28

No Anesthesia Cataract Surgery

Tobias Neuhann

Introduction

As we all know, the surface of the human eye is highly sensitive. A quick approach, a dust particle, a gust of air to dry out the ocular surface—the eyelids will close immediately in a protective reflex. To operate an eye without any anesthesia? The mere idea seems to be absurd. However, disregarding all that we know, it is possible.

On June 13, 1998, Amar Agarwal successfully performed the first no anesthesia cataract operation during the Phaco and Refractive Surgery conference in Ahmedabad, India, in front of an audience of 250 persons, applying the karate chop technique.1,2 On the occassion of the 1999 ASCRS convention in Seattle, live surgery was performed in India by Sunita Agarwal, Amar Agarwal and Mahipal S Sachdev and communicated via satellite to the meeting in Seattle. All these operations were performed under NO ANESTHESIA. The cataracts were removed through a sub 1 mm incision by Sunita Agarwal and Amar Agarwal using a technique called PHAKONIT. Sunita Agarwal demonstrated laser phacoemulsification, while Mahipal S Sachdev performed high vacuum phacoemulsification.3

In the 1999 Indian Intraocular Implant and Refractive Surgery conference, I had the opportunity to personally attend live no anesthesia cataract surgery by Amar Agarwal. He kindly offered me the to perform a live no anesthesia cataract operation, myself. It was a fascinating experience, and even during the operation itself, it was hard to believe that it was really possible.

Back in Munich, I successfully operated two patients under the age of 40 using this astounding new method—both upon their own request. Fourteen other cases followed. However, the specific preconditions of this particular group of patients will be discussed lateron in this chapter.

Incision

Without any anesthesia, naturally the incision is much more critical than in routine cataract surgery under topical (retrobulbar, parabulbar or surface anesthesia) or even general anesthesia.4 The entire procedure is only possible if neither the sclera nor the conjunctiva are touched. In addition, no one-toothed forceps is used to stabilize the eye. Instead, a straight rod is inserted into the eye to guarantee a stable position during the operation.

The first step is essential. A side port is created with a diamond and viscoelastic is injected. This incision is then used to insert a straight rod to stabilize the eye. This is followed by a clear corneal incision.1,2

Capsulorhexis

The capsule is opened using capsulorhexis, like in any routine cataract surgery. The capsulorhexis can be performed alternatively using the needle or the forceps technique.

The needle technique first requires an initial puncture of the anterior capsule within the central area to be removed, which is then extended in a curve-shaped manner to the targeted eccentric circle to be described. The circular tear is started by either pushing or pulling the central anterior capsule in either direction, while the flap to be created is gently lifted. The next step is to turn over the flap and apply the vectorial forces in tearing with the needle in such a way that a more or less concentrical opening originates. Once the full circle is almost completed the end will automatically join the beginning of the curve outside in (Fig. 28.1). It is also possible to place the first puncture directly within the planned curvature and start the rhexis with a curved enlargement of this tiny hole. With this approach, the tear is brought around on both sides, until finally the ends join together.5

Advantages of the needle technique are that it is economical, since it can be performed with

FIGURE 28.1 The ideal capsulorhexis

application of BSS as well as viscoelastics and the cost of the needles is neglectable. The following factors are essential for the success of the needle capsulorhexis: I highly recommend the use of a 23 gauge needle, because the lumen of this type of needle is just sufficient to produce a pressure exchange between anterior chamber and BSS irrigating bottle and the metal of such a cannula supplies just enough rigidity to provide the necessary resistance for difficult manipulations. A higher, that is positive pressure in the anterior chamber compared to the intracapsular pressure is mandatory. This becomes especially noticeable with intumescent lenses, where the lens protein is hydrated resulting

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in a volume increase inside the capsular bag, so that also the endocapsular pressure is considerably increased. Only if the anterior chamber pressure is greater than or equal to that inside the capsular bag can a successful capsulorhexis be performed. The pressure in the anterior chamber can be adjusted by varying the height of the infusion bottle. In addition, the needle tip should be as sharp as possible, since a blunt needle may create stellate burst (Fig. 28.2).5

The forceps technique is easier. For this reason it is also the most frequently applied capsulorhexis technique, which, however, can only be performed after viscoelastic instillation. The principle of the forceps capsulorhexis exactly corresponds to the principle of the needle technique. In addition to the

