title: Effect of volume used in sub-Tenon's anaesthesia on efficacy and intraocular pressure: a randomized clinical trial of 3 mL versus 5 mL.
abstract: OBJECTIVE
  To compare the effect of volume used in sub-Tenon's anaesthesia on efficacy and intraocular pressure (IOP).
  
  
  METHODS
  A prospective, randomised clinical trial was conducted on 52 eyes of 52 consecutive patients undergoing sub-Tenon's anaesthetic for cataract surgery. Eyes were randomly assigned to either 3 mL or 5 mL volume of anaesthetic solution (0.5% bupivacaine/2% lidocaine in a 50:50 mixture). The main outcome measures were akinesia 5 min post-administration of anaesthetic, changes in IOP immediately after and 5 min after anaesthetic administration, and patient pain perception during procedure.
  
  
  RESULTS
  The level of kinesia was greater in the 3 mL group (n = 25) compared to the 5 mL group (n = 27) (P = 0.001, Mann-;Whitney U-test). There was no significant difference in pain perception between the two groups (P = 0.464, student t-test). Although there was great variation in IOP changes following sub-Tenon's anaesthetic, there was a trend for a larger rise in mean IOP immediately after anaesthetic administration in the 5 mL group (mean +/- SD +5.6 +/- 4.2 mmHg) compared to the 3 mL group (+4.3 +/- 3.8 mmHg), but this did not reach statistical significance (P = 0.25, student t-test).
  
  
  CONCLUSIONS
  A 5 mL volume of anaesthetic provides akinesia superior to a 3 mL volume in sub-Tenon's anaesthesia for cataract surgery.
authors.affiliation: Department of Ophthalmology, Queen Margaret Hospital, Dunfermline, Fife, United Kingdom. niallpatton@hotmail.com
authors.forename: Niall
authors.initials: N
authors.lastname: Patton
authors.forename: Tahira Y
authors.initials: TY
authors.lastname: Malik
authors.forename: Tariq M
authors.initials: TM
authors.lastname: Aslam
authors.forename: James H
authors.initials: JH
authors.lastname: Vallance
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000698:Analgesia; D000772:Anesthesia, Local / Q000379:methods*; D019162:Anesthetics, Combined / Q000008:administration & dosage*; D000779:Anesthetics, Local / Q000008:administration & dosage*; D002045:Bupivacaine / Q000008:administration & dosage*; D002387:Cataract Extraction; D003238:Connective Tissue / Q000187:drug effects; D005260:Female; D006801:Humans; D007267:Injections; D007429:Intraocular Pressure / Q000187:drug effects*; D008012:Lidocaine / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D010147:Pain Measurement; D010149:Postoperative Pain; D011446:Prospective Studies
chemical_list: D019162:Anesthetics, Combined; D000779:Anesthetics, Local; D008012:Lidocaine; D002045:Bupivacaine