Ординатура / Офтальмология / Английские материалы / The Art and the Science of Cataract Surgery_Boyd, Barraquer_2000

maximumsafety,lowriskandhighbenefitsfor the patient and minimal stress for him/herself. The fact that phaco also significantly shortens the waiting period for cataract surgery in the second eye, that it has 50% fewer complications than ECCE and that the operation can be done while the cataract is still in its early stages (20/40 vision, lowered contrast sensitivity and glare intolerance) should be another strong incentive to adopt phaco (See Chapter 6). The usual reasoning that the planned extracapsular surgeon assumes are thoughts like: "If I do so wellwithplannedextracapsular,whychange?". This is particularly true when your practice is mostly composed of private patients, some of them important persons in the community and no risks can be taken. The successful extracapsular surgeon continues to find reasons for not making the change, such as: "I have very little postoperative astigmatism with planned extracapsular, so why get into the problem of operatingwithasmallerincisionandthedifficulties thatmayarise?" "Thevisualrecoverycomparing the two techniques after several weeks is about the same; I am not in a hurry for my patient to attain a prompt visual result as long as the final visual recovery will be the same." "It is better for the patient to have a good planned extracapsular than a bad phaco." "I know that with planned extracapsular I will have practically no complications, but I am not so sure that such will be the case with phaco, particularly in the early cases."

In essence, the surgeon has to make his/ her decision rationally and on his or her own initiative. This will provide the stimulus and the perseverance in order to enter into the learning curve and the perseverance to eventually master what is considered one of the best

operations in the field of medicine. Once the decision is made, it must be followed through with firmness and resolve.

UNDERSTANDING THE PHACO MACHINE

A successful phacoemulsification dependsessentiallyontwofactors: 1)thesurgeon's skill; 2) the surgeon's and his team's understanding of how the phaco machine works.

It is fundamental for the surgeon to have a thorough and practical knowledge regarding the specific equipment that he is using and how the technology of phaco machines in general operates.

Becoming Familiar with the Equipment

Becoming first familiar with the phaco machine in an experimental laboratory first, is the best way to learn and understand how the equipmentworks. Thishasbeenreemphasized once and again by Virgilio Centurion M.D., one of the world's best cataract surgeons who has dedicated a great deal of his valuable time to teach the transition through courses and publications. His recommendation is to practice first in the laboratory the use of both hands and the four positions of the phaco machine foot pedal so as to become familiar, comfortable, and adept with the parameters of the machine (Figs. 52, 53). For more sensitive control of the phaco machine foot pedal, use a shoe with a thin sole (keep it in the operating room) and use your dominant foot (equivalent to the dominant hand). Control the surgical microscope with the non-dominant foot.

Practiceusingbothhands canbeattained with pig eyes and synthetic eyes in synthetic heads, often coached by the company representative from whom you acquired the phaco machine and equipment. The surgeon can also practice with a humanocular globe supplied by largeEyeBanksorwithpigeyesremovedsoon after the animal is sacrificed. These globes should be refrigerated, not frozen, with the cornea protected with a sponge. When placed in a 700 W microwave oven for 4 seconds, the lens develops a subcapsular cataract. After 9 seconds, 50% of the lens will be opaque and hard.

Two Hands, Two Feet and Special

Sounds

The surgeon should dedicate appropriately extensive time in the laboratory towards acquiring complete self-assurance in the use of the machine, coordinating his or her hands and the two foot pedals. Additional time may be used to practice how to make the new, smaller incision, the capsulorhexis and other surgical steps. Phaco is mostly a two-handed technique,soyoumustbecometrainedanddevelop reflexes to use both of your hands and both of your feet, together.

During training in the laboratory, the surgeon grasps how the machine works during each step of the operation, learns the method for introduction of the phaco tip and the most comfortable position in which to place the handpiece; why and when to elevate or lower the height of the fluid bottle, when to increase or decrease the flow of fluid or the vacuum and when to increase or decrease the power of the phaco. These parts of the learning curve are mastered in the laboratory so as to really understand and become fully adept with the functions of the equipment before entering the patient's eye.

While learning to use the machine's foot pedal you must also perceive the significance of the sounds of the machine which vary depending on the surgical step or stage, such as the balance of flow when the phaco tip is not occluded(Figs.57,58),andthesoundsalerting the surgeon to changed in fluid dynamics when there is occlusion of the tip. In each instance, the surgeon receives a sonic feedback, constantly informing him about the state of the fluid dynamics in the eye (Figs. 59, 60). So the surgeonmustlearntousebothhands,bothfeet, and to listen to the phaco machine.

In essence, experimental training first in the laboratory is the best investment the surgeon can make to shorten and successfully transverse the learning curve. It is a necessary experience to learn the workings of the equipment fully. Its main aim is not that of learning thesurgicaltechniqueatthisstage. Thatcomes later. We must not improvise or try to learn the use of a phaco machine in the operating room. The surgeon should not begin learning the use of the machine directly on a patient's seeing eye.

