Cataract Incision

The cataract incision serves as more than just the port of access to the anterior segment; it is a critical step of the operation that affects ocular integrity and corneal stability. The traditional limbal or posterior limbal incision has been largely replaced by tunnel constructions, which can be located in the sclera, limbus, or cornea and are characterized by their greater radial length and an anterior entry into the anterior chamber to create the self-sealing internal corneal valve. Advantages of tunnel incisions are increased intraoperative safety, decreased postoperative inflammation and pain, increased postoperative watertightness, and reduced surgically induced astigmatism.

Tunnel Perforation

Tearing of the roof of the tunnel predisposes to excessive intraoperative leakage, which compromises anterior chamber stability, and to postoperative wound leakage. If the tear occurs at either edge of the roof, surgery usually can be completed using the initial incision, proceeding slowly and observing the wound carefully as instruments are introduced or manipulated in the eye. It usually is preferable to suture the incision at the conclusion of surgery, even if the wound is watertight, to restore a more normal architecture and prevent external wound gape.

If, however, the roof is perforated in the center of the flap, and this is noted before the anterior chamber is entered, creation of a new incision should be considered. If the cut is extremely small (e.g., < 0.5 mm), sometimes the same procedure as for lateral roof tears (see above) can be used. Before IOL insertion, the opposite margin of the wound is enlarged, and to prevent further tearing, the incision is made larger than normal for IOL insertion. Suture closure usually is advisable to restore normal wound architecture.

If the floor of the tunnel is perforated, which can happen during scleral tunnel dissection, surgery usually can be performed through this wound; care must be taken to avoid trauma to any prolapsing uveal tissue. The perforation should be closed with sutures or fibrin glue.

Descemet’s Detachment

Detachment of Descemet’s membrane can be a major postoperative complication, resulting in persistent corneal edema and decreased visual acuity. To prevent Descemet’s detachment, the surgeon should carefully observe the inner lip at each phase of the procedure. To avoid blunt stripping of Descemet’s membrane during enlargement of the wound, a sharp metal or diamond blade is recommended.

If detachment is caused by viscoelastic injection, the agent must be removed by using a blunt cannula. Intraoperatively, repositioning of Descemet’s membrane usually can be achieved by injecting balanced salt solution (BSS) or occasionally air or an ophthalmic viscosurgical device (OVD) through the paracentesis site. With the experience we have gained over the last 5 years with Descemet’s membrane endothelial keratoplasty (DMEK) air or gas injection (20% sulfahexafluoride [SF ₆ ]) can perfectly reattach a stripped Descemet’s membrane.

If a visually significant Descemet’s detachment is present postoperatively, the authors of this chapter prefer to intervene after 2–3 weeks; however, late spontaneous reattachment 2–3 months (in one case, 10 months) postoperatively has been reported. To reattach Descemet’s membrane, the patient is positioned at the slit lamp after several drops of anesthetic agent and antibiotics have been administered. A paracentesis incision is made inferotemporally. A 27- or 30-gauge cannula is attached to a syringe with a filter, and the syringe is filled with 0.5–1 cm ³ of air or, for eyes that have an unsuccessful injection of air alone, an expansive gas (e.g., SF ₆ ). Using the cannula, approximately 50% of the aqueous is drained, and the chamber is reformed with injection of the gas. Another technique for repairing Descemet’s detachments using intracameral gas injection at the slit lamp microscope has been reported. A 25-gauge needle on a 3-mL syringe filled with the gas and another 25-gauge needle are advanced through the corneoscleral limbus at opposite clock hours with the bevel up and the needles oriented parallel to the iris plane. The plunger on the syringe is depressed to inject the gas and fill the anterior chamber while aqueous humor is allowed to egress from the opposing 25-gauge needle. More complicated cases may require direct suturing.

