Year : 2011 | Volume
| Issue : 2 | Page : 138-141
Single-injection percutaneous peribulbar anesthesia with a short needle versus sub-Tenon's anesthesia for cataract extraction
Ashraf M Ghali1, Abdul Kader Mahfouz1, Amr Hafez2
1 Department of Anesthesiology, Magrabi Eye & Ear Hospital, Muscat, Oman
2 Department of Ophthalmology, Magrabi Eye & Ear Hospital, Muscat, Oman
Abdul Kader Mahfouz
PO 937, PC 112., Muscat
Source of Support: None, Conflict of Interest: None
|Date of Web Publication||7-Jul-2011|
Purpose: This study compared the efficacy of single-injection percutaneous peribulbar anesthesia (PBA) with a short needle with sub-Tenon's anesthesia (STA) to produce optimal operating conditions for cataract extraction in patients with complicated cataract. Methods: Two hundred patients with complicated cataract were enrolled in this prospective, double-blinded, randomized study. Adequate akinesia was a surgical requisite for all cases included in the study because of the expected difficult surgery. The patients were divided into two equal groups to receive either peribulbar anesthesia (PBA) with a 16-mm needle or sub-Tenon's anesthesia. Surgical akinesia (as a primary end point), analgesia, incidence of complications, as well as patient and surgeon satisfaction (as secondary end points) were assessed. Results: Both techniques provided similar analgesia during the operation and similar rates of incidence of chemosis with no serious complications; while the PBA group provided higher degree of akinesia 10 minutes after injection of the local anesthetic, a lower incidence of subconjunctival hemorrhage (SCH) and higher patient and surgeon satisfaction compared to the STA group. Conclusion: We concluded that when globe akinesia is necessary during surgery, the single-injection technique for percutaneous peribulbar anesthesia with a short needle proved to be more suitable than the STA in providing akinesia for cataract surgery. Also, this PBA technique demonstrated a lower incidence of SCH and was preferred to STA by the patients and surgeon.
Keywords: Cataract extraction, peribulbar anesthesia, sub-Tenon′s anesthesia
|How to cite this article:|
Ghali AM, Mahfouz AK, Hafez A. Single-injection percutaneous peribulbar anesthesia with a short needle versus sub-Tenon's anesthesia for cataract extraction. Saudi J Anaesth 2011;5:138-41
|How to cite this URL:|
Ghali AM, Mahfouz AK, Hafez A. Single-injection percutaneous peribulbar anesthesia with a short needle versus sub-Tenon's anesthesia for cataract extraction. Saudi J Anaesth [serial online] 2011 [cited 2020 Jun 2];5:138-41. Available from: http://www.saudija.org/text.asp?2011/5/2/138/82780
| Introduction|| |
Regional anesthesia is commonly performed for ophthalmic procedures. A variety of local anesthetic techniques have been developed and refined.  In 1992 Stevens described a technique for sub-Tenon's anesthesia (STA), which entailed application of topical anesthesia, use of an eye speculum, making a small incision in the conjunctiva and passing a blunt cannula posteriorly in the subconjunctival space.  Injectate administrated at this site passes into the sub-Tenon's space. Many studies support sub-Tenon's block as a relatively safe and more efficient technique than peribulbar anesthesia (PBA). ,, Sub-Tenon's anesthesia is being widely practiced and is popular as a safe and reliable block.
Peribulbar block is another popular choice for patients undergoing cataract surgery.  Several studies have demonstrated that PBA provided optimal conditions for cataract surgery.  However, the main drawback of peribulbar block is the use of long needles (1-1.25 inches), which may have the potential risk of optic nerve injury, retro-bulbar hemorrhage and globe perforation. In particular, patients with shallow orbits are at a greater risk if long needles are used. , The use of a 25-mm needle is the standard practice for extraconal injections.  The single-injection technique for percutaneous peribulbar anesthesia with a short needle as described by Rizzo et al. has been proved to be a simple and easy-to-perform technique with less pain, using a decreased volume of local anesthetic. It requires a single puncture rather than multiple punctures and provides adequate analgesia and akinesia. 
