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Randomized comparative clinical study of cryoanalgesia versus topical anesthesia in clear corneal phacoemulsification
Randomized comparative clinical study of cryoanalgesia versus topical anesthesia in clear corneal phacoemulsification Francisco J. Gutie´rrez-Carmona, MD, PhD, Jorge Alvarez-Marı´n, MD, PhD Purpose: To compare intraoperative pain scores and objective stress signs during clear corneal phacoemulsification under cryoanalgesia and topical anesthesia. Setting: Hospital Ramo´n y Cajal, Madrid, and Hospital Universitario Nuestra Sra. de la Candelaria, Tenerife, Canary Islands, Spain. Methods: Eighty-two patients were randomized to have phacoemulsification under cryoanalgesia or topical anesthesia. Uncooperative patients and those with shallow anterior chamber and small pupils were excluded. In case of breakthrough pain during the surgery, a supplemental anesthesia protocol was established. Each patient was asked to grade the severity of pain on a 4-point scale (verbal description score; 0 Z none, 1 Z little, 2 Z some, or 3 Z much). Immediately after surgery, the general discomfort and pain were evaluated. Surgeon stress was evaluated during surgery. A comparison of the 2 groups was performed using a statistical analysis of variance. Results: Supplemental anesthesia was required in 1 patient in each group. A total of 95.23% of patients would repeat the same technique under cryoanalgesia versus 97.5% under topical anesthesia. Similar pain levels and surgical stress scores were noted in both groups. Conclusions: Cryoanalgesia clear corneal phacoemulsification was safe with an acceptable level of pain. It induced a physiological stress response to that of topical anesthesia (blood pressure and heart rate). Cryoanalgesia was preferred over topical anesthesia by some patients. It is a suitable technique for anesthetic allergy cases. J Cataract Refract Surg 2005; 31:1187–1193 ª 2005 ASCRS and ESCRS
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ataract surgery is generally performed under local anesthesia consisting of retrobulbar, peribulbar, or subconjunctival injection or under topical
Accepted for publication October 19, 2004. From the Hospital Ramo´n y Cajal, Madrid, and Hospital Universitario Nuestra Sra. de la Candelaria, Tenerife, Canary Islands, Spain. Presented in part at the annual meeting of the American Academy of Ophthalmology, Orlando, Florida, USA, October 2002. No author has a proprietary or financial interest in any material or method mentioned. Reprint requests to Francisco J Gutie´rrez-Carmona, MD, PhD, Zarracı´n 25 – Urb. La Berzosa 28240-Hoyo de Manzanares, Madrid, Spain. ª 2005 ASCRS and ESCRS Published by Elsevier Inc.
anesthesia. The tendency is to reserve general anesthesia for patients with senile dementia, deafness, and noncooperation. The use of a local anesthetic agent in cataract surgery has superseded general anesthesia because of its indisputable advantages, such as the possibility of ambulatory surgery, rapid recovery, and lack of complications. However, local anesthetic surgery performed using the retrobulbar or peribulbar technique is not without possible complications such as perforation of the globe accompanied by retinal detachment and severe intraocular hemorrhage, retrobulbar hematoma, diplopia, direct optic nerve trauma caused by the retrobulbar needle; increased intraorbital pressure, postoperative ptosis, or systemic complications such as 0886-3350/05/$-see front matter doi:10.1016/j.jcrs.2004.12.038
RANDOMIZED COMPARISON OF CRYOANALGESIA AND TOPICAL ANESTHESIA
accidental administration of anesthetic agent to the bloodstream or nervous system. The use of small-incision cataract surgery techniques involving manual phacofragmentation or phacoemulsification has prompted the reintroduction of topical anesthesia. The first known use of topical anesthesia for cataract surgery was in 1884, when Knapp1 described the use of 5% cocaine drops. In 1985, Smith2 used a combination of topical anesthesia with tetracaine and subconjunctival injection of lidocaine for extracapsular cataract extraction (ECCE). However, Fichman3 was the first to reintroduce topical anesthesia for cataract surgery through phacoemulsification and the implantation of an intraocular lens (IOL) in 1992. This was followed by the first cataract, which was operation without the use of pharmacological anesthesia performed by Agarwal et al.4 in 1998. One year later Gutie´rrez-Carmona5 began to perform cataract surgery by the modification of the method of Agarwal et al. using cryoanalgesia. The technique presented here shows the possibility of cataract surgery applying cold, or ‘‘cryo,’’ analgesia. Cryoanalgesia has been successfully used in thoracic surgery for lung lobectomy through a minithoracotomy6,7 and in the treatment of postoperative pain following thoracotomy,8 hip adductor spasticity, and obturator neuralgia.9 About 30 years ago, Krwawicz10 performed the first cataract operation involving cryoextraction of the lens. He not only developed a new area of ophthalmology, cryoophthalmology, for the treatment of certain ocular diseases but also suggested the advantages of the use of low temperatures in medicine. The purpose of this study was to compare the use of phacoemulsification with an IOL implantation under cryoanalgesia versus topical anesthesia, evaluating cryoanalgesia’s validity and the patient and surgeon stress levels as well as the surgical pain level of the patient.
Patients and Methods In a prospective single blind study, 82 patients had clear corneal phacoemulsification and IOL implantation by 2 experienced surgeons (F.J.G.-C., J.A.-M.) who performed the same surgical technique. The patients were randomly distributed in 2 groups. In group 1, 42 patients were operated on under cryoanalgesia and in group 2, 40 patients under topical anesthesia. Each surgeon performed both 1188
procedures, dividing the number of patients in each group between themselves: 21 patients in group 1 were operated on by 1 of the surgeon and the remaining 21 by the other surgeon. Similarly, each surgeon operated on 20 patients in group 2. Mean age was 72.28 years (range 40 to 93 years), and there were 45 women and 37 men. There was no significant difference in age (P Z .48) or sex (P Z .84) distribution between the 2 groups. Excluded from the study were uncooperative patients; patients with monocular sight; and patients with hypermature cataracts, shallow anterior chambers, or pharmacological mydriasis less than 5 mm. Patients with difficulties expressing their pain level were also excluded. All patients signed an informed consent.
