Letters to the Editor: Letters & Announcements
To the Editor:
Ghai et al.1 reported their experiences and successes using subtenon block in preschool children undergoing cataract surgery. In their control/ fentanyl group, they chose to administer a sham subtenon block using normal saline.
Although the subtenon technique is associated with lower risk of complications when compared with other methods of ocular regional anesthesia, it cannot be described as a no-risk technique. The wisdom of performing an invasive procedure on any patient, particularly young children, without any potential benefit must at least be questioned.
In previous studies examining the use of subtenon block in children, the patients were undergoing strabismus surgery in which the extraocular muscles would ordinarily be exposed.2 The introduction of blunt cannula under the tenon’s capsule in which this portion of the eye would not normally be exposed cannot be described as noninvasive. As Ghai et al. correctly point out, there have been reports of globe perforation, extraocular muscle trauma, and orbital hemorrhage after subtenon block.3,4
Where the possibility of such complications exist and no benefit in the form of analgesia may accrue, surely the correct course is to apply the principle of “primum non nocere.” The Declaration of Helsinki clearly states “in medical research on human subjects, considerations related to the well-being of the human subject should take precedence over the interests of science and society.”5
On a practical level, two modes of analgesia should be compared rather than comparing a genuine technique with a technique modified for statistical power. This study did not require this degree of double blinding, and the remainder of the methodology and the principles contained were robust enough to withstand any review.
Cormac J. Fahy, MB, FCARCSI, FANZCA
Department of Children’s Anaesthesia
Womens and Childrens Hospital
North Adelaide, South Australia
1.Ghai B, Ram J, Makkar JK, Wig J, Kaushik S. Subtenon block compared to intravenous fentanyl for perioperative analgesia in pediatric cataract surgery. Anesth Analg 2009;108:1132–8
2.Steib A, Karcenty A, Calache E, Franckhauser J, Dupeyron JP, Speeg-Schatz C. Effects of subtenon anesthesia combined with general anesthesia on perioperative analgesic requirements in pediatric strabismus surgery. Reg Anesth Pain Med 2005;30:478–83
3.Ruschen H, Bremner F, Carr C. Complications after subtenons eye block. Anesth Analg 2003;96:273–7
4.Jaycock PD, Mather CM, Ferris JD, Kirkpatirck JN. Rectus muscle trauma complicating sub-tenons local anesthesia. Eye 2001;15:583–6
5.World Medical Association Declaration of Helsinki. Ethical principles for medical research involving human subjects. Available at: http://www.wma.net/e/policy/b3.htm
. Accessed April 10, 2009