Age Related Macular Degeneration

Human eye has various important parts like Cornea, Pupil, Iris, Lens and Retina. The macula is located in the center of the retina, the light-sensitive tissue at the back of the eye. The retina instantly converts light, or an image, into electrical impulses. The retina then sends these impulses, or nerve signals, to the brain. When the cells of the macula deteriorate, images are not received correctly. In early stages, macular degeneration does not affect vision. Later, if the disease progresses, people experience wavy or blurred vision, and, if the condition continues to worsen, central vision may be completely lost. People with very advanced macular degeneration are considered legally blind. Macular Degeneration is the leading cause of vision loss, more than cataracts and glaucoma combined.

Macular degeneration is classified as:
Dry Age related Macular Degeneration
Wet Age related Macular Degeneration.
Pathophysiology
The dry form is more common than the wet form, with about 85 to 90 percent of AMD patients diagnosed with dry AMD. The less common wet AMD usually leads to more serious vision loss.

Dry AMD causes changes of the retinal pigment epithelium, typically visible as dark pinpoint areas. The retinal pigment epithelium plays a critical role in keeping the cones and rods healthy and functioning well. Accumulation of waste products from the rods and cones can result in drusen, which appear as yellow spots. Areas of chorioretinal atrophy (referred to as geographic atrophy) occur in more advanced cases of dry AMD. There is no elevated macular scar (disciform scar), edema, hemorrhage, or exudation.

Dry AMD has three stages, all of which may occur in one or both eyes:

Early AMD - People with early AMD have either several small drusen or a few medium-sized drusen. At this stage, there are no symptoms and no vision loss.
Intermediate AMD - People with intermediate AMD have either many medium-sized drusen or one or more large drusen. Some people see a blurred spot in the center of their vision. More light may be needed for reading and other tasks.
Advanced AMD - In addition to drusen, people with advanced dry AMD have a breakdown of light-sensitive cells and supporting tissue in the central retinal area. This breakdown can cause a blurred spot in the center of your vision. Over time, the blurred spot may get bigger and darker, taking more of your central vision. You may have difficulty reading or recognizing faces until they are very close to you.
Wet AMD occurs when new abnormal blood vessels develop under the retina in a process called choroidal neovascularization (abnormal new vessel formation). Localized macular edema or hemorrhage may elevate an area of the macula or cause a localized retinal pigment epithelial detachment. Eventually, untreated neovascularization causes a disciform scar under the macula.

Symptoms
Dry macular degeneration symptoms usually develop gradually and without pain. They may include:

Visual distortions, such as straight lines seeming bent
Reduced central vision in one or both eyes
The need for brighter light when reading or doing close work
Increased difficulty adapting to low light levels, such as when entering a dimly lit restaurant
Increased blurriness of printed words
Decreased intensity or brightness of colors
Difficulty recognizing faces
What causes macular degeneration?
Though macular degeneration is associated with aging, there is genetic component to the disease. A strong association between development of AMD and presence of a variant of a gene known as complement factor H (CFH) is observed. This gene deficiency is associated with almost half of all potentially blinding cases of macular degeneration.

Other investigators have found that variants of another gene, complement factor B, may be involved in development of AMD.

Specific variants of one or both of these genes, which play a role in the body's immune responses, have been found in 74 percent of AMD patients who were studied. Other complement factors also may be associated with an increased risk of macular degeneration.

Oxygen-deprived cells in the retina produce a type of protein called vascular endothelial growth factor (VEGF), which triggers the growth of new blood vessels in the retina.

The normal function of VEGF is to create new blood vessels during embryonic development, after an injury or to bypass blocked blood vessels. But too much VEGF in the eye causes the development of unwanted blood vessels in the retina that easily break open and bleed, damaging the macula and surrounding retina.

Risk Factors
The biggest risk factor for Macular Degeneration is age. Your risk increases as you age, and the disease is most likely to occur in those 55 and older.

Other risk factors include:

Genetics – People with a family history of AMD are at a higher risk.
Race – Caucasians are more likely to develop the disease than African-Americans or Hispanics/Latinos.
Smoking – Smoking doubles the risk of AMD.
Diagnosis
AMD is detected during a comprehensive eye exam that includes:

Visual acuity test - This eye chart test measures how well you see at various distances.
Dilated eye exam - Drops are placed in your eyes to widen the pupils. Your eye care professional uses a special magnifying lens to examine your retina and optic nerve for signs of AMD and other eye problems. After the exam, your close-up vision may remain blurred for several hours.
Tonometry - An instrument measures the pressure inside the eye. Numbing drops may be applied to your eye for this test.
Both forms of age - related macular degeneration (AMD) are diagnosed by funduscopic examination. Visual changes can often be detected with an Amsler grid.
Color photography and fluorescein angiography are done when findings suggest wet AMD. Angiography shows and characterizes subretinal choroidal neovascular membranes and can delineate areas of geographic atrophy. Optical coherence tomography (OCT) aids in identifying intraretinal and subretinal fluid and can help assess response to treatment.
What Treatments Are Available for Macular Degeneration?
There’s no cure for macular degeneration. Treatment may slow it down or keep you from losing too much of your vision. Your options might include:

