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http://www.eyeweb.org/cataract_surgery.htm

CATARACT SURGERY

Shady Awwad, MD

HISTORY OF CATARACT SURGERY

There are allusions in the literature that cataract surgery used to be performed as early as 300BC with no description of methods and techniques. Physicians at that time thought of cataract as

a coagulation of the eye humors (“suffusion”) behind the iris, due to the white pupillary reflex

produced by mature cataract (Celsus, AD 30). Constantinus Africanus (AD 1018), a monk and an

Arabic oculist introduced the term "cataract" by translating the Arabic equivalent of “suffusion”into Latin “cataracta,” which meant “something poured underneath something,” or the

“waterfall.”

COUCHING

Couching is the first documented cataract surgery. Early descriptions in history came from

India in 600 BC. Physicians used to insert a sharp instrument (a needle or lancet) around 4 mm

posterior to the limbus or into clear cornea, pointing towards the whitish opacity. Then, in a

downward movement, the lens was dislodged away from the pupil. Manipulation would stopwhen the patient start seeing shapes. Obviously, the patient would be left aphakic and would

need to be corrected by a positive lens (e.g + 11D) which was not available early in history.

Physicians at that time didn't know that the white reflex was actually the human lens nor did they

know that by couching, they had established the modern concept of pars plana vitrectomy. Somevariations of the couching technique included inserting a hollow needle and "aspirating" the

cataract (described by Iraqi and Syrian oculists around 1000 AD. But this method shortly fell outof favor. Couching operation remained popular up through the 19th century and even up to our days in some parts of Africa and the world.

INTRA CAPSULAR CATARACT EXTRACTION

Consists of removing the lens with the capsule intact. This requires the breakage of the

zonules. Different methods to break the zonules were described, but only the cryoprobesurvived. The cryoprobe is a probe which is frozen onto the surface of the crystalline lens. With

gentle teasing, the lens could be delivered without any pushing on the eye.

EXTRACAPSULAR EXTRACTION

In 1753, a French oculist by the name of Daviel (1696 – 1762) described a new method of

cataract surgery which essentially was the first report of a planned extracapsular extraction.Oculists however continued to couch and the extracapsular technique never gained merit until

later on in the 19th century. Recognizing that Daviel's method could produce vitreous loss,

modern surgeon opted to Sharp's technique, which described the removal of the lens in toto(Intracapsular extraction).

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In the early 1970s, and with the introduction of the intra-ocular lenses (IOLs) and the

published results on the complications of absent capsules, surgeons reverted to ECCE. Clearly an

intact capsular bag with its zonules was needed to hold the IOL (as a scaffold). An intact posterior capsule was invaluable in decreasing the risk of retinal detachment and cystoid macular

edema (CME), two of the most dreadful complications in cataract surgery, especially ICCE.

PHACOEMULSIFICATION

ECCE, while offering the remarkable advantage of a preserved capsule, had still manydrawback: a big incision entailed lots of sutures, which produced astigmatism postop. Optimal

visual recovery could only take place after the sutures were removed, i.e. 6-8 weeks postop.

Smaller incision would require fragmentation of the crystalline lens and removal of the

fragments through a small wound. A new technique evolved hence in the early 1970s. It emergedwith the development of a new hydrodynamic system which produced high frequency

mechanical waves out of an electric current, while incorporating irrigation and aspiration all in

one setting.

SURGICAL TECHNIQUE

Extracapsular Cataract Extraction

An 11 mm partial thickness incision is made along the limbus superiorly, in peripheral clear cornea (Fig. 1-A). The anterior chamber (AC) is penetrated at around 12 o'clock, and a bent

needle (cystotome) is inserted into the AC and made to produce multiple radial nicks in the

anterior capsule in a circular fashion keeping with a diameter of around 6-7 mm (Capsulotomy),(Fig. 1-B,C). An alternative method mainly used in phacoemulsification, Capsulorhexis, involvesmaking a controlled circular tear, (Fig. 2-A,B). The nucleus is rocked up and down, right and left

, to free the it from the surrounding capsule. The sclero-limbal incision is then completed full-

thickness with scissors. The nucleus is then expressed out of the capsule by alternating pressureapplied superiorly and inferiorly using special instruments (Fig.1-D). An infusion-aspiration

cannula is then introduced, passed underneath the iris and below the level of the anterior

capsule, and used to engage remaining cortical strands through suction effect (Fig. 1-E). Caution

should be made not to engage the posterior capsule. Visco-elastic material (Healon®, ahyauronic based material to keep the anterior chamber well formed and preventing it from

collapse) is then injected into the capsular bag to increase its volume, and hence, facilitate the

insertion of the intra-ocular lens (IOL). The latter is grasped by the optic, and inserted into the bag with the inferior haptic inserterd underneath the anterior capsule. The IOL is then grabbed bythe superior haptic, which is inserted in a circular motion (as if dialing using an old-style phone)

and made to rest beneath the anterior capsule. The superior haptics springs out upon release due

to its flexibility and rests in the fornix formed by the anterior and posterior capsule (Fig.1-F). Thevisco-elastic is aspirated from the anterior chamber. The pupil is constricted using Miochol

(acetylcholine) into the anterior chamber and the incision is closed using interrupted 10-0 Nylon

sutures.

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Phacoemulsification

A partial-thickness stab incision measuring 3 mm is made 2mm away from the limbus at 12o'clock. The same incision can be made in clear cornea. A tunnel is fashioned in the sclera up to

clear cornea. The AC is penetrated while pointing the blade towards the lens. This would create a

tri-planar incision which ideally can self-seal. A Capsulorrhexis is performed using thecystotome (Fig. 2-A, B). The nucleus is loosened from its cortical and capsular attachments by

introducing a cannula mounted syringe underneath the anterior capsule, but above the level of the

nucleus, and injecting fluids (Balanced Salt Solution, BSS). This Step is called Hydrodissection.Emulsification of the nucleus follows. Many techniques with different variants of the same

technique have been developed. The classical technique involves carving a cross in the nucleus,

then dividing into four pieces (like a pie). The pieces become then freely movable and they are

then aspirated away from the capsule and emulsified (Fig. 2-C, D). This Technique is known as Divide and Conquer technique. When the nucleus is very soft, dividing it might turn out to be

difficult. Carving a bowl then aspirating the thin remaining crust and emulsifying it away from

the posterior capsule is an option (Bowl Carving technique)Other techniques such as Chopping

and Flipping have been developed later on. The scleral or corneal incision is slightly enlargedand a foldable IOL is inserted. A figure of 8 suture is electively put over the incision.

The only justification of a planned whole lens expression (ECCE) is a very hard lens. A hardlens like the mature cataract and catracta rubra would require longer time of emulsification,which can predispose to corneal edema.