FIGURE 28.2 Stellate burst

known Utrata forceps there are mini forceps which are similar in construction to the forceps developed for the posterior segment of the eye. The advantage of these newly designed forceps is that they can be inserted into the anterior chamber via a paracentesis, so that the incision is not exposed to needless strain.5

To point out the difference between the needle and the forceps technique, the following example might be appropriate: To turn over a page of a book you can take the sheet between two fingers and turn it from one side to the other (this is what you do with the forceps), or you take a moistened finger, press the page a bit down and then turn it over (that is what you do with the needle; the counterhold is the cortex). With this in mind the consequences appear quite clear cut. I will always use a needle technique, the initial puncture peripheral or central, for the great majority of my cases. The forceps I will use in situations where the needle—so to say—lacks the other branch. This is mainly the case when liquified cortex is apparent or secondary enlargement of the capsulorhexis diameter is necessary.5

Phacoemulsification Techniques

A variety of phacoemulsification techniques has been developed with the aim to disintegrate the nucleus in the safest and most efficient way. When Howard Gimbel introduced his divide and conquer technique, it was adopted enthusiastically by ophthalmologists throughout the world.6 For many years after, divide and conquer remained the outstanding technique for all nuclei hard enough not to be simply aspirated, until Nagahara presented his new technique, phaco chop, the big brother of divide and conquer. Other than in divide and conquer, the nucleus is no longer divided with the phaco tip, but with a second instrument, the “chopper”, so that hardly any manipulations with the tip itself were necessary any longer, thus reducing the risk to damage the sensitive intraocular structures with the tip to a minimum.7

The phaco chop technique has remained one of the most efficient methods in phacoemulsification until today. The advantages are obvious. The lens can be divided up mechanically into 4, 6 and 8 or more pieces. In this process, the originating forces counteract, since the force exerted by the chopper is directed against the phaco tip. The result is that all force vectors go centrally, so that there is no hazard for the lens capsule or the corneal endothelium.

The phaco chop technique is especially suitable for mature cataracts or cataracta nigra, where mostly weak zonulas are found. A beneficial side effect for the surgeon is the ease of work, because the nucleus can always be rotated into the most favorable position. However, an important aspect of phaco chop is that it is only a technique for experienced surgeons, whereas beginners should start with divide and conquer to develop a feeling for the consistency of the nucleus to stay on the safe side. For the first chopping attempt, a medium nuclear sclerosis should be selected.

To understand the mechanism of phaco chop, you have to consider the anatomic structure of the nucleus, where the crystalline lens fiber runs from one side of the equator towards the opposite side through the center of the nucleus. As a logical consequence, the natural cracking direction follows the lens fiber. As is usual in modern cataract surgery, the capsule is opened with the CCC and hydrodissection is carried out. Then the epinucleus is aspirated inside the CCC with weak phaco energy. For your first chop, you have to catch the lens with your phaco tip at the 12 hours position, advance the phaco tip until you have firm hold of the nucleus and then insert the chopper into the space between the equator and the capsule at the 6 hours position. As the chopper is gradually brought closer to the tip, the nucleus will crack into two halves. Then the nucleus is rotated 90° and the inferior heminucleus is cracked into quadrants applying the same principle. If the nucleus is relatively soft, the quarters can be aspirated and emulsified with the phaco tip. In this process, the tip opening should remain in the center of the lens capsule not to increase the hazard of damaging either the posterior capsule or the corneal endothelium unnecessarily. When aspiration and emulsification of the inferior heminucleus are completed, the superior heminucleus is rotated 180° and disintegrated accordingly. In the case of harder nuclei, a subdivision of the nucleus into 8 or more pieces may be required to exclude that residual fragments escape into the anterior chamber and damage the corneal endothelium with their sharp edges.

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Experience in phacoemulsification shows that it is beneficial to reduce the overall phaco time and power to the necessary minimum. An additional advantage of the phaco chop technique is that here the nuclear matter is first aspirated and then emulsified. In this way, the entire phaco energy is used for emulsification of the nucleus, the aspiration volume concentrates on the nucleus, and less phaco energy and time are required, thus reducing strain for the incision as well as for the corneal endothelium.