Main Elements of Phaco Machines - Their Action on Fluid Dynamics

In this chapter we will thoroughly discuss the optimal use of the phaco machine and the rationale behind it, the three elements of most phaco systems (irrigation, aspiration and ultrasonic energy), fluidics and phacodynamics, the importance of and understanding of the SurgePhenomenon. Therationalebehindhigh vacuum - low ultrasound power technology, the new technology of the peristaltic pump, particularlyinthethreemainequipmentsources available such as the Alcon's Legacy 2000, Allergan's Prestige (and the Sovereign) and Storz Millennium and some useful informa-

tion about the new phaco tips and their contribution toward a better operation.

COMPARISON OF SURGICAL TECHNIQUES FOR TRANSITION VS EXPERIENCED SURGEONS

There are several techniques in phacoemulsification that remain practically the same for the surgeon who is undergoing the transitionandthosewhoaremoreexperienced. On the other hand, there are stages of the operation in which there are definite variations for the experienced surgeon, some of them minor, others moderate and others major.

We have divided the subjects into two

(2) groups: 1) those that are the same for all surgeons and 2) those that vary depending on theskillofthesurgeonforthisparticularoperation.

Techniques Which Are the Same for the Transition and for Advanced Surgeons

Capsulorhexis

These parts of the technique are practically the same for both groups, with slight individual variations (Figs. 43, 44, 45). The main feature that may vary is the size of the capsulorhexis. Some very advanced surgeons do a small capsulorhexis, while in the transition a somewhat larger capsulorhexis is advisable, depending on the size of the IOL to be implanted.

Hydrodissection and Hydrodelineation

These techniques remain essentially the same for the transition and in advanced surgeons (Figs. 46, 47, 48).

Epinucleus Removal

This technique does not vary substantially in the transition from that used by advanced surgeons (Fig. 69).

Cortex Removal

The technique is the same for both groups (Figs. 70, 71). It is important not to feel overconfident at this stage and by all means avoid being aggressive.

Techniques that Vary According to the Skill of the Surgeon

Anesthesia

In the transition, the surgeon may use parabulbar or Sub-Tenon's (flush) anesthesia using Greenbaum's cannula (Figs. 33, 34), particularly because conversion to ECCE may be needed. It is only advanced surgeons who may use topical anesthesia alone or combined with intracameral irrigation anesthesia (Figs. 35, 36).

Fixation of the Globe

In the transition, the surgeon does need to fixate the globe, passing a suture through the superior rectus, versus the experienced surgeon who does not need to do so.

Sclerocornealtunnel,limbaltunnel,corneal tunnel: these three types of incisions dependontheskillandexperienceofthesurgeon. In the transition it is important to use the stepped incision starting at the limbus and performing a sclero corneal tunnel based on a limbal incision, in case there is need to revert to a ECCE. During the transition, it is always important for the surgeon to know that he/she may revert to ECCE whenever they feel uncomfortable with the surgery at any specific stage. Onlymoreadvancedsurgeonsshoulddo the corneal incision and tunnel (Figs. 40, 41, 42).

Foldable lenses should only be used by advanced surgeons. PMMA oval lenses 5.0 x 6.0 mm are the standard in the transition (Fig. 72-A).

Nucleus Removal

There are many different techniques that may be utilized by advanced surgeons. They will be discussed in a separate chapter. For the transition, the basic technique to use when beginning phaco is the "divide and conquer" into four quadrants. "Divide and conquer" is usually done with two hands (Fig. 56). The surgeon must also learn, however, how to perform this technique with one hand.

Anesthesia

During the transition it is advisable that the surgeon utilize the type of anesthesia with which he/she feels more safe and in better control (Figs. 33, 34). It is unnecessary to add a new source of stress or immediate change at thisstageoftheprocedure. Nevertheless,when the surgeon is in charge of the situation and masters the phaco technique, it is ideal to use topical anesthesia because of its ability to provide immediate visual recovery. The combined use of topical anesthesia and intracameral anesthesia is more effective than topical anesthesia alone and should be tried before the surgeon attempts to operate using topical anesthesia alone (Figs. 35, 36). I recommend that

you consult Chapter 5 on this important aspect of the operation.

The Incision

How to Make a Safe Transition from Large to Small Incision

Role of the Ancillary Incision

This is an important step in performing phacoemulsification. Although there are techniques to perform it with only one hand, phaco is fundamentally a two-handed procedure.

Theancillaryincisionismade beforethe main incision is performed. As shown in

Fig. 41, this incision serves as an entry for a second instrument which is necessary for maneuvers to remove the nucleus (Fig. 56). This wound is also utilized in irrigation of the anterior chamber with intracameral local anesthetic as explained in Chapter 5 and illustrated in Fig. 36, and for the insertion of viscoelastic previous to making the main incision and during several other steps of the operation. However, some advanced phaco surgeons do not perform hydrodelamination and remove the epinucleus usually during the emulsification of the nucleus.