Parameters A questionnaire was designed to record all of the data during and at the end of surgery, such as the positive lid pressure and vitreous pressure, pain of the patient during the different steps of surgery, the patient collaboration level, and surgeon stress. A verbal description scale between 0 and 3 was used to rate pain levels and corresponded to a qualitative scale (0 Z none, 1 Z little, 2 Z some, or 3 Z much). Best corrected visual acuity (BCVA) was measured preoperatively and at 1 and 3 months in the postoperative period. Comparison of parameters between the 2 groups was by an analysis of variance. A P value less than 0.05 was considered statistically significant.
Surgical Technique All solutions to be instilled during the operation, except the povidone drops, were cooled to around 4 C. Mydriasis was obtained with 3 to 4 drops each of topical phenylephrine hydrochloride 10% and cyclopentolate hydrochloride 1%. No patient received preoperative sedation. No nonsteroidal antiinflammatory drugs (NSAIDs) were used. Before surgery, an eye mask of cold gel (Eyes Pack Single) was placed over the eye for about 10 minutes (Figure 1). This afforded some degree of analgesia to the eyelids, facilitating the insertion of the lid speculum. Ocular asepsis before surgery was achieved using povidone 5% drops. Next, a drop of cold methylcellulose (Celoftal) was instilled in the eye before placement of the ophthalmic drape to isolate the eyelid to reduce the stinging sensation of the povidone. Phacoemulsification was done through a clear corneal incision and to avoid touching the conjunctiva or sclera, and a forceps was used to hold the globe. A Barraquer speculum was used for lid retraction, although a Castroviejo speculum may also prove useful for this purpose.
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degrees to the paracentesis using a 3.2 mm phaco knife (Alcon Surgical).
Capsulorhexis and Nuclear Hydrodissection Cold Viscoat was injected into the AC. Next, the corneal incision was chilled with cold BSS to perform a continuous curvilinear capsulorhexis (CCC) with a capsulorhexis forceps. The lens nucleus was hydrodissected with cold BSS irrigation using a Binkhorst or a straight Rycroft cannula inserted through the corneal incision.
Phacoemulsification Figure 1. A monolateral eye mask of cold gel is placed over the eye before surgery for about 10 minutes.
Anesthesia Technique In group 1 (cryoanalgesia), the eye was repeatedly irrigated with cold balanced salt solution (BSS) at 4 C during all steps of surgery and the phaco irrigation solution (fortified BSS) was cooled at the same temperature. Patients also received 2 drops of BSS 3 times beginning 10 to 15 minutes before surgery. In group 2 (topical anesthesia), patients received 2 drops of a mixture of tetracaine hydrochloride 1% and oxybuprocaine hydrochloride 4% 3 times beginning 10 to 15 minutes before surgery and the same cold BSS protocol as in group 1. A protocol was established for supplemental anesthesia for breakthrough pain during the surgery. If a patient reported pain, 2 additional drops of topical anesthetic were placed in the eye. If pain persisted, the anterior chamber was irrigated with lidocaine 1% solution.
Paracentesis The cornea was previously cooled by continuous irrigation from a flask of cold BSS in the area in which the paracentesis was conducted. For the paracentesis, the globe was held still with a spatula or lens manipulator placed on the corneal periphery, opposite the area through which the anterior chamber (AC) was accessed using a paracentesis knife.
Depending on the surgeon’s preference, the analgesic method could accommodate the use of a peristaltic pump or venturi pump system. Phacoemulsification was performed using a Legacy 20000 unit (Alcon Laboratories). In both groups, the phaco-chop phacoemulsification technique was used, with cold fortified BSS irrigation, modifying the settings of the phacoemulsifier according to the type of cataract and preferences of the surgeon. During phacoemulsification, the cornea was kept chilled with cold BSS. When the tip of the phacoemulsifier was inserted into the AC, the corneal incision was cooled by continuous irrigation from a flask of cold BSS.
Cortical Aspiration Cortical aspiration was performed with cold fortified BSS irrigation using the irrigation/aspiration (I/A) tip according to the settings of the phacoemulsifier.
Intraocular Lens Insertion and Incision Closure Cold Viscoat was injected into the capsular bag, and the corneal incision was extended to 4.1 mm after chilling. Once the corneal incision was cooled with BSS, a foldable IOL was implanted with an IOL forceps. The viscoelastic material was then aspirated with the I/A handpiece. Closure of the incision was performed by stromal hydration using cold BSS, and the integrity of the corneal valve was tested by filling the AC with cold BSS and pressing on the posterior lip of the incision to detect leakage. When required, the corneal incision was closed with a single radial suture.
Results
Clear Corneal Incision Cold sodium hyaluronate 3%–chondroitin sulfate 4% (Viscoat) was injected through the paracentesis into the AC, and a lens manipulator was subsequently introduced to stabilize the globe. The cornea was then continuously cooled with BSS in the area in which the clear corneal incision was to be made. A corneal tunnel incision was performed at 90
Surgical conditions (nucleus density and duration of surgery) did not differ between the groups (Table 1). There were no significant differences (P!.05) in the postoperative BCVA (Table 2) between groups, including patients with complications.
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Table 1.
Characteristic of the patients by group.
