have been identified in some people with macular degeneration, genetic screening tests are not currently being used to diagnose the disorder, though they may be used to assess early risk in the future.

Treatment

Some treatment options are available for wet macular degeneration. But the success of the treatment — stopping further progress of the disease — depends on the location and the extent of the abnormal blood vessels, or choroidal neovascularization (CNV). The damage already caused by macular degeneration cannot be reversed. The sooner CNV is detected, the better your chances of treatment preserving what's left of your central vision.

Wet macular degeneration treatments are p
rocedures for wet macular degeneration, all of which can be done on an outpatient basis, include:

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Photocoagulation:
In hotocoagulation your doctor uses a high-energy laser beam to create small burns in areas with abnormal blood vessels. The process can seal off and destroy the CNV that has developed under your macula. It can prevent further damage to the macula and halt continued vision loss.

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Photodynamic therapy (PDT):
This therapy is primarily used for treating CNV that is located directly under the fovea. The fovea lies at the center of your macula and in healthy eyes provides your sharpest vision. If conventional hot-laser surgery were used at this location, it would destroy all central vision. PDT increases your chances of preserving some of that vision. It will not bring back any of the vision you have lost, but it may halt the loss of your vision or at least slow down the rate of vision loss.