POSTERIOR CAPSULE CAPSULORRHEXIS

If the rent is visible and size and location allow, performing a posterior capsule capsulorrhexis (PCC) to repair a ruptured posterior capsule is useful. It will prevent the enlargement of the opening during subsequent surgical steps. Unfortunately and commonly, the surgeon’s ability to perform a PCC may be hindered by the lack of visibility of the torn posterior capsule’s borders, residual cortex, or a peripheral location. As a rule, the role of this valuable technique is accordingly limited. In addition, vitreous may block the capsule forceps from adequately grasping the edge of a capsular rent, preventing the surgeon from completing a PCC. A new generation of high molecular weight sodium hyaluronate viscoadaptive viscoelastic Healon5 (Pharmacia and Upjohn) may enhance the surgeon’s capability of performing a PCC under less than ideal circumstances9 (see Chapter 5).

POSTERIOR CAPSULAR RUPTURE

DURING EMULSIFICATION OF

THE NUCLEUS

Whenever the surgeon recognizes a tear in the posterior capsule, successful management requires that two questions be answered: First, is there vitreous in the anterior chamber? Second, is conversion to a large incision extracapsular extraction indicated?

The conversion decision may depend on multiple factors including the hardness and size of the nuclear material in the anterior segment, the size of the pupil, the ability to maintain an adequately deep anterior chamber, and the ease of access to the anterior segment. In addition, these decisions are based on the level of surgical experience and the perceived severity of the posterior capsular rent.

While considering the situation, the surgeon should be careful not to depressurize the anterior chamber by abruptly removing the phaco tip. The resultant subsequent sudden loss of anterior chamber (AC) fluid and pressure will allow the positive vitreous pressure to push the posterior capsule forward. The tear will enlarge, frequently the vitreous face will rupture, and vitreous will pass into the AC. To prevent this, the surgeon should pressurize the AC with viscoelastic or air prior to removal of the phaco tip.

When in doubt, it is prudent to convert to an extracapsular extraction rather than proceed with phaco. The consequences of an inappropriate decision could be the loss of a piece of the nucleus, or perhaps the entire nucleus, into the vitreous. A key factor in the determination as to whether to continue phaco or convert to extracapsular surgery might be

the presence of vitreous in the anterior chamber combined with a large piece of nucleus. If vitreous is present immediately after a capsular tear, generally it indicates a large capsular tear combined with syneretic poor vitreous support. The surgeon at this point should recognize the potential gravity of the situation and be more disposed to convert the procedure.

CONVERSION TO ECCE

To convert to extracapsular surgery, it is of primary importance to immediately secure the lens nucleus with a dispersive viscoelastic. This will prevent the loss of the nuclear fragment or fragments into the vitreous. Viscoelastic should be injected underneath the nucleus to support it. It may be necessary to create a paracentesis opposite the incision to provide access to pass a hook into the superior AC. This hook can be used to loosen and manipulate nuclear material, embedded within the superior capsular bag, into the anterior chamber, where it can be secured for later extracapsular extraction. If a clear corneal incision is used, it may be sutured and abandoned. If a sclerocorneal incision has been utilized, it can be extended. A well-constructed, shelved limbal incision should be accomplished after appropriate conjunctival peritomy and cautery. The size of this incision will be dependent on the size of the nuclear fragment present in the anterior chamber. In general, the incision should be larger than the surgeon thinks is necessary for extraction of the nuclear remnant. Once the incision has been created, the wound should be opened to its full extent and a lens loop and secondary lens manipulator should be used to extrude the lens nucleus. No external pressure should be applied to the opposite limbus, as vitreous will preferentially be expelled. Alternatively, the clear corneal incision can be enlarged for extracapsular extrusion of nuclear material and implantation of a polymethylmethacrylate (PMMA) or foldable small-diameter IOL. Once the lens nucleus has been removed, anterior segment surgery should proceed as described below. Lens implant choice will be dependent on the amount of residual anterior capsule. Suturing of the wound is accomplished with interrupted or running 10-0 nylon radial sutures trimmed on the knot and buried. Conjunctival closure is accomplished with the same suture and a buried knot.8

