The retina is the layer of light-sensitive tissue that lines the back of the eye. It converts light into signals that are sent via the optic nerve to the brain, where they are recognized as images. The macula is the small, central area of the retina that allows sharp, detailed vision, such as that necessary for reading. In age-related macular degeneration (AMD), the macula deteriorates. AMD is the leading cause of severe visual loss in people over 50 years of age. There are 2 main types of AMD, dry and wet.

Dry Macular Degeneration

Most (80% to 90%) of people with AMD have the dry (also called atrophic) form. It causes some visual loss, but the loss usually is not severe. Some people with dry AMD will develop the wet form, which is more likely to cause severe visual loss.

Wet Macular Degeneration

About 10% to 20% of people with AMD have the wet (also called exudative or neovascular) form. Although it is less common, the wet form accounts for 80% to 90% of cases of severe visual loss due to AMD. It is called wet because new, abnormal blood vessels grow beneath the macula and leak blood or fluid.

Causes of AMD

The cause of AMD is not completely understood. Factors that increase the risk of developing AMD include age, family history of AMD, smoking, sunlight exposure, and diet. The risk of having AMD increases with age, from 10% at age 50 to about 30% at age 75.

Symptoms

Especially with the dry form, symptoms may develop gradually. Also, if only one eye is affected, a person may not notice changes in vision until the disease gets worse or the other eye becomes affected. Symptoms may include blurring of vision, a dark area or "blind spot," or a distorted appearance of straight lines or other objects. In wet AMD, symptoms may be sudden, with a severe and rapid loss of central vision. Because worsening of AMD can be indicated by a change in symptoms, it is important for people with AMD to monitor their vision closely and to call their eye doctors when there is a change in vision. One way to monitor vision is with an Amsler grid, which looks similar to a section of graph paper. The grid may appear to have missing, dark, or distorted areas as AMD affects the macula. The examples below show the Amsler grid as seen with a normal eye (left) and as seen with an eye with wet AMD (right).

Diagnosis of AMD

Visual acuity testing.  This test uses an eye chart to determine how well a person can see at various distances.

Ophthalmoscopy.  The changes caused by AMD may be seen by examination of the retina with an instrument called an ophthalmoscope.

Fluorescein angiography (FA).  This is a test procedure in which a dye (fluorescein) that is injected into a vein in the arm travels to the retinal blood vessels. Special photographs allow the physician to see the vessels and identify abnormalities.

Indocyanine green angiography (ICG).  This is like FA but a different dye (indocyanine green) is used to show changes that may not be visible with FA.

Optical coherence tomography (OCT).  OCT uses a thin beam of light and the reflection of that light off the retinal layers to show the anatomy of the retina.

Treatment of AMD

The risk of worsening AMD may be reduced by reducing risk factors through maintaining a healthy life style, for example, quitting smoking, eating lots of fruits and vegetables, and exercising regularly.

Dry AMD.  The Age-Related Eye Disease Study (AREDS) showed that high-dose anti-oxidant vitamins can reduce the risk of progression of dry AMD in some patients. Your doctor can tell you whether these vitamins are appropriate for you.

Wet AMD. Some cases of wet AMD are treated with laser therapy, in which a beam of light is used to seal the abnormal blood vessels and prevent leaking. A newer laser treatment, photodynamic therapy (PDT), uses a low-energy laser to activate a light-sensitive drug that is injected into a vein and travels to abnormal blood vessels in the macula. The light-activated drug then destroys the abnormal vessels. The most recent treatment for wet AMD is the use of drugs that are injected directly into the eye to prevent the growth of new blood vessels.  

The retina is the layer of light-sensitive tissue that lines the back of the eye.  It converts light into signals that are sent via the optic nerve to the brain, where they are recognized as images.  Conditions that affect the retina affect the ability to see.

Diabetes mellitus is a complex disease that affects many different parts of the body. In diabetic retinopathy, the blood vessels in the retina are affected, leading to loss of vision.

There are two types of diabetic retinopathy (DR):

Nonproliferative diabetic retinopathy  (NPDR) occurs when the damage to the retinal blood vessels causes them to leak fluid and blood.

Proliferative diabetic retinopathy  (PDR) occurs when neovascularization, the growth of new, abnormal blood vessels, develops on the retina. These new vessels can led to bleeding and scarring.  Causes of diabetic retinopathy. The principal factor in the development of DR is high blood sugar (hyperglycemia).

The longer a person has diabetes, the more likely it is that DR will develop. High blood pressure (hypertension) and pregnancy are other risk factors. DR is the leading cause of blindness in people of
working age.

