title: Alternative technique for reducing compound waste during intravitreal injections.
abstract: OBJECTIVE
  To describe an intravitreal injection technique using a commercially available 29-gauge insulin needle syringe (29GN syringe) and a 21-gauge (G) needle, comparing compound waste associated with this technique application and the one described in ranibizumab (Lucentis) kit instructions.
  
  
  METHODS
  Ten 0.3 ml doses of distilled water were aspirated using the 29GN syringe and 21G needle (PT technique), and another ten equal doses were aspirated employing the sterilized Lucentis kit (LK technique), which contains a 1ml tuberculin syringe, a 18G needle for compound aspiration and a 30G needle for intravitreal injection. For aspiration using the PT technique, a 21G needle is attached over a 29GN syringe. After compound aspiration, the 21G needle is removed and intravitreal injection is performed using the 29G needle. Using a precision balance, the aspiration needles (21G for PT; 18G for LK) were weighed before and after water aspiration and the syringe-needle complexes for injection (29GN for PT; 30G for LK) were weighed before aspiration and after emptying them. The volumes left in the aspiration needles and needle-syringe complexes were estimated by the difference in weight in grams, which were converted to millilitres.
  
  
  RESULTS
  The mean (+/-SD) residual volume (ml) of aspiration needles (21G for PT; 18G for LK) was significantly lower with PT technique (0.0034 +/- 0.0016) when compared to LK tech nique (0.0579 +/- 0.0011) (p<0.01). The mean (+/-SD) residual volume (ml) of syringe-needle complexes was significantly lower with PT technique (0.0056 +/- 0.0011) than with LK (0.0906 +/- 0.003 ml) (p<0.01).
  
  
  CONCLUSIONS
  The proposed technique is a reasonable alternative for minimizing medication loss during intravitreal injection procedures.
authors.affiliation: Department of Ophthalmology, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Jefferson Augusto Santana
authors.initials: JA
authors.lastname: Ribeiro
authors.forename: André
authors.initials: A
authors.lastname: Messias
authors.forename: Ingrid U
authors.initials: IU
authors.lastname: Scott
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Jorge
mesh_terms: D007267:Injections / Q000295:instrumentation* / Q000379:methods; D009339:Needles / Q000145:classification*; D013594:Syringes / Q000145:classification*; D014822:Vitreous Body