Retinal Diseases

The retina is a layer of tissue in the back of your eye that senses light and sends images to your brain. At the center of the retina is an area called the macula. It provides the sharp, central vision needed for reading, driving and seeing fine detail.

Retinal diseases vary widely — some are common and easily remedied, while others are rare, more difficult to diagnose and require more complex treatment. Clarus Eye Centre ophthalmologists are skilled in differentiating the diseases, and then designing a treatment plan that slows or stops the disease and preserves as much vision as possible.

Retinal treatments and surgery are performed by Penny Reck, M.D.

Floaters, Flashes, & Retinal Detachment

Floaters are shadows or dark objects that "float" across your field of vision. They may appear as dark specks, strings, or cobwebs that float through the eye. They are usually caused by changes in the vitreous gel that fills the center of the eye, blocking light to the retina.

Many people begin to see floaters as they get older and their eyes age. If you’ve previously noticed floaters , or if they occur with a diagnosed migraine headache, this condition is usually not serious. However, the sudden appearance of floaters may signal a more serious medical condition. You should contact your ophthalmologist right away if you experience new floaters, especially if you are over 45 years of age.

When the vitreous gel rubs or pulls on the retina, it may create images that look like flashing lights or lightning streaks. The flashes of light, which are more common as we age, may persist on and off for several weeks or months. A sudden onset of light flashes accompanied by new floaters, may indicate that the retina is torn and requires immediate medical attention.

Diabetic Retinopathy

 If you have diabetes, your body does not use and store sugar properly. High blood-sugar can damage blood vessels in the retina, the nerve layer at the back of the eye that senses light and helps to send images to the brain. The damage to these retinal vessels is referred to as diabetic retinopathy.

It’s important to know that with today’s improved methods of diagnosis and treatment, only a small percentage of people with retinopathy will experience serious vision problems. The best way to lower your risk of vision loss is to maintain strict control of your blood sugar (as directed by your primary care physician) and by visiting your ophthalmologist regularly.

There are two types of diabetic retinopathy: nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR).

• NPDR, also known as background retinopathy, is an early stage of diabetic retinopathy. In this stage, tiny blood vessels within the retina leak blood or fluid. The leaking fluid causes the retina to swell or to form deposits called exudates. Many people with diabetes have mild NPDR, which usually does not affect their vision. When vision is affected it is the result of macular edema and/or macular ischemia.

• Macular edema refers to swelling or thickening of the macula, a small area in the center of the retina that allows us to see fine details clearly. The swelling is caused by fluid leaking from retinal blood vessels. It is the most common cause of visual loss in diabetes. Vision loss may be mild to severe, but even in the worst cases, peripheral vision is still maintained.
• Macular ischemia occurs when small capillaries close. Vision blurs because the macula no longer receives sufficient blood flow to work properly.
• PDR is characterized by growth of abnormal new vessels on the surface of the retina or optic nerve, a process known as neovascularization. PDR is caused by widespread closure of retinal blood vessels, which prevents adequate blood flow. In an attempt to supply blood to the area where the vessels closed, the retina begins to grow new blood vessels.

Unfortunately, the new, abnormal blood vessels do not resupply the retina with normal blood flow, and over time can lead to scarring, wrinkling, or detachment of the retina. Because PDR can affect both central and peripheral vision, patients with PDR may experience more severe vision loss than those with NPDR. PDR causes visual loss in the following ways:

• Vitreous hemorrhage occurs when the fragile new vessels bleed into the vitreous, a clear, jelly-like substance the fills the center of the eye. If the vitreous hemorrhage is small, a person might only see a few new dark floaters, but a very large hemorrhage could block out all vision. When the blood clears, visual acuity may return to its former level unless the macula is damaged.
• Tractional retinal detachment results when the scar tissue associated with neovascularization shrinks, wrinkles, and pulls the retina from its normal position. This can lead to visual distortion or more severe vision loss if the macula or large areas of the retina detach from the back of the eye.
• Neovascular glaucoma occurs when neovascularization extends to the iris (the colored part of the eye) and blocks the normal flow of fluid out of the eye. If left untreated, the pressure increase inside the eye can eventually damage the optic nerve.

A medical eye examination by an ophthalmologist is the only way to reveal changes inside your eye. If your ophthalmologist finds evidence of diabetic retinopathy during your exam, color photographs of the retina or a special test called fluorescein angiography may be performed to determine if you need treatment. If diagnosed early, treatment can begin often before any visual problems begin to occur.

Age-Related Macular Degeneration

   
Age related macular degeneration (AMD) is a chronic eye disease associated with aging that gradually destroys the macula, leading to a loss of central vision. It is the leading cause of blindness in Americans age 65 and older.

Although the exact cause of macular degeneration is unknown, several studies have the following risk factors for developing AMD:

• Age 50 and older
• High blood pressure and other cardiovascular diseases
• Smoking
• Family history of AMD

Macular degeneration affects central vision, but not peripheral vision – therefore, it doesn’t cause total blindness. The progression of AMD can be slow or rapid, but the deterioration of central vision generally occurs over a period of a few years. Pain is not associated with AMD, but if you notice words looking blurry on a page, a dark or empty area in the center of your vision, or crookedness of straight lines, you may have symptoms of macular degeneration.

The “dry” form of macular degeneration occurs in approximately 90% of those with AMD. It occurs when cells under the macula break down and create deposits called drusen. It is this drusen that can lead to vision loss.

The “wet” form of macular degeneration occurs in only 10% of those with AMD, but it accounts for 90% of all severe vision loss from the disease. Wet AMD occurs when blood vessels in the back of the eye begin to grow abnormally. As the blood vessels grow, they can leak blood and fluid, which damage the macula.

Treatment Options for AMD

Early detection and treatment is the best defense against losing your vision. If you are at risk for macular degeneration, it’s important that you have a comprehensive eye exam every one to two years.

Studies have found that high levels of zinc and antioxidants play a key role in slowing the progression of dry macular degeneration in advanced cases. Be sure and talk to your doctor before taking any supplements.

Wet AMD can be treated with conventional laser treatment, photodynamic therapy (PDT), and certain medications called anti-VEGF treatments. PDT uses a combination of a light-sensitive drug and a laser to reduce the risk of moderate to severe vision loss in patients with specific types of wet AMD. Anti-VEGF drugs, which are delivered directly into the eye by injection, block VEGF (vascular endothelial growth factor), the substance that promotes the growth of troublesome abnormal blood vessels in wet AMD.

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