This study aimed to compare the efficacy of the PBA technique described by Rizzo et al. with that of STA for cataract extraction in patients with complicated cataract to produce optimal operating conditions in terms of akinesia (as a primary end point), analgesia, incidence of complications, as well as patient and surgeon satisfaction (as secondary end points).
| Methods|| |
With institutional ethical approval and after having obtained written informed consent from every patient selected for, and consenting to join, the study, 200 adult patients (ASA physical status I-II-III) with complicated cataract scheduled for elective cataract surgery by phacoemulsification were enrolled in this prospective double-blinded, randomized study. Adequate akinesia was a surgical requisite for all cases included in the study because of the expected difficult surgery. Exclusion criteria were patients less than 30 years of age, patients who had vision in only one eye; in addition to the usual contraindications for regional anesthesia, such as patients refusing local anesthesia, clotting abnormalities, impaired mental status, or allergy to the study drugs. This study was performed in the Magrabi Eye and Ear Hospital in Oman between January 2009 and March 2010. Patients were randomly allocated to one of the two groups to receive either the single-injection percutaneous peribulbar anesthesia (PBA group, n = 100) or sub-Tenon's anesthesia (STA group, n = 100) by the block randomization method with the block size determined to be four.
Patients arrived in the operating room unpremedicated and having fasted for the preceding 8 hours. A peripheral IV cannula was inserted; and standard monitoring, including noninvasive arterial blood pressure (NABP), electrocardiogram (5 leads), heart rate (HR) and peripheral oxygen saturation (SpaO 2 ), was used. The local anesthetic solution used was 0.75% ropivacaine plus hyaluronidase 15 IU/mL. In the PBA group, the needle used was a 25-gauge, 16-mm, short-bevel needle. The injection site was percutaneous and limited superiorly by the inferior lacrimal canaliculus, medially by the lateral margin of the nose, laterally by imaginary perpendicular line joining inferior lacrimal papilla to the inferior margin of the orbit and inferiorly by the inferior margin of the orbit. The needle was advanced in an anteroposterior direction for half of its length and then obliquely in the direction of the optical foramen, as described by Rizzo et al. After negative aspiration, 5-7 mL of the local anesthetic solution was slowly injected. Mechanical orbital compression was then applied for 10 minutes, using a Honan balloon set at 30 mm Hg. In the STA group, the block was performed after instilling benoxinate hydrochloride (Novesin 0.4%; Novartis, Switzerland) eye drops to anesthetize the conjunctiva. With the eye in neutral position, the conjunctiva was lifted in the inferonasal quadrant with the help of Moorfields forceps; and using Westcott's scissors, a small incision was made in the conjunctiva. A Visitec 19-gauge Stevens's cannula was carefully placed into the sub-Tenon's space. A 5 mL of local anesthetic solution was injected over 30 seconds and cannula withdrawn, followed by application of orbital pressure for 2 minutes. 
All measures were assessed by an observer who was blinded to the aim of the study. Akinesia was evaluated in the 4 quadrants using a 3-point scoring system: 0 = akinesia; 1 = partial akinesia; and 2 = normal movement giving a maximal score of 8 for the 4 muscles. An akinesia score of 3 or less was defined as a successful block.  If inadequate motor blockade was observed 10 minutes after block, supplementary anesthesia (3 mL) was injected into the involved quadrant in the PBA group, while a further 2 mL of the same anesthetic solution was injected through the same conjunctival incision in the STA group. Additional assessments were performed 5 minutes later. Before the start of surgery, the surgeon who was blinded to the aim of the study assessed the incidence of chemosis and subconjunctival hemorrhage (SCH). Subconjunctival hemorrhage was assessed according to the number of involved quadrants of the ocular surface, which is visible to the naked eye. The patients were asked immediately after the end of surgery to assess the degree of pain experienced during the operation using a 10-point scale. All complications were recorded. The surgeon (immediately after the end of surgery), and the patients (48 hours after the end of surgery) were asked to answer the question 'How would you rate your satisfaction with the regional block?' using a 7-point Likert-like verbal rating scale. 
The number of patients was determined on the basis of the results of a preliminary investigation, during which the sample size was calculated to be 100 patients per group based on the number (%) of patients who developed an akinesia score of 3 or less (a successful block) 10 minutes after injection; a population variance of (2) 2; a two-sided α of 0.05; and a power of 90%. Sample Size Calculations Program version 2.1.31 (Copyright © 1997 by WD DuPont and WD Plummer) was used. Statistical analysis was conducted using SPSS® statistical software (SPSS Inc., Chicago, IL, USA). Data was expressed as mean ± SD or percentages. The 2-way repeated-measures analysis of variance was used to compare the interval data, and the Student t0 test was used as the post hoc test to determine differences between and within groups. χ2 and the Fisher exact test were used to compare nominal data or percentages. P < .05 was considered statistically significant.
| Results|| |
The two groups were comparable with respect to age, sex, weight, ASA physical status, duration of surgery, axial length and surgery side (right/left). The percentage of patients who developed an akinesia score of 3 or less (successful block) 10 minutes after the injection of local anesthetic was significantly higher in the PBA group (87%) compared to that in the STA group (56%). The percentage of patients who required supplementary injection was significantly higher in STA group (13%) compared with that in the PBA group (7%) [Table 1]. The degree of pain experienced during the operation, determined using a 10-point scale, was similar in both groups [Table 1].