The initial phaco chop technique has been modified several times by different ophthalmologists including Nagahara, its inventor. He uses his karate chop technique,7,8 which was also applied in the first live no anesthesia cataract surgery by Amar Agarwal,1,2 for cases with poor mydriasis to be able to perform the whole phacoemulsification procedure within the range of the pupil or the CCC. Other than in the initial phaco chop technique, karate phaco chop goes from the anterior pole to the posterior pole of the crystalline lens. For hard nuclei with a thin epinucleus and the typical dual structure of soft periphery and hard core Nagahara suggests the crater phaco chop technique. To be able to grab hold of the hard core of the nucleus with the phaco tip, first a crater is excavated providing enough space for easy insertion of the tip.

My personal method of choice is the quick-chop technique when performing no anesthesia cataract surgery because of the above mentioned advantages, such as stressand pain-free intraocular manipulations.

Intraocular Lens Implantation

Using no anesthesia cataract surgery, I recommend an implantation of a soft, foldable silicone or acrylic IOL to be able to make use of the advantages of small incision surgery, especially under the aspect that a clear corneal incision is inevitable, because the sclera as well as the conjunctiva must not even be touched. For both intraocular lens families, acrylic as well as silicone, a large variety of IOL models and types from the different manufacturers is available in the market. In this way it is easy to find a lens to meet the specific requirements of the individual patient. As one of the newest developments, even a foldable toric IOL can be implanted using a ring-haptic-fixation with a specific indented capsular tension ring (*Acri.Clip) (Figs 28.3 and 28.4).9 Foldable IOLs can be implanted with forceps or with an injector, which is mostly the easier alternative.

No Anesthesia Clear Lens Extraction

At the Agarwal eye hospitals in Chennai and

FIGURE 28.3 Ring-haptic fixation; computer animation

FIGURE 28.4 Ring-haptic fixation; clinical case

Bangalore, India, clear lens extraction—also without anesthesia—is applied for the surgical treatment of high refractive errors as an alternative to PRK or LASIK, especially in hyperopic or high myopic patients (more than −15 D). Depending on the specific case, an IOL is then implanted or, in cases of extremely high myopia, the patient is left aphakic. The operation follows the same procedure as no anesthesia cataract surgery. For less experienced surgeons, a parabulbar anesthesia is recommended instead of a peribulbar block to avoid the hazard of globe penetration with the needle.1,2

Specific Precautions in No Anesthesia Cataract Surgery

Experience shows that it is beneficial to cover the cornea with HPMC 2.4 percent to reduce the surface sensitivity of the eye. In addition, it is essential to maintain the moisture of the cornea throughout the operation.

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It is important, not to inform the patient prior to the operation to exclude the danger of increased sensitivity caused by the patient’s fear of pain. In addition, it is very important to exclude any sharp or pointed instrument, such as Colibri forceps. However, the use of diamond knives is appropriate.

Furthermore, utmost care with the eyelid is required, because it is experienced as highly disturbing by the patients.

During phacoemulsification, it is very important to only apply low amounts of ultrasound power to avoid the origination of heat, which would be painful for the patient. In addition, the anterior chamber should be well maintained throughout the procedure.1

Recent Cases

Recently, I operated two female patients with a history of allergic shock. In both cases, a severe allergic reaction to anesthetics administered during treatment by their dentist had occurred. In these patients, there was a high probability of allergy against the CAINgroup, thus forming an indication for no anesthesia cataract surgery. One of the patients had been looking desperately for a possibility to have cataract surgery performed despite her allergy.

Both patients were highly motivated, and surgery could be performed without any problems. As a new step in the procedure, I applied very cold BSS solution in the area of the limbus immediately prior to the incision to decrease the ocular sensitivity.

Discussion

No anesthesia cataract surgery is a surprising new development in our highly refined techniques in ophthalmic surgery that have been achieved to date. Without any doubt, the mere existence of this new option is very exciting and also might be very helpful in cases with specific indications. However, in my opinion, the different preconditions of the patient goods in different areas of the world need to be briefly discussed. As we all know, a series of amazing phenomena exists in India. Which other country on earth has been able to produce individuals who are able to stick knives and sabres through their bodies and faces and pull them out again without a drop of blood dripping down and without any wound remaining? On the other hand, documentations of almost unbelievable practices also exist from other areas in the world, like in parts of Africa, where trepanation is performed without any anesthesia, too, and the patients maintain not to feel too much pain when their skulls are opened without any anesthetic relief. On this basis, the no anesthesia approach should be further investigated in terms of its introduction in suitable countries, also taking into account the poverty in large parts of the world, where no anesthesia cataract surgery might be a step into the right direction to improve health care for the population by lovering the costs of treatment.

