|Year : 2002 | Volume
| Issue : 3 | Page : 197-200
Intracameral lidocaine in trabeculectomy. A preliminary safety and efficacy study
Jimmy S Lai, Clement C Tham, Dennis S Lam
Department of Ophthalmology, United Christian Hospital, Hip Wo Street, Kwun Tong, Kowloon, Hong Kong, China
Jimmy S Lai
Department of Ophthalmology, United Christian Hospital, Hip Wo Street, Kwun Tong, Kowloon, Hong Kong
Source of Support: None, Conflict of Interest: None
Purpose: To study the safety and efficacy of intracameral lidocaine as anaesthesia in trabeculectomy for primary open-angle glaucoma.
Methods: Trabeculectomy under intracameral anaesthesia using 1% preservative-free lidocaine was performed in 10 patients with primary open-angle glaucoma. Intraoperative pain score, postoperative intraocular pressure (IOP) and endothelial cell count at 3 months were recorded.
Results: The mean pain score was 1.70 ± 1.34. The mean IOP was lowered from 24.60 ± 8.28 mmHg preoperatively to 14.1 ± 3.11 mm Hg postoperatively. There was no significant decrease in the mean endothelial cell count 3 months after the surgery (P = 0.375).
Conclusion: Intracameral lidocaine may be a safe and effective alternative anaesthesia method in trabeculectomy for uncomplicated primary open-angle glaucoma.
Keywords: Trabeculectomy, intracameral anaesthesia, lidocaine, primary open-angle glaucoma
|How to cite this article:|
Lai JS, Tham CC, Lam DS. Intracameral lidocaine in trabeculectomy. A preliminary safety and efficacy study. Indian J Ophthalmol 2002;50:197-200
|How to cite this URL:|
Lai JS, Tham CC, Lam DS. Intracameral lidocaine in trabeculectomy. A preliminary safety and efficacy study. Indian J Ophthalmol [serial online] 2002 [cited 2020 Jun 3];50:197-200. Available from: http://www.ijo.in/text.asp?2002/50/3/197/14787
Trabeculectomy is the standard surgical treatment for primary open-angle glaucoma (POAG). Trabeculectomy lowers intraocular pressure (IOP) by creating a fistula for the aqueous to drain from the anterior chamber into the subconjunctival space. Several methods of local anaesthesia for anterior segment surgeries are frequently used. These include retrobulbar, peribulbar and sub-Tenon's anaesthesia. These anaesthetic methods may result in potentially serious complications, such as perforation of the eyeball, brain stem anaesthesia, increased intraorbital and intraocular pressures, ptosis, periocular bruises, and subconjunctival hemorrhage.
Topical anaesthesia has gained wide acceptance as a safe and effective form of ocular anaesthesia for cataract surgery.8[ However, in conventional trabeculectomy, a peripheral iridectomy is usually performed. The excision of uveal tissue may be a source of severe pain not tolerated by the patient on topical anaesthetic alone. Recently, intracameral anaesthesia using 1% preservative-free lidocaine combined with topical anaesthesia has been tried clinically on patients undergoing cataract operations.[9-11] The anaesthetic effect and patients' comfort seem satisfactory even during surgical manipulation of the uveal tissue. The advantages of intracameral anaesthesia are: 1) it is fast acting, 2) it is easy to administer, 3) it has relatively less serious ocular complications, and 4) it leads to minimal increase in IOP. However, intracameral lidocaine has potential toxic effects on the corneal endothelium. This prospective study was designed to evaluate the anaesthetic effect and safety of topical amethocaine combined with intracameral lidocaine in trabeculectomy.
