Silicone oil‐free syringes, siliconized syringes and needles: quantitative assessment of silicone oil release with drugs used for intravitreal injection

Abstract

Purpose: This study aimed to quantify the amount of silicone oil (SO) released across a variety of syringe and needle models routinely used for intravitreal injection. Methods: The release of SO was assessed in eight models of syringes, two of which were reported to be 'SO-free', and eleven models of needles with unknown SO content. To evaluate SO release within the context of anti-VEGF therapeutics, syringes were evaluated using aflibercept, bevacizumab, buffer, ziv-aflibercept and formulation buffer. All syringe tests were performed with or without agitation by flicking for syringes. Needles were evaluated without agitation only. Samples were fluorescently labelled to identify SO, and triplicate measurements were collected using imaging flow cytometry. Results: Seven out of 8 syringe models showed a statistically significant increase in the SO particle count after agitation. The two SO-free syringe models (HSW Norm-Ject, Daikyo Crystal Zenith) released the least SO particles, with or without agitation, whereas the BD Ultra-Fine and Saldanha-Rodrigues syringes released the most. More SO was released when the syringes were prefilled with formulation buffer than with ziv-aflibercept. Syringes filled with aflibercept and bevacizumab had intermediate levels. Agitation increased the release of SO into each of the drug solutions. Silicone oil (SO) was detected in all needles. Conclusions: Agitation of the syringe by flicking leads to a substantial increase in the number of SO particles. Silicone oil (SO)-free syringes had the best performance, but physicians must also be aware that needles are siliconized and also contribute to the injection of SO into the vitreous.

Determination of Hyaluronic Acid Dermal Filler Impurities Using SEM/EDS Analysis

“…The total amount of Si oil (~0.6–1.0 mg/mL) and its distribution in prefilled syringes can impact syringe functionality and particle formation [ 25 , 26 ]. The siliconized polypropylene insulin syringes showed significantly higher silicone oil particle counts than the prefilled glass syringes [ 27 , 28 ].…”

Prevalence and implications of the presence of intraocular silicone oil droplets in patients treated with intravitreal injections of anti-VEGF

“…These variations in the prevalence of droplets can be attributed to many other factors, such as the form of presentation, the repackaging, transport and manipulation of the drug, or even the examination technique. Recently, and by means of fluorescence labelling and imaging flow cytometry, micro-sized droplets (0.1–10 μm size range) have been detected in the vitreous of patients [ 5 ]. These cannot be detected by slit-lamp observation and recent literature point to its potential inflammatory power [ 6 ].…”

“…In 2020 Olea et al conducted a study with silicone oil-free syringes and demonstrated absence of oil droplets larger than 25 μm [ 9 ]. Other authors, like Mello et al have found trace amounts of silicone oil released from purportedly silicone oil-free syringes [ 5 ].…”

“…Since 2006, the presence of silicone oil droplets has been observed in the vitreous of those patients who received intravitreal injections [ 2 ] and the quantity of these is directly proportional to the number of doses received [ 3 , 4 ]. Macro-sized droplets (larger than 100 μm) are typically visible to naked eye, while micro-sized droplets (up to 60 μm) can only be observed with technologies such as imaging flow cytometry [ 5 ]. In our study, we will always refer to macro-sized droplets because of the examination technique employed.…”

“…On the other hand, silicone oil when used as a plugger in retinal detachment surgeries can pass into the anterior chamber and cause ocular hypertension by blocking the iridocorneal angle. Most commercially available needles also are siliconized in their inner lumen [ 5 ].…”