To the Editor:—
We read with great interest the articles about ophthalmic blocks by Ripart et al. 1–4The most recent article seems to establish that there is no restrictive intermuscular membrane impeding the flow of local anesthetic from extraconal to intraconal spaces with peribulbar blockade. 1Three of the 10 dye injections in that study were performed with needle puncture at the medial canthus using the technique of Hustead and were reported to produce filling of both extraconal and intraconal spaces. 1,5However, one of the previous dye studies of Ripart et al. 4reported that eight injections at the medial canthus using a similar technique all resulted in filling of the episcleral (sub-Tenon) spaces. Do the subtle differences in technique account for filling two different anatomic spaces, or is the pattern of anesthetic spread unpredictable with injection at the medial canthus?
We share the enthusiasm of Ripart et al. 2for the medial canthal injection site, regardless of which anatomic space is involved. We have been using his technique with a slight modification for more than 3 yr in approximately 2,000 cataract patients. Like Hustead, we perform needle puncture medial to the caruncle rather than lateral to help ensure against perforation by providing an extra few millimeters of separation between the needle and the globe. 5We have had no instances of globe perforation, retrobulbar hemorrhage, or brainstem anesthesia. We have noted that chemosis as an indicator of episcleral anesthetic spread is only occasionally produced. In the past, we performed this block during deep propofol sedation to prevent patient reaction to the needle puncture despite use of topical anesthetic drops. Recently, we discovered that application of topical anesthetic directly to the medial canthal conjunctiva with a cotton swab for 1 min before puncture has virtually eliminated this initial discomfort and has lessened the need for sedation.
A minor problem we sometimes observe is sneezing, which, on occasion, necessitates interruption of the block because of patient movement. We believe that this most likely represents irritation in some way to the ethmoidal nerves as they course through the medial orbit close to the needle tract. 6
We have greatly appreciated the articles or Ripart et al. 1–4and are glad the anesthesia community is becoming more aware of this excellent technique of regional ophthalmic anesthesia.