Most of the published clinical data on corneal toxicity of intracameral lidocaine were derived from studies of phacoemulsification. Phacoemulsification may by itself cause substantial endothelial cell damage and postoperative corneal oedema. It would, therefore, be difficult to separate the effect of phacoemulsification on the endothelial cell from that due to lidocaine. On the other hand, the average endothelial cell loss in POAG eyes undergoing trabeculectomy without postoperative irido-corneal touch was as low as 1.6%. This allows us to evaluate more accurately the effect of intracameral lidocaine on the endothelial cells.
| Materials and Methods|| |
The study was conducted at the United Christian Hospital and the Prince of Wales Hospital, Hong Kong. Ethics Committee approval was obtained prior to the study. Patients included in this study signed an informed consent. Patients with POAG indicated for trabeculectomy were recruited. Indications for trabeculectomy were, (1) IOP greater than 21 mmHg, or (2) documented deterioration of glaucomatous visual field defect, or (3) documented increase in the vertical cup-to-disc ratio, despite maximally tolerated medications. Exclusion criteria were: (1) single-eyed patient, (2) patients with the following types of glaucoma: uveitic, neovascular, phacolytic and angle-closure glaucoma, (3) trabeculectomy requiring anti-fibrotic agent, (4) previous intraocular surgery, and (5) endothelial cell count < 1500/mm2.
Preoperative examination included visual acuity test, applanation tonometry, slitlamp biomicroscopy, gonioscopy, fundoscopy and visual field test. Baseline vital signs were measured and specular microscopy (Konan Specular Microscope Noncon Robo SP 6000, Japan) was performed on both eyes prior to surgery.
The surgery was performed by either of the two surgeons (JSML and CCYT). Each patient received 2 drops of topical amethocaine 5% every 5 minutes three times immediately prior to the surgery. No systemic sedative was given to any of the patients. The eye was rinsed with 5% povidone anti-septic solution. A Katena lid speculum was used to retract the eyelids. No traction suture was used. An anterior chamber paracentesis was made at the 2-o'clock position in the left eye and at the 11-o'clock position in the right eye. 0.3 ml of 1% preservative-free lidocaine (50mg/5ml) (pH 6.5) (Delta West Ply Ltd. Australia) was injected into the anterior chamber. A standard trabeculectomy using fornix-based conjunctival flap and a 3 x 3 mm partial scleral flap using the Beaver blade was performed. The inner sclerotomy was prepared using the Kelly's Descemet membrane punch. A peripheral iridectomy was performed with the Vannas scissors and the scleral flap was closed with 10-0 nylon sutures. The drainage rate was tested by injecting balanced salt solution (BSS) into the anterior chamber through the paracentesis wound and observing drainage into the subconjunctival space and the anterior chamber depth. The conjunctival flap was closed with 8-0 vicryl sutures. Adjunctive antifibrotic agent was not used in any of the cases. Subconjunctival dexamethasone (4 mg) was injected. The eye was irrigated with 5% povidone solution and rinsed with BSS. Maxitrol (dexamethasone 0.1%, neomycin sulfate, polymixin B sulfate) ointment was applied and the eye was patched overnight.
The pulse rate and blood pressure were continuously monitored during the operation. If patients developed significant discomfort during the surgery, additional sub-Tenon's anaesthesia would be given.
Immediately after surgery, patients were presented a 10-point visual analog pain scale. The scale ranges from 0 (no pain) to 10 (unbearable pain). They were asked to grade the level of the most severe pain experienced during the operation. The surgeon also completed an assessment form immediately after surgery. Duration of surgery, lid squeezing, significant increase in the pulse rate defined as an increase ≥ 20 beats/minute, significant increase in the blood pressure defined as a systolic increase of 20 mmHg or a diastolic increase of 10 mmHg, and supplementary sedation and/or sub-Tenon's anaesthesia during the surgery were recorded on a data sheet designed for this study.
The patients were examined on the first postoperative day. The cornea was carefully assessed for oedema and thickening. The anterior chamber reaction was recorded. The visual acuity and the IOP were documented. Any postoperative analgesic required was recorded. The patients were examined again weekly for 2 weeks and monthly for 3 months. In addition to the above ocular examinations, specular microscopy for endothelial cell count was performed 3 months after surgery.
