The eye is very similar to a camera. Both are optical systems containing lenses that focus light rays o­n films; the film in the eye is called the retina. The retina is a tissue that contains many layers of cells, including photoreceptors (the cells that absorb light energy and convert it into electrical signals) and nerve cells, which carry images to the brain via the optic nerve.

The macula is the central portion of the retina. While it is small, measuring o­nly 3 to 4 millimeters in diameter, it is vitally important in terms of quality of life, as it is responsible for o­ne’s central vision. Central, or straight-ahead, vision is important for facial recognition, reading and driving, and so o­n.

The macula is where light-sensitive cells are concentrated and where finely focused vision occurs. This area can be affected by a number of conditions, including diabetes, stroke, inflammation and aging. When the macula is affected by aging, the term age-related macular degeneration is used.

The fovea is the center of the macula. This tiny area is responsible for very sharp vision because it contains a high concentration of photoreceptor cells called cones.

Once light has traveled through the various layers of the eye, it is focused onto the retina, where photoreceptor cells absorb the light rays. In these cells, the energy from the light rays is converted into electrical impulses. Photoreceptors send their energy to other retinal cells. Eventually, the energy leaves the eye in the form of an electrical impulse destined to reach the brain, where it will be converted into images.

There are two types of photoreceptor cells: rods and cones. In the macula, the predominant type of cell is the cone. Cones are important in both color vision and fine vision, and they function in bright light levels.

These light-sensitive cells, being very metabolically active, require a complex infrastructure to support their normal function. Part of this infrastructure involves three different tissues: the retinal pigment epithelium (RPE), Bruch’s membrane and the choroid.

The retinal pigment epithelium consists of a single layer of pigmented cells. These cells, found just below the photoreceptors, are responsible for the nutritional and metabolic support of the light-sensitive cells. The RPE cells sit o­n a membrane called Bruch’s membrane, which separates the RPE cells from the choroid − the blood-vessel layer that brings oxygen and nutrients to the deeper layers of the retina.

The conversion of light rays into electrical impulses requires a series of physical and chemical reactions that rapidly deplete the chemicals in the photoreceptors. Because these reactions occur many times a minute, the ends of the light-sensitive cells are broken down and regenerated many times a day. The RPE cells are responsible for breaking down and regenerating the ends of the photoreceptors.

Macular degeneration is a painless disease of the macula that causes blurring, distortion or loss of central vision. It is caused by wear and tear on the small cells in the macula. It can interfere with many activities in life, including reading, sewing, driving and watching television. Patients with this condition are at risk of becoming socially isolated and depressed and are at much higher risk for falls.

In developed nations, macular degeneration is the leading cause of visual loss in people over the age of 60. It is estimated that over 40 million people are affected by it.

One of the first signs of aging of the retina is the formation of drusen. These are sometimes referred to as “aging spots” in the back of the eye. Drusen are whitish yellow deposits that occur at the level of Bruch’s membrane. They are thought to represent the accumulation of the breakdown products from photoreceptor regeneration. While the vast majority of people over the age of 50 have a few drusen, patients with the dry form of macular degeneration have many of these deposits. Having a few drusen does not necessarily mean that you have macular degeneration.

Broadly speaking, there are two types of macular regeneration: dry and wet. The dry type is much more common, accounting for over 80% of cases. The wet type is more frequently associated with vision loss, distortion and blindness. There are ways to prevent progression of the disease, no matter which type you have.

Macular degeneration is a disease of the deeper retinal layers, affecting the photoreceptors, the RPE cells, Bruch’s membrane and the choroid. The dry form occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As it gets worse, you may see a blurred spot in the center of your vision. As less of the macula functions, you gradually lose central vision in the affected eye.

The most common symptom of dry macular degeneration is slightly blurred vision. You may have difficulty recognizing faces. You may need more light for reading and other tasks. Dry macular degeneration generally affects both eyes, but vision can be lost in one eye while the other seems unaffected.

Dry macular degeneration has There are three stages:

1. Early stage. People with early macular degeneration have either several small drusen or a few medium-sized drusen. At this stage, there are generally no symptoms and no vision loss.

2. Intermediate stage. People with intermediate macular degeneration have either many medium-sized drusen or one or more large drusen. Some people see a blurred spot or central haziness in the center of their vision.

