Understanding some common disorders of the eye’s principal part.

He admits he might be biased, but to Nandesh N. Patel, MD, the retina is the most important part of the eye. The retina is a thin layer of specialized tissue that lines the back of the eye. It senses light as it enters the eye and sends it to the brain to process as images.

Dr. Patel is a board-certified ophthalmologist and fellowship-trained retina surgeon at Florida Eye Specialists & Cataract Institute. To him, the retina is unlike any other part of the body. He sees it as a rare, privileged site that merits special care.

“Think of the eyeball as a camera,” he describes. “There are two crucial elements: the lens to focus the light and the film to register the light that enters. The retina is the film. Any disease that compromises the quality of the film creates problems with the pictures processed by the eye, resulting in a reduction of vision.

“The retina is a critical structure and, as I tell my patients, with every body part there’s a disorder to go with it. Unfortunately, there are many disorders that affect the retina.”

The most common disorders are diabetic retinopathy and macular degeneration, the leading causes of blindness in adults.

Dr. Patel and his colleagues, board-certified ophthalmologists and fellowship-trained retina specialists Evan N. Dunn, MD, Marguerite Kohlhepp, MD, and Dan P. Montzka, MD, have expertise in treating these diseases and more.

Glucose Concerns

According to the Centers for Disease Control and Prevention, about 34.2 million people in the United States – just over 1 in 10 – have diabetes. Type 2 diabetes, which accounts for 90 to 95 percent of all diabetes cases, is the leading cause of blindness among ages 20 to 74 due to diabetic retinopathy.

Diabetic retinopathy is the most common eye disease associated with diabetes. It is caused by changes in the blood vessels of the retina. In some cases, abnormal blood vessels develop on the surface of the retina. In others, blood vessels begin to bleed or leak fluid.

“Anyone who has diabetes is at risk for developing diabetic retinopathy,” Dr. Dunn stresses. “And the risk increases with the duration of having the disease. The main reason: High glucose levels affect the blood vessels and make them unhealthy.

“Diabetic retinopathy generally has no symptoms in its early stages, so screening and early diagnosis are of incredible importance. We have treatments that will overturn poor visual outcomes, but they require early detection.”

There are two main types of diabetic retinopathy, nonproliferative and proliferative.

“The nonproliferative type is an early stage of diabetic retinopathy characterized by small outpouchings of normal blood vessels called microaneurysms and tiny areas of bleeding within the retina,” Dr. Dunn explains.

“These retinal changes may progress to a much more serious type of diabetic retinopathy that, if left untreated, may cause permanent vision loss. We monitor patients with this condition routinely to make sure that if worsening occurs we can treat it before the patients lose vision.”

Nonproliferative is the more manageable form of diabetic retinopathy, he adds.

“If a patient works to control the underlying diabetes with a primary care physician, then it’s possible to reverse some of the findings,” Dr. Dunn states.

With proliferative diabetic retinopathy, the patient experiences an advanced form of the disease marked by an extensive closure of retinal blood vessels. As a result, the retina begins to grow new, leaky blood vessels in an effort to resupply blood to the area where the original blood vessels closed. Partial or total vision loss may occur.

“Unfortunately, these new vessels are abnormal and are not able to supply the retina with normal blood flow,” Dr. Dunn informs. “Instead, fluid leaks into the vitreous, the gel that lies in front of the retina and behind the eye’s lens, causing a vitreous hemorrhage. Small scars also begin to develop on the retina and the vitreous, causing the retina to pull away from the back of the eyeball, resulting in a retinal tear or retinal detachment.

“Once you get into the proliferative states, aggressive treatment is necessary. Some patients will undergo regular treatments such as laser therapy, monthly injections of medication directly into the eye or, in extreme cases, surgery.”

The CDC reports that early detection and treatment of diabetic retinopathy can reduce the development of severe vision loss by an estimated 50 to 60 percent.

“Early detection and treatment are crucial to preventing vision loss,” Dr. Dunn confirms. “Generally, diabetic retinopathy does not exhibit any symptoms during its early stages. Sometimes, a change in eyesight does not occur until the disease has progressed. Proper monitoring of the eyes is the best prevention for diabetic retinopathy.”

Macular Degeneration

Another serious threat to sight as people age is macular degeneration. It occurs when a central area of the retina, called the macula, deteriorates and main images become less discernible.

“Think of the retina as being 10 layers thick with many blood vessels nourishing it,” Dr. Montzka describes. “Macular degeneration is a disease in which some of those layers essentially become diseased and waste away. As a consequence, some of the blood vessels pop and leak. The first situation, where the layers waste away, is what we consider dry macular degeneration. When blood vessels start popping and leaking, that’s wet macular degeneration. This type does considerable damage that translates into poor vision.”

Dry macular degeneration accounts for approximately 90 percent of cases.

Macular degeneration is more common in people 55 and older. Because it occurs so often as you age, it is also called age-related macular degeneration, or AMD.

Macular degeneration generally has no signs or symptoms in its early stages.

“Macular degeneration progresses like a slow-moving conveyor belt,” Dr. Montzka notes. “Every case of wet macular degeneration was at one time the dry form. Patients may have had the dry form for a long time without being aware of it. They are often shocked by the diagnosis because they had no corresponding symptoms.”

When there are symptoms, people might notice a gradual loss of their ability to see objects clearly, especially noticing a blurring of areas of type on a page of print, or dark or empty spaces that may block the center of their field of vision.