Thermal Burns

Part of the energy produced by the phaco tip is dissipated as heat. This heat is conducted into the eye along the titanium tip and then cooled by the ongoing flow of the irrigation–aspiration fluid. If for any reason the flow is blocked, a corneal burn can occur within 1–3 seconds. The most common cause is inadequate flow through the phaco tip because it has been obstructed by a retentive OVD; this problem arises from use of low flow and vacuum settings. The critical warning sign is the appearance of milky fluid that is produced around the tip as emulsification commences.

To avoid corneal burns, phaco and irrigation–aspiration functions should always be tested before the eye is entered. Some of the viscoelastic material that overlies the nucleus can be aspirated before the start of emulsification to ensure that aspiration is adequate. To prevent constriction of the irrigating sleeve, an incision size that is appropriate for each particular phaco tip should be selected. If a burn does occur, meticulous suturing of the wound with multiple radial sutures ( Fig. 5.16.1 ) is required. A bandage contact lens may assist with wound closure. Severe postoperative astigmatism can result. The smaller incision size and new-generation phaco tips continue to contribute to a reduction in the incidence of corneal burns.

Corneal Burn Following Phacoemulsification (Phaco).

In this patient with an apparent filtering bleb, phaco was performed through a temporal, clear corneal incision (CCI). Posterior capsular rupture was suspected; the surgeon injected a highly retentive ophthalmic viscosurgical device beneath and in front of the nucleus to minimize the risk of posterior dislocation of the nucleus. Phaco was instituted with low flow and vacuum settings, and a severe corneal burn was immediately produced because of obstruction of the phaco tip by the viscoelastic material. The incision was closed with several interrupted sutures. Many of these pulled through the injured tissue, and as a result, additional suturing was required several days later. Postoperatively, the patient has 5 D of surgically induced astigmatism that has persisted for more than 5 years.

Anterior Capsulectomy

Nucleus Expression Cataract Extraction

Complications related to nucleus expression are covered in Chapters 5.11 and 5.12 .

Complications During Phaco

Subluxated Lens

The surgical approach for subluxated lenses ( Fig. 5.16.2 ) is determined by lens stability, lens position, and nuclear density. In a subluxated lens with adequate zonular support, phaco (or nuclear expression) can be performed. OVD is injected as needed throughout the surgery to tamponade the vitreous in areas of zonular dehiscence. Extensive hydrodissection and viscodissection should be carried out. Depending on the density of the nucleus, either phaco in the capsular bag or anterior chamber phaco under a retentive viscoelastic is performed. Any form of zonular stress should be minimized, particularly with nuclear rotation. Although not the topic of this chapter, femtosecond laser-assisted capsulectomies can help in these situations because they produce minimal stress to the zonules.

Subluxated Lens.

This patient had a subluxated lens caused by ocular trauma. The crystalline lens was removed using a pars plana approach, and a sulcus-sutured intraocular lens was implanted.

If phacodonesis is present but the lens has not fallen posteriorly, a soft nucleus sometimes can be removed by phaco-aspiration, whereas a hard nucleus should be extracted by using an intracapsular approach. Pars plana vitrectomy is an excellent option for these cases as well; it certainly is preferred when the lens is subluxated posteriorly.

The location of the IOL placement depends on the status of the capsular bag after cataract removal. If zonular disruption is minimal (fewer than 3 clock hours), the IOL can be implanted into the capsular bag with the haptic orientated in the meridian of the zonular defect. If the zonular disruption is larger, options include the following:

• •
  

  Ciliary sulcus implantation, possibly with scleral or iris fixation of one or both haptics.

  
  
• •
  

  Insertion of one haptic into the capsular bag and suturing of the second haptic into the sulcus.

  
  
• •
  

  Endocapsular ring implantation to stabilize the capsular bag or a Cionni ring to suture the capsular bag/ring complex to the sclera.

  
  
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  Anterior chamber lens implantation (angle-supported or iris fixated).

  
  
• •
  

  An angle-supported anterior chamber lens, which is acceptable if no anterior chamber angle pathology, glaucoma, or uveitis is present.