3. Advanced stage. In addition to drusen, people with advanced dry macular degeneration have a breakdown of photoreceptors and RPE cells. On examination, your eye doctor will notice a loss of RPE cells. Sometimes a visible excess of RPE cells will be noted, as remaining RPE cells may work overtime, trying to replicate themselves. These changes can cause the central blurred spot to get larger and darker. People with this type often have difficulty reading or recognizing faces. At its most advanced stage, called "geographic atrophy", patients can become legally blind and have little remaining central vision.

How well someone does in the real world with dry macular degeneration depends on a variety of factors. One of the most important is whether both eyes are affected. Most people who have the condition in only one eye do not notice significant changes in their vision, as the other eye works well enough for reading, driving and facial recognition.

Yes, the dry form of macular degeneration can cause visual loss. Generally, the degree of visual loss is mild. However, in its advanced stages − especially when geographic atrophy occurs − patients can develop significant visual loss. The dry type can also convert to the wet type.

Wet macular degeneration is diagnosed when either blood or fluid is present. They originate from a new blood vessel that grows at the back of the eye, which is fragile and can bleed. Researchers do not know exactly why new blood vessels arise. The bleeding, the fluid or the vessels themselves can block light rays from reaching the back of the eye or they can interfere with photoreceptor or RPE function.

The technical term for new blood vessels in the back of the eye is choroidal neovascularization (“neo” means new, “vascular” means vessels, and “choroidal” refers to the layer from which the blood vessels arise). You may hear your eye doctor use this term.

The vast majority of people who develop the wet type of macular degeneration lose significant central vision.

Those with wet macular degeneration typically notice enlargement of a central spot in their vision. This spot can vary from a small dot to a much larger one (many of my patients say that when they look at someone’s face, they see ears and hair, but the rest of the face is simply not there). Many patients also notice distortion − typically, telephone poles seem curved, door frames have bends and facial features appear abnormally large or small. If you notice enlargement of a central spot or a new distortion, seek immediate medical attention; treatments are available for the wet form of the disease that could prevent further visual loss.

When polled, most people rate going blind as one of their greatest fears. The good news is that those with macular degeneration do not go blind in the sense of being “black-blind” (the loss of the ability to see anything, including light).

Macular degeneration can, however, cause “legal” blindness. In most developed countries, this is defined as 20/200 vision or worse in the better-seeing eye (if you have 20/200 vision, it means that what a normally sighted person sees 200 feet away, you can see only at a distance of 20 feet).

There are two types of advanced macular degeneration: geographic atrophy and the wet form. The early form of dry macular degeneration can convert to either of these two types. Patients who have the advanced form in one eye have a high risk for developing the advanced form in the other eye.

Most patients who have wet macular degeneration had the dry form first. The presence of dry macular degeneration predicts the likelihood of progressing to either geographic atrophy or wet macular degeneration. The risk of progression can be as low as 1% and as high as 50% over a five-year period. Unfortunately, there is no way to tell if or when the dry form will turn into the wet form.

A number of factors can increase one’s risk of developing macular degeneration. These include:

• Age. Increasing age is a risk factor, as most patients with macular degeneration are over the age of 50. A large study conducted in Wisconsin revealed that nearly 30% of those over 75 years of age had some evidence of this condition.
  
• Smoking. Active smokers are at much higher risk for developing this condition. Pooled results from three major studies have estimated that active smokers are three times more likely to develop macular degeneration than those who have never smoked.
  
• Obesity. Recent research from Harvard University has suggested a link between obesity and the progression of dry macular degeneration to its more advanced forms.
  
• Race. People who are lightly pigmented are much more likely to develop macular degeneration than those who are more heavily pigmented. It is believed that pigmentation of the iris and choroid provide a protective effect.
  
• Family history. People with a family history of macular degeneration are known to be at higher risk for getting the disease.

Screening for macular degeneration includes:

An Amsler grid is a test that can be used in the doctor’s office or at home to monitor changes in central vision. Each eye is tested independently; cover one eye, and look at the central dot with the other. Ask the following questions:

In some cases, a physician may want to perform angiography − commonly referred to as a "dye study" − to evaluate circulation at the back of the eye. In this test, a vegetable-based dye is injected into your arm, and pictures are taken as the dye passes through the blood vessels in your retina. This test can confirm the presence of the wet type of macular degeneration and classifies it as to type, allowing for planning potential treatments.

