To the Editor:—

We read with interest the article on sub-Tenon (STB) regional anesthesia by Guise in the Journal. 1The article confirms the usefulness and safety of the technique to provide good ocular conduction anesthesia. Our concern is, however, that the author’s conclusion that STB is safer and preferable to other ocular anesthetic techniques is based solely on a comparison of this approach to a series of retrobulbar anesthetics, without consideration of the many other factors that may determine the choice of ocular anesthesia. As reported previously, 2cannula-based STB techniques should be considered as one option among many for accomplishing adequate ocular anesthesia. In our practices at a major university hospital (Bascom Palmer Eye Institute, Miami, Florida) and an outpatient community facility (Tampa Eye and Specialty Surgery Center, Tampa, Florida), we use a variety of ocular anesthetic techniques, including topical anesthesia, intracameral injection, peribulbar anesthesia, STB, and even general anesthesia.

Selection of the appropriate anesthesia technique should consider many factors that pertain to the patient, surgery, surgeon, anesthesia provider, and operative venue. Patient considerations include the cooperativeness of the patient, anatomic factors such as increased axial length, existence of a staphyloma, previous scleral buckle surgery, and coagulation status. Surgical considerations include the surgical approach (i.e. , scleral tunnel vs.  clear corneal). Surgeons’ preferences also must be considered: whether they require an akinetic eye, or if chemosis affects their approach (e.g. , lateral corneal incisions). The STB technique may not be the best choice in all of these situations. Furthermore, anesthesia providers should perform the techniques in which they are trained, and many are not prepared to use the STB approach. The operative venue is important because, for example, in a community setting where cataract surgery takes 15 min or less, the STB approach may not be efficient.

In Guise’s study, retrobulbar anesthesia complication rates were compared to the STB technique. Of note, the stated retrobulbar complication rate is higher than some quoted in the literature. 3–5Most clinicians practicing ophthalmic regional anesthesia currently use peribulbar anesthesia rather than retrobulbar because this technique carries a lower complication rate. 6Although peribulbar anesthesia affords greater safety, the possibility of scleral perforation, hemorrhage, brainstem anesthesia, and dysrhythmia still exist. The same is true for STB blocks. The author details in his article that all of these complications have been reported with STB anesthesia. 1,7–8 

Finally, we would note that the risks of all ocular anesthetic techniques are inversely proportional to education and experience. This is affirmed by several reports of adverse sequelae of ophthalmic anesthetics rendered by inadequately trained/educated personnel in the early 1990s. 8–11In a survey of 284 directors of anesthesiology and ophthalmology programs, no formal training/education in ophthalmic regional anesthesia was provided to anesthesia residents in the vast majority of programs. 12We strongly advocate that before performing any method of ocular anesthesia, attending anesthesiologists obtain adequate training/education through a suitable university program or via  an organization such as the Ophthalmic Anesthesia Society.

Guise PA: Sub-Tenon anesthesia: A prospective study of 6, 000 blocks. A nesthesiology 2003; 98: 964–8
Gayer S, Flynn HW Jr: Sub-Tenon’s injection for local anesthesia in posterior segment surgery (discussion). Ophthalmology 2000; 107: 46–7
Davis DB, Mandel MR: Posterior peribulbar anesthesia: An alternative to retrobulbar anesthesia. J Cataract Refract Surg 1986; 12: 182–4
Ramsay RC, Knobloch WH: Ocular perforation following retrobulbar anesthesia for retinal detachment surgery. Am J Ophthalmol 1978; 86: 61–4
Edge KR, Nicoll JMV: Retrobulbar hemorrhage after 12,500 retrobulbar blocks. Anesth Analg 1993; 76: 1019–22
Leaming DV: Practice styles and preferences of ASCRS members: 2000 survey. J Cataract Refract Surg 2001; 27: 948–55
Frieman B, Friedberg M: Globe perforation associated with sub-Tenon’s anesthesia. Am J Ophthalmol 2001; 131: 520–1
Olitsky S, Juneja R: Orbital hemorrhage after the administration of sub-Tenon’s infusion anesthesia. Ophthalmic Surg Lasers 1997; 28: 145–6
Hay A, Flynn HW Jr, Hoffman JI, Rivera AH: Needle penetration of the globe during retrobulbar and peribulbar injections. Ophthalmology 1991; 98: 1017–24
Duker JS, Belmont JB, Benson WE, Brooks HL Jr, Brown GC, Federman JL, Fisher DH, Tasman WS: Inadvertent globe perforation during retrobulbar and peribulbar anesthesia: Patient characteristics, surgical management, and visual outcome. Ophthalmology 1991; 98: 519–26
Grizzard WS, Kirk NM, Pavan PR, Antworth MV, Hammer ME, Roseman RL: Perforating ocular injuries caused by anesthesia personnel. Ophthalmology 1991; 98: 1011–6
Miller-Meeks MJ, Bergstrom T, Karp KO: Prevalent attitudes regarding residency training in ocular anesthesia. Ophthalmology 1994; 101: 1353–6