Generally, in the Western World this method is only suitable for especially old patients, where the surface sensitivity of the eye is already considerably reduced or for highly motivated patients. In my own practice, I operated a total of 18 patients without anesthesia to date. All of these patients had a particular mental attitude in common, which

enabled them to undergo this kind of procedure, and which considerably differs from that the majority of the population in any of our industrialized countries. All of these patients asked me to perform no anesthesia cataract surgery, while the larger majority especially of the younger patients rather tend to consider the advantages of general or topical anesthesia, instead, and would not even dream of having an operation performed without any anesthesia. In this way, the special motivation of my 18 cases formed the only possible basis for this new approach.

No anesthesia cataract surgery is a highly fascinating new alternative. It is certainly not designed for routine practice. However, it remains an excellent method for patients with specific indications, where our common forms of anesthesia are not possible, for example in hemophilics.

References

1.Agarwal A, Agarwal S, Agarwal A: No anesthesia cataract/clear lens extraction. Refractive Surgery New Delhi: Jaypee Brothers Medical Publishers (P) Ltd, 487–98, 2000.

2.Agarwal A, Agarwal S, Agarwal A: No Anesthesia Cataract Surgery. Phacoemulsification, Laser Cataract Surgery and Foldable IOLs New Delhi: Jaypee Brothers Medical Publishers (P) Ltd, 139–43, 1998.

3.Azim Siraj A: Dr Agarwal’s Homepage Volume II, No 2: Issues Conference and Seminars: 1999.

4.Lang GK: Operative Therapy. Augenheilkunde Georg Thieme Verlag, Stuttgart: 190–93, 1998.

5.Neuhann T: Capsulorhexis. Phacoemulsification, Laser Cataract Surgery and Foldable IOLs

New Delhi: Jaypee Brothers Medical Publishers (P) Ltd, 81–88,1998.

6.Gimbel HV, Anderson PE: Divide and Conquer Nucleofractis Techniques. Phacoemulsification, Laser Cataract Surgery and Foldable IOLs New Delhi: Jaypee Brothers Medical Publishers (P) Ltd, 97–109, 1998.

7.Nagahara KB: Phaco Chop—Development and Recent Advances. Atlas of Cataract Surgery London: Martin Dunitz Ltd, 98–109, 1999.

8.Agarwal A, Agarwal S, Agarwal A: Karate Chop. Phacoemulsification, Laser Cataract Surgery and Foldable IOLs New Delhi: Jaypee Brothers Medical Publishers (P) Ltd, 144–54, 1998.

9.Neuhann T: New Foldable IOLs. Atlas of Cataract Surgery London: Martin Dunitz Ltd, 169–80, 1999.

29

No Anesthesia Cataract Surgery: Comparison Between Topical, Intracameral and No Anesthesia

Suresh K Pandey

Liliana Werner, Amar Agarwal

Introduction

Ophthalmic surgeons have witnessed a significant evolution in surgical techniques for cataract extraction in the 20th century.1 The most remarkable advance is, of course, the considerable decrease in the size of the wound incision. Small-incision cataract surgery using phacoemulsification through clear corneal self-sealing incisions avoids cauterization, suturing and intraocular pressure (IOP) fluctuations. Moreover, this is faster, more controlled and less traumatic when compared with conventional largeincision extracapsular cataract extraction (ECCE). With the advent of the “phaconit” technique, today it is possible to remove the cataract through a 0.9 mm incision.2 The evolution in surgical techniques for cataract extraction is summarized in Table 29.1.

Anesthetic techniques for cataract surgery have also advanced significantly (Table 29.2).3,4 General anesthesia was preferred in past years, followed by various techniques of injectable anesthesia including retrobulbar, peribulbar, sub-Tenon, and subconjunctival anesthesia. Due to marked improvements in surgical techniques, it is no longer essential to ensure complete akinesia of the eye and as a consequence, the technique of topical anesthesia has been popularized as “phaco anesthesia”.5–22 This includes eyedrops

application, sponge anesthesia, eyedrops plus intracameral injection, and most recently gel application.5,7,11–15,18–21,23,24 Topical anesthesia is the preferred technique for cataract

surgeons in the USA (37%; range 22–63%) according to a survey conducted by David Learning in 1998.25 It revealed that as high as 76 percent respondents using topical anesthesia preferred eyedrops in association with