  
  
• •
  

  Posterior chamber lens implantation (as iris fixated retropupillary Artisan type).

Ruptured Posterior Capsule

Posterior capsule rupture is the most common serious intraoperative complication of cataract surgery. Proper management, however, can result in minimal morbidity to the patient. A posterior capsular rent is more likely to occur in eyes with small pupils, hard nuclei, or pseudo-exfoliation syndrome. Recent reports suggest that the visual prognosis of patients who have broken posterior capsules is excellent. The key factors are to minimize ocular trauma, meticulously clean prolapsed vitreous from the anterior segment, if present, and ensure secure fixation of the IOL.

Dropped Nucleus

Loss of nuclear material into the vitreous cavity ( Fig. 5.16.3 ) is one of the most potentially sight-threatening complications of cataract surgery. Clinical and cadaver eye studies implicate posterior extension of breaks in the capsulorrhexis as a common cause of this complication. Therefore, the surgeon would be wise to use increased caution when phaco is performed with capsulorrhexis tears. Posterior polar cataract, which predisposes to posterior capsular dehiscence, is another risk factor for dropped nucleus.

Dropped Nucleus.

B-scan ultrasonography 1 day after dislocation of a lens nucleus into the vitreous cavity in a patient with high myopia.

Loss of the nucleus into the vitreous cavity can be avoided by recognizing the early signs of posterior capsular rupture. These include unusual deepening of the anterior chamber, decentration of the nucleus, or loss of efficiency of aspiration, which suggests occlusion of the tip with vitreous. If capsular rupture is noted, the steps outlined earlier should be taken to prevent nucleus loss.

Some controversy exists with regard to the appropriate management of loss of the nucleus into the vitreous. Most surgeons recommend completing the procedure with careful anterior vitrectomy and removal of remaining accessible lens material. In general, IOL implantation is permissible; one exception might be loss of an extremely hard, dense nucleus that would require removal through a limbal incision. If a significant amount of nuclear material has been retained, vitreoretinal surgery needs to be performed 1–2 days postoperatively. Patients whose eyes have small residual nucleus fragments may be observed and referred if increased IOP or uveitis refractory to medical treatment develops. Some surgeons advocate irrigating the vitreous with fluid in an attempt to float the nucleus back into position. An obvious concern is that this additional turbulence could increase vitreous traction on the retina resulting in retinal tears and retinal detachment.

Anterior Segment Hemorrhage

The presence of intraocular blood prevents the surgeon’s visualization during the procedure, stimulates postoperative inflammation, and synechia formation, and accelerates capsular opacification. To minimize the risk of bleeding, discontinuation of anticoagulant therapy before surgery can be considered if it does not pose a significant medical risk to the patient. The sites of anterior segment hemorrhage are either the wound or the iris. Steps to minimize or eliminate bleeding from the wound include the following:

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  Careful cautery of bleeding vessels in the vicinity of the incision.

  
  
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  Creation of an adequate internal corneal valve to minimize the likelihood of scleral blood entering the anterior chamber.

  
  
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  Performing a clear corneal incision.

  
  
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  Avoid iris trauma, which can lead to iris bleeding.

Intraocular bleeding can be stopped by taking the following measures:

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  Temporarily elevating the IOP with a balanced salt solution or an OVD.

  
  
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  Injecting a dilute solution of preservative-free epinephrine 1 : 5000 (or a weaker solution).

  
  
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  Direct cautery (if the bleeding vessel can be identified) with a needle-tipped cautery probe.

The most serious complication of cataract surgery is expulsive hemorrhage, which is actually a spectrum of conditions ranging from suprachoroidal effusion to mild hemorrhage to severe hemorrhage with expulsion. A sign of any of these conditions is shallowing of the anterior chamber with posterior pressure that resists further deepening of the chamber, sometimes accompanied by a change in the red reflex. These conditions typically occur intraoperatively but also may occur postoperatively, usually when the IOP is below normal ( Fig. 5.16.4 ). Choroidal effusion also may be a precursor to suprachoroidal hemorrhage, which presumably occurs from the rupture of a blood vessel that is placed under stretch. Risk factors for suprachoroidal hemorrhage include hypertension, glaucoma, nanophthalmos, high myopia, and chronic intraocular inflammation.

