22   Posterior-Segment Complications

Cataract surgery is one of the most common performed operations in the United States and has one of the highest success rate. Previous population surveys have reported up to 7.4% of the population undergoes cataract surgery annually.^1,2 Phacoemulsification techniques have revolutionized the field of cataract surgery, and have facilitated the development of innovations such as small incisions and foldable intraocular lens (IOL) implants. Sutureless clear corneal incision techniques have become the standard methodology of contemporary cataract surgery. Newer innovations related to micro-incisional surgery and laser-assisted surgery remain at the forefront of surgical technique advancement.

Advances in technology have led to equally remarkable refinements in the surgical skills of the ophthalmologist, operations of shorter duration, and higher surgical case loads. Expectations of patients have increased as a result of the rapid visual and physical rehabilitation of what has become a well-refined procedure, with reasonably predictable vision outcomes. Commercial advertising for cataract surgery has fueled this increase in expectations by minimizing the need for injections or patches, reducing postoperative pain, and emphasizing that return to normal activities may be possible within days.

The uncomplicated cataract operation with intraocular implant placement is indeed a refined operation with remarkable outcomes in the vast majority of cases. Although the complication rate is quite low, the consequences of these complications may cause significant vision loss. Awareness of these complications and appropriate management can minimize the vision impairment and enhance the outcome and recovery for the patient, thereby reducing the risk of litigation that so often arises when patients’ expectations are not met.

The posterior-segment complications of cataract surgery are not specific to phacoemulsification. This chapter reviews the important clinical features and treatment options, with emphasis on phacoemulsification. The most serious posterior-segment complications include retained lens fragments, dislocated IOL implant, endophthalmitis, suprachoroidal hemorrhage, and needle penetration of the globe when periocular or retrobulbar anesthesia is used.

Retained Lens Fragments

The most common clinical situation leading to retained lens fragments in the vitreous is posterior capsular rupture, with loss of lens fragments posteriorly into the vitreous cavity during the fragmentation or chopping phase of phacoemulsification. The displaced lens fragment may encompass the entire nucleus or any segmented nuclear or cortical fraction. The best estimate of the incidence of posteriorly displaced lens fragments is 0.3% in both the United States and United Kingdom, but has been suggested possibly to be as frequent as 1.1% in published series.^3–5 Once posterior capsule rupture occurs, the surgeon must proceed with extreme caution in using a limbal approach to retrieve displaced lens fragments. Although in some instances converting to a larger incision and using a lens loop or forceps facilitate retrieval of a nuclear fragment before it migrates posterior through the capsule, once the fragment falls posteriorly a high risk of further complications ensues with limbal retrieval attempts.

Previously, surgeons have advocated vigorous attempts at retrieving the lost lens nucleus from the limbal cataract incision by probing posteriorly with a lens loop or other instrumentation, or by using high volumes of infusion fluid to create vortex currents to float the lens fragment anteriorly.^3,6 However, vigorous attempts at retrieving a posteriorly dislocated nucleus from the limbus with high volumes of intraocular fluid or posterior manipulation of the instrument has been associated with giant retinal tears that have a poor prognosis for visual acuity.⁷ In a case managed by one of the authors, the nucleus was found underneath a giant-tear retinal detachment in the inferior nasal quadrant.

Furthermore, some anterior-segment surgeons have advocated placement of a vitrectomy probe through the pars plana with the use of a small irrigating handpiece to more safely remove lens material. This approach has also been suggested to be used in combination with elevation techniques involving the use of viscoelastic devices to elevate posteriorly dislocated lens material. It is important to note that this pars plana vitrectomy approach differs from the standard three-port system, vitrectomy probe, and vitrectomy machine commonly used by vitreoretinal surgeons.^8–10

