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

The total small incision self-sealing phacosection cataract procedure with lens implantation can be summarized in the following steps:

1)A standard patient preparation with wide dilation of the pupil. Peribulbar anesthesia followed by 40 minutes of oculopression with an equivalent of 30 mm pressure. The patient is draped with isolation of the lid margins and insertion of the speculum.

2)Anasallimbalparacentesisisfollowed by insertion of the anterior chamber maintainer, which is then turned on (Fig. 241).

3)Atemporallimbusbasedconjunctival flap of 3 to 4 mm width is made with mechanical dissection of the limbus and limited bipolar cautery of the episcleral vessels.

4)A 6 mm frown incision is marked with calipersonthesurfaceofthesclera, avoidingany major scleral vessels (Fig. 240).

5)Asuperficialscleraltunnelisdissected with a crescent blade. A paracentesis is created to the right side of the incision tunnel. Then perforationismadethroughthebaseofthetunnel into the anterior chamber at the center of the tunnel with a hooked cystotome.

6)The anterior chamber maintainer is turned off. The anterior chamber is inflated with air through the cystotome, and a capsulorhexis of approximately 6 mm diameter is created.

7) The chamber maintainer is turned on. Perforation is made through the central tunnel puncture with a 15 degree super sharp blade, followed by the crescent blade to enlarge the internal aspect of the tunnel incision to its full dimension.

8) Any remaining air bubbles and the capsule fragment are aspirated through the tunnel incision with a 21-gauge cannula. The chamber maintainer is elevated to increase the hydrostatic pressure. Preliminary aspiration of the anterior cortex and the epinucleus down to the face of the nucleusisdonewiththe 21-gaugecannulathrough the paracentesis (Fig. 241).

9)Hydrodissection of the firm central nucleus is done with a 27-gauge cannula through the paracentesis, tilting forward the equator of the nucleus adjacent to the tunnel (Fig. 242). Hydrodissectionisintendedtoelevatethesmallest identifiable nucleus and to tilt forward only the equator that lies directly in front of the tunnel incision.

10)The anterior chamber maintainer is turned off. The anterior chamber is deepened withviscoelasticofhighviscosity;asmallamount isinjectedbehindthenucleustoholditinthetilted position if necessary. With a cutting board and a single nucleus cutter the surgeon reaches into the anterior chamber (Fig. 243). Depending on the size and hardness of the nucleus, the surgeon decides how many cuts in the nucleus will be needed. With the single cutter he then makes one, two,orthreecutsasrequired. Thetwoinstruments are withdrawn.

11)Additional viscoelastic is injected andthecannulaisusedtopositionthefirstfragment of the cut nucleus that appears most readily accessible for removal (Fig. 244).

12)With the shield of viscoelastic in place, the surgeon reaches into the anterior chamber with the two nucleus extracting instruments, which look very much like a pair of spoons. The two spoons surround the fragment of nucleus and remove it from the anterior chamber (Fig. 245).

The small incision manual phacofragmentation (MPF) that we hereby present has been designed and developed by

Francisco Gutierrez C., M.D., of Spain. It is performed with a 3.2 mm clear corneal incision, which is the same size as in phacoemulsification. This manual phaco fragmentation (MPF) can also be done with a 3.5 mm scleral tunnel incision, which is the same incision size for phaco when we utilize the scleral tunnel technique (Figs. 247 and 248).

Benefits of (MPF)

As advocated by Dr. Gutierrez C., this technique provides several important benefits, as follows:

1)It can be performed with a small 3.2 mm incision if done in clear cornea and with a 3.5 mm incision if done with a scleral tunnel, thereby resulting in minimum astigmatism and rapid recovery (Figs. 247 and 248).

2)It functions well with hard and soft

nuclei.

3)It requires a low investment in the equipment and instrumentation.

4)Presumably, it provides a very good backup when complications arise and phacoemulsification must be discontinued. This technique helps the phacoemulsification surgeon in the event of an accidental rupture of the posterior capsule. Also, the instrumentation facilitatesextractingthenuclearfragmentsfrom

the AC through the small incision, avoiding the need to enlarge it and convert the surgery to an ECCE.

5)Presumably it is a method easier to master than phaco.

6)No less important, it requires no sutures or stitches.

Experiences with Other Phaco Fragmentation Techniques

In order to overcome the two main drawbacks of phaco: 1) difficult learning curve and 2) high cost of equipment, a good number and variety of techniques for manual phacofragmentationhavebeenusedinthepast. The limitations of these techniques have been related to not being able to sufficiently reduce the size of the incision because: 1) the instrumentation was coarse; 2) the nuclear fragments that were to be extracted from the anterior chamber were too large, usually because thenucleuswasdividedintotwoorthreepieces.

Why Use Gutierrez' Technique?

Positive Features of Instrumentation

The phacofragmentor designed by Gutierrez, is manufactured by the English firm of John Weiss & Son Ltd., a subsidiary of the Swiss multinational Haag-Streit. With it

the nucleus is broken into very small 2 x 2 mm pieces that can be extracted through a 3.2 or 3.5 mm incision (Fig. 247). This results in a practically neutral postsurgical residual astigmatism.

