Reply to Drs Palte and Gayer
We would like to thank Drs Palte and Gayer1 for their comments regarding our recent publication exploring the effects of a single retrobulbar block of ropivacaine for pediatric vitreoretinal surgery.2
We agree that the advantages of an intraoperative eye block for pediatric patients should be emphasized. Regarding the nomenclature of eye blocks, intraconal injection corresponds to retrobulbar block in practice, and extraconal to peribulbar block, both describing the target range of injection. As discussed in our report, our choice of retrobulbar block was based on the evidence that it has complete and long-lasting effect. More recent studies suggested both retrobulbar and peribulbar are effective. Dr Carneiro et al3 found that retrobulbar block results in higher quality of anesthesia than peribulbar block, as the anesthetic was delivered intraconally with the retrobulbar technique, whereas 13 to 20 of anesthetic were delivered outside the cone with the latter technique. However Dr Luyet et al4 revealed clear intraconal spread after peribulbar injection using ultrasound in 61 of 100 patients. Therefore, based on the current literature, both retrobulbar and peribulbar blocks are effective, and no single technique has been proven to be superior to the other.
We mentioned in our article that this procedure needs to be carried out by an experienced ophthalmologist with caution, because of clinical risks such as chemosis, retrobulbar hemorrhage, or globe perforation. Although the relatively smaller orbit in young children could pose extra difficulty, it is the skill of the manipulator that prevails in the choice of technique.
In the National Pediatric Eye Center (Beijing, China), where the study took place, the needle-based application of retrobulbar block for pediatric patients has been established since 2008, and no severe adverse effects were observed in more than 100 cases annually. A 25-gauge sterile used needle (Edge SA Medical & Plastic Medical Instrument, Shanghai, China) is adopted to perform retrobulbar block. The tip of used needle is not as sharp as those single-use disposable needles but still sharp enough to enter the eye without much force (Fig. 1). To date, this needle has only 1 size (50 mm). According to the ophthalmologist who performs the technique, the needle is inserted into the eye 20 to 35 mm.
We agree that eye block could be performed by anesthesiologists after sufficient training possibly with the guidance of ultrasound.5 Eye block in the holding room could improve operating room turnover times and ensure intraoperative ocular akinesia.6 But in surgical practice in China, eye block is conducted by ophthalmologists.