As the name implies, intravitreal injections are injections of medication into the vitreous — the gel that fills the back portion of the eye. A variety of medications can be injected in this manner. Below is a description of the most commonly injected medications.
Severe infection can arise inside the eye. This condition is known as endophthalmitis. Although it is rare, it can cause severe visual loss. It is encountered most often after severe eye injuries, cataract surgery and intravitreal injections of medications like Avastin, Lucentis and triamcinolone. Endophthalmitis is most often caused by bacteria but is occasionally due to fungi. Antibiotics (medications that kill bacteria) are injected into the vitreous to treat bacterial endophthalmitis. The antibiotics most commonly injected are vancomycin and ceftazidime. They are often injected together, because this combination of antibiotics is able to effectively treat nearly all intraocular infections.
Avastin is a medication that is injected into the vitreous of the eye for treatment of a number of disorders, including “wet” macular degeneration, retinal swelling and abnormal blood vessel growth due to diabetic retinopathy, and blockages of retinal veins. Avastin was developed and FDA-approved for the treatment of metastatic colon cancer but is used very frequently in the treatment of eye diseases. It is usually injected about every six weeks when treatment is initiated, and the interval between injections is often lengthened gradually. Because the effect of Avastin declines over time, it often has to be injected indefinitely in order to maintain its beneficial effect on the vision.
Lucentis, like Avastin, is injected into the vitreous of the eye for treatment of a number of disorders, including “wet” macular degeneration, retinal swelling and abnormal blood vessel growth due to diabetic retinopathy, and blockages of retinal veins. It was developed and FDA-approved initially for treatment of “wet” macular degeneration but has also been FDA-approved for treatment of branch and central retinal vein occlusions, as well as diabetic retinopathy.
Eylea is also injected into the vitreous and inhibits growth of abnormal blood vessels behind the retina in patients with wet macular degeneration, reduces retinal swelling in patients with central retinal vein occlusions and diabetic macular edema, and can be used for diabetic retinopathy. It is like Avastin and Lucentis, but it works through a different mechanism. It seems to improve and maintain vision at least as well as Avastin and Lucentis and its duration of action seems to be longer. Because of its longer duration of action, it may be able to reduce the burden of treatment on both patients and doctors alike.
Vabysmo is the newest injectable medication for “wet” macular degeneration and diabetic macular edema, approved by the FDA in 2022. Several clinical trials that led to the approval of this medication suggested the drug may be more potent, resulting in less “leaking” of the macular blood vessels. As a result, patients may benefit from fewer required injections in the long-run, with many needing treatments only once every few months, even beginning in the first year.
Triamcinolone is a corticosteroid — a type of medication most known for its ability to reduce inflammation. Inflammation develops when the body’s immune system is overly active. Prednisone is the most well-known corticosteroid. It is taken by mouth for a variety of inflammatory diseases. Triamcinolone can be injected into the vitreous to reduce inflammation in the eye (also known as uveitis), but it can also be used to reduce swelling in the retina (also known as macular edema). Common causes of macular edema for which triamcinolone is sometimes injected into the vitreous include diabetic retinopathy, retinal vein occlusions and cystoid macular edema. The main side effects of triamcinolone are glaucoma (elevated eye pressure) and cataracts. There is approximately a 30% chance of glaucoma with intravitreal triamcinolone injections. Cataracts are accelerated in most patients who receive intravitreal triamcinolone injections, but they usually develop quite gradually.
The Ozurdex implant consists of dexamethasone, a corticosteroid like triamcinolone. It slowly dissolves in the vitreous, exerting its therapeutic effect over several months. It is currently FDA-approved for uveitis (inflammation in the eye), retinal vein occlusions and diabetic macular edema. Like triamcinolone, Ozurdex can cause elevation of the eye pressure and progression of cataracts.
Iluvien/Yutiq is an injectable microimplant designed to release a continuous, low-dose treatment to the retina for up to 36 months to help maintain consistent vision longer in patients with diabetic macular edema (DME) or uveitis. The medicine in the implant is called fluocinolone acetonide, a corticosteroid, helps treat the inflammation associated with DME or uveitis. Similar to other steroid injections, Iluvien can cause elevation of the eye pressure and progression of cataracts.
This medication is a novel FDA-approved treatment of macular edema associated with uveitis. The medication is a corticosteroid (triamcinolone) which is injected into the suprachoroidal space (a location between the sclera and vascular layer of the eye called the choroid). It is yet another option for patients with macular edema associated with uveitis and has a lower reported incidence of intraocular pressure elevation.