title: Impact of the radius of the injector system on the cell viability in descemet membrane endothelial keratoplasty: an ex vivo experimental study.
abstract: OBJECTIVE
  To evaluate the impact of the radius of the injector system on the viability of the endothelial cells in Descemet membrane endothelial keratoplasty (DMEK).
  
  
  METHODS
  Descemet membranes (DMs) of 30 corneoscleral rims were used in a paired design and divided into three groups (A, B, C). The right corneas were used as control (without shooting through the injector after DM preparation) and the left cornea for simulation of the implantation step (shooting through a glass injector of different radii). The injector in Group A had a diameter of 0.5 mm, group B 0.9 mm and group C 1.4 mm. Prior to preparation, endothelial cell count was measured and endothelial cell quality assessed. Quantification of potential damage was achieved by staining with a viability bioassay (calcein acetoxymethyl and ethidium homodimer-1) and DAPI. Apoptosis was evaluated by TUNEL (terminal dUTP nick-end labelling) staining.
  
  
  RESULTS
  The average percentage of the endothelial cell death ratios was 4.9 ± 3.3% in group A (n = 5), 3.7 ± 3.7% in group B (n = 5) and 3.9 ± 3.6% in group C (n = 5) with no significant difference compared to the control. The average percentage of apoptotic endothelial cells was 0.05 ± 0.05%, 0.60 ± 0.53% and 0.15 ± 0.26% in groups A, B and C, respectively, with no significant difference compared to the control.
  
  
  CONCLUSIONS
  Prepared grafts for transplantation in DMEK procedures may be injected through a smaller sized injector system of up to 0.5 mm with no significant increase in cell loss. Clinical studies are necessary to draw a final conclusion.
authors.affiliation: Department of Ophthalmology, Eberhard-Karls University, Tuebingen, Germany.
authors.forename: Efdal
authors.initials: E
authors.lastname: Yoeruek
authors.affiliation: Department of Ophthalmology, Eberhard-Karls University, Tuebingen, Germany.
authors.forename: Karl-Ulrich
authors.initials: KU
authors.lastname: Bartz-Schmidt
authors.affiliation: Department of Ophthalmology, Eberhard-Karls University, Tuebingen, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Hofmann
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002452:Cell Count; D002470:Cell Survival / Q000502:physiology; D055954:Corneal Endothelial Cell Loss / Q000517:prevention & control*; D057111:Descemet Stripping Endothelial Keratoplasty / Q000295:instrumentation*; D004728:Endothelium, Corneal / Q000166:cytology*; D004867:Equipment Design; D006801:Humans; D020287:In Situ Nick-End Labeling; D008875:Middle Aged
keywords: cell viability; descemet membrane; descemet membrane endothelial keratoplasty; injector radius