THE RELATIONSHIP BETWEEN STOPPER POSITION AND INJECTION VOLUME IN RANIBIZUMAB AND AFLIBERCEPT PREFILLED SYRINGES

Risk of transient vision loss after intravitreal aflibercept using vial-prepared vs. the novel prefilled syringe formulation

Purpose

To compare the risk of transient vision loss (TVL) probably attributable to a severe intraocular pressure spike after intravitreal aflibercept application using the novel prefilled syringe (PFS) vs. the established vial system (VS).

Methods

Datasets of the intravitreal injection service of the Ludwig Maximilians-University Munich and the Technical University Munich, Germany, were screened for documentation of TVL after intravitreal injection of aflibercept. The observation period included two full months prior to the introduction of the novel PFS and two months afterwards. TVL was defined as loss of perception of hand motion for a duration of >30 s.

Results

Over a period of four months, 1720 intravitreal injections of aflibercept were administered in 672 patients. There were 842 injections with the old VS, and 878 injections using the novel PFS. Using the VS, TVL was noted during two injections (0.24%) in two patients, as compared to 11 cases of TVL (1.25%) in 10 patients with the PFS (p = 0.015). Using the PFS, patients had a 5.3-fold risk of TVL as compared to the VS (OR: 5.33; 95% CI: 1.2-24.1; p = 0.0298).

Conclusion

There was a more than five-fold risk of TVL using the novel pre-filled aflibercept syringe as compared to the established vial system. During informed consent, this risk should be discussed.

SYRINGE DESIGN AND FILLING TECHNIQUE AFFECT ACCURACY OF ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR INTRAVITREAL INJECTIONS

PURPOSE

To evaluate the effect of syringe design and filling technique on the accuracy of anti-vascular endothelial growth factor delivery.

METHODS

Volume output was measured with three syringe designs: a 1.0-mL slip-tip syringe, a 1.0-mL Luer-lock syringe, and a ranibizumab prefilled syringe-using two filling techniques ("upward" and "downward") and two fluids (water and bevacizumab). A total of 300 simulated injections were performed. Accuracy was determined by difference from the intended volume of 50 µ L and by mean absolute percentage error.

RESULTS

Volume outputs were significantly different between syringe designs, with mean values of 61.99 ± 4.18 µ L with the 1-mL slip-tip syringe, 57.43 ± 4.95 µ L with the Luer-lock 1-mL syringe, and 51.06 ± 4.74 µ L with the ranibizumab syringe, making the latter the most accurate syringe. There were 37 cases (12.3%) of underdosing below 50 µ L, the majority of which occurred with the ranibizumab syringe. The "downward" technique reduced the occurrence of air bubbles.

CONCLUSION

Intravitreal injections using 1.0-mL syringes are less accurate than using the ranibizumab prefilled syringe, which has a low-volume and low dead-space plunger design. The variability in volume output may result in less predictable treatment response, especially in cases of underdosing, which were more common with the ranibizumab syringe.

Deformation of Aflibercept and Ranibizumab Syringes Causes Variation in Intravitreal Injection Volume and Risks Retinal Tear Formation

PURPOSE

The intravitreal injection volume is known to vary with plunger alignment and the speed of injection. We investigated the role that syringe stopper deformation plays in allowing excess volumes to be injected into the eye and the potential for the vitreous humor to become incarcerated when excess force is released within the eye.

DESIGN

Experimental study.

METHODS

Aflibercept prefilled syringes (PFSs), ranibizumab PFSs, and 1-ml tuberculin (TB) syringes were subjected to increasing injection force to assess the extent to which each design allowed for excess volumes to be expelled after the stopper reached the bottom of the syringe barrel (i.e., after the 50-μl dose was expelled).

MAIN OUTCOME MEASURES

Additional volume expelled with stopper deformation.