Clinical Features

Posterior displacement of lens fragments is usually recognized intraoperatively after posterior capsular rupture. Occasionally retained lens material may present with chronic intraocular inflammation and no visible fragments in the posterior pole. The degree of intraocular inflammation usually reflects the size of the retained lens fragment, the time interval since cataract surgery, individual inflammatory reactivity, and the extent of previous intraocular manipulations. Associated clinical signs include corneal edema, elevated intraocular pressure (IOP), uveitis, and vitreous opacities. Initially, these findings are frequently mild, especially in the immediate postoperative interval, but over time they may worsen and lead to other complications such as retinal detachment, causing profound vision loss. Published series have reported a retinal detachment rate ranging from 6.3 to 12.8% in patients presenting for management of IOL dislocation. Macular involvement has been reported to be found on presentation in up to 50% of cases.^5,11–19

Surgical Indications

The size of the lens fragment, the extent of IOP control, the degree of corneal edema, and the severity of intraocular inflammation usually form the basis for surgical intervention. Proceeding with surgical intervention is often most necessary in the setting of large retained nuclear lens fragments in which clinical complications secondary to inflammatory response are highly probable.⁸ Eyes with very small retained fragments have a better prognosis and can often be observed indefinitely. However, if inflammation has not subsided by 1 to 2 weeks, surgical intervention should be considered, regardless of how small the retained fragment is, because other occult fragments may be harbored behind the iris.

Chronic IOP elevation was reported to be more common when the subsequent vitrectomy was performed more than 3 weeks following surgery.⁷ Other studies have not found any outcome differences between earlier and later intervention.^5,8,12,18,19 Published series have reported an incidence in the range of 25 to 37% of patients presenting with IOP greater than 30 mm Hg for vitrectomy following phacoemulsification, with resultant retained lens fragments. The IOP normalized in all but 2 to 3% of patients after vitrectomy.^8,12 The patient’s overall clinical situation may influence the timing, but usually surgery to remove retained lens material is performed within 2 weeks of the original cataract surgery to expedite the vision rehabilitation, to break the cycle of progressive lens-induced inflammation, and to lessen risks of secondary lens-induced glaucoma. These goals may be logistically maximized when lens fragment retrieval and removal can be expertly performed during the original cataract operation. When this is not feasible, a delay of several days or even weeks may be equally effective, because the inflammation, corneal edema, and elevated IOP can improve with topical treatment over several days following cataract surgery.

Surgical Techniques

A variety of techniques have been described for use by the anterior-segment surgeon at the time of lens fragment loss. Although some cases may be satisfactorily managed through a limbal incision, pars plana vitrectomy techniques probably offer superior results in most cases.^{5,9,10,17–24} The technique of removal is dependent in large part on the firmness of the lens material. Almost all material can be fragmented with contemporary ultrasonic instruments, whereas softer material such as cortex may be aspirated with the vitreous cutter. Rarely, nuclear or inspissated old lens material requires direct removal through an anterior incision.

There are three key elements in successful lens fragment removal technique. First, adequate initial vitrectomy avoids unintended vitreous traction during phacofragmentation (Fig. 22.1). Second, reducing fragmentation power as the remnants become smaller and softer, sometimes to as low as 10% of maximum, enables more efficient nuclear extraction by continuous occlusion of the suction port, minimizing the risk of mechanical retinal trauma from projectile fragments. This maneuver also minimizes the risk of fragments dropping back onto the retina even though these fragments rarely strike the retina with sufficient force to damage the retina. Third, fragments should be cautiously aspirated from the retinal surface and moved to the midvitreous before activating ultrasonic fragmentation to avoid suction or ultrasonic damage to the retina (Fig. 22.2).

Previously, perfluorocarbon (PFC) liquids have been described to float the nucleus anteriorly to facilitate removal,^24,25 but are most useful when retinal detachment coexists.²⁶ Techniques for reattaching the retina when associated with retained lens fragments are similar to those for other complex retinal detachments.^27,28 With modern developments in vitreoretinal surgical techniques and equipment, the routine use of PFC liquids in surgical treatment of retained lens fragments is uncommon.

Fig. 22.1 Attention to complete central vitrectomy allows access to retained lens fragments. (From Regillo CD, Brown GC, Flynn HW Jr. Vitreoretinal Disease: The Essentials. New York: Thieme; 1999:568. Reprinted by permission.)

