title: Efficacy of pressure topical anaesthesia in punctal occlusion by diathermy.
abstract: OBJECTIVE
  To prospectively compare the efficacy and safety of pressure topical anaesthesia in punctal occlusion by using cautery in the treatment of dry eye syndrome (DES) with that of conventional treatment by using needle injection of anaesthetic agents.
  
  
  METHODS
  In a randomised controlled trial, 18 consecutive adult patients with DES requiring punctal occlusion were recruited over a 10 month period. Consenting patients were randomised into two groups. Group A patients received pressure topical anaesthesia in the right eye followed by injection anaesthesia in the left eye. Group B was vice versa. Punctal occlusion using cautery was performed in each eye after a specified time following the application of anaesthesia. The main outcome measures were the pain experienced during application of anaesthesia and that during punctal occlusion.
  
  
  RESULTS
  36 eyes of 18 patients were randomised to receive injection anaesthesia in one eye and pressure topical anaesthesia in the other. Nine patients (nine females) were in group A and nine patients (seven females, two males) in group B. The mean age of group A patients was 45.3 (SD 13.5) years, and that of group B patients was 55.6 (12.6) years. The two groups were comparable in terms of mean age (p=0.117) and mean pain score for pressure topical anaesthesia application (p=0.612), injection anaesthesia application (p=0.454), diathermy in pressure anaesthetised eyes (p=0.113), and diathermy in injection anaesthetised eyes (p=0.289). Paired t test was used to compare the mean pain score for pressure topical anaesthesia application (16.8 (24.8)) with those for injection anaesthesia application (56.7 (30.0)). 18 eyes of 18 patients were compared with the fellow eye of the same 18 patients. The mean pain score for injection anaesthesia was greater than for pressure topical anaesthesia application (p<0.0001) (statistical power=0.87). No statistically significant difference was found in the mean pain score for diathermy for eyes that received pressure topical anaesthesia (20.5 (27.5)) compared with eyes that received injection anaesthesia (23.1 (26.3)) (p=0.760) (statistical power=0.96). All 18 patients preferred pressure topical anaesthesia to injection anaesthesia.
  
  
  CONCLUSIONS
  Injection anaesthesia for punctal occlusion is more painful than pressure topical anaesthesia application. However, the pain experienced during diathermy application for punctal occlusion is similar between pressure anaesthetised eyes and injection anaesthetised eyes. Pressure topical anaesthesia is a less painful (in terms of anaesthesia application) but equally effective alternative to conventional injection anaesthesia when used for punctal occlusion.
authors.affiliation: Department of Ophthalmology, United Christian Hospital, Hip Wo Street, Kwun Tong, Kowloon, Hong Kong.
authors.forename: R W K
authors.initials: RW
authors.lastname: Law
authors.forename: R T H
authors.initials: RT
authors.lastname: Li
authors.forename: D S C
authors.initials: DS
authors.lastname: Lam
authors.forename: J S M
authors.initials: JS
authors.lastname: Lai
mesh_terms: D000328:Adult; D000772:Anesthesia, Local / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage; D015352:Dry Eye Syndromes / Q000601:surgery*; D004564:Electrocoagulation / Q000379:methods*; D005143:Eyelids; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D007765:Lacrimal Apparatus / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009883:Ophthalmic Solutions; D010146:Pain / Q000517:prevention & control; D010147:Pain Measurement; D011343:Procaine / Q000008:administration & dosage / Q000031:analogs & derivatives; D011446:Prospective Studies
chemical_list: D000779:Anesthetics, Local; D009883:Ophthalmic Solutions; D011343:Procaine; C005298:benoxinate