COMPLICATIONS OF CATARACT SURGERY

INTRA-OPERATIVE

Posterior Capsular Rupture

This can often occur during phacoemulsification or during the irrigation aspiration process. If no vitreous leaks and the tear is small, a PC-IOL is inserted. If the tear is big enough to

jeopardize the stability of the IOL in the posterior chamber, the iris is constricted using

Miochol® and an AC-IOL is inserted in the anterior chamber. If the tear leaks vitreous, then ananterior vitrectomy is performed following which a decision is to be made whether to put an AC-

IOL or delay the IOL implantation. Anterior vitrectomy can be automated (using a probe called

ocutome) or mechanical, which entails applying sponges on the wound then pulling them out and

cutting any sticking vitreous strands.

Expulsive hemorrhage

This is a dreadful complication that mainly happens following acute drop in intra-ocular

pressure. The patient is usually hypertensive, diabetic, myopic, or having glaucoma. The short

and long posterior ciliary arteries would suddenly bleed and the blood would accumulate in thesupra-choroidal space. The intra-ocular pressure would then rises significantly and push the

ocular content out of the eye. The surgeon should rapidly close the wound and give intra-venous

osmotic agents to lower the intra-ocular pressure. Steroids should be given post-op to decreasethe inflammation. Drainage of the blood should take place after two weeks when clots start

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liquefying. The visual prognosis is usually dismal.

EARLY POST-OPERATIVE

Acute Bacterial Endophthalmitis

It is an intra-ocular bacterial infection which occurs in 1/1000 cases, with crippling visual

complications in more than 50% of the cases, depending on the etiologic organism. The patients

own bacterial flora are usually the culprits. These include Staph. epidermidis, Staph. aureus,

Pseudomonas, and Proteus. Treatment include topical, intra-vitreal, peri-ocular, and systemicantibiotics together with steroid therapy when indicated.

Iris prolapse

Iris tissue may prolapse through the surgical wound. This is usually due to poor surgical

closure. If not corrected, this can sometimes lead to endophthalmitis, astigmatism.

Wound leak

This is a relatively rare complication due to poor wound construction as well as poor surgical

technique in closure (loose sutures.) Low IOP and shallow anterior chamber are noted. Woundleak is usually diagnosed by Seidel Test, which shows clearing of the fuorescein over the

involved area due to the leak of fluid.

High intra-ocular pressure

This complication usually occur when the visco-elastic is left in the eye, or is not adequately

aspirated prior to wound closure. The visco-elastic particles would block the trabecular meshwork and raise the IOP.

Corneal edema (Striate Keratopathy)

Endothelial loss and ischemia due to manipulation during surgery as well due to ultrasonic

shockwaves during phacemulsification lead to corneal decompensation and corneal edema.

Endothelial folds (striae) and increased thickness of the cornea with cloudiness follow.

LATE POST-OPERATIVE

Posterior Capsule Opacification (PCO)

A frequent late complication of cataract surgery. It extremely common in children. PCOcomprises any or a combination of the following:Elshnig's perlsoccurs by proliferation of the anterior lens epithelium over the posterior capsule.

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Primary Opacification occurs following opacification of already existent posterior capsular

plaques.

Retinal Detachment

Occurs mainly in eyes with posterior capsular rupture, vitreous loss, and eyes with peripheralretinal degenerations like lattice degeneration.

Cystoid Macular Edema (CME)

Also known as the Irvine-Guass syndrome. Fluids accumulate in the macula in a

petaloid fashion, dropping the visual acuity. It is thought to occur due to the release of

prostaglandins from the iris and the ocular structures during and after surgery. Vascular

dilatation and permeability follow, resulting in CME. It is also though that vitrous traction,

especially after vitreous leak can predispose to CME as well. ACIOL are also associated

with a higher risk of CME.

Suture-related problems

Astigmatism:

Tight sutures can lead to steepening of the cornea along the same axis. This can

lead to astigmatism along the same axis (i.e. a tight suture at 12 o'clock would produce for example the following refractive error: 0+2x90).

Reaction to the sutures

This can include immunological (superior limbic conjunctivitis) and mechanicalreaction (giant papillary conjunctivitis).

Malposition of the IOL

A tilted IOL can produce astigmatism, monocular diplopia, optical aberrations such as halos

and glare. Miotics sometimes relieve these symptoms. In severe cases, replacement of the IOL

might be necessary.

Corneal Decompensation

Usually occurs when an AC-IOL is implanted. It is very rare to occur after PC-IOLinsertion.

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Chapter 53 – Complications of Cataract Surgery

Section 5 – Complications and outcomes

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Chapter 53 – Complications of Cataract Surgery

THOMAS KOHNEN

LI WANG

NEIL J. FRIEDMAN

DOUGLAS D. KOCH

INTRODUCTION

Phacoemulsification; sutureless, self-sealing tunnel incisions; and foldable intraocular lenses

(IOLs) have changed cataract surgery dramatically over the past two decades. Postoperative

astigmatism and inflammation are typically minimal; visual recovery and patients’ rehabilitationare accelerated. The published literature indicates that modern cataract surgery, though certainly

not free of complications, is a remarkably safe procedure, regardless of which extraction

technique is used. [1]

To put this into perspective, an overview of the visual outcomes and incidence of complications

following cataract surgery is helpful. Using rigid criteria for scientific validity, Powe et al.[1]analyzed 90 studies published between 1979 and 1991 that addressed visual acuity (n = 17,390eyes) or complications (n = 68,316 eyes) following standard nuclear expression cataract

extraction with posterior chamber IOL implantation, phacoemulsification with posterior chamber

IOL implantation, or intracapsular cataract extraction with anterior chamber IOL implantation.Strikingly, the percentage of eyes with postoperative visual acuity of 20/40 or better was 89.7%

for all eyes and 95.5% for eyes with no preexisting ocular comorbidity. The incidence of sight-

threatening complications was less than 2%.

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In this chapter, the key elements in the prevention, recognition, and management of the major

intraoperative and postoperative complications of cataract surgery are discussed.

INTRAOPERATIVE COMPLICATIONS

Cataract Incision

The cataract incision serves as more than just the port of access to the anterior segment; it is acritical 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 andan 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.[2]

Tunnel Perforation

Tearing of the roof of the tunnel predisposes to excessive intraoperative leakage that

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, proceedingslowly 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 isadvisable to restore normal wound architecture.

If the floor of the tunnel is perforated, which can happen during scleral tunnel dissection, surgeryusually 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.

Descemet’s Detachment

Detachment of Descemet’s membrane can be a major postoperative complication; it results in persistent corneal edema and decreased visual acuity. To prevent Descemet’s detachment, the

surgeon should carefully observe the inner lip (cut edge of Descemet’s membrane) at each phase

of the procedure. To avoid blunt stripping of Descemet’s membrane during enlargement of thewound, a sharp metal or diamond blade is recommended.

