A Shot In The Eye?

Specialist explains benefits, removes anxiety of intravitreal injections.

The eye is a globe that is not empty. It is filled with a gel-like substance called vitreous. The vitreous separates the retina, in the back of the eye, from the front. Disorders affecting the retina, and particularly its center portion (macula), are often treated using intravitreal injections.

“Intravitreal injections are among the most, if not the most, common ophthalmic procedures performed in the United States,” asserts Alexander C. Barnes, MD, a board-certified, fellowship-trained retina specialist at Florida Retina Institute. “They are the mainstay of treatment for many retinal conditions, including age-related macular degeneration and diabetic macular edema.

“Many people have family members or friends who see a retina specialist for intravitreal injections but do not know much about them. And new patients who are told they need these injections are often alarmed and sometimes squeamish about getting needles inserted into their eyes.

“But once people learn more about the injection procedure and its potential benefits, much of the anxiety and misunderstanding about intravitreal injections are eliminated.”

The term intravitreal refers to the method of delivery. An intravitreal injection is the delivery of medication through the pars plana, at the junction of the iris and sclera, or white outer layer of the eyeball, and into the cavity that houses the vitreous.

“When medication is delivered into the vitreous cavity, it can reach the retina more directly with few systemic side effects,” Dr. Barnes describes.

“It may seem overwhelming to patients initially when they walk into a retina specialist’s office and are told the cause of their vision problem requires injections of medication into their eyes. I like to point out to patients that intravitreal injections, which were not available years ago, can save their vision and dramatically improve their quality of life.”

Wet or Dry

One of the primary conditions treated using intravitreal injections is age-related macular degeneration, or AMD, a leading cause of vision loss for ages 60 and older in the US. An estimated 11 million Americans have some form of AMD.

There are two forms of AMD, dry and wet. With dry AMD, vision is often reduced due to thinning of the macula, which is responsible for sharp central vision. Central vision is needed for detailed visual activities such as distinguishing faces, driving and reading.

“I like to point out to patients that intravitreal injections, which were not available years ago, can save their vision and dramatically improve their quality of life.” – Dr. Barnes

About 90 percent of patients with AMD have the dry form. But 10 percent of those with dry AMD progress to wet AMD. With the wet form, new blood vessels form in a process called neovascularization. But these vessels are abnormal and unstable, and leak fluid into the retina, which can lead to rapid vision loss.

Intravitreal injections are used to halt the abnormal blood vessel formation.

“One of the main medications used in intravitreal injections is anti-vascular endothelial growth factor, or anti-VEGF,” Dr. Barnes notes. “Endothelial growth factor is a protein that promotes the growth of blood vessels. Anti-VEGF medications stop abnormal blood vessels from growing and leaking underneath the retina.

“There are three main anti-VEGF medications used for intravitreal injections: bevacizumab, which has the brand name Avastin®; aflibercept, brand name Eylea®; and ranibizumab, brand name Lucentis®.”

Ample Applications

Another condition commonly treated using intravitreal injections is diabetic macular edema, or DME, which significantly affects the macula.

“Diabetic macular edema is swelling in the retina and specifically in the macula,” Dr. Barnes observes. “It occurs in people who have a complication of diabetes called diabetic retinopathy, in which the tiny blood vessels in the retina are damaged and leak. Diabetic macular edema affects central vision, which is important for people’s day-to-day functioning.”

Diabetic retinopathy is the most common diabetes-related eye disease. It is estimated that approximately 7.7 million Americans have diabetic retinopathy, and about 750,000 of them also have DME.

“Diabetic macular edema develops when fluid accumulates in the macula,” Dr. Barnes describes. “The fluid comes from the leaky blood vessels in the retina. When the macula becomes filled with fluid, its specialized cells are unable to function properly and central vision becomes blurry.”

Many of the diseases treated by the retina specialists at Florida Retina Institute, including AMD and DME, involve either an abnormal network of blood vessels or a choroidal neovascular membrane, a collection of new, damaging blood vessels that grow underneath the retina.

“A choroidal neovascular membrane develops in the wet form of age-related macular degeneration,” Dr. Barnes notes. “In patients with diabetic retinopathy and diabetic macular edema, the diabetes causes the existing blood vessels to become incompetent.

“To compensate for the incompetent blood vessels, the body tries to grow new blood vessels. But those blood vessels leak and cause bleeding in the eyes, which can lead to vision loss, particularly when it affects the macula.

“Both of these processes are inhibited by the anti-VEGF medications.”

Intravitreal injections can also be used for other purposes.

“There is a broad range of applications,” Dr. Barnes suggests. “For example, we can use them to treat other disorders associated with swelling in the center of the retina such as blocked blood vessels, which are often related to conditions such as high blood pressure. We can also use the intravitreal technique to inject steroid medication to treat inflammation in the eyes and to inject antibiotics for certain eye infections.”

Feeling the Pressure

Intravitreal injections are generally performed in the office at Florida Retina Institute. The process takes only a couple of minutes to complete, Dr. Barnes reports.

“Before we begin the actual injection, we clean the eye to be treated using Betadine®,” he describes. “We ensure that the patient’s eye is nice and numb, typically employing a series of topical numbing drops.

“In many cases, the retina specialist will inject a numbing medication around the eye, but not into the eye. This will help the patient become nice and comfortable for the actual injection, so during the injection procedure, patients really do not feel any pain. They may feel a little pressure, but for the most part, patients do very well during the injections.”

The actual injection takes a matter of seconds and patients go home the same day. The effect of the injections is not instantaneous. Patients typically notice some improvement in their vision over the following several days to weeks. The outcomes vary because patients respond differently to the medication in the injections, as well as to each injection.

“Every patient is treated individually, but most require more than one intravitreal injection to treat their condition,” Dr. Barnes observes. “The injections are usually performed about once a month at the beginning of the treatment process and are then spaced out over longer intervals later in the process.”

Before recommending intravitreal injections, Dr. Barnes carefully reviews the risks versus the benefits to determine whether the treatment is the best course of action.

Dr. Barnes says intravitreal
injections are among the most, if not the most common, ophthalmic procedure performed in the US.

“The main risk of intravitreal injections is infection, but the rate of infection with this procedure is very low, maybe 1 in 5,000,” Dr. Barnes reports.

“We also advise the patients about signs of infection to watch for after the injections so they can return to the office expeditiously and be treated before the problem can become more severe.”
But Dr. Barnes stresses the benefits of the treatment.

“Intravitreal injections may require multiple visits over many months, but in the end they can preserve central vision and day-to-day functioning,” he emphasizes. “They can also improve overall quality and enjoyment of life. In most cases, the benefit of gaining lost central vision far outweighs the risk of the injections.”

Dr. Barnes points out that for some patients with retinal disease, the retina specialists at Florida Retina Institute perform a combination of therapies that include laser treatment and intravitreal injections. But the injections remain the mainstay of treatment for many retinal disorders.

“The intravitreal injections are a nice adjunct to our treatment of patients that we did not always have available to us,” he says. “And over time, they have become a proven innovation in the field of retina medicine.”

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    • Florida Retina Institute

      Founded by James A. Staman, MD in 1979, Florida Retina Institute has 19 locations throughout Central Florida, North Florida, and Southeast Georgia. They have proudly delivered Excellence in Vitreo-Retinal Diseases and Surgery for 40 years. T... Read More

    • Alexander C. Barnes, MD

      Alexander C. Barnes, MD, is board-certified by the American Board of Ophthalmology. He earned a Bachelor of Science degree from Barrett, The Honors College at Arizona State University in Tempe. He received his Doctor of Medicine degree from T... Read More