| Results|| |
Ten eyes of 10 patients were included in the study. There were 4 male and 6 female patients. The mean age was 71.1 ± 7.56 years. The mean preoperative IOP was 24.60 ± 8.28 mmHg. The mean postoperative IOP at 3 months was 14.1 ± 3.11 mmHg. All 10 patients were treated with timolol 0.5%, latanoprost 0.005% and dorazolamide 2% eyedrops from 6 - 8 weeks prior to surgery. The mean preoperative endothelial cell count was 2322.70 ± 346.49/mm2 and the mean postoperative endothelial cell count at 3 months was 2229.70 ± 306.78/mm2. There was no statistically significant difference between the mean preoperative and postoperative endothelial cell counts at the 5% significance level (P = 0.375). The results are summarized in [Table - 1]. The mean pain score was 1.70 (range 1-4). No supplementary anaesthetic was required intraoperatively in any of the patients. One patient had transient increase of systolic blood pressure of more than 20 mmHg during punch excision of the inner scleral flap. One patient reported discomfort during diathermy coagulation of the episcleral blood vessels. One patient required oral analgesic on the first postoperative day. The results are summarized in [Table - 2].
There was no intraoperative complication. One patient had postoperative hyphaema which resolved spontaneously. One patient had conjunctival wound leak on the first postoperative day which responded to bandage contact lens. All patients had clear cornea on the first postoperative day. There was no postoperative flat anterior chamber or hypotony. None of the patients developed fibrinous reaction or other severe postoperative anterior chamber inflammation. There was no reduction in visual acuity more than 2 Snellen lines in all 10 patients at 3 months after surgery.
| Discussion|| |
Conventionally, retrobulbar anaesthesia is used in trabeculectomy. There are potentially serious complications associated with retrobulbar injection of anaesthetic agents. Retrobulbar haemorrhage during injection can result in an abrupt rise in the orbital pressure, and may be hazardous, especially in patients with glaucomatous optic neuropathy. Topical anaesthesia is safe and effective in cataract surgery. However, in trabeculectomy, excision of the iris tissue during peripheral iridectomy and abrupt reduction of the chronically raised IOP may cause significant pain not controlled by the topical anaesthetic agent. Intracameral anaesthesia may be a safe and effective alternative. It avoids the risks of retrobulbar injections and may be effective against the pain associated with trabeculectomy.
Intracameral lidocaine appears to have an anaesthetic effect on the retinal ganglion cells. Koch reported reduced visual acuity and contrast sensitivity in the early post cataract surgery period with intracameral anaesthesia. Intracameral anaesthesia may, therefore, have an additional advantage over topical anaesthesia in patients undergoing trabeculectomy alone. These patients have relatively clear lens, and there is minimal light shielding effect from intraocular surgical instruments during surgery. The patient's sensitivity to the strong light of the microscope and the discomfort thus caused are expected to be greater than in those patients with coexisting cataract receiving phacotrabeculectomy. Intracameral anaesthesia should, at least conceptually, make the trabeculectomy patient more comfortable during surgery.
In our case series, intracameral lidocaine provided comfortable operative circumstances for the patient, even without the use of intravenous sedation. The mean pain score was 1.7. None of the patients required supplementary anaesthetic intraoperatively. Only one patient experienced transient sharp pain during punch excision of the inner scleral tissue. Besides providing a good intraoperative anaesthetic effect, it also had a satisfactory postoperative analgesic effect. Only one patient in the series required oral analgesic to control the postoperative discomfort. However, lidocaine injected into the anterior chamber may damage the endothelial cells. In Crandall's study, there was 9.1% post phacoemulsification endothelial cell loss in the intracameral lidocaine group. It was, however, difficult to determine the contribution of phacoemulsification surgery itself. The endothelial cell loss at 3 months postoperatively in this study was 4.01% but the decrease was not statistically significant at the 5% significance level (p = 0.374) (paired sample t-test). Although the sample size was small, the preoperative and postoperative endothelial cell count approximated normal distribution closely. As mentioned earlier, the endothelial cell loss may be partially due to the surgery itself as it has been reported that the average endothelial cell loss was about 1.6% in POAG eyes undergoing trabeculectomy without postoperative irido-corneal touch.
The preliminary results of this study suggest that 1% preservative-free lidocaine might be a safe and effective intracameral anaesthetic agent in trabeculectomy. A larger-scale comparative study is needed to draw a firm conclusion
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[Table - 1], [Table - 2]