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

INSTRUMENTATION

Phacoemulsification uses many of the same instruments that are used in conventional extracapsular cataract surgery. We will not refer to them in this chapter because every cataract surgeon is fully familiar with such instruments.

This chapter is exclusively focused toward those instruments especially created for phacoemulsification surgery or those that may have common features for both techniques, extracapsular and phaco, but that have required modifications for the surgeon to undertake successful phacoemulsification surgery.

There are multiple variations of each type of instrument. Consequently, rather than referringtotheinstrumentsbythenameoftheir creators or proponents, we will focus here on the specific characteristics needed for phaco surgery. These instruments are:

Eye Speculum

It is very important to have the right eye speculum (Fig. 74). Since topical anesthesia is utilized by most experienced phaco surgeons, the speculum must have a lock to prevent the lids from closing and squeezing during surgery.

The speculum should not interfere with the surgeon's movements and instrumentation when operating in the upper temporal quadrant, which is the approach mostly utilized today.

Fixation Ring

Its use is optional but it may be quite helpful during the construction of the limbal or the clear cornea tunnel incision because it produces fixation of the globe throughout the circumference of the ring. The most popular fixation ring is the Fine-Thornton (Fig. 75). If the surgeon prefers not to use the fixation ring, the globe may be fixed with very fine 0.12 toothed forceps.

Knives and Blades

There are two options for the knives and blades (Figs. 76-77): 1) utilize stainless steel disposable knives (Fig. 76); 2) use diamond knives which can be re-sterilized (Fig. 77). Both types of knives and blades have their advantages and disadvantages. The selection really depends on the preference of the surgeon. The disposable stainless steel blades and kniveshavereachedaveryhighlevelofquality and precision. They may be re-sterilized for a small number of cases, certainly no more than four or five. They require a lower initial investment and less care when handling by the nurses and assistants. Nevertheless, when we are going to make a clear corneal incision and tunnel, it is recommended to use a diamond knife which can be calibrated (Fig. 77). Those knives and blades can be manufactured with different parameters. Those for paracentesis (Fig. 76 B) have an angulation of 30 degrees.

Crescent knives (Fig. 76-C) have a rounded point which is fundamental in the construction of the tunnel in the incision as shown in Fig. 41- B,Chapter8. Thedisposablekniveswithsharp points range from 2.6 to 3.2 mm (Fig. 76-A). They are particularly useful in the small incisions when utilizing different sized phaco probes and tips as shown in Figs. 82 A and B. The 5.2 mm blunt point blades as shown in Figs. 76-D may be highly useful to enlarge the incision in case of PMMA 5.5 mm intraocular lens implantation or larger as shown in Fig. 72 A. There is, however, an increasing tendency to utilize diamond knives because the surgeon is able to obtain a perfect incision. The knives also last for a long time.

Consequently, for surgeons who do a major amount of surgery, the diamond knife may be, in the end, economically more efficient.

In Fig. 77 you may see diamond knives designed for various purposes, 77-A for paracentesis or side port incision (also shown dur-

Carreño's PhacoSub-3technique,also shown in Fig. 40 C. Fig. 77-C shows the crescent type of knife, also seen in the surgical steps in Fig. 41-B and Fig. 42. Very narrow sharp pointed blades are being developed to perform the 1 (one) mm incisions to be used with Dodick's PhotoLysis recently approved by the FDAusing a special ND-YAG laser.

Hydrodissection Cannula

This special cannula is shown in Fig. 78-A and in Figs. 46 - 48. These cannulasareespeciallymadewitha rectangular and 27 G diameter that facilitates the injection of liquid to separate theanteriorcapsulefromthecortex. They are re-sterilizable. They should be connected to a 3 or 5 cc syringe to allow a better effect from dispersion of liquid. For hydrodissection, there are also other special cannulasintheformof "J"which may be useful for specific maneuvers as shown in Fig. 47.

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 77 (left): Diamond Knives

(A) Utilized for side port or paracentesis incision (also shown during surgery in Fig. 41-A).

(B) This blade is used for 3.2 mm incision or slightly smaller as in Carreño's Phaco Sub-3. This knife is also shown in Fig. 42. (C) Crescent diamond knife with rounded point fundamental in the construction of the tunnel incision( also shown in Figs. 41-B and 42).