If detachment is caused by viscoelastic injection, the agent must be removed, such as by using a blunt cannula. Intraoperatively, repositioning of Descemet’s membrane usually can be achieved

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by injecting balanced salt solution or occasionally air or an ophthalmic viscosurgical device

(OVD) through the paracentesis site.

If a visually significant Descemet’s detachment is present postoperatively, the authors prefer to

intervene after 2 – 3 weeks; however, late spontaneous reattachment 2 – 3 months (in one case, 10

months) postoperatively has been reported.[3] [4] To reattach Descemet’s membrane, the patientis 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?cm3 of air or, for eyes thathave an unsuccessful injection of air alone, an expansive gas (e.g., sulfur hexaflueride SF6).

Using the cannula, approximately 50% of the aqueous is drained, and the chamber is reformed

with injection of the gas. Recently, a new technique for repairing Descemet’s detachments using

intracameral gas injection at the slit-lamp microscope was reported.[5] A 25-gauge needle on a3?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. Morecomplicated cases may require direct suturing.[6]

Thermal Burns

Part of the energy produced by the phacoemulsification tip is dissipated as heat. This heat isconducted into the eye along the titanium tip and then cooled by the ongoing flow of the

irrigation-aspiration

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Figure 53-1 Corneal burn following phacoemulsification. In this patient who had an apparent

filtering bleb, phacoemulsification was performed through a temporal, clear corneal incision.

Posterior capsular rupture was suspected; the surgeon injected a highly retentive ophthalmicviscosurgical device beneath and in front of the nucleus to minimize the risk of posterior

dislocation of the nucleus. Phacoemulsification was instituted with low flow and vacuum

settings, and a severe corneal burn was immediately produced because of obstruction of the phacoemulsification tip by the viscoelastic material. The incision was closed with severalinterrupted sutures. Many of these pulled through the injured tissue, and as a result, additional

suturing was required several days later. Postoperatively, the patient has 5D of surgically

induced astigmatism that has persisted for more than 5 years.

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 phacoemulsification tip because it has been

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obstructed by a retentive OVD; this problem arises from using low flow and vacuum settings.

The critical warning sign is the appearance of milky fluid that is produced around the tip as

emulsification is begun.

To avoid corneal burns, phacoemulsification and irrigation-aspiration functions should always be

tested before the eye is entered. Some of the viscoelastic material that overlies the nucleus can beaspirated 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

phacoemulsification tip should be selected. If a burn does occur, meticulous suturing of thewound with multiple radial sutures ( Fig. 53-1 ) is required. A bandage contact lens may assist

with wound closure. Severe postoperative astigmatism can result.

Anterior Capsulectomy

PREVENTING RADIAL TEARS IN THE ANTERIOR CAPSULE.

For phacoemulsification, the preferred method of anterior capsulectomy is capsulorrhexis. It isnow 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[7] 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 isirretrievable loss of the capsulorrhexis tear peripherally beneath the iris. To prevent this, thefollowing steps should be considered:

• The anterior chamber should be reinflated with an OVD.

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

• 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 finish byincorporating 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 extendingequatorially.

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 thecapsulorrhexis; 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. It usually is preferable to enlarge the capsulorrhexisafter IOL implantation, to minimize the risk of radial tears during lens implantation.

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MINIMIZING COMPLICATIONS WHEN RADIAL TEARS ARE PRESENT.

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

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

• 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 overinflationof the anterior chamber (which can cause the tear to extend peripherally).

• The IOL should be placed with the haptics 90° away from the tear. One-piece polymethyl

methacrylate lenses tend to maintain better centration in these situations. Rotation of the IOLshould be minimized. The OVD should be removed in small aliquots, while gentle infusion of

balanced salt solution is performed through a side-port incision.

• 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, thechamber is deepened each time the phacoemulsification 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.

Nuclear Expression Cataract Extraction

Complications related to nuclear expression are covered in Chapters 47 and 48 .

Complications During Phacoemulsification

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 surroundingtissues. Two major complications of hydrodissection are inadequate hydrodissection and

overinflation of the capsular bag. The former results in a nucleus that does not rotate, which

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 beenhydrodissected 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 nuclear prolapse 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

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likely to occur in eyes with long axial lengths or with fragile posterior capsules, such as are

found in patients who have congenital posterior polar cataracts.[8]

IRIS PROLAPSE OR DAMAGE.

Iris prolapse usually is 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

383

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 shouldattempt to identify the cause and lower the IOP. Sometimes digital massage on the eye, pressing

directly on the incision, can successfully lower the pressure. It is useful to examine the fundus to

ascertain whether a choroidal effusion or hemorrhage exists. With choroidal effusion, aspirationof 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 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 phacoemulsification 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 phacoemulsification tip, loose strands

of tissue should be cut to reduce the likelihood of these being aspirated into the

phacoemulsification tip. Another option is to use a single iris hook to retract the inferior iris,holding it away from the phacoemulsification tip for the duration of the procedure.

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, whichshould 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).[9] If this isunsuccessful in achieving 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 reentering the eye with the phacoemulsification tip,

irrigation should not be used until a second instrument has been inserted through the stab

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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 thenucleus 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 andthereby facilitates access to the remainder.

SUBLUXATED LENS.

The surgical approach for subluxated lenses ( Fig. 53-2 ) is determined by lens stability, lens

position, and nuclear density. [10] In a subluxated lens with adequate zonular support, phacoemulsification (or nuclear expression) can be performed. Viscoelastic material 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 nuclear

density, either phacoemulsification in the capsular bag or anterior chamber phacoemulsificationunder a retentive viscoelastic is performed. Any form of zonular stress should be minimized,

particularly with nuclear rotation.

If phacodonesis is present but the lens has not fallen posteriorly, a soft nucleus sometimes can be

removed by phacoemulsification-aspiration, whereas a hard nucleus should be extracted

Figure 53-2 Subluxated lens. This patient had a subluxated lens caused by ocular trauma. Thecrystalline lens was removed using a pars plana approach, and a sulcus-sutured intraocular lens

was implanted.

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 thezonular disruption is larger, options include:

• 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.

• Anterior chamber lens implantation.

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An anterior chamber lens is acceptable if no anterior chamber angle pathology, glaucoma, or

uveitis is present.

Recently, the use of an endocapsular polymethyl methacrylate ring has been introduced for

zonular dialysis. This device allows expansion and stabilization of the capsular bag during

phacoemulsification and following posterior chamber IOL implantation.[11] [12]

Ruptured Posterior Capsule

Posterior capsule rupture is the most common serious intraoperative complication of cataract

surgery[13] ; however, proper management 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

pseudoexfoliation 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 securefixation of the IOL.

BEFORE NUCLEUS REMOVAL.