An angiogram can help determine the nature of leakage from a new blood vessel. Classic vessels fill early in the dye study, are well delineated and sometimes appear “lacy” in nature. These types of lesions leak dye in the late phases of the study.

Occult lesions are everything that classic ones are not. The following are consistent with new occult blood vessels:

Classic lesions located away from the center of vision have been proven to respond well to thermal laser surgery ("hot laser" treatment). Most eye doctors will offer this if the new blood vessels are located away from the center of vision and are classic in terms of their leakage pattern. Photodynamic therapy is offered by most eye doctors for both classic and occult lesions if they are located beneath the fovea.

Up to 20% of patients with macular degeneration develop visual hallucinations − a phenomenon called “Charles Bonnet Syndrome.” The hallucinations are well formed and commonly look like objects, animals or people who are not there. The hallmark of Charles Bonnet syndrome is that patients know the hallucinations are not real. While no one knows for sure why these phenomena occur, they are thought to arise from excessive nerve firing in response to loss of sensory input. In some ways, they are similar to “phantom limb syndrome” − both are associated with nerves “playing tricks” and firing when sensory input is lost.

If you have early macular degeneration, you likely do not need treatment, as the risk of progressing to the more advanced type is minimal. You should, however, periodically check for any changes on an Amsler grid. If changes are noted, seek medical attention right away.

If you have intermediate macular degeneration, your doctor will likely put you on high doses of vitamins. This is because of the findings of the Age-Related Eye Disease Study (AREDS), a National Eye Institute-sponsored clinical trial. This study showed that patients with intermediate dry macular degeneration who were taking a specific high-dose formulation of antioxidants and zinc were significantly less likely to progress to advanced macular degeneration than those taking a placebo.

Unfortunately, once dry macular degeneration reaches the advanced stage, no form of treatment can prevent vision loss. There are, however, various academic research labs and companies that are working on new treatments for the advanced form of dry macular degeneration.

The supplements consisted of vitamin C (500 mg), vitamin E (400 IU), zinc (80 mg), beta-carotene (15 mg) and copper (2 mg as cupric oxide).

AREDS-strength vitamins are available at most pharmacies, retailers and grocery stores. Common brand names include Ocuvite Preservision, Vitalux, and AREDS I-CAPS.

AREDS-strength vitamins are recommended for those who are at high risk for developing advanced macular degeneration.

You are at high risk for developing advanced macular degeneration if you have either:

If you have early macular degeneration, you do not need to take vitamin supplements, but you should have a periodic examination to rule out progression to the more advanced types. If the condition does progress, your doctor may consider prescribing vitamin supplements. Other things that you can do include stopping smoking if you are a smoker; eating a diet rich in salads, fruits, vegetables (especially green leafy ones and orange peppers), nuts and fish; and maintaining an ideal body weight.

No, if you just have a family history of macular degeneration but no signs of the disease, you do not need to take AREDS-strength vitamins. To make sure that you do not have any signs of this condition, you should have a dilated eye examination by a well-trained eye care professional. You should also eat a diet rich in salads, fruits, vegetables, nuts and fish. If you are a smoker - you should stop.

No, the levels of vitamins and minerals used in the AREDS are difficult to achieve from diet alone. But it is recommended that all patients, regardless of their stage of macular degeneration, eat a diet rich in antioxidants. Antioxidants, compounds that protect retinal cells from light-induced damage, are found in many fruits and vegetables.

No, the levels of antioxidants and zinc used in the AREDS are much higher than those in most daily multivitamins. If you are already taking daily multivitamins and your eye doctor suggests you take AREDS-strength vitamins, be sure to review all the vitamins you take with your primary-care doctor or internist before you begin. Do not simply substitute one for the other, as multivitamins may contain important vitamins not found in the AREDS-strength vitamins. For example, people with osteoporosis need to receive high doses of vitamin D; AREDS-strength vitamins do not contain vitamin D.

There are currently three treatments used in select cases of wet macular degeneration:

Angiogenesis is the creation of new blood vessels; anti-angiogenesis refers to suppressing their formation. Many new anti-angiogenic molecules are currently being explored as potential treatments for wet macular degeneration. These include drugs that are injected into the jelly portion of the eye or into the space around the eye.