RESULTS

Syringe stoppers are capable of deformation into the dead space when additional force is applied. This allows for progressively greater medication doses to be administered. At an additional force of 3.92 N after the syringe stopper came in contact with the bottom of the syringe barrel, the aflibercept PFSs, ranibizumab PFSs, and 1-ml TB syringes dispensed an additional 17.2%, 11.4%, and 0.8% higher volume than the intended volume of 50 μl, respectively. Upon release of this force, a proportional volume was observed to be drawn back into the needle.

CONCLUSIONS

The intravitreal injection volume varies with the force applied to fully depressed syringes because of syringe stopper deformation. We advise that performing forceful intravitreal injections be avoided to prevent excessive dosing of medication. We also caution that pressure applied to the plunger during intravitreal injections not be released while the needle is in the vitreous cavity to guard against vitreous incarceration, which could lead to retinal tear formation or detachment.

Incidence of severe rise in intraocular pressure after intravitreous injection of aflibercept with prefilled syringes

Our aim was to analyze the intraocular pressure (IOP) changes following different intravitreous injection (IVI) procedures with or without prefilled syringes (PFS) and to elaborate their possible causes. Clinical study and laboratory assessment. 173 eyes of 141 patients. The IOP was prospectively measured pre- and postoperatively in three groups of patients receiving IVI either with ranibizumab (RP), aflibercept PFS (AP) or aflibercept vials (AV). The AP emptying volume (EV) was assessed using 40 aflibercept PFS vials: the plunger was aligned precisely (normal volume, NV) or right below the indication line (high volume, HV) and the drug was ejected with (wP) or without forced pressure (nP). Primary outcome was post-treatment IOP with type of IVI and pre-treatment IOP as fixed factors. Secondary outcome was identification of possibly confounding factors (age, sex, pathology, presence of pseudophakia, spherical error, and number of injections) and IOP > 30 mmHg post-treatment. An IOP rise above 30 mmHg was observed in 8/38 (22%), 16/51 (31%) and 35/86 (41%) cases in the RP, AV and AP groups, respectively (p = 0.129). Pre-treatment IOP was the only predictive variable for IOP rise (p < 0.001). The EV values in the NVnP, NVwP, HVnP and HVwP groups were 56.06 ± 10.32, 70.69 ± 4.56, 74.22 ± 7.41 and 81.63 ± 3.67 µl, respectively (p < 0.001). We observed a marked, although not significantly higher incidence of IOP elevations with the aflibercept PFS. One possible reason may be the error-proneness of administering the correct volume with the AP. Caution should be taken when using the aflibercept PFS in order to prevent potential optic nerve damage in cases with marked elevation in IOP.

Accuracy of intravitreal injection volume for aflibercept pre-filled syringe and BD Luer-Lok one-milliliter syringe

Background

To evaluate the accuracy of intravitreal injection volume of the pre-filled syringe (PFS) in which aflibercept is packaged compared to the BD Luer-Lok 1-mL syringe.

Methods

Ophthalmologists injected their typical intravitreal volume for aflibercept using either the PFS or BD Luer-Lok 1-mL syringe for 5 times each. The injected fluid was weighed using a micro-scale and converted to volume. The volume of fluid injected was also evaluated when the 0.05 mL line on the PFS was lined up to the tip or base of the dome-shaped plunger.

Results

Injection volume was measured for 12 physicians. The average injected fluid volume was 74.22 ± 15.87 µL for PFS and 53.42 ± 4.61 µL for the BD Luer-Lok 1-mL syringe (p < 0.0001). The average deviation in volume injected for the PFS was higher compared to the BD Luer-Lok 1-mL syringe (11.36 µL vs. 3.35 µL, p < 0.0001). When the PFS was lined up with the tip of the dome-shaped plunger at the 0.05-mL line, the average injected volume was 71.03% higher.

Conclusions

The intravitreal injection volume and variability using the new PFS were significantly higher than the volume injected using the BD Luer-Lok 1-mL syringe previously used, potentially leading to higher rates of visually significant elevation of intraocular pressures.