The racquet-shaped design of the fragmentor (see P and B in Fig. 247) keeps the nuclear fragments within the racquet, avoiding their dispersion as they are removed from the AC.

The phacofragmentor or nucleotome has a straight ophthalmic handle, with a 45º angle at its end, which is 8 mm long and 2 mm wide and racquet-shaped. The racquet is divided in four parts by three transverse bars two millimeters apart (Fig. 247) which keep the small pieces within the racquet. Other important instruments are:

• A spatula with a straight ophthalmic handle, whose end is adapted to the dimensions

Figure 247: Manual Multiphacofragmentation

Technique - Stage 1 - Fragmentation

Following creation of a 3.5mm scleral tunnel (I) or 3.2mm corneal incision, continuous circular capsulorhexis, and hydrodissection of the nucleus, the nucleus is luxated into the anterior chamber. After the nucleus is luxated into the anterior chamber, a high density viscoelastic is injectedintotheareasurroundingthenucleustofill the anterior chamber. The spatula (S) is placed beneath the nucleus (N). The nucleotome, (or phacofragmentor) (P) is placed on top of the nucleus. With the nucleus sandwiched between the two instruments (inset), the nucleotome is pressed downward toward the spatula (arrow). This sections the nucleus into four fragments (1,2,3,4) between the cross bars (B) of the racket shaped nucleotome.

and angle of the nucleotome and serves as support for phacofragmentation (see "S" in Fig. 247).

•Two straight-handled, ophthalmic manipulators, left and right, with a basket end, which serve to collect the nuclear fragments during the nuclear fragmentation (Fig. 250).

•Anterior chamber maintainers were pioneered years ago by Strampelli as well as Joaquin Barraquer, and their use is always emphasized by Michael Blumenthal for his Mini-Nuc cataract extraction technique. The Gutierrez AC maintainer (ACM) maintains continuous irrigation with BSS in the anterior chamber, creating positive pressure that stabilizes the AC depth. During the stages of the operation in which the maintainer is used, the amount of viscoelastic utilized is less, thereby reducing costs.

Surgical Technique

It is important to have good pharmacological mydriasis because the pupil may contract during surgery.

Incision: This method can be performed through a 3.2 mm corneal incision (clear corneal) (Fig. 247) or through a 3.5 mm scleral tunnel incision (scleral tunnel) 2 mm away fromthecorneal-sclerallimbus(Fig.248). The preparatory incision is made without penetrating the anterior chamber (AC).

Capsulotomy: A continuous circular capsulorhexis is performed with a cystotome through a superotemporal paracentesis. This capsulorhexis should be sufficiently wide (approximately 6 mm) to allow an easy luxation of the nucleus into the AC. The AC maintainer is used during this step and when aspirating the anterior cortex and epinucleus in soft and me-

dium-soft nuclei, before hydrodissection.

Nucleus Hydrodissection and Luxation: After entering the AC with a 3.2 mm beveled blade, balanced salt solution (BSS) is injected with a Binkhorst cannula through the corneal or scleral incision between the anterior capsule and the cortex at 12 o'clock.

The BSS must be injected slowly and continuously until the "wave" of dissection is visible on the posterior capsule. Injection of BSS is continued until luxation of the nucleus begins. If the luxation of the nucleus into the AC is partial, it may be completed by rotating thenucleuswithacannula,cystotomeorspatula.

Nuclear Fragmentation: Once the nucleus has been luxated into the AC, highdensity viscoelastic is injected into the surrounding area to fill the AC. The nucleus is then fragmented by placing the spatula beneath the nucleus and the nucleotome on top of it

Figure248-ManualMultiphacofrag-men- tation Technique - Stage 2 - Extraction

While the nuclear fragments (A) remain with the nucleotome (P), the spatula

(S) and nucleotome are extracted (arrow) from the anterior chamber through the incision (I). Notice the remaining nucleus (N) with center removed, within the anterior chamber. This procedure is repeated until the whole nucleus is fragmented and extracted. With hard nuclei, after capturing the nuclear fragments (A) withbothinstruments

(P) and (S), space can be gained by extracting nuclear fragments (A) using only the nucleotome (P), as hard fragments will remain within the nucleotome (P) without the support of the spatula (S), thus reducing corneal injury.

(Fig. 247). Pressure is then created by slowly pressing the nucleotome downward toward the spatula until the part of the nucleus in it is fragmented into four pieces (Fig. 247). The pieces remain within the nucleotome, and with the help of the spatula are extracted from the AC using a "sandwich" technique (Figs. 248 and 249). This maneuver is repeated until the whole nucleus is fragmented.

During nuclear fragmentation it is important to refill the AC with high-density viscoelastic as needed to protect the corneal endothelium and facilitate safe manipulation during surgery.

Manipulation of Nuclear Fragments:

There are right and left manipulators to displace the remaining fragments of the nucleus to the center of the AC to facilitate their fragmentation and subsequent removal (Fig. 250).

Cortex Extraction and Nucleus Removal: The lens cortex is aspirated with a twoway Simcoe irrigation-aspiration cannula (Fig. 251). If small pieces of the nucleus remain in the AC, they can be removed according to their hardness in different ways: with the nucleotome and the spatulatogether (sandwich - Figs. 247, 248, 249) or only with the