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
mately 3 mm |
(Fig. 217). After the |
capsulorrhexis |
has been done, as |
shown |
in Fig. 219 A, |
B and C, the deep plane of |
the incision |
is |
completed with |
scissors |
(Fig. 218). Care must be taken to ensure that
the lid speculum does not exert pressure on the eye, which might induce protrusion or rupture of the posterior capsule.
The capsulorrhexis can be performed by perforating the center of the capsule with a
Figure 217 (above): Incision - Stage 2
A viscoelastic substance is injected with a cannula through a paracentesis to fill the anterior chamber. This will maintain the anterior chamber depth and increase dilation of the pupil. At one end of the non-penetrating limbal incision, a horizontal beveled incision is made (D). This will begin the second plane of the two-plane incision. Fixation forceps (F).
Figure 218 (below): Incision - Stage 3
The two-plane horizontal beveled incision is completed (red arrow) with Barraquer’s scissors (S) in the deep layers of the groove.
C h a p t e r 13: Manual Extracapsular Techniques of Choice - Planned ECCE - Small Incision ECCE
Figure 219 A-C: The Continuous Curvilinear Anterior Capsulorhexis Technique - Stages 1 - 3
(A) After the tear is started in the center of the anterior capsule, traction is exerted at the 10:00 meridian (X) on the operculum that is doubled on itself. Uttrata forceps (N) are used to grasp the underside of the capsular flap (C) and the tear is extended in a counterclockwise direction (blue arrow) to produce a circumferential capsular rupture (red arrow). (B) The tear is continued with the Uttrata forceps in the same direction (blue arrow) to complete the circular tear (red arrow). (C)The capsulorrhexis is completed, and the circular operculum is removed.
needle, or cystotome, which is an insulin injection needle, conveniently bent near its base to produce adequate angulation for better maneuvering (Fig. 97). The bend close to the tip of the needle makes a little hook used to exert traction on the capsule fragment. Cystotomes are also available commercially. Another way of performing a capsulorrhexis is to tear the central part of the anterior
capsule with adequate forceps such as Uttrata forceps. We usually prefer the forceps to the cystotome (Fig. 219 A, B,C).
Once the center of the capsule has been ruptured or torn, a small flap of capsular tissue is grasped and pulled in either a clockwise or counterclockwise direction to eliminate the central part of the anterior capsule (Fig. 219 A,B,C). We attempt to create a
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
circular opening 5.5mm to 6 mm in diameter (Fig. 220). In cases of very large nuclei, of capsular pseudoexfoliation, or when some phacodonesis is present, we prefer to construct a capsulorrhexis with a slightly larger diameter in order to avoid traction on the zonules when the nucleus is brought into the anterior chamber. In these cases a large capsulorrhexis facilitates mobilization and rotation of the nucleus (Fig. 221).
Figure 220 (above): Continuous Curvilinear Anterior Capsulorrhexis - Standard Size
The regular curve of the capsular opening is less prone to radial tears than the irregular edges of the opening that result form the can-opener and envelope techniques.
Figure 221 (below): Large Continuous
Curvilinear Anterior Capsulorrhexis
This illustration depicts a large CCC, adequate for removing a large and/or hard nucleus.
C h a p t e r 13: Manual Extracapsular Techniques of Choice - Planned ECCE - Small Incision ECCE
Hydrodissection
Next is the hydrodissection. Balanced saline solution (BSS+) with epinephrine (dilution 0.06%) is injected with a thin cannula (25 G) between the anterior capsule and the lens cortex (Fig. 222) to separate the nucleus, which tends to pass through the capsulorrhexis into the anterior chamber.
Subsequently, the nucleus is rotated with the same cannula in clockwise or counterclockwise direction, depending on where the nucleus has entered the anterior chamber. The nucleus is lifted slightly during the rotation maneuver to complete the displacement into the anterior chamber (Figs. 223, 224). As the capsule is an elastic structure, even large nuclei can pass through a relatively small
Figure 222 (left): Hydrodissection of the Lens
Capsule from the Cortex - Stage 1
After the continuous curvilinear anterior capsulorrhexis has been completed, a cannula (C) is inserted in the anterior chamber. The tip of the cannula is placed between the anterior capsule and the lens cortex at the locations represented. Fluid is injected (arrows) at these locations to separate the capsule from the cortex. The resulting fluid waves can be seen (W). These waves continue posteriorly to separate the posterior capsule form the cortex.