A capsular break noted before nucleus extraction is a potential disaster. The first objective is to

prevent the nucleus from being dislodged into the vitreous cavity. An OVD can be injected posterior and anterior to the nucleus to prevent its posterior displacement and to cushion the

corneal endothelium. Another alternative is to insert an instrument through a pars plana incision

3?mm posterior to the limbus into the vitreous, which Kelman has described as “posterior assisted levitation” (Charles Kelman, personal communication). The nucleus is pushed gently

anteriorly, so that it can be captured in front of the iris and safely removed from the eye. Once

the nucleus or its remnants have been repositioned in the anterior chamber, the choice is to

convert or to continue the emulsification. The latter course can be more hazardous and predisposes to enlarging the rent and possibly losing the nucleus into the vitreous.

384

In most circumstances, the nucleus should be managed by sufficiently enlarging the wound to

facilitate easy extraction of the nucleus on a lens loop. However, in the case of a small break or when only a small amount of nucleus is left, it may be possible to cover the posterior capsular

opening with a retentive OVD and complete the phacoemulsification. One can also use a Sheets

glide as a “pseudo–posterior capsule” to facilitate completion of phacoemulsification.

Vitreous loss almost always accompanies posterior capsular rupture that occurs before nucleus

removal; whenever feasible, vitrectomy should be performed before the nuclear pieces areremoved. Clearly, one should not do this if it makes loss of the nucleus into the vitreous more

likely.

DURING CORTICAL IRRIGATION-ASPIRATION.

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When capsular rupture occurs during aspiration of the cortex (which is, in fact, the most common

cause),[7] [14] a key factor is the status of the vitreous. If no vitreous is present in the anterior

segment, vitreous loss often can be averted. An OVD can be injected through the capsular opening to push the vitreous posteriorly. Cortical removal can be completed using low-flow

irrigation. Options include using a manual system; a dry approach, aspirating with a cannula in

the chamber filled with OVD; a bimanual approach through two paracentesis openings; andautomated irrigation-aspiration with all settings reduced.[15] Cortex should be stripped first inthe region farthest from the rent, and the direction of stripping should be toward the rent.

Because it can be hazardous to remove cortex in the region of the rent, the cortex is sometimes

better left in the eye, to avoid the possibility of enlarging the rent and precipitating vitreous loss.One option to prevent extension of the rent is to convert the tear into a small posterior

capsulorrhexis, which eliminates any radially orientated tears that could extend with further

surgical manipulation.

If vitreous is present in the anterior segment, vitrectomy should be performed first, with the

necessary caution being taken to prevent extension of the rent. Depending on the type of capsular

tear, the vitrectomy is performed through either the limbal incision or the pars plana. The former approach is used when the tear is located near the incision, which permits vitrectomy with

minimal risk of enlargement of the tear. A pars plana approach is preferred when the tear isremote from the incision and therefore less accessible anteriorly. In either case, irrigation is provided with an infusion cannula in the paracentesis opening. After a thorough anterior

vitrectomy, the remaining cortical material can be removed using one of the techniques described

earlier or using the vitrector in the aspiration mode without cutting.

INTRAOCULAR LENS INSERTION.

Careful inspection of the anatomy of the capsule and zonules is required to determine the

appropriate site for IOL implantation. There are four choices: capsular bag, ciliary sulcus,sutured posterior chamber, and anterior chamber.

Capsular Bag.

If the rent is small and relatively central, and if the anterior capsular margins are well defined,

the posterior chamber IOL can be implanted into the capsular bag. If possible, conversion of posterior capsule tears to posterior continuous curvilinear capsulorrhexis (CCC) is

recommended.[16] With the use of an OVD, posterior CCC is initiated by grasping the

advancing tear in the posterior capsule with forceps, and then applying CCC principles. This

technique is applied to avoid an anticipated extension of the inadvertent linear or triangular tear during maneuvers such as a required vitrectomy or lens placement. The surgeon should ensure

that the haptics are orientated away from the rent (to avoid haptic placement or subsequent

migration into the vitreous) and that the lens is inserted gently to avoid enlargement of the rent.

Ciliary Sulcus.

If the rent exceeds 4 – 5?mm in length or there is extensive zonular loss, the capsular bag

probably is not adequate for IOL support. In such cases, the ciliary sulcus is opened with an

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OVD, and the iris is retracted in all quadrants to assess the status of the peripheral capsule and

zonules. The IOL is inserted with its haptics oriented away from the area of the rent and

positioned in areas of intact zonules and capsule.

Another alternative, if the anterior capsulorrhexis is intact, is sulcus placement of the IOL, with

capture of the optic through the capsulorrhexis. Finally, some surgeons advocate iris suturefixation of one or both haptics to prevent IOL decentration. After the IOL optic is captured

through the pupil, McCannel sutures are used to secure the haptic(s) to the iris, and then the optic

is repositioned through the pupil.

Sutured Posterior Chamber.

If loss of more than 4 – 5 clock hours of capsule or zonules occurs, the ciliary sulcus may be

inadequate for lens stability. The lens can be fixated to the sclera using single or dual 10 – 0

polypropylene sutures. If one region of solid peripheral capsule and zonules exists, one hapticcan be inserted into the sulcus in this area, and the opposite haptic can be sutured to the sclera.

Anterior Chamber.

A Kelman-type multiflex anterior chamber IOL design is a good option for patients who do not

have glaucoma, peripheral anterior synechiae, or chronic uveitis. A peripheral iridectomy should be performed in these patients to prevent pupillary block.

Dropped Nucleus

Loss of nuclear material into the vitreous cavity ( Fig. 53-3 ) is one of the most potentially sight-

threatening complications of cataract surgery.[17] Clinical and cadaver eye studies implicate

posterior extension of breaks in the capsulorrhexis as a common cause of this complication.[7][18] It therefore behooves the surgeon to use increased caution when phacoemulsification is

performed with capsulorrhexis tears,[19] as noted earlier. Congenital posterior polar cataract,which predisposes to posterior capsular dehiscence, is another risk factor for dropped

nucleus.[20]

Loss of the nucleus into the vitreous cavity can sometimes 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 thetip 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 rare exception might be loss of an extremely hard, dense nucleus that would

require removal through a limbal incision. If a significant amount

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Figure 53-3 Dropped nucleus. B-scan ultrasonography 1 day after dislocation of a lens nucleusinto the vitreous cavity in a patient who has high myopia.

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of nuclear material has been retained, the patient is referred to a vitreoretinal surgeon 1 – 2 days

postoperatively. Patients whose eyes have small residual nuclear fragments may be observed andreferred 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 and cause retinal tears.

Anterior Segment Hemorrhage

The presence of intraocular blood decreases the surgeon’s view during the procedure, stimulates

postoperative inflammation and synechia formation, and accelerates capsular opacification. Tominimize 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.[21] The sites of anterior

segment hemorrhage are either the wound or the iris. Steps to minimize or eliminate bleedingfrom the wound include:

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

• Creation of an adequate internal corneal valve to minimize the likelihood of scleral bloodentering the anterior chamber.

• Performing a clear corneal incision.

Iris bleeding is caused by iris trauma. Intraocular bleeding can be stopped by:

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

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

solution).

