This article provides an overview of essential knowledge regarding intra-vitreal injections.

 

With the emergence of anti-angiogenic medications for intra-vitreal application, the prognosis and management of retinal and macular conditions have significantly improved. The increase in life expectancy, among other factors, has led to a rise in the number of injections administered. For instance, in 2016 alone, approximately 5.9 million injections were given in the United States, and this number has since increased and is expected to continue rising. Consequently, it's crucial to understand the technique involved in this procedure.

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The primary focus of the current technique revolves around preventing one of the most dreaded complications in ophthalmology: post-injection endophthalmitis. Several meta-analyses have reported varying rates of this complication, ranging from 1 case per 1,500 to 1,700 injections to as low as 1 case per 7,200 injections¹ ². How can we achieve a lower incidence of this complication? Let's discuss step-by-step considerations.

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Firstly, the injection site is crucial, not referring to the ocular site but the designated space for the procedure. While many ophthalmologists perform injections in-office with acceptable safety rates, recent studies suggest that performing injections in a specifically designated area yields better outcomes. Although there isn't a significant difference in why, for example, performing injections in the operating room might be better, there is a lower incidence of endophthalmitis reported in this setting, with positive cultures showing no bacterial growth.³

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The most common causative agent of endophthalmitis is coagulase-negative staphylococci, typically found on ocular surfaces and adnexa. Therefore, the "environment" of the operating room, with cleaner air, likely doesn't directly influence this outcome; instead, stricter aseptic and antiseptic measures are likely followed, reducing the probability of bacterial contact,⁴

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The second factor involves the manipulation and preparation of the injection area. Pre-injection cleansing of the periorbital area and eyelid margin with 10% povidone-iodine is recommended. There's no evidence that drapes and gloves reduce the risk of endophthalmitis, but it can be done for added precaution, depending on surgeon preference and material availability. The use of a speculum is recommended to isolate the eyelid margins and keep eyelashes away from the injection site. Although some patients find speculum placement uncomfortable, it can be omitted if eyelid isolation can be achieved adequately. However, minimal manipulation of eyelids is recommended to reduce glandular expression to decrease bacterial migration to the ocular surface² ³ ⁵.

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The third criterion is the application of 5% povidone-iodine on the ocular surface, which is considered the gold standard. This agent is highly effective against bacteria, fungi, and viruses, with no reported resistance. It's recommended to apply a drop in the eye, preferably in the quadrant where the injection will occur. Some suggest rinsing with a balanced saline solution afterward. After applying povidone-iodine, wait approximately 15 to 30 seconds, although leaving it for 1 to 2 minutes is recommended. Using 1 to 2% povidone-iodine is also effective, reducing irritation commonly associated with ocular use.²,⁵

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The fourth and arguably most crucial criterion is the use of antibiotics.²,5 They are not recommended, as many studies and meta-analyses confirm. Overuse of antibiotics can lead to bacterial resistance, potentially worsening endophthalmitis outcomes. Only sterile lubricating drops can be recommended a few days post-injection to reduce povidone-iodine irritation. Patients should avoid environments with high pollution (dust, smoke) and refrain from exposing the injected eye to running water for 24 to 48 hours. Patching the eye is not advised, as it removes the protective effect of blinking and producing tearing, allowing bacteria to accumulate more quickly in the conjunctival sac.

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This brief article is evidence-based and draws recommendations from real-world clinical practice. While other agents like chlorhexidine can be used for disinfection, and additional details regarding injection technique can be discussed separately, we aim to provide more information soon. We're eager to engage in dialogue if you have any questions or concerns or wish to share your techniques and suggestions. Our goal is to contribute to the advancement of ophthalmological academia and foster mutual learning. You can watch an illustrative video of the method and topics mentioned in the article in the "Media – Videos- Intravitreal Injections:

The Balance of what we need to know" section or by following this link.

https://youtu.be/nwTSX9UjiWE?si=_QK5bYrEZIeXY-R8.