TABLE 29.1 Evolution of techniques for cataract surgery

*ECCE: extracapsular cataract extraction **ICCE: intracapsular cataract extraction

***PC-IOL: posterior chamber intraocular lens

****AC-IOL: anterior chamber intraocular lens

TABLE 29.2 Evolution of anesthetic techniques for cataract surgery

intracameral injection of lidocaine. In a recent, prospective, randomized, double-masked clinical trial, Gillow et al26 evaluated the efficacy of supplementary intracameral lidocaine in routine phacoemulsification under topical anesthesia. There was no significant relationship between the use of intracameral lidocaine and either intraoperative or postoperative pain scores. The authors concluded that the routine use of intracameral lidocaine as a supplement to topical anesthesia did not have any clinically useful role.

Clear corneal phacoemulsification has the advantage of avoiding touching any superficial sensitive ocular tissue (other than the peripheral cornea) during the surgery. Preserved ocular motility can be used to improve the operating conditions by optimizing the red reflex and wound access. Compared to regional anesthetic techniques such as peribulbar anesthesia, the topical approach does not increase the vitreous pressure, and there is no effect on the optic nerve blood flow. Postoperative recovery is quicker,

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postoperative pain is reduced, and the patient may prefer this technique. Recently, various authors reported their experience concerning topical anesthesia.11–13,15,18–21

However, neither injectable nor topical anesthetics are completely safe, injectable

techniques of these agents can lead to various complications which can be non-sight- threatening, sight-threatening and very rarely, life-threatening.3,4,6,8,27 Topical anesthesia

prevents these complications but it can lead to corneal epithelial, corneal endothelial, and/or retinal toxicity, mostly due to the preservatives in the anesthetic solutions.28–32 Moreover, topical anesthetic agent and its vehicle may serve as reservoir of microbial contamination with the potential for causing an infection. Some of these agents (e.g. proparcaine) can lead to allergic and idiosyncratic reactions. Manifestations of such reactions include periocular swelling, erythema, and the typical rash of contact dermatitis. Further, preoperative instillation of some of the topical anesthetics (e.g. lidocaine) may cause burning and stinging sensations and multiple applications sometimes lead to mild haziness of the cornea during the surgical procedure. There is a potential for cumulative toxicity on account of need for administration of several doses. Recent reports suggested

that cataract surgeons should be aware of the potential for endothelial injury if anesthetic agents are injected into the eye.30–32 This is not surprising because the intraocular

concentration of the anesthetic agent after intracameral injection can be 250 times higher than the concentration after topical application.32 Complications associated with topical anesthesia are summarized in Table 29.3.

TABLE 29.3 Side effects and complications of topical ocular anesthetics

1.Alteration of the stability of lacrimal and tear films

2.Delayed healing of the epithelium in presence of epithelial defects

3.Toxicity to the corneal endothelium secondary to preservative benzalkonium

4.Surface keratopathy

5.Retinal and macular toxicity

The modern cataract surgical procedures are currently so well defined and quickly performed that we can question whether the topical anesthesia represent a dead end or if it is possible to perform the surgery without using it.

Indeed, one of the major advances documented in the last decade of the 20th century is the performance of cataract surgery without using topical anesthesia.34 This was first done by Amar Agarwal (AA), in June, 1998. Interestingly, this happened as an accident. A case of posterior polar cataract was scheduled for an ECCE in the early 1998, under pinpoint anesthesia (preferred by the surgeon: AA) rather than topical anesthesia. At the last moment, the surgeon decided to perform the surgery using phacoemulsification instead of ECCE. In the middle of the surgery, he came to know that he was performing it without anesthesia. To his surprise, the patient was lying comfortably without pain. Since then, more than 5,000 cataract surgeries have been performed using this technique.

We recently completed a collaborative study on no anesthesia cataract surgery in comparison to topical and topical plus intracameral anesthesia. The aim of the study was to avoid the use of topical anesthesia during cataract surgery and to evaluate the efficacy of this technique. We also compared the comfort of the patient and the stress for the surgeon during the surgery in the three groups.