CONTINUED PHACOEMULSIFICATION

If the surgeon feels that continued phacoemulsification is appropriate, a dispersive viscoelastic should be positioned below the lens nucleus to raise it into

the anterior chamber. More viscoelastic should be placed below the endothelium to protect it. Bottle height, vacuum, and flow should be lowered to create a low-flow system, for example, bottle height at 65 mm should be decreased to 55 mm, flow should be decreased to 18 cc/min, and vacuum to 100 mm Hg. (These parameters are machine-dependent.) The nucleus should then be emulsified in the anterior chamber in one piece using two instruments. The second instrument is used to feed the edges into the phaco tip; foot-pedal positions 2 and 3 are used only when the nucleus is adjacent to the phaco tip so as not to emulsify vitreous that might be aspirated preferentially. It is best not to create multiple fragments of nucleus by cracking or other maneuvers, as these fragments are difficult to follow and may then fall through the posterior capsule rent into the posterior segment.

If the capsular tear occurs when only a small fragment of nucleus remains, the small nuclear fragment can be emulsified by manipulating it adjacent to the phaco tip and then applying aspiration and phaco so as to immediately engage the nuclear fragment in the phaco tip, thus preventing the aspiration of vitreous.

THE PSEUDO–POSTERIOR CAPSULE10

When the capsular tear appears large, and risk of loss of the nucleus or fragments of nucleus appears great, a Sheets’ glide may be utilized to create a substitute posterior capsule. This will thus prevent loss of nucleus into the vitreous. The glide can be employed for both extracapsular delivery and continued phaco.

EXTRACAPSULAR EXTRACTION OVER

THE SHEETS’ GLIDE

To accomplish this, the nucleus is secured with dispersive viscoelastic as noted above. The viscoelastic will additionally create space between the nucleus and vitreous (Fig. 18–1). The incision should be enlarged adequately to accommodate passage of the nucleus. A Sheets’ glide is positioned under the nucleus. Often it is helpful to use a hook through another area of the wound to guide the advancing glide into proper position (Fig. 18–2). Once in position, the nucleus is extruded over the glide. Two instruments or viscoelastic can be maneuvered to push the nucleus out of the anterior chamber. Acting as a pseudo–posterior capsule, the Sheets’ glide may act to prevent the nucleus from dropping into the vitreous cavity. At the same time the glide also acts as a relative barrier to prevent the forward displacement of vitreous into the anterior chamber (Fig. 18–3). Compressing the eye to express the nucleus should be avoided. Further loss of vitreous and additional compromise of the posterior capsule could result from expression of the nucleus. Once the nucleus has been removed, I&A can be performed over the glide. Again the glide is of assistance in holding the vitreous back from the I&A tip. Alternatively, the glide can be removed and the wound sutured. I&A and a bimanual anterior vitrectomy can then be performed (see Chapter 19).

When using the Sheets’ glide technique, there are several points to consider. First, as noted above, viscoelastic should be injected under the superior pole of the residual nucleus. This creates a cleavage plane

so the glide can be inserted under the nucleus. Second, the Sheets’ glide should be inserted under the posterior surface of the nucleus gently, so that the capsular bag is not damaged. The surgeon should exercise caution so as to avoid pushing the glide too far. This would result in further damage to the residual capsule or even the ciliary body.

PHACOEMULSIFICATION OVER THE

SHEETS’ GLIDE

An alternative approach to remove nucleus when there is a large tear of the posterior capsule with a

FIGURE 18–2 The Sheets’ glide is placed below the lens fragment. A second instrument is used to guide it into position.

large nuclear reminant or even a complete nucleus and nuclear instability is to phaco the nucleus in the presence of a Sheets’ glide. The incision needs to be widened to 5 mm to accommodate both the Sheets’ glide and the phaco tip. As above, the first step in the recovery of the nucleus is to introduce a dispersive viscoelastic into the lens bag under the superior pole of the nucleus. This will create a cleavage plane between the superior pole of the nucleus and the posterior capsule. Next, a Sheets’ glide (either preordered at 3 mm or cut to size) is inserted through the wound into this cleavage plane and advanced toward the opposite side. A second instrument guiding the glide to the proper position under the nucleus may be of

