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Unmet Needs and the Importance of Selecting Needles for Proper Intravitreal Injection


Nadia K. Waheed, MD, MPH; and David M. Brown, MD, review unmet needs and the importance of selecting the proper needle for intravitreal injections.

Nadia K. Waheed, MD, MPH: Are there any specific unmet needs in the treatment with intravitreal injections? And I know durability was one of the pieces mentioned early on, but anything else that you’d like our pharma colleagues to know, or that you want to highlight here?

David M. Brown, MD: I think the biggest unmet need, and particularly in the technique, is Betadine. We all know that that decreases the amount, but there are patients that are incredibly intolerant to povidone-iodine, there are patients that will refuse to get it—they’d rather go blind than have a red itchy eye for 3 weeks, until 1 week before they come back for an injection. And certainly, there are alternatives to povidone-iodine. I know people are working at that, are there hypochlorite or whatever other options would be great. When the injections first came out in 2006, I worked with a bunch of patients with different needles. And I was trying to figure out if you do topical, what is the best option? And Poiseuille’s Law basically just shows you that the shorter the needle and the bigger the diameter, the easier it is to push fluid through. But the longer the needle is the opposite. I got TSK [Laboratory International], a Japanese company, to make the 11-mm, 22-gauge that a lot of people use now. Japanese Bio Products Co Ltd sort of knocked it off and they make very good needles. They make a 33-gauge that’s shorter. The shorter needles don’t flex as much if you’re using a smaller gauge. That being said, it’s more of a problem with our newer drugs. Well, Vabysmo is pretty viscous. The APL-2 coming out is very viscous. I think we’re going to have to go to even shorter needles and potentially a larger internal bore for the injections.

Nadia K. Waheed, MD, MPH: The needles you’re having must have the appropriate needle design.

David M. Brown, MD: One other thing to talk about is you want to use the Luer-Lok syringe. When you have a viscous drug and a smaller needle, you’ve probably all seen it with Kenalog or triamcinolone where you can shoot the needle out, and the same thing can happen with these more viscous drugs. Thus, Luer-Lok syringes are important as the drugs get more viscous.

Nadia K. Waheed, MD, MPH: And I think that’s a really important point, because I do remember injecting one of the more viscous drugs. I think this was as part of a clinical trial, and just having the 30-gauge, and this was coming off every time I tried to pull off the cap because they are more viscous. They also coat the surface of the needle and then everything is slipping. Then, you have to throw stuff away and start all over again.

David M. Brown, MD: And I hate siliconized syringes. I switched to nonsiliconized syringes in 2006. The HSW syringe, the green one from Germany. Unfortunately, it doesn’t come in a Luer-Lok. That being said, when you look for needles, you do want a siliconized needle. A nonsiliconized needle doesn’t go through the sclera very well. And it turns out you don’t get any silicone in the eye from a needle that’s siliconized on the outside, just a sclera kind of squeegees it out as you go through the sclera. Thus, don’t be afraid of ordering siliconized needles. Although I really don’t like putting exogenous substances in the eyes. I prefer nonsiliconized syringes, which lubricate the plunger inside. To me, that’s important.

Nadia K. Waheed, MD, MPH: Very, very important point.

Transcript Edited for Clarity

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