Randomized Study

Patients

Seventy-five patients were enrolled in this prospective, randomized, double blind study. Informed consent was obtained from the patients after explaining in detail the outline of the study, which was reviewed and approved by the ethics committee of the hospital. All patients were randomized to one of the three groups: group I—no anesthesia, 25 patients; group II—topical anesthesia, 25 patients; group III—topical plus intracameral anesthesia, 25 patients. The patients included in the study were between 38 and 79 years of age. The density of the cataracts varied from grade 2 to 4 (Emery-Little classification).35

Excluded were patients with barrier to communication or cooperation during surgery (extreme anxiety, language and/or hearing impairment, mental retardation, dementia, Parkinson’s disease, very young, etc). Monocular patients and those with hard, mature cataracts (grade 5 Emery-Little classification), shallow anterior chamber(s), pupil(s) less than 5 mm in diameter (when fully dilated), and inability to understand a visual analog pain scale were also excluded.

The patients were prepared for cataract surgery without preoperative (or intraoperative) sedation. The pupils were preoperatively dilated using phenylephrine (5%), cyclopentolate (0.5%) and tropicamide (1%) eyedrops. Nonsteroidal antiinflammatory drugs (NSAIDs) were not used.

Anesthetic Techniques

Patients in group I received, while still in the preoperative area, two drops of balanced salt solution (BSS® Alcon, Forth Worth, TX) every 5 minutes three times, beginning 10 to 15 minutes before the procedure. After the corneal endothelium was coated with viscoelastic, before performing the capsulorhexis, an intracameral injection of BSS® via a 25-gauge Rycroft cannula (Beaver and Visitec Products, Bidford on Avon, England) was performed. Patients randomized to group II received lidocaine (4%) eyedrops preoperatively, and an intracameral injection of BSS®, as described above. Patients in group III received both, preoperative 4 percent lidocaine eyedrops and intracameral injection of preservative-free lidocaine (1%), using the same methods as in the other 2 groups.

The protocol established for the supplemental anesthesia for breakthrough pain during the surgery, if it should occur, was as follows: if the patient was in pain, two additional drops of lidocaine (4%) would be placed in the eye. If the pain persisted, a peribulbar or retrobulbar block would be used.

Surgical Technique

All cataract surgical procedures in this study were performed in a referral institute of South India by the same surgeon (AA). A wire speculum was placed and the patients were asked to look down. No superior rectus sutures were used in any group. Patients were informed that they would be aware of the sensation of touch and would be able to move their eyes. First of all, viscoelastic (Healon®, Pharmacia and Upjohn, Uppasala,

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Sweden) was injected into the anterior chamber using a needle through the area where the second (paracentesis) site was made. This was important in order to distend the eye to create a good self-sealing corneal valve. A straight rod was then used to stabilize the eye (with the left hand) at the 2 O’clock position for the right eye and at the 10 O’clock position for the left eye. With the right hand, a 3.2 mm groove was made in clear temporal cornea using a diamond knife. During the entire surgical procedure care was taken to avoid grasping of the conjunctiva or sclera by tooth forceps. The globe was stabilized by the straight blunt rod during the entire surgery. A 5.0 to 5.5 mm wide capsulorhexis was performed using a 26-gauge bent needle cystotome. Hydrodissection was performed with BSS®. Nuclear emulsification (Alcon, Master 10,000, Fort Worth, TX) was performed with Karate chop technique using less ultrasound power. The capsular bag was filled with viscoelastic. Foldable one-piece plate hap tic PCIOL lenses were then implanted (STAAR Surgical Co, Monrovia, CA). Intracameral miotics were not used in any of the patients. The viscoelastic was removed from the anterior chamber and the capsular bag by irrigation. The corneal incisions were secured by performing stromal hydration.

The operating microscope light was kept at its lowest level and gradually increased in intensity. The level was up to the usual operating levels after hydrodissection and the patient was encouraged to fix the eye toward the microscope light during the surgery. No subconjunctival injections or an eyepad was applied at the completion of the surgery.