Characteristic
Group 1
Group 2
Number of patients
42
40
Sex (men/women)
19/23
18/22
73.14 G 8.62
71.43 G 13.25
Minimum
42
40
Maximum
88
93
Median
74
73
Mean nuclear density (0 to 5)
3.05 G 0.75
2.87 G 0.5
Mean surgical time (min)
15.5 G 3.5
14.2 G 4.5
Mean age G SD (yr)
Group 1 Z cryoanalgesia; Group 2 Z topical anesthesia
Table 2. Best corrected visual acuity preoperatively and 1 month and 3 months postoperatively. Exam
Group 1
Group 2
Preoperatively Mean G SD
0.29 G 0.09
0.26 G 0.1
Minimum
0.1
0.1
Maximum
0.5
0.4
1 month postoperatively Mean G SD
0.78 G 0.12
0.8 G 0.13
Minimum
0.4
0.4
Maximum
1.0
1.0
3 months postoperatively Mean G SD
0.87 G 0.08
0.83 G 0.1
Minimum
0.7
0.6
Maximum
1.0
1.0
Group 1 Z cryoanalgesia; Group 2 Z topical anesthesia
Intraoperative Complications The incidence of complications was similar with both anesthesia techniques. There were 3 capsule ruptures (7.14%) in the cryoanalgesia group and 1 capsule rupture in the topical anesthesia group (2.5%); there were no significant differences (P Z .21). In group 1, the 3 capsule ruptures occurred in the first patients operated on (patients 5, 34, and 36), when the surgeons had a higher level of stress; whereas in group 2, the capsule rupture took place during nuclear fragmentation (patient 38). All capsule ruptures in both groups occurred during lens manipulation in eyes with hard nuclei. There were no nuclear fragments lost into the vitreous cavity in any of the 4 patients. In these 1190
patients, after the corneal incision was enlarged to 4.1 mm, an anterior vitrectomy was performed, ending the surgery by means of ECCE (manual phacofragmentation) and implantation of the IOL. In 2 of the cryoanalgesia patients, posterior chamber IOLs were implanted in the capsular bag; in the third cryoanalgesia patient and in the topical anesthesia patient, the IOLs were implanted in the sulcus. A single radial suture was used to close the corneal incisions. It was not necessary to modify the anesthetic technique in any of the patients. One patient in each group required supplemental anesthesia (intracameral lidocaine 1%). Patient Preferences There were no significant differences between the cryoanalgesia and topical anesthesia groups in reference to the anesthesia technique. Forty patients (95.23%) in the cryoanalgesia group would have been happy to have the same surgical technique again, and 39 patients (97.5%) in the topical anesthesia group would repeat this technique. The specifics with regard to intraoperative pain were evaluated using the following parameter: With regard to the patient preferences for a certain analgesic technique, there were no significant differences between the groups (P Z .96). One patient operated on by means of cryoanalgesia decided to have surgery on the second eye using the same anesthesia technique. Two patients in whom the surgery was performed in the contralateral eye before the study by means of retrobulbar anesthesia preferred cryoanalgesia. In 3 patients, 1 eye was operated on under topical anesthesia and the other by means of cryoanalgesia. One of the 3 preferred the topical anesthesia and the other 2 cryoanalgesia. One patient under topical anesthesia needed intraoperative sedation. Two patients under topical anesthesia needed active hypertension treatment during surgery. The 2 patients operated on with topical anesthesia in which the contralateral eye had been operated on with retrobulbar anesthesia preferred topical anesthesia. Intraoperative Pain The pain reported by the patient was evaluated at each step of the surgery. There were 3 stages that were most painful or uncomfortable to the patient. They
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Figure 3.
Heart Rate and Blood Pressure There were no significant differences (P!.05) between groups in the patient heart rate during the different steps of surgery. There were no significant differences in the values of the maximum and minimum blood pressure except for higher maximum blood pressure at the moment of the closure of the corneal incision by stromal hydration in the cryoanalgesia group (P Z .03) (Figures 4 and 5).
Discussion
Surgeon stress
Vitreous Pressure
Lid Pressure
IOL implantation
Mydriasis
Corneal Transparence
CCC
Ocular stabilization
3 2,5 2 1,5 1 0,5 0
Surgeon stress.
80 75 70 65
Figure 4.
Closure
Basal
IOL
50
Incision
60 55 Pre-Op
Surgeon Stress In reference to the surgeon’s stress, there were no significant differences in any of the studied parameters. The surgeon stress during surgery was higher in the cryoanalgesia group (P Z .21), without statistically significant differences (Figure 3). There were no significant differences in the patients’ global collaboration (P Z .07).
statistical differences between the 2 groups. We believe that although the stress level of the surgeons performing the cryoanalgesia technique was higher, it is also true that the capsule ruptures were in eyes with in hard nuclei, in which this type of complication more frequently occurs. Furthermore, we believe that increasing the size of the study would help determine
Global score
were the paracentesis, the corneal incision, and IOL implantation. The pain registered at each of the 3 points did not exceed a rating of 1.5 of 3 (Figure 2). There were no differences in comfort related to the lid speculum (P Z .07) between the anesthesia techniques. Patients operated on under cryoanalgesia reported more pain at the moment of the paracentesis (P Z .02). There were no significant differences in the rest of the surgical steps (corneal incision, hydrodissection, CCC, phacoemulsification, cortex aspiration, IOL implantation, and incisional stromal hydration).
Heart rate curve.
Although the rate of capsule rupture was higher in the cryoanalgesia group, there were no significant 3 2,5
17
2
15
1,5
13
1
11
0,5
9
Figure 2.
Pain curve.
Figure 5.
BP closure
BP IOL
BP Incision
5
BP Basal
7 Pre-Op
24 h
Final score
Stromal Hydr.
IOL
Cortex I/A
Phaco
Hydrodissection
CCC
Corneal Incision
Paracentesis
Speculum
0
Blood pressure curve.