Figure 223 (right): Hydrodissection - Stage 2
A 25 gauge needle (A) is introduced parallel to the edge of the nucleus (N), and a solution of BSS+ and epinephrine is injected. This hydraulic force (arrow) produces a cleavage plane between the posterior capsule and the posterior surface of the nucleus. The nucleus passes into the anterior chamber without tearing the capsulorrhexis.
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
capsulorrhexis without tearing the capsule when a continuous circular capsulotomy without notches is performed.
Other methods of opening the capsule are: 1) the envelope technique, which uses a more or less straight incision between the central and superior third. 2) The can-opener technique produces small, less circular capsule ruptures. These techniques, which are based on lineal incisions, however, may result in a higher incidence of rupture or tearing of the posterior capsule during the cleaning maneuvers of the capsular bag.
Removal of Nucleus
Once the nucleus has passed into the anterior chamber, gentle compression is applied 1mm to 2mm from the inferior limbus (Fig. 224) with a round-tipped or blunt instrument. The nucleus is displaced upwards (Fig. 224), resulting in some gaping of the incision. Simultaneously, the scleral lip of the incision is depressed with another instrument such as Colibri or Adson forceps to facilitate the expulsion of the nucleus (Fig. 224). Expression of the nucleus should never be attempted while the nucleus is still inside the capsular bag because zonular rupture may occur, necessitating the continuation of surgery as an unplanned intracapsular extraction.
Removal of Cortex - Irrigation
and Aspiration
The anterior chamber is irrigated with BSS+ and epinephrine (0.06% dilution) to remove persistent residual lens matter or epinuclear elements. A nylon 10-0 cross suture is applied in the central part of the incision to
maintain adequate anterior chamber depth during irrigation and aspiration of the cortex that remains adherent to the capsular bag. An aspiration probe with a 0.3mm opening at the tip is used. This probe has a special cover with two lateral openings at the inferior end for irrigation to maintain the anterior chamber depth while the cortical lens matter is aspirated (Fig. 225). The height of the bottle is adjusted from 20cm to 78cm to increase or reduce the irrigation in relation to the depth of the chamber. An adequate chamber depth makes it possible to work with greater safety, although excessive irrigation may result in iris prolapse through the wound. This can be corrected by reducing the height of the bottle. For aspiration of the lens matter, a variable vacuum with an upper limit of 450mmHg is applied.
Once all the lens matter has been removed, the anterior capsule is “polished” using the same probe and a low vacuum power between 20mmHg and 60mmHg to avoid capsular retraction and rupture. Careful, exhaustive cleaning of most of the posterior capsule surface is essential in order to postpone as long as possible the opacification of the capsule and the subsequent Nd: YAG laser capsulotomy. The surgeon must be careful not to be aggressive during this step of aspiration-irrigation of the cortex so as to avoid posterior capsule rupture or zonules rupture during these maneuvers. If this should occur, vitrectomy would be required, and the IOL would have to be placed in the sulcus.
If irrigation-aspiration equipment is not available, the lens matter can be removed manually. A cannula and syringe are used to gently irrigate, mobilize the lens matter, and aspirate it in the four quadrants. A curved
C h a p t e r 13: Manual Extracapsular Techniques of Choice - Planned ECCE - Small Incision ECCE
Figure 224 (left): Removal of
Nucleus
Once the nucleus is in the anterior chamber, nucleoexpression is performed. Slight compression is exerted with a blunt instrument 1 or 2mm over the inferior limbus (H). the nucleus is displaced upwards, separating the lips of the incision. Simultaneously, another instrument (F) is used to depress the scleral lip of the incision in order to facilitate the expulsion of the nucleus.
Figure 225 (right): Removal of the
Residual Cortex
The aspiration probe has an opening 0.3 mm in diameter at the upper end. It also has a cover or sleeve with two inferior lateral openings for irrigation to maintain the depth of the anterior chamber during aspiration of the lens matter.
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
probe tip is used for the superior quadrants (Fig. 226). The posterior capsule may also be polished manually using this technique at the end of the procedure. In cases of central capsular fibrosis, posterior capsulorrhexis can be performed at the end of the procedure or at a later stage in a Nd: YAG laser capsulotomy.
A viscoelastic is injected in the capsular bag and the anterior chamber. The surgeon should check carefully to ensure that the capsular bag is completely filled with viscoelastic. The preplaced cross-point suture is removed from the wound.