Lifestyle changes - like dieting, exercise, avoiding smoking, and protecting your eyes from ultraviolet light.
Anti-angiogenesis drugs - These medications – aflibercept (Eylea), bevacizumab (Avastin), pegaptanib (Macugen), and ranibizumab (Lucentis) -- block the creation of blood vessels and leaking from the vessels in your eye that cause wet macular degeneration. Many people who’ve taken these drugs got back vision that was lost. You might need to have this treatment multiple times.
Laser therapy - High-energy laser light can destroy abnormal blood vessels growing in your eye.
Photodynamic laser therapy - Your doctor injects a light-sensitive drug verteporfin (Visudyne) into your bloodstream, and it’s absorbed by the abnormal blood vessels. Your doctor then shines a laser into your eye to trigger the medication to damage those blood vessels.
Low vision aids - These are the devices that have special lenses or electronic systems to create larger images of nearby things. They help people who have vision loss from macular degeneration make the most of their remaining vision.
Submacular surgery - This removes abnormal blood vessels or blood.
Retinal translocation - A procedure to destroy abnormal blood vessels under the center of your macula, where your doctor can’t use a laser beam safely. In this procedure, your doctor rotates the center of your macula away from the abnormal blood vessels to a healthy area of your retina. This keeps you from having scar tissue and more damage to your retina. Then, your doctor uses a laser to treat the abnormal blood vessels.

Cornea Surgery in Ghatkopar
The cornea is the clear dome shaped transparent, outermost layer of the eye, about 12 mm in diameter. It serves as a physical barrier against dust, microorganisms and other harmful particles. The cornea also plays an important role in vision. It filters some amount of ultraviolet light and protects iris, pupil and anterior chamber.

As light is refracted by the curvature of the cornea, it is focused on the object and forms a clear Image. Any infection, disease or trauma to the cornea can interfere with vision by blocking or distorting light as it enters the eye. It contains specialized tissue having no blood vessels and is nourished with your tears and aqueous humor (behind the cornea).

Cornea is made up of three major components.
Epithelium – Cornea has numerous nerve endings, that’s why you experience pain while rubbing your eyes. It absorbs oxygen and nutrients from the tears. Epithelium is connected with stroma with the help of basement membrane.
Stroma – The stroma is the thickest part of the cornea and is made up of collagen and water. Collagen fives elasticity and keeps cornea firm. These collagen fibres are arranged in strictly in a regular, geometric fashion. This arrangement is responsible for clear cornea, while in case of trauma, collagen fibres laid down in repair, often leads to cloudy cornea. Below stroma is the Descemet’s membrane, which connects it with endothelium.
Endothelium - The innermost layer of the cornea is made up of endothelium. Function of endothelium is to maintain fluid balance by acting as a pump, expelling excess water as it is absorbed into the stroma. Without this specialized function, the stroma could become waterlogged and hazy and opaque in appearance, also reducing vision.

Symptoms of corneal conditions
Minor injuries of cornea heal by itself while major injuries may result in
scarring and impaired vision.

Intense pain.
Blurred vision.
Double vision
Tearing.
Redness.
Extreme sensitivity to light.

Corneal conditions
Injuries/Trauma
Eye allergies
Keratitis.
Ocular herpes
Herpes zoster (shingles)
Dry eye
Nutritional Deficiencies like Vitamin A
Corneal dystrophies – Keratoconus, Map-dot-fingerprint dystrophy, Fuch's
dystrophy
Common diseases that can affect the cornea — Abnormal growths,
autoimmune diseases, Stevens - Johnson syndrome, iridocorneal endothelial
syndrome and pterygium.

Treatment
Simple corneal conditions can be treated with antibiotic or anti-inflammatory
eye drops or pills. If you have advanced corneal disease, you may need an
advanced treatment.

Laser treatment – In Corneal dystrophies, doctors can use a type of laser treatment called phototherapeutic keratectomy (PTK) to reshape the cornea, remove scar tissue, and make vision clearer.

Corneal transplant surgery – In case cornea is damaged and cannot be repaired, doctors can remove the damaged part and replace it with healthy corneal tissue from a donor.

Artificial cornea - As an alternative to corneal transplant, doctors can replace a damaged cornea with an artificial cornea, called a keratoprosthesis (KPro).

Corneal Arcus
Corneal Arcus or Arcus senilis appears as a white, gray, or blue ring or arc around the cornea of the eye. The condition is usually seen in older adults but can affect people of all ages, even appearing at birth. Arcus senilis is generally harmless, and an involutional change modified by genetic factors. However, arcus is sometimes indicative of hyperlipidoproteinemia (involving low-density lipoproteins) with elevated serum cholesterol, especially in patients under 40 years of the age.