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

The most dire complication of cataract surgery is expulsive hemorrhage, which is actually a

spectrum of conditions that ranges from suprachoroidal effusion to mild hemorrhage to severehemorrhage 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

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also may occur postoperatively, usually when the IOP is below normal ( Fig. 53-4 ). 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 suprachoroidalhemorrhage include hypertension, glaucoma, nanophthalmos, high myopia, and chronic

intraocular inflammation.[22]

If sudden shallowing of the anterior chamber occurs and the eye becomes firm, the retina is

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

Figure 53-4 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.

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. A microsurgical steel knife is used to make a radialincision approximately 2?mm in length, avoiding the horizontal plane, scratching through the

sclera to the level of the suprachoroidal space. Usually, blood begins to ooze from this site. Asthis 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; cataractsurgery can always be completed at a later date, typically 2 or more weeks later.

POSTOPERATIVE COMPLICATIONS

Wound Dehiscence

With small-diameter tunnel incisions, wound dehiscence is relatively uncommon. The creation of

an internal corneal valve typically prevents the major complications of wound leakage,inadvertent filtering bleb, and epithelial downgrowth. The wound healing process varies

according to the site of the posterior entry. Scleral limbal incisions heal by the ingrowth of

episcleral vascular tissue. New fibrovascular tissue is deposited with an orientation parallel to the

edges of the incision and perpendicular to existing collagen bundles. Over the ensuing few years,

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collagen remodeling occurs so that the new collagen becomes oriented parallel to existing

collagen bundles, which increases the strength of the healed area.[23] Ultimately, the strength of

the healed area is approximately 70 – 80% that of the native tissue. For corneal incisions, closureof the external wound takes place by apposition or, in areas of wound gape, by epithelial

ingrowth. A gradual process of remodeling then occurs; this consists of fibrocytic metaplasia of

keratocytes with deposition of new collagen, again parallel to the incision, followed over a period of years by remodeling similar to that seen with scleral incisions. In the absence of vascular tissue, this process occurs much more slowly than in scleral or limbal tissue.

Postoperative abnormalities in wound structure are produced by defects in the tunnel architecture

or by defective wound healing because of systemic disorders, preexisting tissue abnormalities(e.g., excessively thin or weak tissue), or incarceration of material, such as lens, vitreous, or iris,

in the wound, which inhibits the normal healing process.

Wound Leakage

A wound leak that occurs in the immediate postoperative period is usually the result of

inadequate suture closure for a specific wound configuration. This entity is rare with tunnelconstructions. Scleral pocket incisions have a longer tunnel and can readily be demonstrated to

be watertight at the conclusion of surgery. Corneal incisions as small as 3.5?mm in width sealremarkably well, even though intraoperative pinpoint posterior lip pressure in these eyes often

can induce a wound leak. Some surgeons perform hydration of the corneal stroma to prevent a

wound leak that can be elicited with posterior lip pressure; however, this hydration clears within

a few minutes to hours, and it is uncertain whether it has any actual clinical value.

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Figure 53-5 Wound dehiscence. This patient had 5D of against-the-wound astigmatism followingnuclear expression. The surgeon resutured the wound 4 weeks postoperatively, but the

astigmatism immediately recurred. Note the thin, fragile sclera, sometimes characterized as

scleral “melting.”

Wound leaks in scleral incisions typically are covered by conjunctiva and usually resolve within

a few days; occasionally, they lead to the formation of a filtering bleb. Medical management of scleral or corneal wound leaks may include the following:

• Decreasing or discontinuing corticosteroid therapy.

• Administration of prophylactic topical antibiotics.

• Pressure patching.

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• Use of a collagen shield, bandage lens, or disposable contact lens.

• Administration of aqueous inhibitors.

It usually is necessary to suture a wound if the leak persists after 5 – 7 days or if there is a flat

anterior chamber, iris prolapse, extensive external tissue gape, or excessive against-the-woundastigmatism ( Fig. 53-5 ).

Inadvertent Filtering Bleb

Formation of a filtering bleb after cataract surgery occurs if the wound leaks under a sealedconjunctival flap. If early filtration is recognized, progression might be prevented by

discontinuation of corticosteroid treatment. If the patient is asymptomatic, the physician can

observe the bleb. Elimination of the bleb can be considered if it causes irritation, tearing, or

infection. Blebs that tend to be more symptomatic are tall and cystic and encroach over thecorneal surface. Options for late closure include cryotherapy, chemical cautery,

neodymium:yttrium-aluminum-garnet (Nd:YAG) laser,[24] or surgical closure. The latter can becomplex because of endothelialization of the fistula. The surgical approach requires excision of the conjunctival bleb, scraping or cryotherapy of the cells that line the fistula, and closure of the

fistula, which sometimes requires a scleral patch graft.

Epithelial Ingrowth

Epithelial downgrowth is a rare but serious complication of intraocular surgery . It occurs

most commonly after intracapsular cataract extraction and less often following nuclear

expression; it is extremely rare after phacoemulsification. Surface epithelium that invades the

intraocular structures, such as over the cornea, iris, ciliary body, lens capsule, and Bruch’s

membrane,[25] can cause corneal decompensation, chronic anterior uveitis, and intractablesecondary angle-closure glaucoma. Conditions for the onset of this entity are highly variable,

but it appears to be more common in patients who undergo multiple intraocular procedures or have postoperative wound dehiscence.

The presence of epithelial downgrowth may be confirmed by irradiation of the affected iris withan argon laser (epithelial tissue turns white with argon ablation, compared with the dark or

brown appearance of normal iris) or diagnosed with specular micrography (noting a sheet of

abnormal tissue that obliterates the normal endothelial mosaic); however, the definitive diagnosis

is dependent on the histopathological confirmation of epithelial tissue in the eye. Treatmentconsists of complete destruction of all intraocular epithelial tissue using cryotherapy,

iridocyclectomy, or pars plana vitrectomy. Unfortunately, the prognosis for this postoperative

complication is poor, except for a well-defined cyst that can be excised en bloc.[26]

Postoperative Astigmatism

Complications related to postoperative astigmatism are covered in Chapters 41 and 54 .

Corneal Edema and Bullous Keratopathy

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Factors that predispose to corneal edema following cataract surgery include the following:

• Prior endothelial disease or cell loss.

• Intraoperative mechanical endothelial trauma.

• Excessive postoperative inflammation.

• Prolonged postoperative elevation of IOP.