Fig. 22.2 Low ultrasonic fragmentation power allows more controlled removal of fragments. (From Regillo CD, Brown GC, Flynn HW Jr. Vitreoretinal Disease: The Essentials. New York: Thieme; 1999:569. Reprinted by permission.)

Most anterior-segment surgeons proceed to IOL insertion at the time of the original cataract surgery, as is recommended by the majority of vitreous surgeons in spite of the intraoperative complication of posteriorly displaced lens fragments. If there is sufficient capsular support, a three-piece IOL is often placed in the ciliary sulcus, because a single-piece acrylic lens is not suitable for such anatomic positioning. If not, suture fixation or scleral fixation techniques may be used,^29–47 or an anterior chamber (AC) IOL may be placed. If the cataract surgeon is reluctant to insert the IOL primarily, it can be inserted at the time of the subsequent vitrectomy or later.

Outcomes of Vitrectomy for Retained Lens Fragments

The vision outcomes in these cases are generally good.^{4,5,17–24,48,49} Published reports have suggested that final postoperative visual acuity equivalent to 20/40 is achievable in 60 to 82% of cases.^{5,8,18–23,49} This apparent improvement may reflect changing patterns of cataract surgery technique, because a poorer prognosis (20/60 final acuity) has been suggested with dropped lens nuclei when extracapsular cataract extraction (ECCE) techniques are used compared with phacoemulsification extraction methods.¹⁷ Postoperative complications related to vitrectomy surgery may be difficult to differentiate from those attributable to complicated cataract surgery, and may include corneal edema, glaucoma, persistent intraocular inflammation, and new retinal detachment. Retinal detachment coexisted with retained lens material in 8.0 to 12.8% of reported series, and retinal detachment has been reported after vitrectomy for removal of retained lens fragments in 5.5 to 8.3% of reported series (Table 22.1).^12,14,50,51 Thus, it is of critical importance to evaluate the retina throughout the perioperative course in such patients.

Recommendations for Management of Retained Lens Fragments

Recommendations for the anterior-segment surgeon experiencing the complication of posterior dislocation of lens fragments include the following: (1) confine the posterior migration of fragments by the immediate use of dispersive viscoelastic; (2) use a glide sheet or even extractor spoon to stabilize the nucleus in the presence of a large capsular tear; (3) attempt lens fragment retrieval only if the fragment is readily accessible (at or near the iris plane; (4) perform anterior vitrectomy as necessary to avoid vitreous prolapse into the surgical incision; (5) if possible, insert a posterior chamber (PC) IOL using a residual posterior capsule, or insert an AC IOL, as merited by the situation; (6) suture the closure of the cataract wound in a standard fashion and remove viscoelastic (sutures are indicated to ensure wound integrity during subsequent vitrectomy); (7) prescribe frequent postoperative topical anti-inflammatory treatment and IOP-reducing agents as clinically indicated; and (8) refer the patient for vitreoretinal consultation within a few days for consultation (Box 22.1). If the opportunity exists, perform the vitrectomy for retrieval of displaced lens fragments at the same operation.^52,53

Recommendations for the vitreoretinal surgeon include the following: (1) consider recommending observation initially for eyes with minimal inflammation and a very small lens fragment; (2) reassess supportive treatment with topical corticosteroids and antiglaucoma agents as clinically indicated; (3) intervene surgically if inflammation or IOP is not controlled, or if the fragment is estimated be sizable; (4) time the surgical intervention to maximize the initial treatment of postoperative inflammation and corneal edema.

If surgery is undertaken: (1) perform adequate core vitrectomy and induce posterior vitreous detachment as necessary to maximally remove vitreous before attempting phacofragmentation; (2) use lower fragmentation power settings for more efficient removal of smaller fragments; (3) be prepared for secondary IOL insertion in aphakic eyes or IOL exchange in some pseudophakic eyes by having measured or retrieving IOL calculations; and (4) examine peripheral retina thoroughly with scleral depression for possible retinal tear or detachment (Box 22.2).

