uncomfortable, they may tell the surgeon so that the problem can be promptly rectified.

It is important to counsel patients to expect to see bright lights, feel pressure (although they don’t always feel pressure), and feel the surgeon touching their eyelids. They should be aware that they will be expected to participate by looking in the direction that the surgeon requests.

With this information, and with appropriate intraoperative coaching in the form of calm reassurance, patients will be relaxed and cooperative. Many patients are aware of brilliant, prismatic lights during the surgery. They find these aesthetically pleasing. In fact, patients who are told to expect to see beautiful kaleidoscope-like lights find this an additional source of relaxation.

A remarkable amount of anxiety can be relieved just by telling patients that their experience, even if slightly unpleasant, is routine. It appears that patients’ greatest fear is not discomfort, but rather that these experiences are the unwarranted anticipation of a poor visual outcome.

The neophyte will find that the patients best suited for topical anesthesia are the elderly, as they tend to be more cooperative, more stoic, less anxious, and require less IV sedation.

THE OPERATING ROOM MILIEU:

MAKING THE PATIENT COMFORTABLE

Patients undergoing topical anesthetic cataract surgery are generally more alert than their injectible anesthetic counterparts. The operating room team should avoid loud and boisterous talk or laughter. Instead, peaceful music should be played. Studies have shown that music played during cataract surgery actually lessens the requirement for IV sedation, and lowers heart rate and blood pressure.37 Further, surgeon performance is enhanced with music background selected by the surgeon.38

EYE MOVEMENT

There is no ocular akinesia with topical anesthetic methods. Although the uninitiated may imagine a patient wildly looking about during surgery, in reality this is a very rare occurrence.39 Most patients, when instructed to keep a steady fixation on the microscope light, or to gaze eccentrically, are able to follow instructions. The ability to cooperate is enhanced with mild IV sedation such as with propofol, or a balanced technique using midazolam and fentanyl.

For the experienced surgeon, the patient’s voluntary eye movement becomes a natural and desirable feature of the procedure. Patient cooperation is excel-

lent in most cases and obviates stretching the extraocular muscles to produce the desired globe position. For example, the patient is encouraged to look directly into the microscope light during capsulorrhexis and phacoemulsification, and downward during incision and intraocular lens (IOL) insertion. The lack of extraocular muscle (EOM) stretching may account for the rarity of surgically induced ptosis. Patients who have trouble self-positioning their eye may be instructed. To do this the surgeon must gently grasp and move the eye to the desired position (with the patient’s cooperation). The patient is then requested to maintain that position. The eye is never forced into position, however; as in the unanesthetized EOM the afferent limb of the oculocardiac reflex is intact and stretching it may provoke bradycardia.

It is helpful to instruct the patient to keep the companion eye open during the procedure. Instillation of topical anesthetic in the companion eye prior to surgery is helpful in reducing the blink reflex and improves cooperation.

VIRTUAL REALITY DEVICE

To further aid in control of eye movement during anterior segment surgery, I have developed a “virtual reality” device (Fig. 2–5). This is a miniature computer monitor and visual simulation program that is presented to the companion eye during surgery. Static visual images can be used as fixation targets for patients who have retained ocular motility. The enhanced ability for patients to participate in surgery by controlling their eye movement facilitates performance of surgical maneuvers and obviates the need

FIGURE 2–5 The virtual reality headset is placed in front of the unoperated eye. A small video monitor is mounted under the visor, causing a virtual image to be projected out into space in front of the patient.

for fixation instruments. Because a virtual image is projected out into space, the patient’s sense of claustrophobia is diminished, thus enhancing the surgical experience. The requirement that the patient open the fellow eye also discourages squeezing against the eyelid speculum in the operated eye. Visual images such as scenes from nature can be delivered to encourage relaxation. The images can even be coordinated with auditory stimuli by an earpiece fitted in the ipsilateral ear. The ability to provide nonpharmacologic relaxation by this means reduces the amount of IV sedation required compared with surgery without the device in the companion eye.40