Causes of corneal arcus
Arcus is a deposition of lipid in the peripheral corneal stroma. Cholesterol and triglycerides are two types of fats in your blood. Some of the lipids in your blood come from foods you eat, such as meat and dairy products. Your liver produces the rest. Lipid deposition starts at the inferior and superior poles of the cornea and in the late stages encircle the entire circumstances. Arcus senilis is more common in men than in women. In people under age 40, arcus senilis is often due to an inherited condition and in rare cases, children are born with arcus senilis ( arcus juvenilis).

Arcus senilis can also appear in people with Schnyder central crystalline dystrophy. This rare, inherited condition causes cholesterol crystals to deposit on the cornea.

Symptoms
A person with arcus senilis may develop:

A white, gray, or blue circle around the cornea of the eye.
The circle or arc will have a sharp outer border but a blurred inner border.
If someone has an arc, the lines could grow to form a complete circle in front of the iris.
The presence of corneal arcus in patients younger than 40 year-old warrants evaluation for systemic lipid abnormalities.
Unilateral arcus is a rare condition associated with contra lateral artery disease or ocular hypotony. Usually it is an asymptomatic condition and does not affect your vision.

Diagnosis
Eye examination performed by eye doctor can diagnose arcus senilis. A slit lamp microscope is a very helpful tool to evaluate eye thoroughly. A special eye drop is used to widen the pupil of the patient. Once the eye drops works, ophthalmologist can inspect all parts of the eye with back of the eye as well for any disease. In arcus, thickness of the vessels increases due to fat deposition. Surgeon has to look for signs of atherosclerosis also, which is a condition where arteries become clogged with fatty substances.

A blood test will determine whether someone has high cholesterol. If they do, they may be prescribed medicine or advised on a suitable diet and exercise program to lower the cholesterol in their blood.

How corneal arcus is managed?
The good news is, you don’t need to treat arcus senilis. It typically affects both eyes, but in some cases only one eye has a grayish arc around the cornea, which may be a sign of poor blood circulation.

Eating healthy foods and exercising regularly are some good ways to keep your eyes healthy. We recommend wearing sunglasses with 100% UV protection when outdoors and safety goggles when doing hazardous tasks as well.

If arcus senilis is a sign of high cholesterol, a doctor may recommend a diet that is low in saturated fats and high in fruit, vegetables, and fiber.

If lipid levels are not controlled by diet and exercise are not enough, several medications can help lower your lipid levels:

Statin drugs block a substance your liver uses to make cholesterol. These drugs include atorvastatin, fluvastatin, pravastatin and rosuvastatin.
Bile acid binding resins force your liver to use more cholesterol to produce digestive substances called bile acids. This leaves less cholesterol in your blood. These drugs include cholestyramine, colesevelam and colestipol.
Cholesterol absorption inhibitors like ezetimibe reduce your body’s absorption of cholesterol.
Drugs may be used to lower triglyceride levels:
Fibrates reduce production of lipids in your liver and increase the removal of triglycerides from your blood.
Niacin reduces the production of lipids by your liver.
Increased exercise and quitting smoking can also help.
Possible complications
Arcus senilis alone is not known to have any complications unless it is a sign of high cholesterol. High levels of cholesterol in a person’s blood can cause significant problems, such as coronary artery disease or cardiovascular disease.

Follow-Up
Arcus senilis may sometimes appear as a white ring around the iris due to calcium deposits on the circumference of the cornea, where the white section of your eye (the sclera) and the colored part (the iris) meet (called the limbus). When the deposits consist of calcium, the limbus appears milky and may indicate tissue damage that needs correction.

The blue (or sometimes gray) ring around the iris often is associated with high cholesterol and triglycerides. In turn, this may be an indicator of heart condition that yor are more prone to heart attacks and strokes. When this condition appears in people younger than 60 years old, regular blood tests are normally recommended to monitor elevated lipid levels.

In few other cases, when corneas become opaque, due to genetic mutation it could be from a lowered high-density lipoprotein (HDL) cholesterol level. This condition can result in other eye problems. Principally, this opacification may be related to deficient levels of lecithin cholesterol acyl transferase (LCAT). LCAT is an enzymatic protein responsible for converting free cholesterol into cholesteryl ester.

Cholesterol ester, is then separated into the nucleus of the lipoproteins to produce a synthetic high-density lipoprotein (HDL) chain. This reaction is forced one way, since the deposits are removed from the exterior. So the enzyme is attached to both HDLs and low-density lipoproteins (LDLs) in blood plasma.

This process can result in the manifestation of fish eyes, and it is actually called “fish eye disease.” Corneal opacification can also result from mutations in another HDL protein, the adenosine triphosphate-binding protein ABCA1.

Just because you are younger than 40 and have arcus does not mean you absolutely have elevated lipid levels, but at a very minimum, it is recommended that you have them checked.

Unilateral corneal arcus may be associated with vascular or inflammatory etiologies.

Important Reminder: This information is only intended to provide guidance, not a definitive medical advice. Please consult eye doctor about your specific condition. Only a trained, experienced board certified eye doctor can determine an accurate diagnosis and proper treatment.