Intraocular Lens Dislocation

Postoperative decentration of PC IOLs occurs in 0.2 to 1.2% of cases and usually does not require treatment.^54,55 A less common but more significant complication is IOL dislocation into the vitreous cavity. A common element in all cases is insufficient posterior capsule support. This is typically due to posterior capsule rupture during cataract extraction. When dislocation occurs within the first few days or weeks after surgery, the cause may be less apparent and may be the result of unknowingly placing the IOL through a posterior capsule defect, or as a result of subsequent IOL haptic rotation out of a zone of residual capsule remnants. Late dislocation is less common and may be due to traumatic⁵⁶ or spontaneous loss of zonular support, such as in eyes with pseudoexfoliation syndrome.^57,58

Clinical Characteristics

Dislocation of PC IOLs into the vitreous cavity is typically observed within the first week following surgery (26 of 32 cases in one series). Less commonly it occurs during surgery or several months after surgery.^57–59 The presenting visual acuity with aphakic correction may be very good, but is commonly decreased to a moderate degree despite the best spectacle correction. Patients with luxated or subluxated PC IOLs are usually symptomatic because of the variable position of the optic within the visual axis. In addition, a mobile PC IOL may also generate unique floater-like symptoms, or even lead to pupillary block glaucoma.

The presenting symptoms of patients with dislocated IOLs range from minimally symptomatic lens decentration to complete luxation into the vitreous cavity.⁵⁵ Decentration or subluxation refers to mild malposition with the optic still covering more than half of the pupillary space. In many cases of decentration, one haptic is in the ciliary sulcus and the other is in the capsular bag. Progressive decentration may become apparent with progressive capsular fibrosis. Patients at this milder end of the spectrum usually present several weeks after cataract extraction with good visual acuity and normal IOP, and without inflammation.

Visual symptoms usually are mild and may be related to glare from the edge of the optic.

Management Options

There are four general classes of management options for dislocated IOLs: observation, removal, exchange, or repositioning (which may incorporate suture fixation or sutureless scleral fixation).^{13,29–47,59–65} The management plan and timing are formulated based on clinical factors such as the type of IOL and any observed secondary complications.

Patients presenting with substantial intraocular inflammation, vitreous hemorrhage with or without concomitant hyphema, retinal detachment, or cystoid macular edema (CME), especially when associated with vitreous to the cataract incision, most clearly constitute candidates for surgery. Another possible contributing factor to the development of such complications may include a malpositioned haptic causing posterior iris surface chafing and inflammation. When such clinical suspicion exists, ultrasound biomicroscopy (UBM) or anterior-segment optical coherence tomography (OCT) imaging may provide more definitive evaluation. Although a posteriorly dislocated IOL may be well tolerated in many patients, the difficulty in vision rehabilitation necessitates surgical intervention in most. For symptomatically subluxated IOLs, surgery may be performed via a limbal or a pars plana approach. Patients with less extensive subluxation can be managed through a limbal incision with minimal or no anterior vitrectomy if the posterior capsule is largely intact. However, if there is a large posterior capsular rent, vitrectomy using a pars plana approach may offer optimal control to achieve the goals of surgery and address unforeseeable intraoperative complications.

Observation

An IOL with limited decentration is usually minimally symptomatic, so it is satisfactorily managed by observation. Observation also may be recommended even for more extensive subluxation if other superseding medical or ophthalmic problems prohibit further surgery, or if the patient simply elects not to pursue further surgery. Occasionally, management with topical miotics can be visually beneficial, especially for minor subluxations. In a series of 15 patients with dislocated or subluxated anterior chamber or iris plane IOLs that were managed with observation, a visual acuity of ≥ 20/40 was reported in 60%, but retinal detachment occurred in two patients.⁶⁰

Removal or Exchange

The IOL exchange is most commonly associated with the following: damage to the IOL (e.g., broken haptic); lack of available instrumentation to reposition; and certain IOL designs, such as those with highly flexible haptics (e.g., polypropylene) or plate haptic design, which make the IOL unsuitable for sulcus fixation unless the peripheral capsule is almost completely intact.