Preoperatively, patients should be carefully examined for evidence of Fuchs’ dystrophy or other

conditions that produce a low endothelial cell count. Patients who have marginal corneal

endothelial function may complain of poorer vision in the morning because of corneal edema

produced by hypoxia overnight. Although most patients who have Fuchs’ dystrophy have guttaethat are readily visible with slit-lamp examination, in rare instances, patients can have low

endothelial cell counts in the absence of guttae. It is often advisable to obtain an endothelial cell

count in the fellow eye. Finally, corneal pachymetry can be helpful to assess such patients, because those with a corneal thickness in excess of approximately 0.63?mm presumably havemarginally compensated corneas and are at great risk of developing permanent postoperative

corneal edema. If the corneal thickness is greater than 0.63?mm but no corneal edema is evident,

the authors generally perform cataract surgery alone and advise patients of the increased risk of developing postoperative corneal decompensation. If frank epithelial and stromal edema is

present, a combined cataract extraction with penetrating keratoplasty may be advisable.

Several measures can be taken intra- and postoperatively to minimize the risk of corneal injury.

For some surgeons, nuclear expression may be safer than phacoemulsification. Techniques to

remove the nucleus in the posterior chamber seem to minimize endothelial cell loss,[27] and

evidence exists that highly retentive OVDs are more protective when surgical removal of thenucleus near the endothelium is carried out. Postoperatively, inflammation should be

aggressively treated with topical corticosteroids, and IOP should be controlled below 20?mmHg.Mechanical factors, such as Descemet’s detachment or retained nuclear fragments in the angle

touching the endothelium, should be addressed. For symptomatic relief, hypertonic saline

ointment is sometimes helpful as a temporary measure. Sequential corneal pachymetry is an

excellent way to document the resolution of postoperative corneal edema, which may take up to3 months; it is usually advisable to wait at least this long before recommending penetrating

keratoplasty.

Hyphema

A postoperative hyphema is caused by bleeding from the wound or iris ( Fig. 53-6 ). As thehyphema resolves, the IOP should be controlled. Surgical reintervention to remove a blood clot

is indicated if severe, medically resistant pressure elevation exists for

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Figure 53-6 Postoperative hyphema. This hyphema was produced by hemorrhage from the

scleral incision in a patient who had a small postoperative wound leak. The hyphema resolvedonce the incision closed, which led to cessation of ongoing bleeding and restoration of normal

intraocular pressure.

several days. The duration of tolerated pressure elevation depends on the patient’s age and the

status of the optic nerve. The incidence of postoperative hyphema is reduced by making clear corneal incisions.

Late hyphema or microhyphema most often is caused by chafing of the IOL against the iris or

ciliary body (uveitis-glaucoma-hyphema syndrome).[28] This most typically occurs because of loss of fixation of the sulcus-fixated posterior chamber IOL; micromovements of the lens cause

chafing against a vessel, which produces the postoperative bleeding. Treatment consists of IOLexchange and ensuring that the new lens is well fixated; this might require suture fixation to thesclera or implantation of an anterior chamber lens. A rare cause of postoperative bleeding is

hemorrhage from vascularization of the internal margin of the incision (Swan’s syndrome)[29] ;

this can be diagnosed by noting neovascularization of the wound using gonioscopy, and it istreated by argon laser photocoagulation.

Endocapsular Hematoma

Endocapsular hematoma is the postoperative entrapment of blood between the posterior surface

of the IOL and the posterior capsule.[30] It is a variant of hyphema, with the exception that the

blood can become entrapped within the capsular bag for months or even permanently.Fortunately, in most instances the amount of blood is minimal and either does not significantly

impair vision or is absorbed over a few weeks or months.[31] When the accumulation isextensive and persistent, Nd:YAG laser posterior capsulectomy is curative when used to enable

the blood to flow immediately into the vitreous, where it can be resorbed.

Intraocular Pressure Elevation

Elevation of IOP following cataract surgery is a common occurrence. Fortunately, it usually ismild and self-limited and does not require prolonged antiglaucoma therapy. Causes of acute

pressure elevation are retention of viscoelastic substances, obstruction of the trabecular

meshwork with inflammatory debris, and pupillary or ciliary block. Patients who have preexisting glaucoma are at much greater risk of developing acute significant pressure elevation.Prevention of this problem includes careful removal of the OVD at the time of surgery, control

of intraocular bleeding, and the use of intra- and postoperative antiglaucomatous agents.

Intracameral injection of 0.01% carbachol at the conclusion of surgery is effective, as is the postoperative administration of pilocarpine gel; topical beta blockers; apraclonidine; and topical,

intravenous, or oral carbonic anhydrase inhibitors. If marked elevation of IOP is present on the

first postoperative day, this can be immediately controlled by “venting” the anterior chamber.

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After topical anesthetic agents and antibiotics have been administered, a forceps or other fine

instrument is used to depress the posterior lip of the paracentesis incision, which allows the

egress of a small amount of OVD and aqueous.[32] This is repeated as necessary until the IOP is brought into the low-normal range. The patient can then be treated with topical antiglaucoma

therapy and followed carefully to ensure that pressure is controlled.

Chronic IOP elevation can be caused by corticosteroid use, retained lens (particularly nuclear)

material, chronic inflammation, peripheral anterior synechiae formation, endophthalmitis, and

ciliary block. The correct diagnosis of the underlying cause is required to institute appropriatetherapy.

Capsular Block Syndrome

Capsular block syndrome (CBS) is initially defined by the entrapment of an OVD in the capsular

bag, because of apposition of the anterior rim of the capsulorrhexis with the anterior face of theIOL.[33] [34] This may be more common with acrylic IOLs because of their slightly “stickier”

surface. Postoperatively, the bag becomes more distended (perhaps through osmotic imbibitionof aqueous), and the IOL is pushed anteriorly to create a myopic refractive shift. This can be

prevented by meticulous removal of the OVD from the bag at the conclusion of surgery. Toaccomplish this, it is helpful to gently depress the IOL optic to displace the OVD trapped behind

the IOL.[35] Treatment requires Nd:YAG laser puncture of the anterior capsule peripheral to the

edge of the capsulorrhexis, which permits the OVD to escape into the anterior chamber.Alternatively, if the pupil is relatively small and the anterior capsule is not accessible to laser

treatment, a small posterior capsulectomy can be performed, which permits the OVD to drain

into the vitreous.

A new classification of CBS includes intraoperative CBS, early postoperative CBS, and late

postoperative CBS.[36] Intraoperative CBS occurs during rapid hydrodissection using a largeamount of BSS and has been discussed in the hydrodissection section. Early postoperative CBSrepresents the initial type of CBS, with accumulation of the OVD in the capsular bag, as

discussed earlier. Late postoperative CBS refers to eyes with accumulation of a milky-white

substance in the closed capsular bag. [37] [38] [39] Reduction of vision with this type of CBS israre, and Nd:YAG laser capsulotomy can be performed, if necessary.

Intraocular Lens Miscalculation

Complications related to IOL miscalculation are covered in Chapters 38 and 39 .

Intraocular Lens Decentration and Dislocation

Common causes of IOL dislocation are asymmetrical loop placement, sunset syndrome, loss of

zonular support for a lens fixated in the capsular bag, and pupillary capture of the IOL optic.[40]

ASYMMETRICAL HAPTIC PLACEMENT.