assistance (Fig. 18–2). The glide essentially will occlude the posterior capsular opening, again acting as a barrier preventing the nucleus or nucleus fragments from dropping posteriorly into the vitreous cavity. The phaco tip can now be reintroduced into the anterior chamber and the remaining nucleus emulsified over the Sheets’ glide (Fig. 18–4). The Sheets’ glide again acts as a barrier to discourage the advance of vitreous into the anterior chamber with subsequent aspiration by the phaco tip. Next, I&A and vitrectomy can be performed over the glide. The glide is then removed, final vitrectomy, if necessary, is completed, and the IOL is inserted into the capsular bag or ciliary sulcus. Alternatively, the glide can be removed. Dispersive viscoelastic is injected into the residual capsular bag and the IOL is implanted into the bag or sulcus. I&A and vitrectomy can then be performed using the IOL as a barricade to further vitreous movement.

Not infrequently the large bulk of nucleus and adherent cortex may obscure the view of the glide as it is advanced under the nucleus. Therefore, a perceived pitfall to this approach is that the Sheet’s glide may be advanced through the opening in the posterior capsule and into the vitreous (Fig. 18–5). If the glide should pass through the opening of the posterior capsule, its integrity will be severely compromised. In this circumstance, although not desirable, removal of the residual nucleus by phacoemulsification can, after all, be efficiently performed (Fig. 18–6). Despite significant destruction of the posterior capsule, if the original capsulorrhexis capsulotomy is intact, a posterior chamber IOL can be implanted with ciliary sulcus fixation. Careful guidance of the glide beneath the nucleus with the assistance of ade-

quate viscoelastic and a second instrument through the paracentesis should assist in prevention of this problem.

BIMANUAL LIMBAL ANTERIOR

VITRECTOMY

At the completion of nucleus removal the rent in the posterior capsule should be evaluated for performance of a PCC. If a posterior capsular rent cannot be converted into a continuous curvilinear capsulorrhexis, every effort should be made to avoid enlarging the tear during subsequent anterior vitrectomy and cortical removal. This becomes increasingly critical if the anterior capsulotomy is not continuous. Accordingly, the surgeon should avoid performing an anterior vitrectomy with coaxial infusion. The infusion port at the tip of a coaxial infusion sleeve is located adjacent to the vitrector cutting port. Therefore, when the vitrectomy instrument is advanced toward the vitreous and broken posterior capsule, the infusion pressure will force the already open capsule to rapidly enlarge. This will result in the extension of the rent to the equatorial zonules.

Ideally, the infusion should be separated from the vitrectomy tip to prevent direct infusion pressure on the capsular defect. A bimanual infusion vitrectomy technique allows more control than a coaxial infusion vitrectomy and helps to preserve the already altered capsular anatomy11 (see Chapter 19). The vitreous instrument should be placed below the capsular hole to draw vitreous back. If the vitrectomy is performed above the plane of the posterior capsule, vitreous will be drawn anteriorly. The physical forces

exerted by the vitreous on the open capsule will further enlarge the capsular opening. The amount of vitreous advancing anteriorly and passing through the capsular defect cannot be easily controlled if the vitrectomy is performed in the anterior chamber.

The vitrectomy is completed once vitreous has been removed to a level several millimeters below the iris plane.

POSTERIOR ASSISTED LEVITATION12

In certain situations it is impossible to stabilize the nucleus. This is most likely to occur when the phaco

FIGURE 18–5 The Sheets’ glide is shown passing through the rent in the posterior capsule and residing in the anterior vitreous beneath the lens fragment.

tip creates a large zonular dehiscence opposite from the incision. In such a circumstance zonules are present subincisionally so that the distal pole of the nucleus falls into the vitreous, but the nucleus remains attached subincisionally, preventing the entire nucleus from disappearing. In this unique setting, a stab incision should be made into the pars plana at 3.5 mm posterior to the incisional limbus. Alternatively, the pars plana incision can be moved to wherever the zonular hinge occurs. As described by Charles Kelman, a cyclodialysis spatula is then used to lever the nucleus into the anterior chamber through the pars plana approach. Once the nucleus is secured within the anterior chamber, it can be re-

moved either by emulsification or preferentially by extruding it through an extracapsular approach.