COMPLICATIONS ARISING FROM

EYE MOVEMENT

Inadvertent eye movement may, of course, be the result of inadequate anesthesia, but more often is a manifestation of anxiety. IV sedation as an appropriate adjunct is therefore essential. Unanticipated eye movement may create problems at any stage of the procedure. During creation of the incision, especially with supersharp diamond knives, it is possible to extend the incision. A sudden movement during capsulorrhexis may cause it to tear into the equator. Posterior capsular rupture may occur during phacoemulsification, irrigation and aspiration (I&A), or IOL insertion. One method to avoid unexpected eye movement is to gently stabilize the eye with a second instrument. This can be done with a FineThornton ring externally. Alternatively, by first making the paracentesis, a second instrument such as a chopper, Tenant manipulator, etc., can be inserted. This instrument can then serve as a tether to stabilize the globe while making the phaco incision. In this manner not only will eye movement be reduced, but the second instrument will telegraph impending movement to the surgeon.

Alternatively, incision extension may be avoided by the use of diamond blades with unsharpened parallel sides (Fig. 2–6). The diamond blade allows a swift incision without tissue drag. Once inserted, the blunt parallel sides of the blade are within the incision, so that any lateral movement of the blade will fail to extend the incision.

Inadvertent movement during phaco, I&A, and IOL insertion can be similarly avoided by the use of two instruments, one through the phaco incision and the other through the paracentesis incision. This will act to create an “oarlock,” preventing voluntary ocular movement.

Posterior capsular rupture using topical anesthesia is rare. My experience is that the posterior capsule is torn less commonly than with retrobulbar

CHAPTER 2 TOPICAL ANESTHESIA • 19

FIGURE 2–6 Diamond blade with blunt parallel sides affords protection from inadvertent lateral extension of the wound.

anesthesia. The reason for this may lie in evolving improvement of surgical techniques, instrumentation, and perhaps the surgeon’s heightened awareness of the patient’s potential for movement.

Piovella et al41 as well as Uusitalo et al42 have collected data to show that complications secondary to eye movement occur more frequently during the early phase of the learning curve. However, with proper patient instruction and, with the development over time of a “second sense” of anticipating patient eye movement, these potential problems can be reduced.

EYELID SQUEEZING, PHOTOPHOBIA,

AND PHOTOTOXICITY

Any anesthetic technique that does not block the seventh cranial nerve creates the potential for squeezing. This can be overcome by using an adjustable speculum such as the Lieberman design (Fig. 2–7). This design incorporates an adjustable thumbscrew. The thumbscrew can be gradually opened against the lid margins, thus minimizing the patient’s tendency to squeeze. The speculum should be opened as widely as possible without causing undue indirect pressure on the globe. By so doing, the orbicularis oculi is extended to the end of its length-tension curve. Therefore, there is the least overlap of myosin and actin filaments. This will result in weakening of the patient’s ability to squeeze.

Additionally, RDTNBA has less motor neuron effect than retrobulbar anesthesia. However, some globe and lid “hypokinesia” is seen with this technique. This is probably due to the prolonged presence of the sponges in the fornix, in proximity to the

FIGURE 2–7 The Lieberman speculum can be placed in the closed position and gradually opened to produce the optimal amount of lid separation.

orbicularis. This property further lessens the potential problems with lid squeezing.

Light sensitivity must be considered during topical anesthesia surgery. Topical anesthesia does not cause amaurosis. Consequently, excessive intensity of the microscope light will be uncomfortable for the patient. For that reason, the microscope light intensity must be turned to a low setting initially, and then gradually increased only to the level necessary for visualization. In so doing, the surgeon soon will realize that much less light is needed to perform surgery than originally believed.

Light sensitivity may have an important protective benefit as well. It can be implied that a light too bright to look at with the nonamaurotic eye is, in all probability, also too bright for the amaurotic eye (e.g., after injectible block). Lower microscope light will result in decreased light toxicity from the operating microscope.43

CONJUNCTIVAL BALLOONING

This problem is unique to subconjunctival or subtenon’s anesthetic techniques. The conjunctiva, upon injection with the anesthetic mixture, may become tumescent and interfere with surgical access and visualization. This problem is often avoided by the use of a Greenbaum style cannula,44,45 which features an enlarged hub. This hub can be used to engage and seal the conjunctival opening, directing fluid posteriorly.

