title: Tunnelled versus straight intravitreal injection: intraocular pressure changes, vitreous reflux, and patient discomfort.
abstract: OBJECTIVE
  To compare tunnelled scleral intravitreal injection with straight scleral intravitreal injection concerning short-term intraocular pressure (IOP) changes, occurrence and amount of vitreous reflux, and patient discomfort.
  
  
  METHODS
  Sixty patients were randomly allocated to two groups (tunnelled intravitreal injection and straight intravitreal injection). IOP was measured before and directly (<1 minute) after the injection of 0.05 mL of an antivascular endothelial growth factor agent and then every 5 minutes until IOP was <30 mmHg. Occurrence and amount of vitreous reflux were recorded. Patient discomfort during injection was assessed with a Wong-Baker faces pain rating scale.
  
  
  RESULTS
  IOP (mmHg +/- SD) increased significantly directly after injection to 35.97 +/- 8.13 (tunnelled intravitreal injection) and 30.19 +/- 12.14 (straight intravitreal injection). These pressure spikes differed significantly between both groups (P = 0.01, mean difference: -7.11). Five minutes after injection, there was no significant difference in IOP increase between the groups. All IOP measurements were <30 mmHg after 15 minutes. Occurrence and amount of vitreous reflux were significantly higher with straight intravitreal injection. There was no significant difference in Wong-Baker faces pain rating scale score between both groups.
  
  
  CONCLUSIONS
  Tunnelled intravitreal injection seems to be the technique of choice for low-volume intravitreal injection (0.05 mL). There is neither a difference in patient discomfort nor a difference in IOP increase 5 minutes after injection between both groups. Significantly less vitreous reflux with tunnelled intravitreal injection should lead to less postinjectional drug loss.
authors.affiliation: Department of Ophthalmology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Pascal Bruno
authors.initials: PB
authors.lastname: Knecht
authors.forename: Stephan
authors.initials: S
authors.lastname: Michels
authors.forename: Veit
authors.initials: V
authors.lastname: Sturm
authors.forename: Martina Monika
authors.initials: MM
authors.lastname: Bosch
authors.forename: Marcel Nico
authors.initials: MN
authors.lastname: Menke
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020533:Angiogenesis Inhibitors / Q000008:administration & dosage; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D061067:Antibodies, Monoclonal, Humanized; D000068258:Bevacizumab; D005260:Female; D006801:Humans; D056965:Injections, Intraocular / Q000009:adverse effects / Q000379:methods*; D007429:Intraocular Pressure / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D017060:Patient Satisfaction; D011446:Prospective Studies; D000069579:Ranibizumab; D012164:Retinal Diseases / Q000188:drug therapy* / Q000378:metabolism; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000068258:Bevacizumab; D000069579:Ranibizumab