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• Re:re: Trends and complications of local anaesthesia in cataract surgery: an 8-year analysis of 12 992 patients
  Thanigasalam Thevi
  Published on: 19 January 2017
• re: Trends and complications of local anaesthesia in cataract surgery: an 8-year analysis of 12 992 patients
  Tom Eke
  Published on: 4 January 2017

• Published on: 19 January 2017

  Re:re: Trends and complications of local anaesthesia in cataract surgery: an 8-year analysis of 12 992 patients

  • Thanigasalam Thevi, Ophthalmologist
  • Other Contributors:
    • Godinho MA, Abas AL

  Response to: Role of Case Series Studies in the Identification of Anaesthetic Complications Dear Editor, We would like to acknowledge Eke and Kumar for their comments on our article.1 In our retrospective case series study of 12,992 patients, we noted that subtenon anaesthesia had more complications and that both topical and subtenon anaesthesia in our series were the ideal anaesthetics.

  Retrospective case series studies s...

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  Response to: Role of Case Series Studies in the Identification of Anaesthetic Complications Dear Editor, We would like to acknowledge Eke and Kumar for their comments on our article.1 In our retrospective case series study of 12,992 patients, we noted that subtenon anaesthesia had more complications and that both topical and subtenon anaesthesia in our series were the ideal anaesthetics.

  Retrospective case series studies still play an important role in the progress of medical science2 with aims that complement other research designs in the pursuit of evidence.3 Shyam et al further noted that case series studies are well placed at the apex of hypothesis generation and play a role in the identification of side effects and complications4 as similarly intended in our study. Further, other case series studies5,6 and a systematic review of case series7 have sought to analyze the association of side effects and complications with surgical treatment and procedures.

  Almost all cases of phacoemulsification were conducted under topical anaesthesia in our set-up. This included cases where difficulties were anticipated such as pseudoexfoliation, small pupils and dense cataracts. The switch to topical was made in recent years once the surgeons were comfortable and convinced that topical anaesthesia works well without complications of injections and patients were happy with the white eye appearance. A recent Cochrane review on the topic noted that "all trials were performed at a time when surgeons were only starting to use topical anesthesia".8 In light of this, we look forward to further research as surgeons become more proficient in their use of topical anesthesia.

  References

  1. Thevi T, Godinho MA. Trends and complications of local anaesthesia in cataract surgery: an 8-year analysis of 12 992 patients. Br J Ophthalmol 2016;100:1708-1713.

  2. Vandenbroucke JP. Case reports in an evidence-based world. J R Soc Med. 1999;92:159-63.

  3. Vandenbroucke JP. In defense of case reports and case series. Ann Intern Med 2001;134(4):330-4.

  4. Shyam A, Shetty G. Case Reports and Evidence Based Medicine: Redefining the Apex of the Triangle. J Orthop Case Rep 2012;2(2):1-2.

  5. Saito Y1, Uraoka T, Matsuda T, Emura F, Ikehara H, Mashimo Y, Kikuchi T, Fu KI, Sano Y, Saito D. Endoscopic treatment of large superficial colorectal tumors: a case series of 200 endoscopic submucosal dissections (with video). Gastrointest Endosc 2007;66(5):966-73.

  6. Sowash M, Barzilai O, Kahn S, McLaughlin L, Boland P, Bilsky MH, Laufer I. Clinical outcomes following resection of giant spinal schwannomas: a case series of 32 patients. J Neurosurg Spine. 2017;13:1-7. doi: 10.3171/2016.9.SPINE16778.

  7. Hasimoto CN, Cataneo C, Eldib R, Thomazi R, Pereira RS, Minossi JG, Cataneo AJ. Efficacy of surgical versus conservative treatment in esophageal perforation: a systematic review of case series studies. Acta Cir Bras 2013;28(4):266-71.

  8. Guay J, Sales K. Sub-Tenon's anaesthesia versus topical anaesthesia for cataract surgery. Cochrane Database of Systematic Reviews 2015; Issue 8. Art. No.: CD006291. DOI: 10.1002/14651858.CD006291.pub3.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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• Published on: 4 January 2017

  re: Trends and complications of local anaesthesia in cataract surgery: an 8-year analysis of 12 992 patients

  • Tom Eke, Consultant Ophthalmologist
  • Other Contributors:
    • Chandra M Kumar, Professor and Senior Consultant in Anaesthesia, Khoo Teck Puat Hospital, Singapore

  Editor,

  We read Thevi and Godhino's article (1) with interest, but we feel that the methodology does not support their conclusions. They aimed to 'find out the most suitable anaesthesia for patients with fewer complications' in cataract surgery, and reported that 'sub-Tenon anaesthesia [STA] was associated with more intraoperative and postoperative complications ... topical anaesthesia [TA] ... is the ideal a...

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  Editor,

  We read Thevi and Godhino's article (1) with interest, but we feel that the methodology does not support their conclusions. They aimed to 'find out the most suitable anaesthesia for patients with fewer complications' in cataract surgery, and reported that 'sub-Tenon anaesthesia [STA] was associated with more intraoperative and postoperative complications ... topical anaesthesia [TA] ... is the ideal anaesthesia'(1). However, this was a retrospective observational case- series, not a randomised study. Therefore, any association does not necessarily imply causation. We believe that the authors have overlooked other more plausible explanations for an association between STA and surgical complications.

  The paper does not explain why some patients had STA and others TA. Many surgeons use TA for uncomplicated phacoemulsification, and STA or other blocks when surgical difficulties are anticipated: e.g. small pupil, dense cataract. For very dense cataracts, large-incision (manual) cataract surgery may be preferred: this has a different complication profile, and generally requires STA or other blocks. We suspect that surgeons chose STA for "higher-risk" cataracts, and this could easily explain the higher complication rate.

  There have been few randomised trials comparing surgical complication rates for TA and STA. The recent Cochrane review concluded 'there was not enough evidence to suggest that one technique would result in a higher or lower incidence of intraoperative complications' and predicted that a randomised trial comprising 116,884 eyes would be required.(2)

  We agree that, for many cases, topical (or topical-intracameral) anaesthesia may be the nearest to an 'ideal' anaesthesia, but for many other cases, STA may be nearest to the ideal. Joint Colleges Guideline 2012 stated: "When deciding which type of anaesthesia to use, consideration needs to be given to patient, surgical and operator factors....No local anaesthetic technique is entirely safe."(3) Clinicians should continue to use informed judgement in recommending appropriate anaesthesia for their patients.

  Tom Eke, Consultant Ophthalmologist, Norwich and Norfolk University Hospital, Norwich, UK

  Chandra M Kumar, Professor and Senior Consultant in Anaesthesia, Khoo Teck Puat Hospital, Singapore

  References

  1. Thevi T, Godinho MA. Trends and complications of local anaesthesia in cataract surgery: an 8-year analysis of 12 992 patients. Br J Ophthalmol 2016;100:1708-1713.

  2. Guay J, Sales K. Sub-Tenon's anaesthesia versus topical anaesthesia for cataract surgery. Cochrane Database of Systematic Reviews 2015, Issue 8. Art. No.: CD006291. DOI: 10.1002/14651858.CD006291.pub3.

  3. Kumar CM, Eke T, Dodds C, et al. Local Anaesthesia for Ophthalmic Surgery. Royal College of Anaesthetists, Royal College of Ophthalmologists, London; 2012.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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