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Pathological studies indicate that asymmetrical loop placement is an extremely common

occurrence, particularly when can-opener capsulotomies are performed. The incidence of this

complication has been greatly reduced with the advent of capsulorrhexis, which permitsexcellent visualization of the capsular edge and ensures that a lens placed in the capsular bag is

retained there. An IOL with asymmetrical loop placement becomes symptomatic if the lens is

decentered sufficiently relative to the pupil; symptoms include polyopia, glare, induced myopia(from looking through the peripheral portion of the IOL), and loss of best-corrected acuity.Depending on the

388

severity of the symptoms, treatment includes IOL repositioning or IOL exchange. In some

instances, topical miotics can be prescribed; however, few patients prefer this mode of management.

SUNSET SYNDROME.

Sunset syndrome occurs when a sulcus-fixated posterior chamber IOL dislocates through a

peripheral break in the zonules, typically inferiorly. Sunset syndrome is usually an acute,

nonprogressive event. Treatment options again depend on the severity of the patient’s

symptoms. The authors have found that simple IOL repositioning is often unsuccessful and

predisposes to recurrence. Therefore, several other options are recommended:

• Repositioning the lens, combined with iris fixation sutures.

• IOL exchange with a larger, more rigid lens.

• Scleral fixation of a posterior chamber lens.

• Replacement with an anterior chamber lens.

LENS-BAG DECENTRATION.

In rare instances, a lens that is placed in the capsular bag can dislocate as a result of bag

decentration caused by zonular rupture or dehiscence, especially in pseudoexfoliation syndrome.

Treatment of this condition, if sufficiently severe, requires IOL exchange with some form of

scleral fixation or implantation of an anterior chamber lens.

PUPILLARY CAPTURE.

Pupillary capture of the IOL optic consists of the posterior migration of some portion of the iris beneath the IOL optic ( Fig. 53-7 ). Predisposing factors are can-opener capsulectomy and sulcus

implantation of the posterior chamber IOL, particularly in the absence of angulated haptics;

however, in rare instances, pupillary capture can occur with capsular fixation of the lens after

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capsulorrhexis, especially when the capsulorrhexis is large.[41] [42] Pupillary capture can

produce acute and chronic iritis, posterior synechiae formation, visual loss from deposition of

inflammatory cells on the IOL surface, and, if the lens is displaced sufficiently eccentrically andanteriorly, chronic endothelial trauma with corneal decompensation. Pupillary capture diagnosed

within a few days of its occurrence can be treated pharmacologically or by manually

repositioning the optic into the posterior chamber. Chronic pupillary capture may be moredifficult to manage, because firm synechiae form between the iris and posterior capsule. In suchsituations, the IOL should be repositioned if there are visual symptoms, chronic uveitis, or

corneal endothelial trauma. Chronic cellular precipitates on the IOL surface can often be

managed by the administration of topical corticosteroids and occasional Nd:YAG laser “dusting”of the anterior IOL surface.[43]

Figure 53-7 Pupillary capture of the intraocular lens. Predisposing factors in this patient includeda can-opener capsulectomy, intraoperative iris trauma, and nonangulated haptics.

Sulcus-Fixated Intraocular Lens Dislocation

Another subtle but important form of IOL dislocation is loss of fixation of the sulcus-fixated

IOL. This can produce recurrent microhyphema or hyphema, as well as chronic iritis and even

pigmentary glaucoma. The loss of lens fixation is often subtle, but it can be diagnosed at the slitlamp by observing the third and fourth Purkinje images. If the patient is asked to look

eccentrically and then refix centrally, these images can be seen to flutter or wobble excessively

(pseudophacodonesis), which indicates lack of adequate IOL fixation. Intraoperatively, this can

be verified by touching the IOL with an instrument; there is obvious IOL instability.

Posterior and Anterior Dislocation

In rare instances, a posterior chamber lens can fall posteriorly and either become suspended in

the anterior vitreous ( Fig. 53-8 ) or dislocate completely into the vitreous cavity. In the former instance, IOL exchange is advisable, because the lens is within reach and can produce visual

symptoms or chafe on uveal tissue. Management of a complete posterior IOL dislocation is more

controversial. Although in some eyes this condition is well tolerated, in others, the lenses can

become entrapped in the vitreous base and cause vitreous traction and retinal tears, or they can produce visual symptoms by intermittently moving into the visual axis. Consultation with a

vitreoretinal surgeon is advised for the management of these patients.

Even more rarely, anterior luxation of a posterior chamber lens into the anterior chamber may

occur.[44] This can be prevented with a small and continuous capsulorrhexis and in-the-bag

implantation of the lens.

Intraocular Lens Exchange

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Several principles of IOL exchange need to be emphasized. It is generally preferable to exchange

lenses that have haptics that are poorly designed, too short, or deformed from lens malposition in

the eye. Patients who have a marginal corneal endothelium status generally should be subjectedto the least traumatic surgery possible, such as iris repositioning with iris fixation sutures rather

than IOL exchange, particularly if the latter requires anterior vitrectomy. It is important to

distinguish between IOL

Figure 53-8 Intraocular lens dislocation. During surgery, a capsular rupture was noted. A lens

was, however, implanted in the posterior chamber. On the morning following surgery, the lenswas found to be dislocated posteriorly and inferiorly, and the patient was referred for treatment.

At the time of lens exchange, it appeared that insufficient capsular support was present, and anew lens was sutured into the ciliary sulcus.

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decentration and pupil displacement. In some instances, the patient’s symptoms result from an

eccentrically displaced pupil in the face of a relatively well-positioned IOL. Clearly, surgery, if indicated, should address the underlying problem by reconstructing the pupil. This can be done

by suturing the pupil in the peripheral region and opening the pupil centrally with several small

sphincterotomies. If certain complications are associated with the site of the dislocated IOL (e.g.,recurrent microhyphema with a posterior chamber IOL or peripheral anterior synechiae with an

anterior chamber IOL), it may be advisable to place the new lens in a new site. Finally, if sufficient intact posterior capsule exists, an attempt can be made to reopen the capsular flaps to

permit fixation of the new lens within the capsular bag; this, clearly, is the most desirable

location.

Cystoid Macular Edema

Cystoid macular edema (CME) is the most common cause of unexpected visual loss following

cataract surgery. Fluorescein angiographic CME can occur in up to 50% of patients at 4 – 8 weeks

postoperatively, but clinical CME occurs in less than 3% of patients. The typical time of onset of clinical CME is 3 – 4 weeks postoperatively. Predisposing factors are intraoperative complications

(e.g., vitreous loss or severe iris trauma), vitreous traction at the wound, diabetic retinopathy,[45]

and preexisting epiretinal membrane. In cases without predisposing factors, CME typicallyresolves over several weeks, although most surgeons prefer to treat this topically with

nonsteroidal and corticosteroid drops. Other modes of treatment that have been employed

include sub-Tenon’s corticosteroid injection and administration of systemic nonsteroidal anti-

inflammatory drugs with corticosteroids. In patients who have epiretinal membranes, CME may

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take months to resolve. When associated with diabetic retinopathy, CME often is resistant to

medical therapy and can persist indefinitely; macular laser photocoagulation is sometimes

helpful to document angiographically the leaking vessels and microaneurysms. Patients whohave ongoing structural abnormalities, such as vitreous traction or extensive iris chafing, are less

likely to experience spontaneous resolution of CME and may benefit from surgical correction of

the precipitating factor.

