title: Topical anesthesia with pH-adjusted versus standard lidocaine 4% for clear corneal cataract surgery.
abstract: OBJECTIVE
  To evaluate and compare the efficacy of a sodium-bicarbonate-adjusted preparation of lidocaine 4% (pH = 7.2) and standard lidocaine (pH = 5.2) for topical anesthesia in clear corneal cataract surgery.
  
  
  METHODS
  Department of Ophthalmology, University of Vienna, Austria.
  
  
  METHODS
  In a prospective, randomized, double-blind clinical trial, clear corneal cataract surgery was performed under topical anesthesia in 44 eyes of 34 patients. In 22 eyes, pH-adjusted lidocaine 4% was administered; in the other 22, standard lidocaine 4%. Aqueous and serum concentrations of lidocaine were measured by high-performance liquid chromatography and ultraviolet detection. Subjective pain was assessed using a visual analog scale of no pain (0%) to worst imaginable pain (100%). On the first postoperative day, visual acuity, intraocular pressure, and corneal staining with fluorescein were examined.
  
  
  RESULTS
  In the pH-adjusted lidocaine group, significantly higher lidocaine concentrations were found in the aqueous humor (15.06 microg/mL +/- 8.2 [SD] versus 4.75 +/- 3.5 microg/mL; P < .0001). In all samples (n = 8), serum lidocaine concentrations were below a minimum detectable level of 0.02 microg/mL. Subjective pain ratings were similar in the pH-adjusted and standard lidocaine groups (mean 9.73 +/- 10.4% and 10.0 +/- 15.4%, respectively). There was no significant between-group difference in intraoperative and postoperative outcomes.
  
  
  CONCLUSIONS
  In this study, pH-adjusted lidocaine 4% was a safe, effective topical anesthetic for clear corneal surgery and had minimal local and systemic toxicity. Administration of pH-adjusted lidocaine 4% resulted in significantly higher aqueous humor lidocaine concentrations than administration of standard lidocaine 4%.
authors.affiliation: Department of Ophthalmology and Pharmacology, University of Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Zehetmayer
authors.forename: G
authors.initials: G
authors.lastname: Rainer
authors.forename: K
authors.initials: K
authors.lastname: Turnheim
authors.forename: C
authors.initials: C
authors.lastname: Skorpik
authors.forename: R
authors.initials: R
authors.lastname: Menapace
mesh_terms: D000287:Administration, Topical; D000368:Aged; D000772:Anesthesia, Local / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001082:Aqueous Humor / Q000378:metabolism; D002021:Buffers; D002851:Chromatography, High Pressure Liquid; D003315:Cornea / Q000601:surgery*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007429:Intraocular Pressure; D008012:Lidocaine / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008297:Male; D009883:Ophthalmic Solutions; D018918:Phacoemulsification / Q000379:methods*; D011446:Prospective Studies; D017693:Sodium Bicarbonate; D016896:Treatment Outcome; D014792:Visual Acuity
chemical_list: D000779:Anesthetics, Local; D002021:Buffers; D009883:Ophthalmic Solutions; D017693:Sodium Bicarbonate; D008012:Lidocaine