IOL Implantation
The lens is grasped at the superior rim of the optics with straight forceps. With a slight inclination, the inferior haptic is introduced into the capsular bag (Fig. 227). The optic is centered with the capsulorrhexis and rotated using a Sinskey hook until the superior haptic is in the correct position inside the bag. The IOL should be implanted horizontally. Introduction of the superior haptic may be easier if it is grasped with thin forceps without teeth (Fig. 228). The haptic is guided
Figure 226: Irrigation/Aspiration of the Residual Cortex (modification by Malbran).
The residual cortex (C) is removed from the capsular bag with a curved irrigation/ aspiration probe. A slightly curved tip is used to gently aspirate the residual cortex nasally and temporally. The residual cortex located in the difficult-to-reach areas of the superior capsular bag is removed using a curved irrigation/aspiration probe tip.
C h a p t e r 13: Manual Extracapsular Techniques of Choice - Planned ECCE - Small Incision ECCE
Figure 227 (left): Intraocular Lens Implantation.
After the cataract is removed and viscoelastic is injected into the anterior chamber and the capsular bag, the PMMA (L) lens is grasped with forceps (F). The inferior haptic (H) is placed in the capsular bag (C) inferiorly. Forceps are used to introduce the optic part into the capsular bag.
Figure 228 (right): IOL Implantation
The superior haptic (H) is grasped with straight forceps and bent inferiorly (red arrow) so that the elbow of the haptic can be directed (blue arrow) into the capsular bag
(C) superiorly.
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
toward the center of the capsulorrhexis and rotated 90 degrees. The forceps are removed from the capsulorrhexis, and the IOL settles in the capsular bag. The capsulorrhexis is clearly seen in front of the optic part of the IOL (Fig. 229). Generally, PMMA lenses are used, and the preferred diameter of the optic is 6.5 mm.
Acetylcholine 1% is applied to induce 4 mm of miosis. Subsequently, a peripheral iridectomy is performed.
Suturing and Aspiration of the
Viscoelastic
The incision is closed with 5 to 7 nylon radial sutures. The knots must be buried in the sclera (Fig. 229).
The viscoelastic material is aspirated. The anterior chamber is restored to normal depth with 1% acetylcholine (lyophilized acetylcholine dissolved in BSS) The conjunctival flap is repositioned to cover the incision. The two extremities of the flap are anchored with 10-0 nylon sutures.
Figure 229: Conclusion of the Operation
Cross-sectional view. The IOL occupies its normal position within the capsular bag. The incision is sutured with 10-0 nylon, preferably radial sutures, and the knots are buried in the sclera. The fornix-based conjunctival flap is repositioned to cover the wound. The flap is anchored with 10-0 nylon sutures at the two ends of the incision (not shown in this illustration).
C h a p t e r 13: Manual Extracapsular Techniques of Choice - Planned ECCE - Small Incision ECCE
THE MANUAL, SMALL INCISION
EXTRACAPSULARS
There is significant interest about these methods. They allow successful removal of the cataract through a small incision and manually, without the need to use mechanized equipment.
We hereby present the three most widely accepted: 1) Michael Blumenthal’s Mini-Nuc (Israel); 2) David McIntyre’s Phaco Section (USA); and 3) Francisco Gutierrez C., Manual Phacofragmentation.
THE MINI-NUC TECHNIQUE
This procedure caught-on in the minds of many clinical ophthalmologists since its inception, 10 years ago. Blumenthal has continuously worked at improving the method he created and its results.
Principles of the Mini-Nuc
Technique
The procedure requires only a small incision and no stitches. It has proven to be safe surgery. It is possible to use topical anesthesia, and rehabilitation is speedy. Moreover, it is cost-effective. There are some disadvantages, however, of manual ECCE. It is not an easy technique to learn and perform.
There is a significant learning curve, and experience is required.
The proposed Mini-Nuc technique must be performed under positive intraocular pressure during all stages of surgery. The desired IOP is achieved during surgery with the use of an anterior chamber maintaining system, and controlled by the height of the BSS bottle (Anterior Chamber Mainteiner (ACM) in Fig. 230).
Importance of Constant
Irrigation and Positive 100% IOP
The principle of maintaining positive IOP during cataract surgery is gradually becoming acceptable to more surgeons, even those performing phacoemulsification. In the mini-nuc technique, positive IOP exists 100% of the operating time. Any fluid lost during intraoperative maneuvers is promptly recovered because of the large internal diameter of the ACM tubing (“A” in Figs. 230-231). The steady flow ensures a constant depth of the anterior chamber. This flow continuously washes all debris: blood, pigment, and leftover cortical material from the eye with low turbulence and low fluctuation of anterior chamber depth. Consequently, less postoperative inflammatory reaction occurs.
