1 Department of Ophthalmology, Hairmyres Hospital, Lanarkshire Acute Hospitals NHS Trust, Lanarkshire, UK. 2 Tennent Institute of Ophthalmology, Gartnavel General Hospital, Glasgow, UK. 3 Highlands and Islands Health Research Institute, University of Aberdeen, Inverness, UK
* Corresponding author. St. Paul's Eye Unit, 8Z Link, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK. E-mail: sathish{at}tiscali.co.uk
Accepted for publication July 14, 2004.
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Abstract |
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Methods. A randomized double-blinded placebo-controlled clinical trial of 210 patients assigned to either a sub-Tenon's group (sub-Tenon's anaesthesia with placebo topical balanced salt solution, n=140) or a topical anaesthesia group (topical anaesthesia with placebo sub-Tenon's injection of balanced salt solution, n=70) was carried out. All patients underwent phacoemulsification with intraocular lens implantation. Patients in the sub-Tenon's group received a single injection (3 ml) of a combination of lidocaine 2% (2 ml) and bupivacaine 0.75% (1 ml), and four doses of topical placebo (balanced salt solution). Patients in the topical anaesthesia group received four doses of topical proxymethocaine 0.5% and a placebo sub-Tenon's injection (3 ml) of balanced salt solution. No intracameral injection of local anaesthetic was given. A 10-point visual analogue pain scale was used preoperatively and for postoperative pain assessment immediately after the operation and 30 min postoperatively. The intraoperative complications in the two groups were recorded.
Results. The mean pain score immediately after surgery was 2.42 (SD 2.2) in the sub-Tenon's group and 3.44 (2.3) in the topical anaesthesia group (P=0.0043). The mean pain score 30 min after surgery was 1.24 (1.7) in the sub-Tenon's group and 2.25 (2.2) in the topical anaesthesia group (P=0.0009).
Conclusions. Patients undergoing cataract surgery under topical anaesthesia experience more postoperative discomfort than patients receiving sub-Tenon's anaesthesia. Surgery-related complications were similar in both groups.
Keywords: anaesthesia, topical ; anaesthetic techniques, regional, sub-Tenon's ; surgery, cataract
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Introduction |
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Several local anaesthetic techniques for cataract surgery are currently available. These include retrobulbar (intraconal),4 peribulbar (extraconal),5 sub-Tenon's,6 7 subconjunctival8 and topical anaesthesia. Posterior sub-Tenon's delivery of the anaesthetic, as described by Stevens,7 has the advantage of using a blunt sub-Tenon's cannula. This avoids placement of sharp needles into the retrorbital or periorbital spaces, and has been shown to be an efficient and safe technique.7 9
Topical anaesthesia alone for cataract removal and intraocular lens implantation was first described by Fichman.10 Since then there have been several reports of its safety and efficacy.11 12 However, Fukasaku and Marror,13 comparing topical and peribulbar anaesthesia, and Patel and colleagues,14 comparing topical and retrobulbar anaesthesia, reported more intraoperative pain in patients receiving topical anaesthesia for cataract surgery.
To our knowledge there has been no randomized placebo-controlled clinical trial comparing sub-Tenon's and topical anaesthesia in routine cataract surgery. Therefore we designed a prospective double-blinded randomized placebo-controlled clinical trial comparing topical anaesthesia with sub-Tenon's anaesthesia. We measured the patient's pain score immediately after the operation and 30 min postoperatively. We also recorded the intraoperative complications.
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Methods |
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Randomization
An independent researcher provided the hospital pharmacy with an individual randomization schedule of 250 allocations. A customized pack was prepared from this schedule for each patient. The pack comprised a syringe containing either 3 ml of local anaesthetic lidocaine 2% (2 ml) and bupivacaine 0.75% (1 ml) or placebo, a minims dropper containing either placebo or proxymethocaine 0.5%, and a separate minims dropper containing proxymethocaine 0.5%. These packs were sequentially labelled 1 to 210. The randomization schedule was retained in the hospital pharmacy and was not seen by the investigators until the trial was completed. All patients received a sub-Tenon's injection and topical eyedrops. They were randomized such that the patients receiving the sub-Tenon's anaesthesia received a topical placebo, and patients receiving topical anaesthetic had a placebo sub-Tenon's injection. Each patient entering the trial was allocated a unique trial number from 1 to 210 and received the contents of the pack matching the number. In this way the patients, the ophthalmologist administering the anaesthetic, the surgeon and the nurse measuring the pain score were fully masked from the identity of the contents of the pack.
Technique for sub-Tenon's anaesthesia
All the 210 patients received a single drop of proxymethocaine 0.5%, placed locally in the infernonasal quadrant of the conjunctiva at the site of the sub-Tenon's injection. A lid speculum was placed and a small nick incision was made simultaneously in the conjunctiva and Tenon's capsule, about 5 mm from the limbus in the inferonasal quadrant, using curved Westcott scissors. Depending on the group to which they were randomized, patients then received either a mixture of 2 ml of lidocaine 2% and 1 ml of 0.75% bupivacaine, or 3 ml of balanced salt solution through a 19-gauge sub-Tenon's cannula in to the posterior sub-Tenon's space. Hyaluronidase was not used in this study. No device was used to induce ocular compression.