Parameters Assessed

After the surgery, the patients were taken to the postoperative area where vital signs were obtained. There, one constant observer also collected patient assessment responses. Questions were presented to the patients in a standardized written form. Each patient was shown a 10-point visual analog graphic pain scale with numeric and descriptive ratings where 0 represented no pain and 10 represented severe, “unbearable” pain.35 They were asked to grade the level of discomfort or pain during the surgery and postoperatively, on separate scales. If the patient was unable to see the scale or read the accompanying text, the scale was described and verbal score was obtained. They were also asked to differentiate “pain” or “discomfort” from “touch” or “movement” sensation. The degree to which the patients were bothered due to ability to move their eyes, sense of touching their eyes and by the operating microscope light was also assessed. This was graded as “not at all” (0), “not very much” (1) and “very much” (2). If the surgeon was bothered by the patients’ eye movement, it was also graded as “not at all” (0), “not very much” (1) and “very

TABLE 29.4 Characteristics of the patients included in each group

*Group I **Group II ***Group III

*No anesthesia

**Topical anesthesia

***Topical and intracameral anesthesia

much” (2). Stress for the surgeon during the surgery (from 0–2) and total surgical time (minutes) were also noted. The patients were kept in the recovery area for a minimum of 30 minutes. The surgeon also completed a questionnaire on the surgical conditions, complications and need for supplemental anesthesia.

Comparison of various parameters between the three groups was performed using analysis of variance (ANOVA). A P value inferior to 0.05 was considered statistically significant.

Results

A total of 75 patients were recruited into the study. No patient refused to take part. Patient data are listed in Table 29.4. There was no significant difference in age and density of cataracts of the patients from the three groups (Figs 29.1A and B). Therefore, the patients included in the study were comparable. The average surgical time was 8.25±1.78 minutes for the no anesthesia group (group I), 8.88±2.24 minutes in the topical anesthesia group (group II) and 8.38± 1.70 minutes in the topical plus intracameral anesthesia group (group III). The surgical time was slightly higher in the topical anesthesia group when compared to the no anesthesia or topical plus intracameral anesthesia groups, but this difference was not significant (P=0.3562—Fig. 29.1C). No patients in any group required supplemental anesthesia.

FIGURE 29.1A

due to the ability of the patients to move the eyes, the difference between the three groups was also not statistically significant (P= 0.1580—Fig. 29.1H). However, the stress for the surgeon during the surgery was significantly greater in the no anesthesia group when compared to the topical or topical plus intracameral group (P =0.0206—Fig. 29.1I).

In summary, the only two parameters that differed significantly in the 3 groups were patient discomfort due to ability to move the eyes and stress for the surgeon during the entire surgical procedure.

Current Study/Experience of Other Surgeons

This is the first randomized, double-masked, controlled trial comparing three techniques, namely no anesthesia, topical anesthesia and topical plus intracameral anesthesia. The use of either topical anesthesia or topical anesthesia combined with intracameral lidocaine was not associated with significantly lower intraoperative and early postoperative pain scores.

Assessments of other parameters in the 3 groups besides the pain scores revealed that only patient discomfort due to ability to move the eyes and stress for the surgeon during the procedure were significantly different.

No anesthesia cataract surgery has been currently performed by other surgeons in various countries. Dr Francisco J Gutierrez-Carmona performed no anesthesia cataract surgery on 50 patients in Spain.37 He used cooled balanced salt solution in the operating eye and termed this technique as “cryoanalgesia”. The experience of Dr Tobias Neuhann from Germany concerning no anesthesia cataract surgery performed on 30 cases is also interesting (Neuhann T, personal communication). He performed it mostly on patients over 50 years, but interestingly some of the patients less than 50 years of age also asked for the no anesthesia technique. This is due to a trend of “no medical treatment”, which is common in very selective group of peoples in Germany. The use of 2 percent hydroxypropylmethyl cellulose (HPMC) to cover the cornea, helped in avoiding corneal dryness during the surgery. Although motivation is important, according to Dr Neuhann’s experience no anesthesia cataract surgery works better in older patients. Dr Keiki R Mehta from India also performed more than 450 cases using this technique (Mehta KR, personal communication). The need for supplemental anesthesia in his series was about 10 to 12 percent. He believes that the limbus is a watershed area for tactile sensations and therefore the corneal sensitivity in the peripheral cornea is significantly lower than the central cornea (see below: anatomical factors). Other surgeons currently performing this technique include Drs Oman Almullah (USA), Mohan Rajan (India) etc.

No Anesthesia Cataract Surgery: Why Does it Work?

It seems surprising that cataract surgery can be performed through one of the most sensitive structures (cornea) without using any anesthesia. The precise explanation for this fact is still unknown to us. However, we can advance some hypotheses related to surgical factors and anatomical factors.