Choroidal Effusion.

This patient experienced deep ocular pain 1 day postoperatively. A choroidal hemorrhage was noted on close examination. This resolved over several months, leaving no permanent sequelae.

If sudden shallowing of the anterior chamber occurs and the eye becomes firm, the retina should be examined, if possible, to ascertain the cause. If a dark choroidal elevation is noted, a choroidal hemorrhage is likely, and the incision should be closed as quickly as possible. The worst scenario is expulsion of intraocular contents through the wound. With tunnel incisions, the wound typically is self-sealing and resists expulsion of a significant amount of tissue. This self-sealing construction can save an eye from complete loss of intraocular contents. However, the surgeon can assist by using a finger tamponade on the wound while hyperosmotic solution is given intravenously. The wound should be closed and the anterior chamber deepened further, if possible, using a balanced salt solution or an OVD.

In the event of severe ongoing prolapse of tissue through the incision, a posterior sclerotomy should be performed; this must be done quickly. Time permitting, a conjunctival peritomy is made 3–4 mm posterior to the limbus. Using a microsurgical steel knife, a radial incision approximately 2 mm in length is made, scratching through the sclera to the level of the suprachoroidal space. Usually, blood begins to ooze from this site. As this occurs, infusion of fluid and OVD into the anterior chamber is commenced in an attempt to restore normal anterior segment anatomy. This bleeding site can be left open, or it can be sutured once the rate of hemorrhage has diminished, the incision has been closed, and the normal anterior chamber depth has been restored. The goal in these cases is to preserve the eye; cataract surgery can always be completed at a later date, typically 2 or more weeks later.

It is recommended that postoperative examinations should be performed 1 day, 7–10 days, and 4–6 weeks after cataract surgery.

Preventing Radial Tears in the Anterior Capsule

For phaco, the preferred method of anterior capsulectomy is capsulorrhexis. It is now recognized that radial tears in the anterior capsule can pose significant risks because of their tendency to tear into the equatorial region of the lens and extend into the posterior capsule. This causes posterior capsular rupture, loss of lens material, and IOL decentration. The surgeon’s goal, therefore, must be to retain an intact capsulorrhexis. A common cause of radial tears is irretrievable loss of the capsulorrhexis tear peripherally beneath the iris. To prevent this, the following steps should be considered:

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  The anterior chamber should be reinflated with an OVD.

  
  
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  The vector forces of the tear should be changed to redirect the tear in a more central direction.

  
  
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  If the tear is lost beneath the iris, the capsulorrhexis should be restarted from its origin, proceeding in the opposite direction (if possible, this new capsulorrhexis should end with the incorporation of the original tear in an outside-in direction; however, the original tear is often too peripheral to permit this, and a single radial tear is created).

An alternative approach to a “lost” capsulorrhexis is to convert to a “can opener” capsulectomy. It may, indeed, be safer to have multiple tears, rather than a single one, because forces that extend these tears can be distributed to multiple sites, which reduces the likelihood of a tear extending equatorially.

Excessively Small Capsulorrhexis

If the diameter of the capsulorrhexis opening is excessively small, the tear should be directed more peripherally and continued beyond the original point of origin before completion of the capsulorrhexis; this procedure removes an annulus of capsule and enlarges the opening. If the capsulorrhexis has been terminated and the opening is too small, a new tear can be started by making an oblique cut with Vannas scissors or a sharp needle. It usually is preferable to enlarge the capsulorrhexis after IOL implantation, to minimize the risk of radial tears during lens implantation.