Symptoms of diabetic retinopathy

In the early stages of DR, there may be no symptoms. Symptoms may not develop until DR is quite advanced, so it is important for people with diabetes to have regular eye exams even if they have no symptoms. As the disease progresses, symptoms may occur suddenly, or they may develop gradually over time. They include reduced vision, blurred or distorted vision, spots, streaks, or floaters. Severe bleeding can cause serious or even complete loss of vision, as can detachment of the retina caused by scarring.

Complications of diabetic retinopathy

Macular edema . The macula is the small, central area of the retina that allows sharp, detailed vision, such as that necessary for reading. Blood and fluid leaking into the macula cause swelling, a condition called macular edema, which causes blurring and/or loss of vision.

Vitreous hemorrhage.   With neovascularization, the abnormal blood vessels may bleed into the vitreous, the clear, jelly-like substance that fills the inside of the eye.  With a small hemorrhage, small spots or clouds, called floaters, may appear in the field of vision. A large hemorrhage may block vision completely.

Retinal detachment .  Neovascularization may also lead to the growth of scar tissue on the retina. The scarring can pull the retina way from its normal position, causing retinal detachment.

Neovascular glaucoma . New blood vessels in certain parts of the eye can prevent the normal flow of fluid out of the eye. This can lead to a dangerous increase in pressure that can damage the optic nerve.

Blindness . Vitreous hemorrhage, retinal detachment, and neovascular glaucoma can cause complete loss of vision.

Diagnosis of diabetic retinopathy

People with DR should have regular, thorough eye examinations.

Ophthalmoscopy . After the pupils of the eyes are dilated (widened) with the application of eye drops, the retina and the inside of the eye can be examined with an instrument called an ophthalmoscope.

Fluorescein angiography . This is a test procedure in which a dye that is injected into a vein in the arm travels to the retinal blood vessels. Special photographs allow the physician to see the vessels and identify abnormalities or leakage.

Optical coherence tomography (OCT) .  OCT uses a thin beam of light and the reflection of that light off the retinal layers to show the anatomy of the retina.

Treatment of diabetic retinopathy

Intravitreal injections.  In some cases of DR, a drug is injected into the vitreous through a small needle. The drugs used may include steroids, which reduce inflammation, or drugs that prevent neovascularization.

Laser treatment.  With laser treatment, a beam of light is used to create small burns on the retina. In focal laser treatment, used for macular edema, burns are placed near the macula to seal the leaking vessels. In scatter or panretinal laser treatment, used for PDR, the burns are placed throughout the retina, except in the area of the macula, to shrink the new vessels and inhibit future neovascularization.

Vitrectomy.  If vitreous hemorrhage is severe or longstanding, a surgical procedure may be necessary to remove the vitreous, which is replaced with a substitute.

Retinal reattachment surgery . If the retina detaches, a surgical procedure is performed to release the tissue pulling the retina and restore the retina to its correct position.

Prevention of diabetic retinopathy

Research studies have shown that careful control of blood sugar slows the onset and progression of retinopathy and other complications of diabetes. It is important to work with your diabetes doctor to determine the best treatment plan for you.

A retinal detachment (RD) is an urgent medical condition – anyone experiencing the symptoms of detachment should call for an appointment with their eye care professional or a retinal specialist.

Retinal detachment occurs when the thin lining at the back of your eye, called the retina, begins to pull away from its blood supply of oxygen and nutrients.  Without a constant blood supply, the nerve cells in the retina begin to die, which can lead to a permanent loss in vision, or blindness, if left untreated.

Detached or Torn Retina

As one gets older, the vitreous, or clear, gel-like substance that fills the inside of the eye, tends to shrink slightly and take on more watery consistency.  Sometimes, as the vitreous shrinks, it exerts a pulling force on the retina to make it tear.  Liquid vitreous, passing through the tear, lifts the retina off the back of the eye like wallpaper peeling off a wall.

Symptoms of RD

The sudden appearance of floaters or spots, which are caused by cells or clumps of gel inside the vitreous, may indicate a retinal tear. 

Floaters can also result if blood enters the vitreous, and vision can become blurred or distorted.  Sudden or short flashes of light, or a gray curtain moving across the field of vision, or a sudden loss in peripheral vision, are all possible indications of a retinal detachment.

Risk Factors for RD

A retinal detachment is more likely to occur in people who:

• Are over the age of 50 (risk increases with age)
• Are very nearsighted
• Have a family history of retinal detachment
• Have had cataract surgery
• Have had an eye injury or severe trauma to the eye.
   

Treatment Options for Repairing a Detached or Torn Retina

Retinal holes or tears are most often treated with laser or cryotherapy.  Laser treatment uses a laser beam to create a series of small scars that form a barrier around the tear.  Cryotherapy involves a freezing probe used by the doctor to seal the torn retinal tissue and prevent progression to a retinal detachment.  Both procedures can be performed in the office, and discomfort is usually minimal.