Figure 78 A (right): Hydrodissection Cannula Under the Anterior Capsule.

For this purpose it is recommended to use a 25 G flat tip cannula. Observe how the cannula enters below the edge of the capsulorhexis performed on the anterior capsule. The surgeon then injects the BSS to separatethecapsulewiththecortexfromthenucleus.

CystotomesorCapsulorhexisForceps

There are several alternatives to the selection of cystotomes. One group is already designed and manufactured for this purpose, with 25, 27 and 30 G calibers. Some surgeons prefer to bend the tip of an insulin needle, which provides a very sharp point. The main characteristic of the cystotome is that it must be very sharp to facilitate the creation of the first capsular flap during capsulorhexis and enable the surgeon to continue performing a curvilinear capsulorhexis. These cystotomes must be easily adjustable to the needs and comfort of the surgeon in his/her maneuvers.

As to the capsulorhexis forceps (Fig. 78 B-C) there is a large variety and types of designs. ThebestknownistheUtratta-Kershner forceps (Fig. 78-B left). The main characteristic of all capsulorhexis forceps is that they have very fine, resistant arms and tips that prevent trapping of the iris. Curved ends are highly useful so that the surgeon can manipulatemorecomfortablywithintheanteriorchamber. In any case, they must be easily connected to a syringe that contains air or balance salt solutionforinjection inadditiontotheconventional viscoelastic, when the surgeon feels it is needed. There are other very useful capsulorhexis forceps such as the ones designed by Gimbel (Fig. 78 C), the Masket, the Corydonand several designed by Buratto.

Nuclear Manipulators or Choppers (Second Instrument)

These ancillary instruments are absolutely essential in order to adequately perform themaneuversnecessarytoremove thenucleus, as described and illustrated in Chapter 9. There is a large variety of types and designs. These instruments are introduced into the anterior chamber through the ancillary or side port incision. The purpose of this second instrument, either the manipulator shown in Fig. 79

or the chopper shown in Fig. 80, is to facilitate the bimanual maneuvering and rotation of the nucleus, as well as allowing the chopping of it intofragments that are going to be emulsified. In Fig. 79 we show two well known lens manipulators: 79-A is the Lester instrument and Fig. 79-B is the Osher. In Fig. 80, you may see different types of choppers: 80-A the Fukasaku chopper and 80-B the DodickKamman chopper.

Some of these instruments have a blunt tip, some longer or shorter length tips. All of them must have angulation as a common char-

acteristic, with the angulated tip being of very smalldiameter(0.25-0.50mm). Thetipisable to cut or slice the nucleus. They must have sufficient strength or resistance in the tip to create and lead the forces of traction and rotationofthenucleusandtheymustbesmoothand blunt on the posterior surface in order to avoid damage to the surrounding tissues. Some surgeons have available both types of instruments, manipulators and choppers, depending on the type of surgery they are doing, because

although the surgeon has his procedure of choice,he/sheisnotboundtorigorouslyfollow that same procedure in all cataracts. The surgeon has to adapt to different circumstances and situations.

Other commonly known choppers are those of Seibel, Nagahara, Nichamin. There are some hooks that are specifically utilized for rotation of the nucleus. They need to be angulated and have the shape of a shirt button. The best known is the Lester.

Forceps and Cartridge Injector Systems for Insertion of Foldable Intraocular Lenses

Small incremental advancements continue to take place for placement of foldable IOL’s through small incisions. There is a definite trend toward the development of separateinstrumentsforfoldingandinsertingIOL’s ratherthanusingtheinsertiondevicetofoldthe IOL.

The majority of foldable lenses are inserted either by forceps designed by out-

standing cataract surgeons for this purpose (Fig. 81) or by a combination of instruments designed by the manufacturer to facilitate folding and insertion known as cartridge injector systems. Examples of often used forceps are shown in Fig. 81 and injectors in Fig. 82. Dodick prefers to use forceps to implant Alcon'sAcrySof(acrylicfoldableIOL). Other very popular and useful forceps are the Fine Universal III forceps (Rhein Medical, Tampa, Fla.)andtheBurattoinsertionforceps(American Surgical Instruments. Westmont, Illinois). The latter is used specifically for the acrylic lens.