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whether the type of anesthesia technique used influences the rate of these types of complications. As reported by Pandey and coauthors,11 we consider that the surgeon’s skill level is paramount; therefore, this anesthesia technique is not adequate for all surgeons and patients. We have observed in the young patient a lower tolerance for this anesthesia method due to a lower pain threshold. Surgeons frequently do not prefer needle anesthesia techniques for cataract surgery. The main reason is the avoidance of serious needle-tip complications such as orbital hemorrhage and inadvertent ocular perforation but also the possibility of quicker visual recovery. With some no-needle anesthesia techniques, eye movement is preserved, which can be regarded either as an advantage or a disadvantage by the surgeon.12 Clear corneal phacoemulsification has the advantage of avoiding touching superficial sensitive ocular tissue other than the peripheral cornea during the surgery.13 Topical lidocaine alone provides adequate anesthesia for phacoemulsification and foldable IOL implantation, but some studies13,14 report further intraoperative comfort with associated intracameral lidocaine administration. In contrast, Gillow et al.15 found that there were no significant relationships between the use of intracameral lidocaine and the intraoperative and postoperative scores and concluded that intracameral anesthesia as a supplement to topical anesthesia has no useful clinical role. Topical anesthesia can induce corneal epithelial, corneal endothelial, or retinal toxicity, which are mainly the result of preservatives in the anesthetic solutions.16–19 Some anesthetic agents, such as proparacaine, can lead to allergic reactions such as periocular swelling, erythema, and contact dermatitis.16 Preoperative instillation of anesthetic agents can cause ocular discomfort (burning and stinging), and multiple applications can lead to mild corneal haziness during surgery. The toxicity of ocular anesthetic agents has been reported and discussed in several studies.16,19 Cat corneal physiology is relevant to the use of cryoanalgesia. The cat cornea is an avascular tissue of very simple structure, innervated almost exclusively by thin myelinated and unmyelinated trigeminal ganglion neurons that belong to the classes of high-threshold mechanosensory, polymodal, and cold primary sensory neurons.20 The role played by cold-sensitive neurons in 1192
the production of ocular sensations in the human has not been established. In 1981, Belmonte and Giraldez21 observed that temperatures under 20 C tend to diminish or silence the activity in the polymodal neurons. This can explain a possible effect of the cryoanalgesia. In studies of cats, it was proved that the concomitant stimulation of the polymodal nociceptors induce a pain sensation that can change in quality when mechanosensory or thermal fibers are activated concomitantly.20 In phacoemulsification under cryoanalgesia, the sustained stimulation of the corneal receptors by means of cold and the AC pressure can induce a saturation of the nervous transmission by means of mechanical and thermal stimuli, which reduces the transmission of pain sensations with the same intensity. Another possible hypothesis on the effects of cryoanalgesia is that the vasoconstriction because of cold can reduce the liberation of inflammation mediators (leukotrienes and prostaglandins) and therefore induce a local analgesic effect similar to that with NSAIDs.22,23 Nielsen13 proved a lesser analgesic effect of topical anesthesia over the peribulbar anesthesia and over the retrobulbar, although the patients preferred the peribulbar anesthesia, which lacks the pain induced by the retrobulbar injection. In our study, some patients who had retrobulbar anesthesia in the contralateral eye preferred topical anesthesia or cryoanalgesia. We did not observe significant differences in the pain level reported by the patients operated on under cryoanalgesia or topical anesthesia, nor were significant differences detected in the surgical stress level of the patient evaluated by means of blood pressure variations and the heart rate. From these results, we can deduce that the analgesia level would be similar with both techniques. In our study, the most painful surgical steps were be the paracentesis, incision, IOL insertion, and the closure of the corneal incision by stromal hydration. In these steps, we highly recommend greater cooling of the eye to reduce the pain sensation.
Conclusion Phacoemulsification under cryoanalgesia appears to be a safe technique. In the current study, we did not see
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a greater incidence of complications in comparison with topical anesthesia. There were no significant differences between the pain reported by the patient operated by clear corneal phacoemulsification under cryoanalgesia versus topical anesthesia. There were no significant differences in the physiological response to the surgical stress of the patient in phacoemulsification performed under both analgesia types. Some patients preferred cryoanalgesia to topical anesthesia. There were no significant differences in the surgeon stress between anesthesia techniques. Within the parameters (capsule rupture rate, comfort related to lid speculum, surgeon stress, and patient’s global collaboration), the slight statistical difference between the 2 groups indicates the need for a larger sample group to confirm that these occurrences are not random. For this reason, we must view these results with some reserve. Cryoanalgesia is a useful technique in the case of allergy to anesthetic agents.