At the end of surgery, the ancillary incisionalsoservestoinjectfluidintoACtotestfor leaks in the wound (Fig. 73).

The Main Incision

During the early stages of the transition, the surgeon should plan to start the operation as a phaco but learn how to convert to the planned extracapsular he or she is accustomed to do successfully if this becomes necessary. This will provide additional comfort and con-

fidence. The surgeon may start with a small stepped limbal valvulated incision slightly larger than the phaco tip (Fig. 42) even though he knows that he plans to convert to his usual planned extracapsular. It is not advisable to start the transition with a corneal incision because, upon enlarging it, the resulting astigmatism may be severe. The more anteriorly located the incision, the more astigmatism the patient may end up with. By starting the transition with a limbal incision, the surgeon will use the same area for the incision that he is accustomed to use in his planned extracapsular butwillmaketheincision valvulated (stepped) and smaller than th e usual extracapsular (Figs.40,41,42). The surgeonmustmasterthe technique of the small incision valve like incision at the limbus, so that it can be part of his armamentarium inthefuture(Fig.40-C). Once the surgeon is certain that he will not need to convert from phaco to planned extracapsular and therefore will not need to enlarge the incision, he may choose to make a corneal incision if he wishes, but not before (Fig. 40-C). This is what we refer to as a safe transition from a large to a small incision, a transition that must

Figure 41 B: Initial Stages of Self-

Sealing, Stepped, Valvulated Tunnel

IncisionattheLimbus-Surgeon'sView

This surgeon's view shows the Crescent knife blade (K) entering the first incision (1) just at the limbus. The blade is advanced(redarrow)forsomedistance in the plane of the cornea, and a tunnel (blue arrows) is created. This forms the second step (2) in the three-step incision. Theknifedoesnotentertheanteriorchamber at this stage.

T H E A R T A N D THE S C I E N C E OF C ATA R A C T S U R G E R Y

Figure 41-A: Making the Ancillary

Incision

This is a most important stage of phacoemulsification since the operation itself is mainly a two-handed technique. Thestepsinvolvedare:1)First,markthe limbalarea(A)wherethe limbalstepped main incision will be made (Figs. 41 B and 42) between 9 and 12. In the transition it is recommended to place the stepped incision at 12 o'clock as shown here. 2) Make the ancillary incision (I) always at 3 o'clock. This is performed with a special 15 º blade designed for paracentesis (K). 3) Proceed to perform the limbal valvulated stepped incision andentertheanteriorchamber,asshown in Figs. 41-B and 42 (surgeon's views). The ancillary incision serves to introduce a second instrument as shown in Fig. 67, inject intracameral local anesthesia as shown in Fig. 36 and irrigate viscoelastic into the anterior chamber.

be undertaken step by step as the surgeon progresses in his learning curve (Figs. 40, 41, 42).

Later, as he progresses and learns to master phacoemulsification, the surgeon is ready to make two significant changes in the technique: 1)Operatefromanobliqueposition and make the incision in the upper right quadrant,temporally asshowninFigs.41-Band42; 2) Perform a corneal incision (Fig. 40-C) instead of a limbal incision (Figs. 40-A, 41-B, 42

Role of Conjunctival Flap

In the early stages of the transition, the surgeon may prefer to start with a small fornix based conjunctival flap from 10:00 to 2:00 o'clock, and place light cautery under each edge of the flap. If the limbal incision is extended because one of the initial phaco steps becomes a source of problem and there is need for conversion to ECCE, there will be less bleeding.

Anterior Capsulorhexis

This again is a vital step in the transition. Changing from the can opener capsulotomy (Fig. 37) to the anterior continuous circular capsulorhexis (CCC) is one of the fundamental steps in the transition (Figs. 43, 44, 45). The surgeon must learn first by practicing capsulorhexis on the skin of a grape or by using a very thin sheet of plastic wrap such as the one that covers some chocolate candies. Once the surgeon understands the concept of the technique and can do it in the laboratory, he or she may begin to use it for the patient.

The surgeon must keep in mind that the space needed to adequately maneuver the cystotome (Fig. 43) or the capsulorhexis forceps (Figs. 44, 45) in order to do a proper continu-

ous circular capsulorhexis is larger than the wound or paracentesis required to simply introduce a cystotome and perform a can opener capsulotomy.

It is highly recommended to make the capsulorhexis under sufficient viscoelastic . The latter should be injected into the anterior chamber as a first measure before trying the capsulorhexis (Fig. 2). It is also fundamental not to begin with dense, hard cataracts where itisdifficulttoseetheedgeofthecapsulorhexis. It is prudent to try performing this procedure over and over again in cataracts that are less dense until the surgeon is able to perform them in eyes with poor visualization of the edge of the capsule.

Because the surgeon, in the initial stages that we are discussing here, will most probably