All syringes used for intravitreal injections have pros and cons. Some recently marketed and forthcoming products are coming closer to meeting “ideal” criteria.
Syringes from different models and brands outlined throughout the text. (Photo courtesy of Gustavo B. Melo, MD, PhD)
This article was reviewed by Gustavo B. Melo, MD, PhD
The ideal syringe for administering intravitreal injections does not exist. With improved awareness of the drawbacks of existing devices and the characteristics desired for intravitreal use, however, syringe manufacturers are stepping up to design products that will help maximize the safety and efficiency of intravitreal injection, said Gustavo B. Melo, MD, PhD.
“Retina specialists are well aware that intravitreal injection can lead to the presence of silicone droplets in the vitreous. The droplets come from the syringes used for injection because most are manufactured with silicone oil to allow for better glide of the plunger. In addition, almost all needles are dipped in a silicone oil bath to coat the outer surface to enable tissue penetration,” said Melo, an associate researcher at the Federal University of São Paulo and the head of the ophthalmology residency at Sergipe Eye Hospital, Brazil.
“Available data show these droplets matter,” he said. “In the 2018 American Society of Retina Specialists PAT [Preferences and Trends] survey, 5% of US retina specialists said they had done vitrectomy for symptomatic droplets and 2% have patients seeking legal action for their floaters. In addition, silicone droplets are linked to inflammatory reactions after aflibercept injection.”
Defining the ideal syringe
According to Melo, the ideal syringe for intravitreal injections would be silicone oil free; have negligible dead space to minimize expensive medication waste; use an attachable needle, giving physicians the option to choose their needle; and feature a Luer lock tip that allows for an attachable needle and prevents liquid leakage along with accidental needle removal.
“Preferably, it would also be designed for ophthalmic use,” Melo said.
Outlining pros and cons
Melo and Geoffrey G. Emerson, MD, PhD, an ophthalmologist in private practice at The Retina Center in Minnesota, reviewed the advantages and disadvantages of syringes used for intravitreal injections, including those most commonly used in the Americas and Europe, along with emerging products.
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They based their information on the silicone oil released by each syringe on scientific publications and personal research. Clinical and scientific experiences were the foundation for comments on additional features.
“Our review included the syringes that we are aware are being used for intravitreal injection. Other syringes, both good and bad, may be available,” Melo said.
Best of the batch
The OcuJect syringe (SJJ Solutions), which is expected to receive CE and FDA certification in mid 2021, seems to meet all the ideal criteria outlined by Melo. It is silicone oil free, has a low volume of dead space and a Luer lock tip, and is designed for ophthalmic use.
The StaClear syringe (TriboFilm Research) recently received FDA clearance for marketing for use in intravitreal injections. It has low dead space and low particulates, complying with USP Chapter 789 testing for ophthalmic solutions.
The syringe is manufactured with a silicone lubricant, but the lubricant is fixed to the syringe’s lumen.
The Zero Residual Luer Lock syringe (SJJ Solutions) is another syringe that has a lot of positive characteristics. It has a low volume of dead space and a Luer lock tip, can be prefilled air free, and is designed for ophthalmic use. It is not silicone oil free, as it is lubricated with a small amount of oil.
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The Daikyo Crystal Zenith (West Pharmaceutical Services) and Plajex (Terumo) syringes have the advantages of being silicone oil free and having a Luer lock tip. In addition, the Daikyo Crystal Zenith complies with USP Chapter 789. However, both syringes have significant dead space and are not available to be filled at point of care.
The Injekt-F (B. Braun Medical Inc) and Norm-Ject (Henke-Sass Wolf) syringes have the advantage of being silicone free. However, they both have moderate dead space and a Luer slip tip.
“The protruding tip of the Injekt-F syringe helps to minimize dead space. However, the design of this syringe can lead to some confusion regarding the injected volume,” Melo noted.
The longer list
The BD Luer-Lok syringe (Becton, Dickinson and Company), which is distributed with aflibercept in some markets, has a Luer lock tip. On the downside, it is siliconized, albeit with a small amount of silicone oil. In addition, this syringe has a large dead space that wastes expensive drugs, and it is heavy.
Similarly, the company’s BD Plastipak syringe, which is available worldwide, and BD Tuberculin syringe, which is more commonly used in the US, are also siliconized and have significant dead space. Another disadvantage is that they have a Luer slip tip.
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Available in many markets, the BD Ultra-Fine syringe is an insulin syringe that has negligible dead space. However, it is siliconized with a large amount of oil.
“This syringe is notorious for its association with silicone oil droplets in the vitreous,” Melo pointed out. “It has a fixed needle that cannot be substituted.”
Distributed with ranibizumab (Lucentis, Genentech/Roche) in some markets, the Omnifix-F syringe (B. Braun Medical Inc) is siliconized but with just a small amount of silicone oil. However, it has significant dead space and a Luer slip tip.
The Comfort Point insulin syringe (Exel) is available in the US. It has negligible dead space but a fixed needle, and although it is also siliconized, it releases less oil than the BD Ultra-Fine syringe, according to Melo.
Available in many markets, the insulin syringe manufactured by Terumo Medical also has a low volume of dead space. However, it has a fixed needle and releases a large amount of silicone oil.
Gustavo B. Melo, MD, PhD
This article is based on Melo’s video presentation at the European Society of Retina Specialists 2020 Virtual meeting. Melo and Emerson have no financial interests to declare.