This procedure uses a laser beam to destroy new blood vessels. The patient sits at a slit lamp (a machine similar to the kind used to examine the eye), and a contact lens is placed on the eye’s surface. A laser beam is then focused on the new blood vessel and it is cauterized. Because the new blood vessel is deep in the retinal tissue and the laser has to move through the overlying retina to reach it, some of the retinal tissue will be damaged by this procedure. In some ways, one can think of the retinal damage from the laser as “collateral damage.”

This type of surgery is performed in an eye doctor’s office or a clinic. Before the procedure, eye drops are instilled to freeze the eye. A small contact lens is placed on the eye to help focus the laser energy. The laser energy is delivered in a series of applications that appear as very bright lights to the patient. The procedure is generally painless. Afterwards, patients are free to go home and resume their regular activities.

Large clinical trials have proven the safety and efficacy of this treatment for managing wet macular degeneration. It is used if the blood vessel is well defined on an angiogram and is located away from the center of vision.

New blood vessels located under the fovea (that is, under the center of the retina) are not treated with thermal laser surgery because it will cause immediate visual loss by destroying overlying healthy tissue. You may hear or read the terms juxtafoveal and extrafoveal, which refer to the location of a new blood vessel. Lesions that are more than 200 microns away from the center of the fovea are said to be extrafoveal. Those that are greater than 1 micron but less than 199 microns away are said to be juxtafoveal. When a blood vessel is juxtafoveal, thermal laser may be offered. However, some may be too close to the fovea, and the risk of thermal laser surgery may be too high.

Thermal laser surgery causes a permanent scar on the retina. Following this treatment, all patients are left with a permanent blind spot. Laser surgery can reduce vision in some cases. Additionally, the risk of developing a recurrent blood vessel is high following laser surgery, and repeated applications of the laser may be necessary.

PDT consists of a two-step process: an infusion of a drug (in the form of a dye) over a 10-minute period, followed by light activation of the dye using a "cold" laser.

In this procedure, a drug called Verteporfin (Visudyne^®) is injected into your arm, not the eye. Verteporfin travels through the body’s blood-vessel system. When it pools in the new blood vessel responsible for wet macular degeneration, the eye surgeon shines a light into the eye for 83 seconds. The light activates the drug, which closes off the new blood vessel by causing a series of chemical reactions that result in the formation of a clot. Clinical trials have shown that this treatment leads to a slower rate of vision decline and improves one’s chances for stabilizing vision. While visual improvement is the exception rather than the rule, up to 15% of those with wet macular degeneration find that their vision is improved with this treatment.

Unlike laser surgery, this treatment does not destroy healthy surrounding tissue. Because the drug is activated by light, you must avoid exposing your skin or eyes to direct sunlight or bright indoor light for two to five days after treatment. Photodynamic therapy is relatively painless. It takes about 20 minutes and can be performed in a doctor’s office.

Photodynamic therapy with Visudyne^® is the only drug-based method that has received FDA approval for the treatment of wet macular degeneration. Although many patients benefit from this treatment, it is important to note that it is not a cure.

In clinical trials, patients needed three to seven treatments over a three-year period to achieve complete closure of the new blood vessel. Typically, a patient is treated and then reviewed three months later. The three-month assessment includes a dilated examination and a dye study to evaluate the response to the treatment. If the blood vessel continues to ooze fluid, additional treatment will likely be offered.

Haziness and blurring of vision occur in nearly 20% of patients. Between 1% and 4% of patients treated with PDT develop severe vision loss. This can be permanent. Flashing lights can also occur. Between 2% and 10% of patients develop low back pain at the time of infusion.

Not all cases of wet macular degeneration are treatable with laser, PDT or injection of an anti-angiogenic drug. Your doctor may not want to subject you to a treatment that has little benefit but significant risk. Your doctor is in the best position to assess whether treatments are a realistic option for you.

If you have lost some sight from macular degeneration, don’t be afraid to use your eyes to do the things you want to do. Feel free to continue to read, watch TV and perform other routine activities. Normal use of your eyes will not cause further damage to your vision.

In addition, if you have one eye with poor vision and the other is fine, do not worry about using the “good” eye too much − use either or both eyes as much as you want.