The incidence of chemosis was similar in both groups: 16% in the PBA group and 18% in the STA group. There was significantly lower incidence of SCH in the PBA group (2%), which involved only one quadrant of ocular surface; compared to the STA group (21%), which included 16% involving only one quadrant of ocular surface and 5% involving two quadrants of ocular surface. There was no incidence of retrobulbar hemorrhage or eye perforation in both groups. There was a significantly higher patient and surgeon satisfaction in the PBA group compared to the STA group [Table 2].
| Discussion|| |
This study demonstrated that both techniques provided similar analgesia during the operation and similar incidence of chemosis with no serious complications. PBA provided a higher degree of akinesia 10 minutes after injection of the local anesthetic, a lower incidence of SCH and a higher patient and surgeon satisfaction compared to the STA group.
Many studies have compared STA with conventional PBA.,,, However, no previous study has compared PBA with short-needle technique like that used in the current study with STA. Budd et al. demonstrated that both STA and the two-point injection conventional PBA provided similar effectiveness in terms of anesthesia and akinesia for cataract surgery. Also, Parkar et al. proved that both STA and the two-point injection conventional PBA provided equally good analgesia, while the PBA provided more consistent akinesia compared to STA. In contrast to our study, an audit reported by Van den Berg  demonstrated that STA was more effective than the PBA technique (using 15-mm needle, two-point injection of 14 mL of local anesthetic) in providing reliable and consistent analgesia and akinesia. Also, Ripart et al. reported that medial canthus episcleral STA is more efficient than PBA in terms of akinesia. These differences with our results concerning analgesia and akinesia could be attributed to the differences in the volume of local anesthetic injected (as they used more volume of local anesthetic for STA), differences in the types of local anesthetic drugs used, or to the differences in the site of entry and anatomical disposition of the local anesthetic.
The authors  proved in a previous study that the single-injection technique for percutaneous PBA with a short needle as described by Rizzo et al. provided adequate akinesia and analgesia for cataract surgery. The hypothesis of the efficacy of this technique was revealed in previous studies , using B-scan ultrasonography to determine the exact pattern of distribution of the injectate in PBA. They demonstrated that a small volume of local anesthetic (5-6.5 mL) injected in this space is adequate to surround the eyeball and produce analgesia. The circumferential diffusion of the local anesthetic with the addition of hyaluronidase from extraconal to the intraconal space, where the sensory and motor nerves of the eye are located, explains the more adequate akinesia achieved with this technique.  On the other hand, a previous study using ultrasound monitoring during STA clearly demonstrated leakage of solution out of Tenon's space. There is a valve effect and some of the volume injected spills out of the incision and so an increased volume or a second injection is needed to achieve absolute akinesia. , In this study, we found that the incidence of chemosis was comparable in both groups, while the incidence of SCH was significantly higher in the STA group compared to the PBA group. Similar results were found by Budd et al. and Parkar et al. The frequency of SCH during STA injections is often a consequence of the procedure and has been reported to occur in up to 56% of cases. , The most likely source of bleeding is the conjunctival vessels, which get injured, cut or sheared during the process of creating a conjunctival entry site for the cannula to pass into the sub-Tenon's space. Although this does not necessarily have any direct morbidity associated with it, a chemosed hemorrhagic conjunctiva not only results in an unsightly postoperative eye but can also make visualization during cataract surgery more challenging owing to pooling of ocular surface fluids. Gauba et al. reported in a previous study that controlled localized bipolar conjunctival cautery before STA injection may significantly reduce the frequency of SCH.
In this study, we found a higher patient and surgeon satisfaction in the PBA group compared to the STA group. The unsightly postoperative eye was the reason of lower patient acceptance of the STA, while the lack of complete akinesia and the higher incidence of SCH, which affected the visualization during the surgery with STA, influenced the surgeon's decision in favor of PBA.
We concluded that when globe akinesia is necessary during surgery, the single-injection technique for percutaneous PBA with a short needle is more suitable than the STA in providing akinesia for cataract surgery. Also, this PBA technique demonstrated a lower incidence of SCH and was preferred to STA by the patients and surgeon.
| Acknowledgments|| |
We thank Dr. Mahmoud M. Ibrahim, Assistant Professor of Educational Psychology (Statistical Education), Sultan Quaboos University, Sultanate of Oman, for his assistance.
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[Table 1], [Table 2]
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