18 Conversion to Extracapsular Cataract Extraction Planned extracapsular cataract extraction (ECCE) is a technique that involves removal of an intact crystalline lens from the eye through a large incision without disturbing the integrity of the posterior capsule and zonules. It is also an important technique to master for cases in which a nucleus is not amenable to phacoemulsification or there is a need to convert from a small-incision phacoemulsification procedure to safely extract the lens. Manual small-incision cataract surgery (MSICS) is a low-cost, highly efficient, high-quality procedure first described in 1994; it is an excellent solution for black or brunescent cataracts. It does not have the same limitations as phaco surgery, with increased surgical time and ultrasound energy required to break the dense nuclear material typical of advanced cataracts. In cases of dense nuclei, this technique may be preferable to avoid endothelial damage and corneal edema. The advantages of MSICS over standard ECCE are that it entails a much smaller, self-sealing incision that essentially eliminates the need to suture the wound, and therefore decreases the surgically induced astigmatism, and improves the vision recovery and long-term wound stability. Other situations where MSICS is preferable as a primary method of lens extraction is in cases of zonular laxity. In the divide-and-conquer technique, excessive stress may be placed on the bag-zonular complex, which can lead to capsular rupture. A thickened posterior plate of the lens can also be very difficult to disassemble in piecemeal lens extraction. These challenges can be avoided by MSICS. When performed by an experienced surgeon, the technique will take 5 minutes or less, and it treats the thickest and blackest cataracts with minimal zonular and endothelial stress. When performing MSICS, fewer instruments are required (Table 18.1). The incision can be made from a temporal or superior approach, typically guided by keratometry measurements or by surgeon preference. A temporal tunnel is preferred over a superior tunnel due to the effective decrease in against-the-rule astigmatism. This position also minimizes the effect of a prominent brow or enophthalmos on proper instrument handling and improves intraoperative exposure and red reflex visualization. To gain better surgical exposure and aid in the nucleus delivery step, a bridle suture may be helpful. If the surgeon elects a superior approach, a 4-0 silk bridle suture is placed beneath the superior rectus tendon, and for a temporal approach a bridle of the lateral rectus may be used. A bridle suture is not required in all cases where there is good surgical exposure. The next step is wound construction—creation of a fornix-based conjunctival flap of ~ 7 mm in length, taking care to displace the Tenon’s capsule. Light cautery may be used in this step to stop any bleeders. The external scleral incision is placed 1.5 mm from the limbus and at a 50% depth. A bevel-up crescent blade is then advanced parallel to the ocular surface to extend the tunnel 1.5 mm into clear cornea. The external incision should be 5.5 to 7.0 mm in length, depending on the size of nucleus. The internal portion fans out to 9.0 mm, yielding a trapezoidal incision with a wider base facing the anterior chamber and tapering narrower toward the external incision (Fig. 18.1). This conical, multiplanar tunnel construction enables a smooth delivery of a large, dense nucleus through a self-sealing wound. A larger nucleus will require a slightly larger tunnel profile. Avoid premature entry into the anterior chamber at this point. The depth of the tunnel is very important: too shallow and there is risk of button-holing and wound instability, but too deep and there is risk of premature entry and iris prolapse. After creating a corneal tunnel, the anterior chamber is filled with viscoelastic and a large curvilinear capsulotomy is created with or without relaxing incisions. The size of the capsulorrhexis will need to have a minimum diameter of 5 to 6 mm up to 7 to 8 mm, depending on the size of the cataract. A capsulorrhexis that is too small for the size of the nucleus will need to be converted to a “can-opener” capsulotomy by adding four or more radial relaxing incisions to afford easy nucleus delivery into the anterior chamber. The capsulorrhexis is usually accomplished through a paracentesis incision. Alternatively, a small entry wound could be made through the sclerocorneal incision to accommodate a cystotome (Fig. 18.2). After an adequate capsulorrhexis is created, a 3.2-mm angled keratome is used to enter the anterior chamber and to extend the wound from side to side for the full extent of the internal tunnel. Care