If the retina is detached, it must be reattached before sealing the retinal tear.  There are currently three types of surgery to repair a retinal detachment.

Pneumatic retinopexy involves injecting a special gas bubble into the eye; the bubble pushes on the retina to seal the tear.  A scleral buckle procedure requires the fluid to be drained from under the retina before a flexible piece of silicone is sewn on the outer wall to give support to the tear while it heals.  Vitrectomy surgery removes the vitreous gel from the eye, replacing it with a gas bubble, which is slowly replaced by the eye’s fluids.

Risks and Complications Associated with RD Repair

Some of the risks and complications associated with retinal detachment surgery include infection, scar formation, bleeding, glaucoma, cataract, and loss of vision.  The decision about which type of treatment will be used and which anesthesia will be used is made by your physician based on a number of factors, including the type and location of detachment.  Tell your doctor if you are taking any medications such as aspirin, ibuprofen, or blood thinners, and follow the doctor’s instructions for eating or drinking before surgery.

Arteries carry blood from the heart to other parts of the body, and veins carry the blood back to the heart. A blockage in an artery or vein is called an occlusion. The retina is the layer of light-sensitive tissue that lines the back of the eye. It converts light into signals that are sent via the optic nerve to the brain, where they are recognized as images. Conditions that affect the retina affect the ability to see.

Retinal Vein Occlusion (RVO)

When a retinal vein is blocked, it cannot drain blood from the retina. This leads to hemorrhages (bleeding) and leakage of fluid from the blocked blood vessels. There are two types of retinal vein occlusion:

Central retinal vein occlusion (CRVO) is the blockage of the main retinal vein.

Branch retinal vein occlusion (BRVO) is the blockage of one of the smaller branch veins.

Causes of RVO

Certain conditions increase the risk of developing retinal vein occlusion. These include diabetes, glaucoma, high blood pressure, high cholesterol, vascular (blood vessel) disease, and blood disorders.

Symptoms of RVO

RVO often causes a sudden, painless blurring or loss of vision. It may also cause a person to see floaters or flashing lights. However, some people with retinal vein occlusion have pain, and some have no symptoms.

Complications of RVO

Macular edema.  The macula is the small, central area of the retina that allows sharp, detailed vision, such as that necessary for reading. Blood and fluid leaking into the macula cause swelling, a condition called macular edema, which causes blurring and/or loss of vision.

Neovascularization.  RVO can cause the retina to develop new, abnormal blood vessels, a condition called neovascularization. These new vessels may leak blood or fluid into the vitreous, the jelly-like substance that fills the inside of the eye. Small spots or clouds, called floaters, may appear in the field of vision. With severe neovascularization, the retina may detach from the back of the eye.

Neovascular glaucoma.  New blood vessels in certain parts of the eye can cause pain and a dangerous increase in pressure inside the eye.

Blindness.  The complications of RVO, especially if they are not treated, can lead to irreversible loss of vision.

Diagnosis of RVO

Ophthalmoscopy.  The changes caused by RVO may be seen by examination of the retina with an instrument called an ophthalmoscope.

Fluorescein angiography.  This is a test procedure in which a dye that is injected into a vein in the arm travels to the retinal blood vessels. Special photographs allow the physician to see the vessels.

Treatment of RVO

Currently, there is no known way to cure RVO. In some cases, laser treatment may be used to stabilize the condition or to prevent worsening. Some retinal specialists are evaluating the use of drugs, such as steroids to reduce inflammation and other drugs that prevent new blood vessel growth, that are injected into the eye. Someone who has had an RVO has an increased risk of having another one. This risk may be reduced with management of any conditions, such as diabetes or high blood pressure, that contribute to development of RVO.

If you are interested in the clinical trials we are involved in concerning RVO, please see the  Research/Clinical Trials  section of our site.

Retinal Artery Occlusion (RAO)

When a retinal artery is blocked, blood cannot get to the retina. Like RVO, RAO may affect the central retinal artery or a branch artery.

Causes of RAO

RAO is usually caused by a small clot. Conditions that increase the risk of developing RAO include atherosclerosis, diabetes, heart disease, glaucoma, high blood pressure, and high cholesterol.

Symptoms of RAO

RAO causes sudden, painless, complete (central artery) or partial (branch artery) loss of vision.

Complications of RAO

Unless the blood supply to the retina can be restored quickly, the affected area will not survive, and vision loss will be permanent.

Diagnosis of RAO

The changes caused by RAO may be seen by examination of the retina with an ophthalmoscope.

Treatment of RAO

There is no treatment that has been proven to be successful. Potential treatments include eye massage, removal of fluid from the eye, oxygen therapy, and injection of drugs that dissolve clots. The outcome is more likely to be better if the occlusion is partial and treatment is begun promptly. People with RAO often have serious underlying health problems that require thorough medical evaluation.