Abstract
Purpose :
We described a novel method to quantify the waste volume left into the plastic syringe after anti-VEGF injection and elected the best plastic syringe to use during intra-vitreous injections.
Methods :
We evaluated the amount of fluid retained in eight different types of insulin/tuberculin syringes with permanent needle design and without needle design used to perform intra-vitreous injections commercially available in the Brazilian marketing. Firstly, we divided the syringes types in group of ten samples and they all were weighted using a precise (0.01g) caliper balance.
In a second phase we filled the syringes with water, removed air bubbles and then pushed the syringe piston to the mark of 0,05ml. All the syringes were immediately weighted again. Then, we simulated an intra-vitreous injection pushing the piston to the end (mark 0.00) and we immediately weighted.
Results :
All results are described in the table 2 and 3. Mean residual weight into the dead space of syringes with permanent needle design was between 0.002 to 0.006 g and the syringe without needle was 0.032g. No statistic significant was observed in samples of syringe with permanent needle design but comparing all syringes with permanent needle design to the syringe without needle all results were statistically significant (P < 0.01). This indicates that a significant amount of volume loss is due to dead space if we use syringe without needle design.
Conclusions :
Our study showed if we use a syringe without needle a residual volume of 58 per cent of the total amount injected remains in dead space, which means a despise of one dose treatment (0.05ml) for each two injections . During the years of 2006 to 2015 almost one billion injections were performed in USA. Considering the use of syringe with permanent needle we should save almost half treatment dose per injection and consequently reducing the cost treatment.
In conclusion, we highly incentive physicians to use syringe with permanent needle to perform intra-vitreous injections. New techniques to compounder into multiple doses the anti-VEGF using syringes with permanent needle is necessary to reduce the treatment cost per patient.
This is a 2021 ARVO Annual Meeting abstract.