References 1. Knapp H. On cocaine and its use in ophthalmic and general surgery. Arch Ophthalmol (old series) 1884; 13:402–448 2. Smith RJH. Cataract extraction without retrobulbar anaesthetic injection. Br J Ophthalmol 1990; 74:205–207 3. Fichman RA. Phacoemulsification with topical anesthesia. In: Fine IH, Fichman RA, Grabow HB, eds, ClearCorneal Cataract Surgery and Topical Anesthesia. Thorofare, NJ, Slack, 1993; 113–118 4. Agarwal A, Agarwal S, Sachdev MS, et al. No anesthesia cataract surgery with karate chop. In: Phacoemulsification, Laser Cataract Surgery and Foldable IOLs. New Delhi, Jaypee Brothers, 1998; 144–154 5. Gutie´rrez-Carmona FJ. Phacoemulsification with cryoanalgesia: a new approach for cataract surgery. In: Phacoemulsification, Laser Cataract Surgery and Foldable IOLs, 2nd ed. New Delhi, Jaypee Brothers, 2000; 226–229 6. Tovar EA, Roethe RA, Weissig MD, et al. One-day admission for lung lobectomy: an incidental result of a clinical pathway. Ann Thorac Surg 1998; 65:803–806 7. Tovar EA, Roethe RA, Weissig MD, et al. Muscle-sparing minithoracotomy with intercostal nerve cryoanalgesia: an improved method for major lung resections. Am Surg 1998; 64:1109–1115
8. Pastor J, Morales P, Cases E, et al. Evaluation of intercostal cryoanalgesia versus conventional analgesia in postthoracotomy pain. Respiration 1996; 63:241–245 9. Kim PS, Ferrante FM. Cryoanalgesia: a novel treatment for hip adductor spasticity and obturator neuralgia. Anesthesiology 1998; 89:534–536 10. Toczolowski J. [Thirty years of cryo-ophthalmology. Work dedicated to the memory of Dr. Tadeusz Krwawicz]. [Polish] Klin Oczna 1994; 96:129–131 11. Pandey SK, Werner L, Agarwal A. No anesthesia cataract surgery. In: Agarwal S, Agarwal A, Sachdev MS, et al, eds, Phacoemulsification, Laser Cataract Surgery and Foldable IOLs, 2nd ed. New Delhi, Jaypee Brothers Medical Publishers, 2000; 217–225 12. Pandey SK, Werner L, Apple DJ, et al. No-anesthesia clear corneal phacoemulsification versus topical and topical plus intracameral anesthesia; randomized clinical trial. J Cataract Refract Surg 2001; 27:1643–1650 13. Nielsen PJ, Allerød CW. Evaluation of local anesthesia techniques for small incision cataract surgery. J Cataract Refract Surg 1998; 24:1136–1144 14. Crandall AS, Zabriskie NA, Patel BCK, et al. A comparison of patient comfort during cataract surgery with topical anesthesia versus topical anesthesia and intracameral lidocaine. Ophthalmology 1999; 160:60–66 15. Gillow T, Scotcher SM, Deutsch J, et al. Efficacy of supplementary intracameral lidocaine in routine phacoemulsification under topical anesthesia. Ophthalmology 1999; 106:2173–2177 16. Rosenwasser GOD. Complications of topical ocular anesthetics. Int Ophthalmol Clin 1989; 29(3):153–158 17. Werner LP, Legeais JM, Obsler C, et al. Toxicity of Xylocaine to rabbit corneal endothelium. J Cataract Refract Surg 1998; 24:1371–1376 18. Liang C, Peyman CA, Sun G. Toxicity of intraocular lidocaine and bupivacaine. Am J Ophthalmol 1998; 125:191–196 19. Judge AJ, Najafi K, Lee DA, Miller KM. Corneal endothelial toxicity of topical anesthesia. Ophthalmology 1997; 104:1373–1379 20. Acosta MC, Belmonte C, Gallar J. Sensory experiences in humans and single-unit activity in cats evoked by polymodal stimulation of the cornea. J Physiol 2001; 534:511–525 21. Belmonte C, Giraldez F. Responses of cat corneal sensory receptors to mechanical and thermal stimulation. J Physiol 1981; 321:355–368 22. Epstein RL, Laurence EP. Effect of topical diclofenac solution on discomfort after radial keratotomy. J Cataract Refract Surg 1994; 20:378–380 23. Szerenyi K, Sorken K, Garbus JJ, et al. Decrease in normal human corneal sensitivity with topical diclofenac sodium. Am J Ophthalmol 1994; 118:312–315
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C
ataract surgery is generally performed under local anesthesia consisting of retrobulbar, peribulbar, or subconjunctival injection or under topical
Accepted for publication October 19, 2004. From the Hospital Ramo´n y Cajal, Madrid, and Hospital Universitario Nuestra Sra. de la Candelaria, Tenerife, Canary Islands, Spain. Presented in part at the annual meeting of the American Academy of Ophthalmology, Orlando, Florida, USA, October 2002. No author has a proprietary or financial interest in any material or method mentioned. Reprint requests to Francisco J Gutie´rrez-Carmona, MD, PhD, Zarracı´n 25 – Urb. La Berzosa 28240-Hoyo de Manzanares, Madrid, Spain. ª 2005 ASCRS and ESCRS Published by Elsevier Inc.
anesthesia. The tendency is to reserve general anesthesia for patients with senile dementia, deafness, and noncooperation. The use of a local anesthetic agent in cataract surgery has superseded general anesthesia because of its indisputable advantages, such as the possibility of ambulatory surgery, rapid recovery, and lack of complications. However, local anesthetic surgery performed using the retrobulbar or peribulbar technique is not without possible complications such as perforation of the globe accompanied by retinal detachment and severe intraocular hemorrhage, retrobulbar hematoma, diplopia, direct optic nerve trauma caused by the retrobulbar needle; increased intraorbital pressure, postoperative ptosis, or systemic complications such as 0886-3350/05/$-see front matter doi:10.1016/j.jcrs.2004.12.038
RANDOMIZED COMPARISON OF CRYOANALGESIA AND TOPICAL ANESTHESIA
accidental administration of anesthetic agent to the bloodstream or nervous system. The use of small-incision cataract surgery techniques involving manual phacofragmentation or phacoemulsification has prompted the reintroduction of topical anesthesia. The first known use of topical anesthesia for cataract surgery was in 1884, when Knapp1 described the use of 5% cocaine drops. In 1985, Smith2 used a combination of topical anesthesia with tetracaine and subconjunctival injection of lidocaine for extracapsular cataract extraction (ECCE). However, Fichman3 was the first to reintroduce topical anesthesia for cataract surgery through phacoemulsification and the implantation of an intraocular lens (IOL) in 1992. This was followed by the first cataract, which was operation without the use of pharmacological anesthesia performed by Agarwal et al.4 in 1998. One year later Gutie´rrez-Carmona5 began to perform cataract surgery by the modification of the method of Agarwal et al. using cryoanalgesia. The technique presented here shows the possibility of cataract surgery applying cold, or ‘‘cryo,’’ analgesia. Cryoanalgesia has been successfully used in thoracic surgery for lung lobectomy through a minithoracotomy6,7 and in the treatment of postoperative pain following thoracotomy,8 hip adductor spasticity, and obturator neuralgia.9 About 30 years ago, Krwawicz10 performed the first cataract operation involving cryoextraction of the lens. He not only developed a new area of ophthalmology, cryoophthalmology, for the treatment of certain ocular diseases but also suggested the advantages of the use of low temperatures in medicine. The purpose of this study was to compare the use of phacoemulsification with an IOL implantation under cryoanalgesia versus topical anesthesia, evaluating cryoanalgesia’s validity and the patient and surgeon stress levels as well as the surgical pain level of the patient.