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Surgical Factors

The skill and experience of the surgeon is one of the most important factors for the no anesthesia cataract surgery. While using this technique, it is important to avoid grasping the conjunctiva or sclera with tooth forceps. The surgeon should use a straight and relatively blunt rod to stabilize the eye during the entire procedure. Also, the use of a clear corneal incision avoids the use of cautery, necessary to achieve hemostasis with scleral tunnel incisions. In addition, gradual increase in the microscope luminance, minimization of the iris-lens-diaphragm movement and iris manipulations are important factors for topical as well as no anesthesia techniques. The phaco power should be used minimally to avoid excessive heating of the phaco tip, which in turn can produce pain.

Anatomical Factors

The cornea is supplied by the medial and lateral long ciliary nerves, which are branches of the trigeminal nerve. It is sensitive to touch, pain and temperature.38 However, there are marked topographical variations in the corneal sensitivity. Besides the diurnal variations, corneal sensitivity also varies according to age, sex and race.38–40 The central part of the cornea is the most sensitive. There is an overall reduction in the corneal sensitivity from the center to the periphery. The superior part of the cornea is the least sensitive, probably because of a decreased concentration of acetylcholine.

Concerning the diurnal variations, corneal sensitivity is the lowest in the morning and highest in the evening. This decreased sensitivity in the morning must be attributed to the reduction in oxygen tension at the epithelium surface when the eye is closed.39

Corneal sensitivity remains practically unchanged from 10 to about 50 years of age. Beyond that age, the decline is significant reaching a half beyond 65 years of age. The precise mechanism is not clear, however, some authors relate it to the formation of arcus senilis and to a decreased concentration of acetylcholine. In females, corneal sensitivity decreases during the premenstrual and menstrual periods.

The role of racial factors should not be underestimated.40 It was documented during contact lens fitting and many studies confirmed that corneal sensitivity in non-white (dark-brown eyed: Indians, Chinese, and Negroes) peoples is 4 times less than in white (blue-eyed: Caucasians) peoples. As reported by Michel Millodot in 1975, this phenomenon is obviously relevant to the wearing of contact lenses.40 It may also have some bearing on problems of anesthesia as it is possible that different quantities of anesthetics may be needed according to eye color. This is similar to the clinical fact that more ocular drugs are needed for people with dark rather than light-pigmented irises to obtain the same effect (for example, cycloplegia). The reason for this is not known, although it may be related to the amount of melanin pigment present in the iris. Since the cornea does not contain any pigment, however, it is not easy to explain the diminution of corneal sensitivity with darker pigmentation of the iris. It is not known whether the thickness of the cornea varies with eye color. It has been shown that thicker corneas, as a result of edema, are less sensitive than normal corneas. It is also unknown whether nerve supply density varies widely among these different peoples. Another possibility is that the difference in sensitivity arises in the central nervous system and not at the periphery The difference in tactile sensitivity may also be relevant to understand that the practice of

acupuncture may be more acceptable in China than it is in countries inhabited by blueeyed people.

Finally, recent studies have documented that frequent exposure to ultraviolet rays (between 280 and 310 nm) may give rise to a loss in corneal sensitivity, as high as 73 percent.38 Also, decrease in temperature can lead to reduction in corneal sensitivity, which have been documented up to nine folds.38

Thus, no anesthesia cataract surgery works due to atraumatic surgical techniques in suitable patients by a very experienced and confident surgeon. The speed and dexterity of the surgeon are paramount to the successful use of this technique, as it is the proper patient selection. Incision and manipulations through the least sensitive (superior) part of the cornea are probably the most important factors. Further decrease in corneal sensation due to the dark iris of patients in India, and aged patients exposed to ultraviolet rays probably accounted for the results obtained in our study.

As mentioned earlier, the reasons for the racial variations are still unknown. However, the differences may be important in adapting the technique for more sensitive corneas in white patients, as did Dr Francisco Gutierrez-Carmona’s in Spain by using cooled balanced salt solution (“cryoanalgesia”) for corneal desensitization.37

Conclusion

In conclusion, we demonstrated that cataract surgery could be performed without the use of anesthetic agents. The advantage is that it avoids any toxicity associated with topical and/or intracameral anesthetic solutions. However, it is certainly not suitable for every cataract surgeon or every patient and its real benefits have to be measured carefully, in a case-by-case basis.

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