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Intravitreal Injection

What is an Intravitreal Injection?
A major advantage when treating diseases of the eye is the ability to give medications directly to the area involved, minimizing systemic risk and side-effects. Topical medications are most commonly used to accomplish the delivery of medications to the eye but are limited by the inability to penetrate deeply into the ocular structures. Often, it is necessary to administer the medication directly into the eye using an injection. The medication is injected into the main body of the eye known as the vitreous body giving the name, intravitreal injection. Many different medications can be given this way, most commonly to treat Age Related Macular Degeneration and Diabetic Macular Edema but also steroids to treat Uveitis or Retinal Vascular Occlusions. 
 
Will it hurt?
Before the medication is given, the eye is well anesthetized with topical gel and often an anesthetic injection under the skin of the eye. Most injections do not hurt but sometimes have a pressure sensation. The procedure does not last long and any discomfort associated with the injection quickly goes away. 
 
How is the procedure performed?
After the eye is numb, a small eyelid speculum is placed to hold the eyelids open. If necessary the surface of the eye is measured and marked to ensure proper placement of the needle. Povidone iodine is used to clean the surface of the eye and the eyelids to kill any bacteria present that may lead to an infection. The injection is then performed using a 30-gauge or 32-gauge needle to inject 0.05 mL to 0.1 mL of medication.
 
What are the risks?
The greatest risk when performing an intravitreal injection is the risk of infection. Large studies of patients reveal an overall risk of about 1 in 2000 or about 0.05%. While the risk is small, it cannot be made zero so precautions are taken to reduce the risk as much as possible. The greatest way to reduce the risk is to clean the eye with povidone-iodine (Betadine) prior to injection. If an eye infection occurs after an injection it will cause significant pain and decreased vision from a significant inflammatory reaction. Any symptoms following an injection should be reported and an examination performed to determine if an infection is present because the infection can cause serious and permanent damage to the eye and the sooner the eye is treated the better. Other risks associated with intravitreal injections are possible bleeding in the eye, damage to the lens, elevated eye pressure, and retinal tears or detachments. While all possible measures are taken to reduce these risks as much as possible they can never be zero and are important to consider when undergoing treatment. 
 
What do I need to do after the procedure?
After the injection the does not require a patch and no eye drops are necessary. Normal activity can be resumed the day of procedure and heavy lifting 1 day after. It is recommended to avoid any water or liquid in the eye for 1 day after the injection and avoid swimming or hot tub for 3 days to further reduce the risk of infection. If any irritation is present from the betadine, preservative free artificial tears can be applied, since they have an individual container they will be sterile and not add any risk of contamination to the surface of the eye. 
 
What symptoms should I be concerned about?
As above, the most concerning thing is the development of an infection that can start as significant eye pain, decreased vision, or seeing floaters. Any of these symptoms should be reported immediately so an exam can be scheduled to evaluate the eye.
 
Due to the anesthesia and the medication injection the eye can bruise, causing the skin of the eye to be bright red. Similar to a bruise of the skin it can take up to a week for the redness to go away. Sometimes, especially if taking blood thinners, the bruising can be significant but does not cause any damage to the eye and will resolve without treatment. 
 
Sometimes, the medication will have small air bubbles that are transferred into the eye. These bubbles will be seen directly after the injection as small, black spots in the vision. They represent no risk and the eye will absorb then in 1-2 days. 
 
Dr Kruti Dajee Dr Jawad Qureshi Dr Johnathan Warminski