Some patients may notice that straight lines in the landscape – such as telephone poles, the sides of buildings or streetlight posts – appear wavy, crooked or distorted. Some may notice the need for brighter light when reading or a gradual loss of color intensity.

“For intermediate-level dry macular degeneration, specific vitamin supplements can help slow down the conveyor belt,” Dr. Montzka reports. “They don’t halt progression of the disease and they certainly don’t reverse it. But they can buy the patients more time. For example, if they would normally turn wet in five years, this treatment may give them 10 to 15 years, which is substantial.

“With the wet form, which is an end stage of the disease, we have a variety of medications that are injected directly into the eye on a monthly basis. These can help contain the amount of leakage and bleeding and can often result in a stabilization of the eye, but not improvement.”

Patients with macular degeneration should monitor their vision daily with a tool called an Amsler grid and notify their eye doctors about any changes as soon as possible.

An Amsler grid consists of a network of horizontal and vertical lines with a dot in the center. People look at the grid intently. If the lines begin to look wavy or distorted, or if there are areas missing, the individual’s macular degeneration may be progressing.

Surgical Situations

The retina specialists at Florida Eye Specialists & Cataract Institute treat medical and surgical retinal disorders. Diabetic retinopathy and macular degeneration are examples of medical retinal disorders. Retinal vein occlusion is another.

“A retinal vein occlusion is a blockage of a vein in the retina,” Dr. Patel describes. “This can lead to bleeding and leaking of fluid into the eye and interrupted blood flow to nerve tissue, which can then lead to a loss of vision. Without immediate medical intervention, a retinal vein occlusion can cause permanent vision loss.”

The blockage may be caused by a blood clot, or the walls of the blood vessel may be too narrow. Vein occlusions are more common in people who have diabetes, high blood pressure, high cholesterol and other health problems that also affect blood vessels. The most common treatment for a retinal vein occlusion is injection of a medication into the eye.

“Of the surgical disorders, some of the more common are retinal tears and retinal detachments,” Dr. Patel states.

Other disorders include macular puckers and macular holes.

“Macular puckers and macular holes are not as catastrophic as retinal detachments or vitreous hemorrhages, where there’s a complete loss of vision that evolves quickly, sometimes within hours or days,” he says. “Macular puckers and macular holes are conditions that come on somewhat slowly and involve a disruption in the normal architecture of the macula.”

If a person develops a macular hole, then all of a sudden, they have a hole in the middle of their vision and they literally don’t see anything. There’s a blank spot dead center, which is very discomforting for the patient.

“The macular pucker is like scar tissue that develops on the macula and creates wrinkles,” Dr. Patel remarks. “This is due to the normal aging process. A wrinkled macula will make images appear wrinkled or distorted. Straight lines that look wavy is a common descriptor that naturally has repercussions if you are driving and want to stay within the lines.”

Macular puckers and macular holes can be corrected during a same-day surgical procedure called a vitrectomy. During a vitrectomy, the vitreous gel between the lens and retina is removed and replaced with a bubble of gas or air. Over a short time, the bubble will help to smooth out the retina and close the hole.

“We suspect a retinal tear as soon as we hear a patient report flashing lights or floaters, which are common complaints,” Dr. Patel relates. “Flashing lights and floaters can be due to normal changes of the eye, but one of five who presents with those symptoms will likely have a retinal tear to explain them.”

A retinal tear is a consequence of a normal, age-related process in which the vitreous is liquefied but inadvertently pulls at the retina. If a retinal tear occurs, it is critical that it is treated right away. If not, it can develop into a retinal detachment.

“The big, gaping hole in the retina allows fluid to pass through it,” Dr. Patel educates. “You find the fluid on the undersurface of the proverbial wallpaper, and the next thing you know, the wallpaper is falling off of the wall, and that’s a retinal detachment.”

Retinal tears are typically treated using a laser or freezing procedure. Retinal detachments are treated using vitrectomy.

Future Solutions

In 2021, Florida Eye Specialists & Cataract Institute expects to receive FDA approval for a treatment method for macular degeneration: an implanted delivery system for anti-vascular endothelial growth factor medications. Anti-VEGF medications help to halt the blood vessel growth characteristic of wet macular degeneration.

“The new treatment involves implanting a port into the eye to deliver the anti-VEGF medications, which we currently inject into the eye monthly,” Dr. Kohlhepp describes. “Having this implant system will decrease the number of appointments and injections that patients require. It will also enable the anti-VEGF medications to be released at a constant, low level over multiple months.”

It is projected that once the port is implanted, patients will return to Florida Eye Specialists & Cataract Institute every six months instead of monthly. At these six-month appointments, the patient’s port will be refilled with anti-VEGF medication.

“Also on the horizon is gene therapy for macular degeneration,” Dr. Kohlhepp states. “The principle behind gene therapy is to place genetic material into the eye to correct a genetic disease or deliver a gene that allows the body to produce a therapeutic protein that can treat a specific eye disease.

“We are currently using gene therapy for certain inherited retinal diseases. It has been proven safe and effective for diseases such as Lebers congenital amaurosis and retinitis pigmentosa. Trials are ongoing to develop gene therapy for macular degeneration.

For macular degeneration, gene therapy will enable the body to produce the therapeutic protein that inhibits VEGF.

“The protein will work similarly to the anti-VEGF medications Avastin, Lucentis and Eylea, which inhibit VEGF when they are injected into the eye,” Dr. Kohlhepp explains.

Most likely, gene therapy for macular degeneration will be administered in the office through injections, but will not require monthly injections.

© FHCN article by Patti DiPanfilo. FHCN file photos. mkb