Minimizing Complications When Radial Tears Are Present

If radial tears are present, several modifications in surgical technique should be considered to minimize the risk of tear extension into the posterior capsule:

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  Hydrodissection or hydrodelineation is performed gently to minimize distention of the capsular bag.

  
  
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  Cracks during emulsification are made gently away from the area(s) with radial tears. Alternatively, as much of the nucleus as possible is sculpted within the capsular bag, and the rest is removed at the iris plane. The height of the infusion bottle is kept low to prevent overinflation of the anterior chamber (which can cause the tear to extend peripherally).

  
  
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  The IOL should be placed with the haptics 90° away from the tear. One-piece polymethyl methacrylate (PMMA) lenses tend to maintain better centration in these situations. Rotation of the IOL should be minimized. The OVD should be removed in small aliquots while gentle infusion of BSS is performed through a side-port incision.

  
  
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  It is important to avoid anterior chamber collapse at any phase of the operation when radial tears are present. Anterior bulging of the posterior capsule can place increased stress on a radial tear, which predisposes its extension into the equator and posterior capsule. To avoid this, the chamber is deepened each time the phaco or irrigation–aspiration tip is removed from the eye; this is done by injecting fluid, OVD, or perhaps air through the paracentesis incision with a syringe while the instrument is removed from the incision.

Hydrodissection

Hydrodissection was developed to permit easy rotation of the nucleus in the capsular bag and to facilitate removal of various layers of the lens by eliminating their adhesion to surrounding tissues. Two major complications of hydrodissection are inadequate hydrodissection and overinflation of the capsular bag. The former results in a nucleus that does not rotate, and this predisposes to zonular dehiscence if excessive force is exerted on the nucleus. This can be avoided by making an additional hydrodissection, particularly in quadrants that have not been hydrodissected before. U-shaped cannulas are useful to hydrodissect subincisional regions of the lens not accessible with straight or angulated cannulas.

Overinflation of the capsular bag can predispose to prolapse of the nucleus into the anterior chamber, which might compromise the ease or safety of nucleus emulsification. A serious complication of overinflation is posterior capsular rupture, with loss of the nucleus into the vitreous. This is more likely to occur in eyes with long axial lengths, (hyper)mature cataracts, or with fragile posterior capsules, such as those found in patients who have posterior polar cataracts.

Iris Prolapse or Damage

Iris prolapse is usually caused when the anterior chamber is entered too posteriorly, such as near the iris root. If this is noted early in the case and interferes with the easy introduction of instruments into the eye, it is advisable to suture the incision and move to another location.

A second and more ominous cause of iris prolapse is an acute increase of intraocular pressure (IOP) accompanied by choroidal effusion or hemorrhage. In this instance, the surgeon should attempt to identify the cause and lower the IOP. Digital massage on the eye, pressing directly on the incision, may successfully lower the pressure. It is useful to examine the fundus to ascertain whether a choroidal effusion or hemorrhage exists. With choroidal effusion, aspiration of vitreous can be helpful, as can the administration of intravenous mannitol. If a choroidal hemorrhage occurs or if the increased IOP from an effusion is resistant to treatment, it usually is best to terminate the surgery. The wound is sutured carefully; intraocular miotics are administered, and a peripheral iridectomy may be performed to help reposition the iris. For effusions, surgery can be deferred until later in the day or the next day, when the fluid dynamics of the eye have returned to a more normal state. If a limited choroidal hemorrhage has occurred, it is best to wait 2–3 weeks before attempting further surgery.

Trauma to the iris from prolapse or emulsification with a phaco tip can produce an irregularly shaped pupil and iris atrophy and can predispose to posterior synechiae formation. If iris damage is produced inferiorly through contact with the phaco tip, loose strands of tissue should be cut to reduce the likelihood of these being aspirated into the phaco tip. Another option is to use a single iris hook to retract the inferior iris, holding it away from the phaco tip for the duration of the procedure.