Technique of topical anaesthesia
Depending on the group to which they were randomized, the patients received either topical proxymethocaine 0.5% or a placebo of topical balanced salt solution. Four doses (approximately 40 µl per dose) of unpreserved proxymethocaine 0.5% or placebo were used. They were installed on the ocular surface (two doses on the cornea, and one each in the superior and inferior conjunctival cul de sac) 10 min before surgery. Five minutes before surgery two further doses were installed on the cornea. An additional two doses of proxymethocaine 0.5% on the cornea were allowed in the event of breakthrough pain, which was treated in the same way in both groups.
Pain evaluation
Each patient was shown a visual analogue pain scale with numerical and descriptive ratings from 0 (no pain) to 10 (severe pain), as described by Stevens,7 to rate their pain. Patients were encouraged to use this pain scale to rate the level of pain felt pre- and postoperatively. If patients were unable to read the printed numbers and descriptive text on the pain scale, a trained ophthalmic nurse read them to the patient.
Following administration of the local anaesthetic (prior to commencement of surgery), baseline pain scores were obtained in both groups (Table 1). This pain was probably caused by the sub-Tenon's injection. Any verbal expression of pain that patients made during the operation (e.g. on manipulation of the iris) was recorded. These pain scores were repeated immediately and 30 min postoperatively. A blinded independent observer (ophthalmic trained nurse) performed the pain score recording in all the patients.
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The data were entered into Microsoft Excel (Microsoft Inc., Redmond, WA, USA) and was analysed using Stata 8.0. We used the unpaired Student t-test for normally distributed continuous variables (patient's age and baseline pain score following administration of the anaesthetic before surgery), and the Wilcoxon rank-sum (MannWhitney) test for non-normally distributed variables (pain score immediately after surgery and 30 min postoperatively). The 2-test was used to compare the sex distribution between the two groups. P-values <0.05 were considered to be statistically significant.
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Results |
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No patient required a change in the anaesthetic technique for the surgery to be completed. Nine patients (four in the sub-Tenon's group and five in the topical anaesthesia group) were excluded from the analysis as their pain scores were not recorded. The overall intraoperative complication rate was 2.4% for posterior capsular tear and vitreous loss, and 0.5% for iris prolapse. Three patients (4.3%) in the topical anaesthesia group and two (2.1%) in the sub-Tenon's group had posterior capsular tear and vitreous loss. One patient (0.5%) in the sub-Tenon's group had iris prolapse intraoperatively and required a single interrupted stitch to close the corneal wound. The difference between groups was not statistically significant (P=0.391). The pain scores reported by the patients are shown in Table 2. Although patients in the topical anaesthesia group experienced more immediate postoperative pain, none of them required any supplemental analgesia.
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Discussion |
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Although, according to a national survey,2 the peribulbar technique is used most commonly for intraocular surgery, sub-Tenon's and topical anaesthesia are gaining popularity. Neither of these techniques requires sharp needles, and they can be performed in the absence of an anaesthetist.1
In 1992, Stevens introduced sub-Tenon's anaesthesia for cataract surgery. He reported no pain or only slight discomfort in 50 patients who underwent both large-incision (extracapsular cataract surgery) and small-incision (phacoemulsification) cataract surgery. Since then there have been several reports confirming the efficacy and safety of sub-Tenon's anaesthesia during cataract surgery.9 17 18
To our knowledge, this is the first report of a double-blind randomized placebo controlled trial comparing topical and sub-Tenon's anaesthesia for routine cataract surgery. In our study, the patients undergoing topical anaesthesia had a higher mean pain score (3.44) immediately and 30 min after surgery (2.25), which was statistically significant when compared with the sub-Tenon's group. Although the pain score was higher in the topical group, none of the patients in this group required supplemental anaesthesia during surgery.
In their study comparing topical oxybuprocaine with sub-Tenon's lidocaine 2%, Chittenden and colleagues17 reported a significantly higher median pain score in the topical group. They concluded that sub-Tenon's anaesthesia produced less pain in patients undergoing cataract surgery through a scleral tunnel, and they recommended topical anaesthesia only if the cataract surgery was performed through a clear corneal incision. Similarly, Manners and Burton18 reported a higher pain score in the topical group despite the fact that the patients in this group received an additional subconjunctival injection of lidocaine 2% to facilitate scleral cautery, as the surgery was performed through a scleral incision.