REMOVING THE CORTEX

To remove cortex in the presence of a capsular tear, dispersive viscoelastic should be placed over the rent to minimize the chance of further vitreous advancement and the need for further vitrectomy. A reverse “soft shell” technique may be of assistance (see Chapter 24). The remaining cortex should be stripped toward the capsular tear. The 0.3-mm I&A tip should be embedded into the cortex before the application of vacuum so as not to aspirate vitreous. Lowering the infusion bottle will decrease inflow and resultant turbulence, which might enlarge the capsular rent and/or force more vitreous forward. The surgeon should attempt to avoid working directly over the capsular tear and never strip cortex directly away from the capsular tear, as this will immediately enlarge the tear. Manual cortex removal may be utilized. If cortex is difficult to remove, and not too voluminous, it should be left behind. The vitrectomy tip can be alternately used in the vitrectomy or I&A mode for complete cortical removal.

NUCLEUS LOSS INTO THE VITREOUS

Loss of nuclear fragments into the vitreous cavity is a potentially serious complication.13 Nuclear particles displaced in the anterior vitreous can be carefully removed. Nuclear chips that become displaced into the deeper vitreous create the need for a decision as to whether to attempt a primary removal or to complete the surgery and leave the fragments for a secondary removal by a vitreoretinal surgeon.14

The management choice depends on the size, consistency, and location of the piece. If the nucleus becomes displaced through an open posterior capsule into the anterior vitreous, an attempt should be made to secure or trap it from further posterior displacement. An anterior vitrectomy should be avoided until the nucleus has first been secured and removed. The vitreous framework actually may help to support the nucleus from further posterior displacement. A vitrectomy will disrupt this vitreous framework, enabling the nucleus to drop into the posterior vitreous cavity. Once the nucleus drops into the posterior vitreous cavity, the surgeon should perform an adequate anterior vitrectomy without regard for the dropped nucleus, remove the cortex, and insert the IOL. The wound should also be secured with a suture (even if it’s a planned sutureless case). This will reinforce the incision during subsequent pars

plana vitrectomy. The patient is then referred to a vit- reo-retinal surgeon for a trans–pars plana vitrectomy for complete fragmatome lens removal.

Only minimum effort should be applied in attempting a primary retrieval of a nuclear particle in the posterior vitreous. Gentle irrigation may be successful at elevating the nucleus to the iris plane where it can be secured. However, if the nucleus does not readily float, this technique should be abandoned. Excessive vitrectomy, and irrigation of the vitreous, vitreous base, and retina may incite a suprachoroidal hemorrhage. In the presence of a large vitrectomy, inadequate tamponade may allow the hemorrhage to become large and se- vere.14–16 Excessive manipulation increases the likelihood of postoperative cystoid macular edema and retinal detachments with poor visual outcomes.17,18

Perfluorocarbon installation may be utilized at this juncture. Anterior segment surgeons have little experience with this modality. Therefore, this should only by employed by a retinal surgeon present in the operating room at the time of the dropped nucleus.

Residual nuclear material remaining in the vitreous cavity can be observed. If soft (i.e., more cortical in nature) and small, it will be absorbed over time with little vitreous inflammatory change. However, if hard (i.e., endonuclear) and large, there is a likelihood that the residual material will incite a phacoanaphylactic response, producing iritis, vitritis, and secondary glaucoma. Furthermore, if the origin of a dropped nuclear chip is the adult or epinucleus, a retained nuclear chip will probably be absorbed in the vitreous without significant inflammatory complications. In contrast, fetal and infantile nuclei may be more immunogenic. Thus, if a retained nuclear chip originates from the fetal or infantile nucleus, inflammation, vitritis, and glaucoma are likely to result. These usually demand immediate removal by a pars plana approach.16 Any of these conditions could result in corneal edema, cystoid macular edema, or optic nerve damage.

The timing of dislocated nucleus removal remains controversial. As discussed previously, some patients with retained nuclear fragments do not require additional surgery. They can be observed closely to monitor signs of inflammation or secondary glaucoma. If the eye remains quiet and the vision progressively improves, the retained nuclear fragments will be absorbed slowly over 6 to 8 weeks. In these cases, medical therapy with intensive topical steroids, and occasionally subconjunctival steroid, is sufficient. In those patients where the nuclear fragment is large and or hard, vitrectomy within 1 week of the original surgery is indicated. The vitritis and glaucoma will otherwise become impossible to manage and lead to significant postoperative visual loss.13,14