must be taken to keep the incision in one plane. The nucleus is prolapsed into the anterior chamber by hydrodissection, viscoelastic, Sinskey hook, or a Simcoe cannula (Fig. 18.3). One should preplace additional viscoelastic around the nucleus to protect the endothelium from injury in the nuclear expression step. At the conclusion, the nucleus is gently delivered through the tunnel using viscoelastic or fluid pressure. After safely delivering the nucleus, a Simcoe cannula or another irrigation and aspiration (I/A) device can be used to remove cortex and epinucleus. After cortical cleanup, the bag is reinflated with viscoelastic, and a 6-mm lens can be placed through the tunnel without folding, taking care not to damage the endothelium. Occasionally, a surgeon may opt to preplace the lens at an earlier step in the surgery if the capsular bag is unstable. In that situation, the haptics of the rigid polymethylmethacrylate (PMMA) lens act as a capsular tension ring and protect the bag and zonules during cortical removal. If a V-capsulotomy was performed at the beginning of the surgery, the flap is severed with Vannas scissors to avoid obstruction of the visual axis. The viscoelastic is then removed with the use of a Simcoe or I/A cannula, and the anterior chamber reformed with balanced salt solution (BSS) on a 27-gauge cannula. If a watertight wound was created, no sutures are necessary. This is verified by pressing down on the central cornea and noting no wound distortion or collapse of anterior chamber. At the conclusion of the procedure, the conjunctiva is replaced back to the limbus and reapposed either with cautery or a single interrupted suture. Table 18.1 Instruments for Manual Sutureless Small-Incision Cataract Surgery
Manual Sutureless Small-Incision Cataract Surgery Technique
Tray | Toothed 0.12 Forceps | Cautery (Low-Temp or Wet-Field) |
Gauze pads | Bevel-up crescent blade | 25- to 27-gauge needle |
5% betadine | Microkeratome blade | 1-mL syringe |
Eyelid speculum | Viscoelastic | 3-mL syringe |
4-0 silk | 27-gauge cannula | Sinskey hook |
Needle driver | Corrugated Simcoe irrigation and aspiration cannula | Posterior chamber intraocular lens |
Superior rectus forceps | Tying forceps | Microscope |
Westcott scissors | Long blade Vannas scissors |
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In the following situations, MSICS should be considered as primary surgery:
- Morgagnian and brown or black cataract
- Pseudoexfoliation, weak zonules, poor pupil dilation
- Subluxed lenses
- Phacolytic glaucoma
- Shallow anterior chamber
- Poor visibility due to corneal scar or milky liquefied cortex
These scenarios are well suited for small-incision cataract surgery (SICS) with some additional precautions. In a morgagnian cataract with a fibrotic capsule and poor visibility, if a continuous curvilinear capsulotomy is not achievable, an envelope or V-capsulotomy could be performed instead (Fig. 18.4). This is accomplished by introducing a 27-gauge needle and making a linear cut with the bevel tip from the 4 to 12 o’clock positions and the 8 to 12 o’clock positions (if sitting superiorly) to create a triangular V-shaped flap with apex oriented toward the surgeon. Place each point of the triangle ~ 3 mm from the center of the pupil. The flap is then lifted to verify that it is connected at the apex, and gentle hydrodissection is employed to hydro-rotate the nucleus out of the bag. Delivering the nucleus with a bimanual technique using a spatula can protect the bag or iris. Use the sweep below and a Sinskey hook from above. Another trick is to preplace the intraocular lens into the capsular bag under the viscoelastic to aid in nucleus expression while protecting the capsular bag from coming forward.
In cases of pseudoexfoliation, poor pupil dilation, posterior synechiae, shallow chamber, phacodonesis, or subluxed lenses, there is an increase in difficulty, but these patients are still very well suited for the SICS method. Small sphincterotomies can be made to facilitate nuclear expression and minimize zonular trauma. If the iris is poorly dilated and floppy, iris edges could be gently brought out through small, equally spaced paracentesis incisions with a Sinskey hook, effectively enlarging the pupil as a Malyugin ring would, without impeding fluidics of whole lens extraction.
In cases with phacolytic glaucoma, weakened zonules, and poor visibility from elevated pressure, the additional factors could be controlled by initially lowering the intraocular pressure with preoperative mannitol or by applying pressure on the globe for 10 minutes after peri/retrobulbar block. A Simcoe cannula is also useful for clearing anterior chamber debris at any portion of the procedure.