Zafirakis and colleagues19 were the first to compare topical and sub-Tenon's anaesthesia for phacoemulsification and intraocular lens implantation through a clear corneal incision. They recruited 100 patients in whom the randomization was stratified so that half of the first-eye surgeries and half of the second-eye surgeries were assigned to each anaesthetic group. They concluded that patients having cataract surgery under topical anaesthesia had more intraoperative and postoperative discomfort than patients receiving sub-Tenon's anaesthesia.
It has been thought that, with topical anaesthesia, phacoemulsification and intraocular lens implantation were less painful when performed through a clear corneal incision than when performed through a scleral tunnel incision, as the former has the advantage of preserving the conjunctiva and avoiding the use of cautery. However, this study shows that even with a clear corneal incision, patients undergoing topical anaesthesia had more pain immediately (3.44) and 30 min postoperatively (2.25) than those with sub-Tenon's anaesthesia (2.42 and 1.24, respectively).
As this study was designed primarily to detect a difference in the pain score, there was inadequate power to demonstrate a statistically significant difference in the intraoperative complications between the two groups. Also, no provisions were made to compare the degree of operating difficulty encountered by the surgeon that were induced by the anaesthetic technique (e.g. degree of chemosis, subconjunctival haemorrhage). However, we assume that the degree of difficulty would be the same in both groups as both sets of patients received a sub-Tenon's injection, albeit a placebo in the topical group.
In conclusion, both topical and sub-Tenon's anaesthesia are safe and effective for routine cataract surgery. Although routine cataract surgery is less painful under sub-Tenon's anaesthesia, topical anaesthesia is well tolerated by patients. Patients who have a phobia for needles and those who prefer topical anaesthesia should be warned that they may experience discomfort during cataract surgery.
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Footnotes |
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References |
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2 Eke T, Thompson JR. The National Survey of Local Anaesthesia for Ocular Surgery. I. Survey methodology and current practice. Eye 1999; 13: 18995[ISI][Medline]
3 Desai P, Reidy A, Minassian DC. Profile of patients presenting for cataract surgery: national data collection. Br J Ophthalmol 1999; 83: 8936
4 Ellis PP. Retrobulbar injections. Surv Ophthalmol 1974; 18: 42530
5 Davis DB II, Mandel MR. Peribulbar anesthesia: a review of technique and complications. Ophthalmic Clin North Am 1990; 3: 10110
6 Hansen EA, Mein CE, Mazzoli R. Ocular anesthesia for cataract surgery: a direct sub-Tenon's approach. Ophthalmic Surg 1990; 21: 6969[ISI][Medline]
7 Stevens JD. A new local anaesthetic technique for cataract surgery by one quadrant sub-Tenon's infiltration. Br J Ophthalmol 1992; 76: 6704[Abstract]
8 Smith R. Cataract extraction without retrobulbar anaesthetic injection. Br J Ophthalmol 1990; 74: 2057[Abstract]
9 Roman SJ, Chong Sit DA, Boureau CM, Auclin FX, Ullern MM. Sub-Tenon's anaesthesia: an efficient and safe technique. Br J Ophthalmol 1997; 81: 6736
10 Fichman RA. Use of topical anaesthesia alone in cataract surgery. J Cataract Refract Surg 1996; 22: 61214[ISI][Medline]
11 Kershner RM. Topical anaesthesia for small incision self-sealing cataract surgery. A prospective evaluation of the first 100 patients. J Cataract Refract Surg 1993; 19: 2902[ISI][Medline]
12 Grabow HB. Topical anaesthesia for cataract surgery. Eur J Implant Refract Surg 1993; 5: 204
13 Fukasaku H, Marror JA. Pinpoint anesthesia: a new approach to local ocular anesthesia. J Cataract Refract Surg 1994; 20: 46871[ISI][Medline]
14 Patel BCK, Burns TA, Crandall A et al. A comparison of topical and retrobulbar anesthesia for cataract surgery. Ophthalmology 1996; 103: 11961203[ISI][Medline]
15 Report of the Joint Working Party on Anaesthesia in Ophthalmic Surgery. London: Royal College of Anaesthetists and College of Ophthalmologists, 1993
16 Hodgkins PR, Luff AJ, Morrell AJ, Teye Botchway L, Featherston TJ, Fielder AR. Current practice of cataract extraction and anaesthesia. Br J Ophthalmol 1992; 76: 3236[Abstract]
17 Chittenden HB, Meacock WR, Govan JAA. Topical anaesthesia with oxybuprocaine versus sub-Tenon's infiltration with 2% lignocaine for small incision cataract surgery. Br J Ophthalmol 1997; 81: 28890
18 Manners TD, Burton RL. Randomised trial of topical versus sub-Tenon's local anaesthesia for small-incision cataract surgery. Eye 1996; 10: 36770[ISI][Medline]
19 Zafirakis P, Voudouri A, Rowe S, et al. Topical versus sub-Tenon's anesthesia without sedation in cataract surgery. J Cataract Refract Surg 2001; 27: 8739[CrossRef][ISI][Medline]