Endophthalmitis

Endophthalmitis can occur in an acute or a chronic form. It is characterized by ciliary injection,

conjunctival chemosis, hypopyon,

Figure 53-9 Postoperative endophthalmitis. This patient developed an acute postoperative

endophthalmitis after clear cornea cataract surgery and implantation of a polymethyl

methacrylate posterior chamber intraocular lens. During cataract surgery, a capsular break occurred, and an anterior vitrectomy was performed. The patient was treated successfully with

vitrectomy and injection of intravitreal antibiotics combined with postoperative topical antibiotictherapy. Final visual acuity was 20/50 (6/15).

decreased visual acuity, and ocular pain. The acute form generally develops within 2 – 5 days of

surgery and has a fulminant course ( Fig. 53-9 ). Common causative organisms are gram- positive, coagulase-negative micrococci, Staphylococcus aureus, streptococcus species, andenterococcus species.[46] [47]

Chronic endophthalmitis is caused by organisms of low pathogenicity, such as

Propionibacterium acnes or Staphylococcus epidermidis. It typically is diagnosed several

weeks or longer after surgery. Signs include decreased visual acuity, chronic uveitis with or

without hypopyon formation, and, in some instances, plaque-like material on the posterior capsule. Histopathologically, this material consists of the offending microorganism embedded in

residual lenticular tissue.

Treatment of endophthalmitis consists of culturing aqueous and vitreous aspirates, followed by

administration of intravitreal,[48] topical, and subconjunctival antibiotics, as discussed

elsewhere. In the Endophthalmitis Vitrectomy Study, no evidence was found of any benefit fromthe use of systemic antibiotics. [49] Pars plana vitrectomy helped increase the final visual

outcome only of those patients who had an initial visual acuity of light perception or worse.[49]

For further discussion of endophthalmitis, see Chapter 169 .

Posterior Capsular Opacification

Secondary cataract formation is a major complication of IOL implantation after extracapsular

cataract extraction (ECCE or phacoemulsification). The incidence is in the range of 18 – 50% in

adults followed for as long as 5 years; in infants and juveniles, an opacification rate of 44% wasfound within 3 months of surgery after in-the-bag IOL implantation with an intact posterior

capsule. [50] Posterior capsular opacification (PCO) is caused by proliferation and migration of

residual lens epithelial cells. These can produce visual loss through two mechanisms:

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• Formation of swollen, abnormally shaped lens cells called Elschnig’s pearls, which migrate

over the posterior capsule into the visual axis ( Fig. 53-10 ).

• Transformation into fibroblasts, which may contain contractile elements (myofibroblasts) and

cause the posterior capsule to wrinkle (see Fig. 53-8 ).

Standard treatment of PCO consists of opening the capsule with Nd:YAG laser. Complications

of this treatment include

Figure 53-10 Posterior capsular opacification. Elschnig’s pearl formation and capsular wrinklingcausing a severe decrease of visual acuity.

390

acute and, in rare instances, chronic IOP elevation, pitting of the IOL, and retinal detachment.

Factors that predispose to retinal attachment include an axial length greater than 24.5?mm, malegender, and preexisting retinal pathology. [51] [52] [53]

A related and unusual abnormality is the formation of striae in the posterior capsule in theabsence of abnormal proliferation of lens epithelial cells. In some patients, this produces a

Maddox-rod effect; the typical symptoms are linear streaks that radiate from lights, and their

orientation is 90° from the meridian of the striae. The cause is stretching of the capsular bag bythe IOL, which produces the striae aligned with the axis of the lens haptics. Typically, this is present on the first postoperative day but may not be mentioned by the patient until later. In

many eyes, the striae resolve in the first week or two after surgery as capsular contraction occurs,

which counteracts the stretch forces of the IOL haptics. If the condition persists and issufficiently symptomatic, it can be corrected readily with a laser posterior capsulectomy. For

further discussion of PCO, see Chapter 34 .

Retinal Detachment

Retinal detachment is a well-recognized complication of cataract surgery; it occurs in 0.2 – 3.6%

of persons after extracapsular cataract surgery. The incidence of retinal detachment increasesfivefold if an intracapsular procedure is performed.[54] Predisposing factors include Nd:YAG

laser capsulectomy, axial length greater than 24.5?mm, myopic refractive error, latticedegeneration, male gender, intraoperative vitreous loss, postoperative ocular trauma, posterior

vitreous detachment, and history of retinal detachment in the fellow eye.[52] [55] [56] Steps to

prevent retinal detachment include the following:

• A careful preoper ative fundus examination.

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• Preservation of the integrity of the posterior capsule at the time of surgery.

• Education of patients with regard to the symptoms of retinal tears and detachment.

• Regular postoperative dilated fundus examinations.

Oftalmologia. 2003;56(1):36-9.

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[Postoperative complications in cataract

surgery].

[Article in Romanian]

Koos MJ, Muntean A, Lehaci C.

Clinica de Oftalmologie II Timişoara.

Abstract

The paper is a statistical retrospective trial that evaluates the prevalence of postoperativecomplications of the cataract surgery in the IInd Department of Ophthalmology Timisoara. The

parameters of interest were the type and the frequency of the postoperative complication

encountered after the extracapsular cataract extraction (ECCE) followed by a PMMA intraocular lens (IOL) implantation. The most frequent early postoperative complications were

endoepithelial comeal edema (20.8%), inflammatory complications (uveitis) (8.72%),

hemorrhagic complications (4.02%), and postoperative rise of IOP (8.05%). Out of latecomplication, we encountered cystoid macular edema (1.34%), bullous keratopathy (1.34%),

IOL malposition (0.67%) and secondary glaucoma (1%).

PMID: 12886680 [PubMed - indexed for MEDLINE]

Publication Types, MeSH Terms http://www.ncbi.nlm.nih.gov/pubmed/12886680

http://www.ncbi.nlm.nih.gov/pubmed?term=%22Koos%20MJ%22%5BAuthor%5D


http://www.ncbi.nlm.nih.gov/pubmed?term=%22Muntean%20A%22%5BAuthor%5D



http://www.ncbi.nlm.nih.gov/pubmed?term=%22Lehaci%20C%22%5BAuthor%5D



http://www.ncbi.nlm.nih.gov/pubmed/12886680






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