Patients and Methods In a prospective single blind study, 82 patients had clear corneal phacoemulsification and IOL implantation by 2 experienced surgeons (F.J.G.-C., J.A.-M.) who performed the same surgical technique. The patients were randomly distributed in 2 groups. In group 1, 42 patients were operated on under cryoanalgesia and in group 2, 40 patients under topical anesthesia. Each surgeon performed both 1188
procedures, dividing the number of patients in each group between themselves: 21 patients in group 1 were operated on by 1 of the surgeon and the remaining 21 by the other surgeon. Similarly, each surgeon operated on 20 patients in group 2. Mean age was 72.28 years (range 40 to 93 years), and there were 45 women and 37 men. There was no significant difference in age (P Z .48) or sex (P Z .84) distribution between the 2 groups. Excluded from the study were uncooperative patients; patients with monocular sight; and patients with hypermature cataracts, shallow anterior chambers, or pharmacological mydriasis less than 5 mm. Patients with difficulties expressing their pain level were also excluded. All patients signed an informed consent.
Parameters A questionnaire was designed to record all of the data during and at the end of surgery, such as the positive lid pressure and vitreous pressure, pain of the patient during the different steps of surgery, the patient collaboration level, and surgeon stress. A verbal description scale between 0 and 3 was used to rate pain levels and corresponded to a qualitative scale (0 Z none, 1 Z little, 2 Z some, or 3 Z much). Best corrected visual acuity (BCVA) was measured preoperatively and at 1 and 3 months in the postoperative period. Comparison of parameters between the 2 groups was by an analysis of variance. A P value less than 0.05 was considered statistically significant.
Surgical Technique All solutions to be instilled during the operation, except the povidone drops, were cooled to around 4 C. Mydriasis was obtained with 3 to 4 drops each of topical phenylephrine hydrochloride 10% and cyclopentolate hydrochloride 1%. No patient received preoperative sedation. No nonsteroidal antiinflammatory drugs (NSAIDs) were used. Before surgery, an eye mask of cold gel (Eyes Pack Single) was placed over the eye for about 10 minutes (Figure 1). This afforded some degree of analgesia to the eyelids, facilitating the insertion of the lid speculum. Ocular asepsis before surgery was achieved using povidone 5% drops. Next, a drop of cold methylcellulose (Celoftal) was instilled in the eye before placement of the ophthalmic drape to isolate the eyelid to reduce the stinging sensation of the povidone. Phacoemulsification was done through a clear corneal incision and to avoid touching the conjunctiva or sclera, and a forceps was used to hold the globe. A Barraquer speculum was used for lid retraction, although a Castroviejo speculum may also prove useful for this purpose.
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degrees to the paracentesis using a 3.2 mm phaco knife (Alcon Surgical).
Capsulorhexis and Nuclear Hydrodissection Cold Viscoat was injected into the AC. Next, the corneal incision was chilled with cold BSS to perform a continuous curvilinear capsulorhexis (CCC) with a capsulorhexis forceps. The lens nucleus was hydrodissected with cold BSS irrigation using a Binkhorst or a straight Rycroft cannula inserted through the corneal incision.
Phacoemulsification Figure 1. A monolateral eye mask of cold gel is placed over the eye before surgery for about 10 minutes.
Anesthesia Technique In group 1 (cryoanalgesia), the eye was repeatedly irrigated with cold balanced salt solution (BSS) at 4 C during all steps of surgery and the phaco irrigation solution (fortified BSS) was cooled at the same temperature. Patients also received 2 drops of BSS 3 times beginning 10 to 15 minutes before surgery. In group 2 (topical anesthesia), patients received 2 drops of a mixture of tetracaine hydrochloride 1% and oxybuprocaine hydrochloride 4% 3 times beginning 10 to 15 minutes before surgery and the same cold BSS protocol as in group 1. A protocol was established for supplemental anesthesia for breakthrough pain during the surgery. If a patient reported pain, 2 additional drops of topical anesthetic were placed in the eye. If pain persisted, the anterior chamber was irrigated with lidocaine 1% solution.
Paracentesis The cornea was previously cooled by continuous irrigation from a flask of cold BSS in the area in which the paracentesis was conducted. For the paracentesis, the globe was held still with a spatula or lens manipulator placed on the corneal periphery, opposite the area through which the anterior chamber (AC) was accessed using a paracentesis knife.
Depending on the surgeon’s preference, the analgesic method could accommodate the use of a peristaltic pump or venturi pump system. Phacoemulsification was performed using a Legacy 20000 unit (Alcon Laboratories). In both groups, the phaco-chop phacoemulsification technique was used, with cold fortified BSS irrigation, modifying the settings of the phacoemulsifier according to the type of cataract and preferences of the surgeon. During phacoemulsification, the cornea was kept chilled with cold BSS. When the tip of the phacoemulsifier was inserted into the AC, the corneal incision was cooled by continuous irrigation from a flask of cold BSS.
Cortical Aspiration Cortical aspiration was performed with cold fortified BSS irrigation using the irrigation/aspiration (I/A) tip according to the settings of the phacoemulsifier.
