Purpose
Millions of intravitreal drug injections are performed each year. The most serious ocular complication of intravitreal injection is endophthalmitis, potentially resulting in severe and permanent visual loss. Causative factors include needle contamination by eyelids, eyelashes, or airborne pathogens. The purpose of this study was to evaluate a shielded intravitreal injection needle in maintaining needle sterility and to assess the potential risk of needle contamination between standard and shielded needles.
Methods
A novel device for intravitreal drug delivery was fashioned by encasing an injection needle within a retractable shield (Figure 1). Sterile standard hypodermic needles (30G) and shielded intravitreal injection needles were contaminated with human saliva, either on the side-surface or ocular contact surface (OCS; Figure 1) as follows: hypodermic needles (group 1); side-contaminated shielded needles (group 2); OCS-contaminated shielded needles (group 3). Following surface contamination needles from each experimental group were immersed in LB culture medium for 3 seconds and culture tubes were incubated at 37°C for 1 week. The optical density of the media was measured by spectrophotometer and bacterial concentrations calculated using a MacFarland standard assay. Statistical significance was determined using Student’s t-test.
Results
Standard hypodermic needles contaminated with saliva exhibited heavy microbial growth, yielding 2.13 x 10^8 ± 6.84 x 10^7 bacteria/ml in culture. OCS- and side-contaminated shielded needles yielded minimal or no microbial growth comparable to non-contaminated sterile control groups. Bacterial contamination was markedly greater in the standard hypodermic needle group in comparison to both side- and OCS-contaminated shielded needle groups (p = 0.002 and p = 0.012, respectively).
Conclusions
Bacterial surface-contamination of intravitreal injection needles is greatly reduced by using a shielded injection needle. Utilization of shielded intravitreal needles may substantially reduce the risk of needle exposure to eyelid and eyelash bacteria as well as airborne pathogens, and enhance the safety of intravitreal injections.
Keywords: 561 injection •
688 retina