Swinging vs Flicking: Assessing Safer Removal Techniques for Air Bubbles in Intravitreal Injections

To evaluate whether a gentler swinging motion, rather than flicking, can effectively eliminate air bubbles from syringes before intravitreal injections while minimizing particle generation.

Three syringe models were assessed under controlled conditions: Zero Residual Silicone Oil (SO)-free 0.2 mL syringe, BD Tuberculin 1 mL slip-tip syringe (siliconized syringe 1), and HSW Soft-Ject 1 mL Luer-Lock syringe (siliconized syringe 2). Two solutions were tested: a polysorbate-based buffer and bevacizumab (Avastin). Each syringe was subjected to 3 handling conditions: no agitation (control), swinging (hand-induced centrifugal movement), and flicking. The number of released particles was quantified using FlowCam imaging, and statistical analyses were conducted to compare handling techniques and syringe models.

Flicking significantly increased particle release compared with both swinging and the control condition (P < .01). Swinging consistently resulted in lower particle counts across all syringe models compared with flicking, although the decrease in magnitude varied. The SO-free syringe demonstrated the lowest overall particle release, whereas siliconized syringes exhibited greater variability in particle release. Particle distribution also differed between the buffer and bevacizumab solutions, suggesting that fluid composition influences particle formation and release.

Compared with flicking, a gentle swinging motion reduced particle release across syringe models while allowing air bubbles to be removed. This technique may represent a simple modification to intravitreal injection preparation that could reduce particulate contamination.