Intraocular Lens Insertion and Incision Closure Cold Viscoat was injected into the capsular bag, and the corneal incision was extended to 4.1 mm after chilling. Once the corneal incision was cooled with BSS, a foldable IOL was implanted with an IOL forceps. The viscoelastic material was then aspirated with the I/A handpiece. Closure of the incision was performed by stromal hydration using cold BSS, and the integrity of the corneal valve was tested by filling the AC with cold BSS and pressing on the posterior lip of the incision to detect leakage. When required, the corneal incision was closed with a single radial suture.
Results
Clear Corneal Incision Cold sodium hyaluronate 3%–chondroitin sulfate 4% (Viscoat) was injected through the paracentesis into the AC, and a lens manipulator was subsequently introduced to stabilize the globe. The cornea was then continuously cooled with BSS in the area in which the clear corneal incision was to be made. A corneal tunnel incision was performed at 90
Surgical conditions (nucleus density and duration of surgery) did not differ between the groups (Table 1). There were no significant differences (P!.05) in the postoperative BCVA (Table 2) between groups, including patients with complications.
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Table 1.
Characteristic of the patients by group.
Characteristic
Group 1
Group 2
Number of patients
42
40
Sex (men/women)
19/23
18/22
73.14 G 8.62
71.43 G 13.25
Minimum
42
40
Maximum
88
93
Median
74
73
Mean nuclear density (0 to 5)
3.05 G 0.75
2.87 G 0.5
Mean surgical time (min)
15.5 G 3.5
14.2 G 4.5
Mean age G SD (yr)
Group 1 Z cryoanalgesia; Group 2 Z topical anesthesia
Table 2. Best corrected visual acuity preoperatively and 1 month and 3 months postoperatively. Exam
Group 1
Group 2
Preoperatively Mean G SD
0.29 G 0.09
0.26 G 0.1
Minimum
0.1
0.1
Maximum
0.5
0.4
1 month postoperatively Mean G SD
0.78 G 0.12
0.8 G 0.13
Minimum
0.4
0.4
Maximum
1.0
1.0
3 months postoperatively Mean G SD
0.87 G 0.08
0.83 G 0.1
Minimum
0.7
0.6
Maximum
1.0
1.0
Group 1 Z cryoanalgesia; Group 2 Z topical anesthesia
Intraoperative Complications The incidence of complications was similar with both anesthesia techniques. There were 3 capsule ruptures (7.14%) in the cryoanalgesia group and 1 capsule rupture in the topical anesthesia group (2.5%); there were no significant differences (P Z .21). In group 1, the 3 capsule ruptures occurred in the first patients operated on (patients 5, 34, and 36), when the surgeons had a higher level of stress; whereas in group 2, the capsule rupture took place during nuclear fragmentation (patient 38). All capsule ruptures in both groups occurred during lens manipulation in eyes with hard nuclei. There were no nuclear fragments lost into the vitreous cavity in any of the 4 patients. In these 1190
patients, after the corneal incision was enlarged to 4.1 mm, an anterior vitrectomy was performed, ending the surgery by means of ECCE (manual phacofragmentation) and implantation of the IOL. In 2 of the cryoanalgesia patients, posterior chamber IOLs were implanted in the capsular bag; in the third cryoanalgesia patient and in the topical anesthesia patient, the IOLs were implanted in the sulcus. A single radial suture was used to close the corneal incisions. It was not necessary to modify the anesthetic technique in any of the patients. One patient in each group required supplemental anesthesia (intracameral lidocaine 1%). Patient Preferences There were no significant differences between the cryoanalgesia and topical anesthesia groups in reference to the anesthesia technique. Forty patients (95.23%) in the cryoanalgesia group would have been happy to have the same surgical technique again, and 39 patients (97.5%) in the topical anesthesia group would repeat this technique. The specifics with regard to intraoperative pain were evaluated using the following parameter: With regard to the patient preferences for a certain analgesic technique, there were no significant differences between the groups (P Z .96). One patient operated on by means of cryoanalgesia decided to have surgery on the second eye using the same anesthesia technique. Two patients in whom the surgery was performed in the contralateral eye before the study by means of retrobulbar anesthesia preferred cryoanalgesia. In 3 patients, 1 eye was operated on under topical anesthesia and the other by means of cryoanalgesia. One of the 3 preferred the topical anesthesia and the other 2 cryoanalgesia. One patient under topical anesthesia needed intraoperative sedation. Two patients under topical anesthesia needed active hypertension treatment during surgery. The 2 patients operated on with topical anesthesia in which the contralateral eye had been operated on with retrobulbar anesthesia preferred topical anesthesia. Intraoperative Pain The pain reported by the patient was evaluated at each step of the surgery. There were 3 stages that were most painful or uncomfortable to the patient. They
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Figure 3.
Heart Rate and Blood Pressure There were no significant differences (P!.05) between groups in the patient heart rate during the different steps of surgery. There were no significant differences in the values of the maximum and minimum blood pressure except for higher maximum blood pressure at the moment of the closure of the corneal incision by stromal hydration in the cryoanalgesia group (P Z .03) (Figures 4 and 5).
Discussion
Surgeon stress
Vitreous Pressure
Lid Pressure
IOL implantation
Mydriasis
Corneal Transparence
CCC
Ocular stabilization
3 2,5 2 1,5 1 0,5 0
Surgeon stress.
80 75 70 65
Figure 4.
