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

Phacoemulsification is the "state of the

art" operation of choice for cataract surgery in academic institutions and private eye centers worldwide. Ophthalmologistsintraining(Residencies and Fellowships) receive training in phacoemulsification first and manual extracapsular as a second choice.

COMPARING PLANNED

EXTRACAPSULAR WITH PHACO

EXTRACAPSULAR

With planned extracapsular extraction an 8-9 mm limbal incision is performed, preceded by a conjunctival flap (either limbal based or fornix based). The anterior capsule is usually opened with a "can opener" capsulorhexistechnique. Somesurgeonshave developed the expertise to do a continuous circular capsulorhexis. The nucleus is then expressed with gentle pressure inferiorly such that the lens is subluxated in its entirety into the anterior chamber and out of the eye through a superior limbal incision (Fig. 37). Aspiration is used to remove the remaining cortex from the capsular bag and viscoelastic is irrigated into the anterior chamber and capsular bag (Fig. 38). A PMMA intraocular lens implantation is performed (Fig. 39) and the wound is sutured.

In planned extracapsular, which is still ably and successfully performed by a significant number of ophthalmic surgeons, the final

visual recovery takes place slowly through a period of 5 to 6 weeks.

In small incision manual extracapsulars such as with Blumenthal's

MINI NUC and Gutierrez manual phacofragmentation, a foldable IOL may be implanted. Both of these procedures are fully presented in the Section on Manual Extracapsular Extraction in this same Volume following Phacoemulsification. Visual recovery is much more rapid.

ADVANTAGES OF THE PHACO TECHNIQUE

The phacoemulsification technique offersthefollowingbenefitsandadvantagesover planned extracapsular as outlined by Edgardo Carreño: 1) it is performed through an incision 3mm or less in size which is self-sealing and watertight thereby improving safety during the procedure. 2) It is significantly less invasive thereby leading to much less ocular trauma and consequently less postoperative inflammation. 3) It results in minimal or no induced astigmatism. 4) It provides much more rapid visual and physical recovery and prompt refractive stability. The visual recovery is immediate if topical anesthesia is used. All these advantages lead to an important increase in the patient's quality of life. In addition, a smaller incision also may reduce the risk of endophthalmitis.

MAIN TECHNICAL DIFFERENCES ASSOCIATED WITH PHACO

The opening of the anterior capsule is done as a continuous curvilinear capsulorhexis (CCC) as described by Gimbel et al (see Figs. 43, 44, 45). An ultrasonic probe (Figs. 50-A and B) is used to emulsify the nucleus and draw it out of the eye through an aspiration port (Chapter 8). This allows the removal of a 10 mm cataract through a 3 mm incision (or less). Because the integrity of the anterior chamber is maintained throughout the procedure, the intraocular pressure is subject to less fluctuation and poses much less of a risk for suprachoroidal hemorrhage.

Removalofthelensbyphacoemulsification is followed by placement of a posterior chamber foldable intraocular lens implant through a 3 mm incision. The wound may require one or no sutures. Variations of technique may involve a superior limbal incision with dissection of a sclero corneal tunnel to form a self-sealing valve incision, a clear corneal incision with corneal tunnel and selfsealing valve incision (with experienced surgeons) and the scleral tunnel incision which is used increasingly less but is a safe procedure fordifficultcases(Figs.40,41,42). Thelimbal and the corneal incision are either placed at 12 o'clock or in the superior temporal quadrant.

The limbal incision and tunnel is the proce-

dure of choice for surgeons in the transition stage or who do not have a large cataract surgical volume because it allows conversion intoextracapsularifnecessary.Enlargementof a corneal incision in order convert to an extracapsular extraction, often results in intolerable postoperative astigmatism.

Both standard polymethylmethacrylate (PMMA) or foldable (acrylic, silicone or hydrophilic) intraocular lenses may be used. A foldable lens allows for an even smaller incision and less risk of postoperative astigmatism as a result of wound construction. Because of the watertight wound construction of this method and the stability of the anterior chamber during phacoemulsification, this technique is amenable to topical anesthesia in a cooperative patient (Fig. 35) or a combined topical and sub-Tenon's local anesthesia, (Figs. 33, 34) or a combined topical and intracameral anesthesia ( Fig. 36) advised by Gills. The choice mainly depends on the experience and skill of the surgeon , but there may be special considerations such as difficulty in communication with the patient and in cases complicated by a patient's poor general health.

