Expert panel provides guidelines on how to perform suprachoroidal space injection
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Key takeaways:
- A panel of experts published guidelines on suprachoroidal space injection.
- The guidelines promote current best evidence and clinical experience.
In a paper recently published in Retina, an expert panel of retina specialists provided guidance on suprachoroidal space injection.
“The objective here was to provide guidelines for the issues to be aware of before treatment, during delivery of the treatment and post-treatment when managing patients,” Charles C. Wykoff, MD, PhD, told Healio. “We also go through the anatomy and the medications that are currently approved and those in development. ... But the core objective is to give a blueprint for the steps involved and the mechanics on how to successfully delivery medications into the suprachoroidal space.”
So far, injection into the suprachoroidal space (SCS) has been a niche procedure. However, it presents an opportunity for targeted delivery of medications more directly to affected tissues such as the choroid and retina, according to Wykoff.
“The suprachoroidal space is a potential space that exists between the choroid and the sclera,” he said. “The nice thing about drug delivery into the SCS is that it can serve as a depot for medications that can slowly be delivered to the choroid and/or retinal tissues adjacent to the suprachoroidal space.”
Novel strategy with potential advantages
Wykoff specified that the goal is not to replace intravitreal injections but to add another tool for drug delivery, with potentially multiple applications.
Xipere (triamcinolone acetonide injectable suspension, Bausch + Lomb) is currently the only commercially available drug approved in the U.S. for suprachoroidal administration through a proprietary SCS microinjector. The indication is uveitis-associated macular edema.
“The steroid delivered into the suprachoroidal space may have a lower impact on IOP and potentially on cataract formation compared with intravitreal delivery. You may be able to get the same level of efficacy with good durability and an optimized safety profile,” Wykoff said.
Other therapies administered via suprachoroidal administration currently in clinical trials include axitinib (Clearside Biomedical), a tyrosine kinase inhibitor; ABBV-RGX-314 (Regenxbio, AbbVie), a gene therapy for neovascular age-related macular degeneration and diabetic retinopathy; and AU-011 (Aura Biosciences) for ocular melanoma.
“An intravitreal injection is very common for retina specialists. A suprachoroidal injection involves a slightly different skill set and is very doable for retina specialists,” Wykoff said.
How to inject
SCS injection can be safely performed in an office setting. In addition, 84% of retina specialists participating in triamcinolone acetonide SCS trials stated in a survey that the procedure was not meaningfully more difficult than intravitreal injection and did not present new challenges.
“The biggest challenge is access to the space. ... Two needles are available in the Xipere package. One is 900 µm, and the other one is 1,100 µm,” Wykoff said, noting that the recommendation is to start with the shorter one to decrease the chance of inadvertently injecting into the vitreous cavity.
The needle is inserted perpendicularly through the conjunctiva and the sclera, with firm pressure being applied with the needle to form a dimple on the ocular surface. While maintaining this dimple, the plunger is depressed to slowly inject the liquid.
“Injecting slowly is key to give time for the potential space between the choroid and sclera to expand and the drug to slowly dissipate across the space posteriorly and circumferentially,” Wykoff said.
Retina specialists are used to intravitreal injections, which last about 1 second, while 10 to 30 seconds are required for SCS injections. Injecting slowly is crucial, he said, to avoid causing patient pain or discomfort, to give time for the suprachoroidal space to expand and to prevent the risk of reflux.
“Once the injection is completed, do not withdraw the needle, but wait for another 5 to 10 seconds to allow the injectate to disperse posteriorly and circumferentially so there is less reflux when you remove the needle,” Wykoff said.
While any quadrant can be used for SCS delivery, for ease of access and optimized visualization, the best site for injection is often within the superior temporal quadrant, 4 mm to 4.5 mm posterior to the limbus. In the triamcinolone acetonide trials, the use of the shorter 900-µm needle in the superior temporal quadrant warranted success in 78% of patients. However, other quadrants can be considered, depending on the indication and physician’s judgment. Reattempting injection at a different site or switching to the 1,100-µm needle may be required in some cases.
“It is important to know that 22% of injections were not successful and required a change to the longer needle,” Wykoff said. “There is a tactile release sensation that tells you that you are in the right space when you slowly depress the plunger, and the fluid disperses into the suprachoroidal space; you will feel that the medication is being delivered as needed. However, if you feel resistance, this could mean that the tip of the needle is in the sclera, and you won’t be able to inject. Forcing the injection at this point could lead to scleral dissection and patient discomfort or some other problem.”
There is variability in scleral thickness, both from patient to patient and in the different quadrants for each patient, he said. In some cases, a longer needle may be required to go through a thicker sclera, but this is not something that can currently be predicted upfront, and the shorter needle should always be used at first. If there are signs that the potential suprachoroidal space has not been reached, the recommendation is to stop the procedure and switch to the 1,100-µm needle.
Best evidence and clinical experience
The guidelines feature a series of considerations and provide detailed guidelines and comments to address questions retina specialists may have when performing suprachoroidal injection.
“Do you need to use povidone-iodine? Do you need to use a lid speculum? How do you monitor intraocular pressure? We talk specifically about the needle length and selection, the risk of a short needle vs. the risk of the longer needle and much more,” Wykoff said.
The authors of the paper, Wykoff said, convened in person specifically to discuss the experiences and learnings they have gained from performing multiple SCS injections with the commercial product and in clinical trials over many years.
“SCS injection is still an evolving and relatively novel approach, and our guidelines reflect the current best evidence and clinical experience of the expert panel. There is currently only one product and one specific indication, but I believe this mode of injection will be used more broadly over time,” Wykoff said.
Reference:
For more information:
Charles C. Wykoff, MD, PhD, of Retina Consultants of Texas, can be reached at charleswykoff@gmail.com.
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