Many devices are available that may be of benefit to you. These can include something as simple as a hand-held magnifier or better lighting; more complex devices such as computer software to help on the Internet are also available. If you have lost some sight from macular degeneration, ask your eye-care professional about low-vision services and devices that may help you make the most of your remaining vision. Many community organizations and agencies offer information about low-vision counseling, training and other special services for people with visual impairments.

Eat a healthy diet, don't smoke, keep your blood pressure under good control and maintain an ideal body weight. If you are over the age of 55, you should also have a dilated eye examination to determine whether you have macular degeneration or any other age-related eye condition.

If you have dry macular degeneration, you should have a comprehensive dilated eye exam at least once a year. Your eye-care professional can monitor your condition and check for other eye diseases. If he or she tells you that you have the intermediate stage of dry macular degeneration in one or both eyes or advanced macular degeneration in one eye only, AREDS-strength vitamins will likely be prescribed. In addition, since the dry type can convert to the wet type, you will need to monitor for changes on the Amsler grid. I recommend that my patients place the grid on their refrigerator so that they see it on a regular basis. Remember to test each eye independently (cover one eye and look at the grid with the uncovered one, then switch to test the other eye).

If you have new distortion, central haziness or blurring you may have wet macular degeneration. If your doctor advises treatment with either laser or PDT, do not wait, because you may lose further vision. After laser surgery or PDT, you will likely need frequent eye examinations to detect any recurrence of leaking blood vessels. In addition, check your vision at home with the Amsler grid. If you detect any changes in this grid, schedule an eye examination immediately.

Our mission is to provide our readers with the latest scientific information about o­ne disease – macular degeneration. Our hope is that this information will not o­nly be of educational benefit to our readers but will also serve to initiate an informed dialogue with a health-care provider.

Our website, products and services are not, however, intended to replace the advice of an eye healthcare provider, and they should in no way compromise the integrity of the relationship you have with such a provider.

To achieve our mission, we have created the following services:

• MacDegen^TM – The Story, our free electronic educational novel
• MacDegen^TM Science, our free electronic newsletter

MacDegen^TM Science is an electronic newsletter that will be sent directly to a subscriber’s e-mail address o­n a monthly basis. It will consist of summaries of three to five key scientific articles about the pathogenesis of macular degeneration (pathogenesis refers to what goes wrong in the eye to create the disease), its epidemiology (who gets macular degeneration and what causes it), its diagnosis (how health-care providers determine that you have the condition), and its treatment (what can ultimately be done for it).

To provide this service, we regularly do the following:

• Review most of the key peer-reviewed published ophthalmic journals and search scientific databases such as PubMed. (The peer-review process is o­ne in which o­nly articles of sufficient scientific validity are published; in our opinion, this process is the best way to determine whether the claims are made o­n a scientific basis or not.)

• Read promising articles in their entirety to determine whether they are relevant to our readers, employ appropriate scientific methodology and have scientifically valid results and conclusions.

• Have our editorial staff (a physician, a biostatistician and a scientific writer) thoroughly review the article if it has met the abovementioned criteria.

• Summarize the article to create a succinct and easily readable précis, which is then delivered along with others as MacDegen^TM Science.

MacDegen^TM – The Story is a book that provides you with basic information about macular degeneration. It is written in what we believe to be an engaging format - a story about a mother who develops the condition and a daughter who serves as her advocate by learning about it. At its heart, however, the book is not intended to be a masterpiece of fiction, but rather a practical information guide for those interested in learning about macular degeneration.

MacDegen^TM – The Story provides the basics, and MacDegen^TM Science provides the latest scientific information to the reader on an ongoing basis.

MacDegen.com’s philosophy is that the patient is the central figure in the health-care process. Other key players include family members and health-care workers. Our goal is to educate you in many aspects of macular degeneration so that you are more informed when it comes time to participate in important decisions about your health.

It is important to note that MacDegen.com is not intended to replace your healthcare provider. We know nothing of the specifics of your individual case. We are not, therefore, in a position to comment on what care you should or should not be receiving. Our site does, however, provide you with important information that can assist in your understanding of the disease and its treatments.

Our site is run and maintained by professionals who are well trained in both the clinical aspects of macular degeneration and the science surrounding it. We believe that this service will save you time, and provide you with information that has been heavily scrutinized from the perspective of scientific validity.