The medications are injected directly into the eye. The eye can safely be injected at the point where the white part of the eye meets the colored part of the eye(the pars plana). Injections in front of the white part of the eye could damage the lens in the eye. Injections too far behind the white part of the eye could injure the retina.
The most serious complication of intravitreal injections is infection. The risk of infection is about 1 in 5,000. Infection can be serious and lead to loss of vision and loss of the eye. Subconjunctival hemorrhage, bleeding on the surface of the eye occurs in 10 percent – 20 percent of treatments. Floaters occur in about 10 percent of treatments. With long term treatments about 10 percent of patients develop increased intraocular pressure.
Avastin and Lucentis were first given for wet AMD in 2005. Since then, several newer medications have come on the market and more are in development. The goal of most of the newer treatments is to reduce treatment burden. Treatment burden is the frequency with which the treatments need to be administered. In addition, some newer treatments may be more effective because they are stronger. Very few treatments have been compared head to head in clinical trials. When studies have been done, most treatments have been shown to be equivalent if given frequently.
In general, the longer someone has been treated with an intravitreal injection, the less often they require treatment.
Some of the more recently developed medications, like Vabysmo and Eylea HD are designed to only require treatment every 4 months in the majority (but not all) patients.
There are three different methods of administering anesthetic for intravitreal injections, topical drops, a pledget (sponge soaked with anesthetic) and a subconjunctival injection of lidocaine. Different people prefer different methods. As of this writing (2023), the majority of our patients prefer the pledget.
It is impossible to know how many injections each individual patient will need. Some patients require a limited number of injections and some require ongoing therapy for years. Depending on your disease (macular degeneration, retinal vein occlusion, diabetic macular edema) and the drug being used (Lucentis, Eylea, Avastin, Ozurdex, Illuvein), the answer may be slightly different. All medications injected into the vitreous eventually wear off. Most have an effect for only a few months. Also medications used to treat retinal disorders do not cure the disease, they only control it. Most injections are given for macular degeneration. Macular degeneration is a chronic disease and often requires ongoing therapy. Most studies have shown that patients treated more frequently for retinal diseases do better than those treated less frequently. Most retina doctors in the county use a ‘treat and extend’ protocol with intravitreal injections. Monthly injections are given for a time and then treatments are given less frequently and the disease is assessed. If a longer treatment interval results in recurrent disease, then the treatment interval is shortened. If not, the treatment interval can be maintained or lengthened.
Intravitreal injections work. Without treatment, many patients lose their central vision. With treatment, central vision is usually maintained. It is easier to live an independent life when you can see. Therefore, we usually encourage our patients to proceed with treatment regardless of their age.
Patients rarely recover normal vision. Most macular disease causes some permanent damage. Treatment can significantly reduce the risk of vision loss. In addition, most patients see better with treatment than they did before starting treatment. Normal vision is rare. About 10 percent of patients recover normal vision with intravitreal therapy. Most of those patients started with very good vision before therapy.
There are several medications available to treat most retinal diseases. Treatment can take 3 to 6 months before a benefit is realized. If one medication doesn’t work, sometimes switching to a different one helps. In addition, there are sometimes alternative to intravitreal therapy that can be considered if intravitreal therapy is not working. In almost all cases, intravitreal injections are the safest and most effective treatment. For some disorders (especially diabetes), laser can be considered. Some retinal vein occlusions also respond to laser. Wet AMD can be treated with cold laser (photodynamic therapy). Studies have shown that in almost all cases, photodynamic laser is not as effective at improving vision as intravitreal injections.
With many macular disease, distortion can persist for a year or two even when the visual acuity improves. In some cases, as the visual acuity improves, the distortion may become more noticeable because the patient, in seeing better, sees the distortion better. Usually, over time, distortion becomes less bothersome as the eye and the brain adapt to the state of the macula.
Most intravitreal injections cost over a thousand dollars per dose. Some cost much more. One reason the medications are so expensive is that research and development of medications is very expensive. It can cost 100 million dollars in research to bring a drug to market. Another reason is that, in the US, Medicare is prohibited from negotiating price of drugs with drug companies. In 2003, Congress and President Bush enacted the “Medicare Prescription Drug, Improvement and Modernization Act,” which established a prescription drug program for Medicare. That legislation expressly prohibited Medicare from negotiating drug prices with pharmaceutical companies.
As of 2023, medicare is starting to negotiate drug prices with pharmaceutical companies, but on a limited basis. Eventually, this may bring down the costs of intravitreal therapy.
The anti-VEGF medications are proteins that cannot be administered into the eye in any way other than injection. Topical therapy was tried and did not work. Steroid injections into the eye (ozurdex and illuvein) can be given systemically and topically. The doseage level achieved by these alternate routes does not work to treat most macular disease.
Yes, there are several potentially longer acting treatments being researched. None are close to being approved by the FDA for use outside of research studies. Genetic therapy has the potential to treat a patient with a single treatment. Then the patient would start making their own drug. There is an encapsulated cell technology that might be able to deliver therapy over a few years. Until something long acting is avialable, ongoing treatment with intravitreal injections is the best and most effective treatment for many macular diseases.
Intravitreal injections for wet AMD were approved by the FDA in 2006. So there are many patients who started treatment then and have had over 100 treatments. The needles used for the injections are very small and don’t cause scarring. There may be some adverse affects of long term anti-VEGF therapy. About 10 percent of patients getting long term therapy develop increase intraocular pressure. This could be from inflammation or possibly from the build up of material in the drainage channels in the eye. There may be increased risk of geographic atrophy in some patients receiving long term anti-VEGF therapy. These risks are small and considered acceptable given the tremendous benefit that ongoing anti-VEGF therapy confers on pateints.