TOXICITY OF TOPICAL AGENTS

The availability of relatively nontoxic, effective topical and intracameral drugs has resulted in an accept-

able risk/benefit ratio. However, all routes of administration carry some potential risks.

INTRACAMERAL TOXICITY

Intracameral concentrations of anesthetics may reach as much as 250 times the concentration in the anterior chamber as may be achieved with topical administration. This gives rise to concerns about potential toxicity. Systemic absorption and toxicity of the drug given intracamerally is insignificant.46 Garcia et al,47 Elvira et al,48 Masket and Gokmen,49 and Gills50 report no change in endothelial cell counts in humans with 1% lidocaine MPF. Sun et al51 studied the effects of both lidocaine and bupivacaine and found no toxic corneal effects. However, a study by Anderson et al52 in the rabbit model shows that endothelial cell damage can occur with instillation of bupivacaine 0.5% unless diluted 1:1 with glutathione bicarbonate Ringer’s solution. The same study compared clinical pain scores in humans with lidocaine vs. bupivacaine and found them to be similar in efficacy, suggesting therefore that lidocaine is the preferred drug for intracameral use.

Studies by Judge et al53 showed that bupivacaine 0.75%, lidocaine 4%, and proparacaine all caused corneal clouding and increased corneal thickness for up to 7 weeks in an animal model. Therefore, lidocaine 1% MPF is the ideal agent for intracameral use.

Lidocaine instilled intravitreally will temporarily affect visual acuity,54 and electroretinographic activity; however, no permanent functional or histologic changes occur.55 These findings confirm the clinical occurrence of transient but reversible loss of vision after intracameral instillation of lidocaine in the presence of a broken capsule. The demonstration that intracameral agents may be toxic to the endothelium may suggest a narrow therapeutic/toxic ratio of which the surgeon should be cognizant.

TOPICAL TOXICITY

Anesthetic Agents

Of the topical agents in use, tetracaine has the most potential for causing superficial punctate keratitis. However, this problem has been associated with almost all topical anesthetics56 (D. Davis, personal communication) (Fig. 2–8). Repeated or excessive administration of topical agents can produce superficial punctate keratitis (SPK) sufficiently severe to interfere with visualization of the anterior chamber structures during surgery. The substitution of lidocaine gel 2% MPF may be considered as an acceptable alternative and may obviate this problem. Marcaine 0.75% may be mucogenic in susceptible

FIGURE 2–8 Presumed corneal and conjunctival toxicity from lidocaine.

patients, thus interfering with visualization as well (S. Masket, personal communication).

Hyaluronidase

A potential hazard of working in a surgical suite where a variety of anesthetic and surgical techniques are employed is that of confusion regarding anesthetic mixtures. I have reported three consecutive cases of moderately severe epithelial keratitis.57 The diffuse nature of the clinical presentation led me to suspect, and later confirm, that sodium hyaluronidase had been mixed with the usual unpreserved lidocaine and bupivacaine and was intended for an-

FIGURE 2–9 Corneal epithelial sloughing on the first postoperative day following inadvertent administration of topical hyaluronidase.

CHAPTER 2 TOPICAL ANESTHESIA • 21

other surgeon who was using retrobulbar anesthetic. A first-day postoperative photograph (Fig. 2–9) of one of these patients shows the sloughing epithelium and keratitis, which resolved in about a week with judicious debridement of loose epithelium, bandage contact lenses, topical nonsteroidal antiinflammatory drug (NSAID), and antibiotic.

CONCLUSION

The evolution of less invasive methods of cataract surgery has been successfully coupled with less invasive and safer methods of anesthesia. The result is less risk to the patient, more rapid visual recovery, and consequently earlier return to normal daily activities. A proper respect for, and understanding of, the limitations and requirements of these techniques will provide satisfactory results.

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