Varied Syringe Accuracy Affects Intravitreal Injection Safety

For a study, researchers delved into the accuracy and residual volume of commonly used syringes for intravitreal injection (IVI) and investigates their potential impact on intraocular pressure (IOP). Considering that many of the syringes in use were not specifically developed for IVI, and given the small drug volumes involved, the researchers aimed to assess their precision and residual volume, along with the resultant IOP changes at different injection volumes.

Eight syringe models, including BBraun Injekt-F 1 mL, BBraun Omnifix-F 1 mL, BD Plastipak Brazil 1mL, BD Plastipak Spain 1 mL, BD Ultra-Fine 0.3 mL, HSW Norm-Ject 1 mL, Zero Residual 0.3 mL, and Zero Residual Silicone Oil-free 0.2 mL, were meticulously examined with two different needle setups (TSK and Zero Residual), utilizing two different solutions (distilled water or glycerin) and target volumes (50 and 70 µL). The study included ten samples in each subgroup, totaling 80 samples for seven syringe models (half with each needle model) and 40 for the BD Ultra-Fine (own staked-in needle).

Through precise weighing before liquid withdrawal, with the liquid, and after its release, the researchers calculated the residual and delivered volumes. To evaluate IOP changes, an experimental eye model was designed, and the transient rise in pressure following injections of various water volumes (ranging from 20 to 80 µL) was measured using a standard Hamilton Microliter Syringe.

The results revealed substantial differences in accuracy and residual volume among the various syringe models. BD Ultra-Fine, Zero Residual, and Zero Residual Silicone Oil-free demonstrated the lowest residual volumes, while Zero Residual Silicone Oil-free, Zero Residual, and BD Ultra-Fine showcased the highest accuracy. Additionally, the peak IOP varied with injection volume, indicating potential implications for patient safety due to volume excess.

This study highlights the critical importance of syringe accuracy and residual volume assessment for IVI procedures. The findings provide valuable insights for clinicians, raising awareness of the potential impact on IOP and patient safety when using different syringe models for intravitreal injections.