LIMITATIONS OF

PHACOEMULSIFICATION

Surgeons who have a successful clinical practice, ample experience and well earned prestige and are using planned extracapsular are understandably reticent and apprehensive about shifting from a technique they already master to onewhich depends a great deal on the understandingofhowthephacomachine functions. 50% of the success in doing phacoemulsification depends on the proper use of the equipment at each stage of the operation. Ophthalmic surgeons are used to depend on their surgical skill. It is part of their self-esteem. As emphasized by Centurion, phacoemulsifica-

tion is equipment and instrument-dependent as well as team-dependent, because the team assisting with surgery must fully understand all the steps of the operation and, by all means, how the phaco machine works.

The Importance of Mental Attitude

Understandingtheworkingsofthephaco machine requires a complete change in mental attitude and the undergoing of a rigorous training not only in the surgical technique, but learning to use two feet (microscope and pedal) instead of one (microscope). The surgeon must also beattentive to the perceptionof different sounds emitted by the machine, each one signaling a different function and parameters which in turn the surgeon must act upon. It is essential for the physician to understand exactly how to obtain the optimal use of the machine, the rationale behind it, the fluid and phacodynamic processes within the machine and the eye and how to manage safely the equipment, safely, including the various handpieces and, of course, the phaco power, and the irrigation and aspiration (see Figs. 49- A through 65).

Motivation to Undertake this Task

This is not an easy task. The multiple mechanical functions of the equipment are not "friendly" to those physicians who , althoufh excellent surgeons, are not mechanically minded. Only the knowledge that such a change, if successfully done, will be best for his/her patients can serve as the motivation to undertake such a significant step.

For all these reasons, many excellent surgeons decide not to enter into phaco, and many others have the equipment available in their eye center or hospital but allow it to remain idle.

In order to overcome these negative aspects of phacoemulsification, it is fundamental tohaveasmoothtransitionintophaco. Inorder to achieve it, it is essential that you read and reread the next chapter (Chapter 7), which presents the very best ways to achieve a successful transition with little stress or apprehension.

ComparisonofCosts-PhacovsECCE

One of the strong limitations of phaco has been the cost of not only the phaco equipment but also the supplies related to its use. This is important for a significant number of ophthalmologists when operating on patients who are not economically advantaged.

Fixed Costs with ECCE

Let us analyze, however, the updated situation related to costs of performing phacoemulsification, and compare it with the costs of the supplies needed to perform extracapsular extraction. With the latter, there is the cost of very fine sutures, which are unnecessary in phaco; there is the cost of local anesthesia involvedwitheitheraretrobulbaroraparaocular injection versus phaco in which only topical sometimes with intracameral anesthesia is utilized. Thecostofthepostoperativeinjectionof steroid in the fornix often done following extracapsular is also unnecessary with phaco although the trend now is to inject steroid in the anterior chamber (see Chapter 5). The cost of even a fairly short stay in the recovery room following the often used sedation needed with anextracapsularextractionforanxiety ishigher than in patients with phacoemulsification who have had only topical anesthesia without sedation and walk to their home within a few minutes following surgery.

The significant economical savings to the patient from lost working hours with ECCE vs almost immediate recovery with phaco and the improved quality of life with phaco are other major important contributions. All these are important features to consider when the socalled expenses for both operations are taken into account.

Phaco'sProgressivelyDecreasing

Investment

Whataboutthe highexpenseswithphaco equipment? There was a time when the equipment or phaco machine required a significant investment. The supplies or tubing needed for each patient was also a heavy expense when performing several cases. All this has changed due, in great part, to the ingenuity and understanding by the industry that these high expenses and initial investment were a significant barrier which prevented more ophthalmic surgeons from adopting phaco.

At present, most of the companies that manufacture phaco units are helping physicians and hospitals to acquire the equipment andsupplies. The equipmentismadeavailable at much more reasonable prices than their real sales cost, with the understanding that there will be a monthly utilization by the surgeon of the phaco supplies of that particular manufacturer. In addition, the manufacturer provides advice and hands-on-training by experts to the surgeon so that he/she will be able to enter into the transition period (Chapter 7) utilizing his/ her own personal equipment acquired from that manufacturer.