Floppy Iris Syndrome

This complication has been observed during phaco in patients receiving α ₁ -antagonist agents, such as tamsulosin (Flomax). The symptoms include billowing and floppiness of the iris, prolapse of the iris to the main and side incisions, and progressive constriction to the pupil during surgery.

When treating patients who receive α ₁ -antagonist agents, the surgeon can try to avoid severe intra- and postoperative complications by preoperative use of atropine, intraoperative epinephrine (adrenaline), lower phaco vacuum and aspiration settings, the use of supercohesive OVDs, and various iris hooks and pupil dilators.

Trapped Nucleus

In this situation, the nucleus seems to be trapped within the capsular bag; it resists rotation, elevation, or both. This usually indicates a nucleus that requires further hydrodissection, which should be repeated in regions not previously hydrodissected (e.g., laterally and inferiorly with angled or straight cannulas, superiorly with U-shaped cannulas; if these cannulas are not available, additional paracentesis sites can be created in strategic locations). If this fails to achieve adequate mobilization of the nucleus, viscodissection can be performed. An OVD is injected in the plane of the hydrodissection, which usually results in elevation of the nuclear remnant. When re-entering the eye with the phaco tip, irrigation should not be used until a second instrument has been inserted through the stab incision and placed below the nucleus; when irrigation and aspiration begin and the OVD is removed, the second instrument prevents the nuclear piece from falling back into the posterior chamber.

If the capsulorrhexis is small and the nuclear circumference is intact, nuclear elevation through the capsulorrhexis may not be possible. Additional sculpting might be required to thin the nucleus centrally or to remove some of the peripheral nucleus. After the nucleus has been sufficiently thinned, an instrument, such as a Sinskey hook or spatula, can be teased posteriorly through the remaining nuclear tissue. This enables elevation of a portion of the nucleus and thereby facilitates access to the remainder.

Subluxated Lens

The surgical approach for subluxated lenses ( Fig. 5.16.2 ) is determined by lens stability, lens position, and nuclear density. In a subluxated lens with adequate zonular support, phaco (or nuclear expression) can be performed. OVD is injected as needed throughout the surgery to tamponade the vitreous in areas of zonular dehiscence. Extensive hydrodissection and viscodissection should be carried out. Depending on the density of the nucleus, either phaco in the capsular bag or anterior chamber phaco under a retentive viscoelastic is performed. Any form of zonular stress should be minimized, particularly with nuclear rotation. Although not the topic of this chapter, femtosecond laser-assisted capsulectomies can help in these situations because they produce minimal stress to the zonules.

Subluxated Lens.

This patient had a subluxated lens caused by ocular trauma. The crystalline lens was removed using a pars plana approach, and a sulcus-sutured intraocular lens was implanted.

If phacodonesis is present but the lens has not fallen posteriorly, a soft nucleus sometimes can be removed by phaco-aspiration, whereas a hard nucleus should be extracted by using an intracapsular approach. Pars plana vitrectomy is an excellent option for these cases as well; it certainly is preferred when the lens is subluxated posteriorly.

The location of the IOL placement depends on the status of the capsular bag after cataract removal. If zonular disruption is minimal (fewer than 3 clock hours), the IOL can be implanted into the capsular bag with the haptic orientated in the meridian of the zonular defect. If the zonular disruption is larger, options include the following:

• •
  

  Ciliary sulcus implantation, possibly with scleral or iris fixation of one or both haptics.

  
  
• •
  

  Insertion of one haptic into the capsular bag and suturing of the second haptic into the sulcus.

  
  
• •
  

  Endocapsular ring implantation to stabilize the capsular bag or a Cionni ring to suture the capsular bag/ring complex to the sclera.

  
  
• •
  

  Anterior chamber lens implantation (angle-supported or iris fixated).

  
  
• •
  

  An angle-supported anterior chamber lens, which is acceptable if no anterior chamber angle pathology, glaucoma, or uveitis is present.

  
  
• •
  

  Posterior chamber lens implantation (as iris fixated retropupillary Artisan type).