How is an intravitreal injection for wet (exudative) age-related macular degeneration (AMD) administered?

Updated: Oct 10, 2019
  • Author: David T Wong, MD, FRCSC; Chief Editor: Andrew A Dahl, MD, FACS  more...
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Answer

Answer

Confirm the eye undergoing treatment.

Apply anesthetic of choice.

Instill povidone-iodine solution. The authors use Povidine-iodine 5%. It is applied to the conjunctival sac, lids, and lashes following the instillation of anesthetic. After a few minutes, another drop is instilled over the site. As an alternative to povidone-iodine solution, chlorhexidine may be used. This is useful in patients who have an allergy or intolerance to povidone-iodine. [11]

Insert speculum (see image below). This is optional but prevents the lids from closing during the injection. If no lid speculum is to be used, the location of injection should be the inferior quadrants to reduce the likelihood of the lids touching the needle.

After a subconjunctival injection of lidocaine 1% After a subconjunctival injection of lidocaine 1% and topical anesthesia, a lid speculum is placed. A 5% povidone iodine solution is used to clean the conjunctival surface.

Use the scleral marker to mark the injection site at 3.5 mm for a pseudophakic eye and 4 mm for a phakic eye. The author prefers the superotemporal quadrant, although some protocols describe an inferotemporal approach.

Inject gently into the mid-vitreous. An oblique entry (tunneled approach) may reduce the risk of reflux and aid in the construction of a self-sealing wound. [12] This can be particularly relevant in vitrectomized eyes.

Gently apply the sterile cotton tip to tamponade the injection site following withdrawal of the needle for 10 seconds with a gentle rub. This helps reduce reflux.

Check vision and central retinal artery perfusion.

Flush the eye with lubricants/balance salt solution to remove any residual povidone-iodine to reduce postinjection irritation. Topical antibiotics are optional, although evidence is growing that they are unnecessary and potentially increase the risk of bacterial resistance. [13, 14, 15]

The patient needs to be aware that severe pain, visual loss, or marked hyperemia of the globe requires urgent re-assessment by the ophthalmologist. A mechanism must be in place to allow the patient to contact the treating ophthalmologist or a member of the team urgently after hours.

A recent survey of intravitreal techniques by retinal specialists in the United States found only one third of participants wear sterile gloves for intravitreal injections. [16] Most (83%) did not displace the conjunctiva prior to injection, and most used a 30-gauge needle for injection of ranibizumab or bevacizumab. Although most respondents in this study did not use prophylactic topical antibiotics pre-injection, 81% used topical antibiotics post injection.


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