Closure
Basal
IOL
50
Incision
60 55 Pre-Op
Surgeon Stress In reference to the surgeon’s stress, there were no significant differences in any of the studied parameters. The surgeon stress during surgery was higher in the cryoanalgesia group (P Z .21), without statistically significant differences (Figure 3). There were no significant differences in the patients’ global collaboration (P Z .07).
statistical differences between the 2 groups. We believe that although the stress level of the surgeons performing the cryoanalgesia technique was higher, it is also true that the capsule ruptures were in eyes with in hard nuclei, in which this type of complication more frequently occurs. Furthermore, we believe that increasing the size of the study would help determine
Global score
were the paracentesis, the corneal incision, and IOL implantation. The pain registered at each of the 3 points did not exceed a rating of 1.5 of 3 (Figure 2). There were no differences in comfort related to the lid speculum (P Z .07) between the anesthesia techniques. Patients operated on under cryoanalgesia reported more pain at the moment of the paracentesis (P Z .02). There were no significant differences in the rest of the surgical steps (corneal incision, hydrodissection, CCC, phacoemulsification, cortex aspiration, IOL implantation, and incisional stromal hydration).
Heart rate curve.
Although the rate of capsule rupture was higher in the cryoanalgesia group, there were no significant 3 2,5
17
2
15
1,5
13
1
11
0,5
9
Figure 2.
Pain curve.
Figure 5.
BP closure
BP IOL
BP Incision
5
BP Basal
7 Pre-Op
24 h
Final score
Stromal Hydr.
IOL
Cortex I/A
Phaco
Hydrodissection
CCC
Corneal Incision
Paracentesis
Speculum
0
Blood pressure curve.
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whether the type of anesthesia technique used influences the rate of these types of complications. As reported by Pandey and coauthors,11 we consider that the surgeon’s skill level is paramount; therefore, this anesthesia technique is not adequate for all surgeons and patients. We have observed in the young patient a lower tolerance for this anesthesia method due to a lower pain threshold. Surgeons frequently do not prefer needle anesthesia techniques for cataract surgery. The main reason is the avoidance of serious needle-tip complications such as orbital hemorrhage and inadvertent ocular perforation but also the possibility of quicker visual recovery. With some no-needle anesthesia techniques, eye movement is preserved, which can be regarded either as an advantage or a disadvantage by the surgeon.12 Clear corneal phacoemulsification has the advantage of avoiding touching superficial sensitive ocular tissue other than the peripheral cornea during the surgery.13 Topical lidocaine alone provides adequate anesthesia for phacoemulsification and foldable IOL implantation, but some studies13,14 report further intraoperative comfort with associated intracameral lidocaine administration. In contrast, Gillow et al.15 found that there were no significant relationships between the use of intracameral lidocaine and the intraoperative and postoperative scores and concluded that intracameral anesthesia as a supplement to topical anesthesia has no useful clinical role. Topical anesthesia can induce corneal epithelial, corneal endothelial, or retinal toxicity, which are mainly the result of preservatives in the anesthetic solutions.16–19 Some anesthetic agents, such as proparacaine, can lead to allergic reactions such as periocular swelling, erythema, and contact dermatitis.16 Preoperative instillation of anesthetic agents can cause ocular discomfort (burning and stinging), and multiple applications can lead to mild corneal haziness during surgery. The toxicity of ocular anesthetic agents has been reported and discussed in several studies.16,19 Cat corneal physiology is relevant to the use of cryoanalgesia. The cat cornea is an avascular tissue of very simple structure, innervated almost exclusively by thin myelinated and unmyelinated trigeminal ganglion neurons that belong to the classes of high-threshold mechanosensory, polymodal, and cold primary sensory neurons.20 The role played by cold-sensitive neurons in 1192
the production of ocular sensations in the human has not been established. In 1981, Belmonte and Giraldez21 observed that temperatures under 20 C tend to diminish or silence the activity in the polymodal neurons. This can explain a possible effect of the cryoanalgesia. In studies of cats, it was proved that the concomitant stimulation of the polymodal nociceptors induce a pain sensation that can change in quality when mechanosensory or thermal fibers are activated concomitantly.20 In phacoemulsification under cryoanalgesia, the sustained stimulation of the corneal receptors by means of cold and the AC pressure can induce a saturation of the nervous transmission by means of mechanical and thermal stimuli, which reduces the transmission of pain sensations with the same intensity. Another possible hypothesis on the effects of cryoanalgesia is that the vasoconstriction because of cold can reduce the liberation of inflammation mediators (leukotrienes and prostaglandins) and therefore induce a local analgesic effect similar to that with NSAIDs.22,23 Nielsen13 proved a lesser analgesic effect of topical anesthesia over the peribulbar anesthesia and over the retrobulbar, although the patients preferred the peribulbar anesthesia, which lacks the pain induced by the retrobulbar injection. In our study, some patients who had retrobulbar anesthesia in the contralateral eye preferred topical anesthesia or cryoanalgesia. We did not observe significant differences in the pain level reported by the patients operated on under cryoanalgesia or topical anesthesia, nor were significant differences detected in the surgical stress level of the patient evaluated by means of blood pressure variations and the heart rate. From these results, we can deduce that the analgesia level would be similar with both techniques. In our study, the most painful surgical steps were be the paracentesis, incision, IOL insertion, and the closure of the corneal incision by stromal hydration. In these steps, we highly recommend greater cooling of the eye to reduce the pain sensation.
Conclusion Phacoemulsification under cryoanalgesia appears to be a safe technique. In the current study, we did not see
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a greater incidence of complications in comparison with topical anesthesia. There were no significant differences between the pain reported by the patient operated by clear corneal phacoemulsification under cryoanalgesia versus topical anesthesia. There were no significant differences in the physiological response to the surgical stress of the patient in phacoemulsification performed under both analgesia types. Some patients preferred cryoanalgesia to topical anesthesia. There were no significant differences in the surgeon stress between anesthesia techniques. Within the parameters (capsule rupture rate, comfort related to lid speculum, surgeon stress, and patient’s global collaboration), the slight statistical difference between the 2 groups indicates the need for a larger sample group to confirm that these occurrences are not random. For this reason, we must view these results with some reserve. Cryoanalgesia is a useful technique in the case of allergy to anesthetic agents.
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