The "tubing" which previously had to be discarded after each operation is no longer a problem cost-wise. Now it may be used for as many as 60 cases in the same day. No re-

sterilization is needed. The tubing may be used without replacement for a complete day of phaco surgery. Upon completion of all the phaco cases in one day, the tubing must be discarded. Therefore, by programming the surgeon´s cases accordingly, a great deal of savings can be made.

All of this makes the phaco technique moreaccessibletoalargernumberofsurgeons. We still have to cope, however, with the needs of surgeons in countries in which the gross national product is very low.

Major Limitations in Non-Eco- nomically Advantaged Countries

Experts in programs for rehabilitation of sight in large numbers of indigent patients-- such as Francisco Contreras, M.D. in Peru, Everardo Barojas, M.D. in Mexico, Juan Batlle, M.D. in the Dominican Republic, Newton Kara, M.D., in Brazil,-- all of whom are magnificent surgeons with a large private practicebutalsodoagreatdealofservicetothe communities, have stated that most patients in this category earn no more than US$1.00 (one dollar) a day and that the maximum that can be charged to a patient for a cataract operation should be what that particular patient earns in one month.

This is important information that needs tobeappreciatedbycataractsurgeonsthroughouttheworldinterestednotonlyintheprogress of the technology of our profession but also in the humanitarian aspects of what we do best which is ophthalmology.

It is also of great interest as outlined by Contreras that the number of phaco operations being performed has increased in those countries with the highest gross national product per person. In countries where earnings by patients are low, phaco is still behind. In many countries, only 5 to 10% of the population can afford phacoemulsification in spite of the facilities that we have outlined. Of the rest, thirty percent of the population has a mid-level of income, 30% are very poor, and 30% of the population are in extreme poverty.

Aswecontinuetoprogressinthetechnological developments of ophthalmology, which is a blessing, we also need to be aware of the limitations existing in the populations of many countries throughout the world.

An exemplary case is that achieved by Professor Arthur Lim, M.D., in Singapore, who has put together significant funds from privateorganizationsandhastrainedlargenumbers of young ophthalmologists to learn these moderntechniquestocombatblindnessinSouth East Asia and China.

GENERALOVERVIEWAND STEP BY STEP CONSIDERATIONS

Complete comprehension of what is presented in this chapter is essential for the successfulundertakingofphacoemulsification. Before you read it, we strongly recommend that you first read Chapter 6 which refers not onlytotheunquestionableadvantagesofphaco but to its limitations, most of which are related to the challenge of understanding how the phaco machine works and how to attain its optimal use.

Equipment - Dependent and

Phase-Dependent Technique

The transition from planned extracapsular extraction to phacoemulsification fundamentally refers to the gradual change that the ophthalmic surgeon who already masters the planned extracapsular must undertake in order todominatethenewtechniqueofphaco,which isequipment-dependent. Thistransitionshould be progressive and atraumatic. As the surgeon advances step by step, he or she should never go on to the following step if he has not dominated the previous step. This operation is also a phase-dependent technique, as emphasized by Centurion. Each phase must be completedwiththeprecisionofawatchmaker. If you pass on to the following step without masteringthepreviousstep,complicationsmay arise with consequent failure and grief. This learning curve is achieved with effort, dedica-

tion and proper training to perform each phase of the transition well.

Outlining the steps necessary in the transition from extracapsular surgery to phacoemulsification, we will present you a detailed picture of what it really takes to enter into the transition and to master the learning curve. We will describe and fully illustrate each one of the steps in sequence.

For young ophthalmologists who enter directly into phacoemulsification in their training, this "bitter pill" of changing from planned extracapsular to phaco is an experience they will fortunately miss. But when they later teach others who have not been trained in phaco, but learned and have spent their career doing extracapsular instead, they need to recognize - as we do in this presentation - the difficulties their colleagues face, and teach accordingly. Extracapsular surgeons still constitute the majority of ophthalmologists worldwide.

Mental Attitude

The surgeon must be absolutely convincedthatchangingfromplannedextracapsular to phacoemulsification will be best for his patients, particularly because of a very rapid visualrecoveryandphysicalrehabilitationback into normal life. As long as the surgeon is not completely persuaded of the reasons why he wants to take this crucial step in his professional development, he will never attain a positive experience during the transition with