In patients for whom repositioning PC IOLs proves problematic, an intraoperative decision can be made to remove and exchange it with an AC IOL or scleral suture-fixated PC IOL (with or without the need for suture material). Exchange for a suture-fixated (PC) IOL was initially simplified by the availability of IOL designs that include holes (eyelets) in the haptics alone. Newer IOL design produced three-piece Prolene haptic IOLs, which may be readily amenable to scleral fixation by methods of scleral tunnel or pocket formation, scleral glue, or suture fixation.^{13,29–47,61–67}

Explanting and reimplanting an IOL may risk more corneal endothelial cell trauma as compared with repositioning techniques.

Exchange for an AC IOL may be less traumatic to the corneal endothelium and may be easier and faster to accomplish. Newer AC IOL designs reportedly avoid complications caused by the mechanical side effects of earlier AC IOL designs compared with PC IOLs, and the results presumably can be extrapolated to dislocated IOL management.⁶⁸ In any case, it is important that the possibility of either PC IOL or AC IOL implantation should be anticipated with proper IOL power calculations, and IOL availability, before surgery.

An ancillary option is observation of the dislocated IOL, in which case visual rehabilitation is achieved with implantation of a second (usually AC) IOL.^69–71 This should be considered an option of last resort, however, as most patients are concerned about the presence of a dislocated lens implant.

Intraocular Lens Repositioning

Intraocular lens repositioning completes the initial surgical objectives of the cataract surgery and is the most commonly elected surgical approach. There are three basic approaches to IOL repositioning: (1) without sutures, using residual peripheral anterior or posterior capsule; (2) iris-sutured fixation; and (3) scleral fixation with or without the use of suture material.

Subluxated IOLs associated with an intact, or mostly intact, posterior capsule may be repositioned from an anterior approach if there is only moderate subluxation. Usually at least one haptic is posteriorly malpositioned—either protruding through an unseen zonular dehiscence in an area without posterior capsular support or posterior to the residual capsule. A pars plana approach is optimal for patients with large posterior capsule defects, for patients with IOL luxation into the vitreous cavity, and for patients with coexisting ocular complications such as retinal detachment.

Recognition and use of adequate capsular support are as important for repositioning the PC IOL as they are for primary placement. Generally, the IOL remains well supported if at least 180 degrees of peripheral capsular material is intact. More extensive support is necessary, however, when the inferior capsule is absent or if the margin of the residual capsule where IOL haptics are to be placed is of questionable integrity. Repositioning by capsular fixation is the most common management technique in reported series,^13,59–65 and is our first choice when technically possible and when the design of the PC IOL is appropriate for such positioning (i.e., not a one-piece acrylic IOL). Surgical success depends on accurate placement of the haptics into the ciliary sulcus, which requires visualization of the residual capsule.^72,73 Placement of iris hooks is useful in selected cases, but usually strategic local iris retraction with a hooked instrument allows confident visualization. The use of viscoelastic devices can serve as an additional measure to aid in visualization of the ciliary sulcus and provide mechanical opening of this space to facilitate IOL placement. A useful maneuver in a pars plana approach is to bring the IOL anteriorly and capture at least one haptic anterior to the iris (Fig. 22.3). After the IOL is stabilized in the anterior chamber, the second haptic can be guided between the residual capsule and posterior iris surface either by rotating the lens or by grasping the haptic with an intraocular forceps via the pars plana. Because of the modern techniques related to capsulorrhexis creation, the peripheral anterior capsule is usually intact and serves as an effective interface for sulcus fixation. Repositioning a PC IOL permanently into the anterior chamber also has been reported, but is not recommended because of chronic chafing of the iris by the IOL and lens power considerations.⁷⁴

Fig. 22.3 When repositioning a posterior chamber (PC) intraocular lens (IOL) onto residual capsular remnants, it may be useful to bring one haptic anterior to the iris to facilitate accurate visualization of haptic placement over residual capsule. (From Regillo CD, Brown GC, Flynn HW Jr. Vitreoretinal Disease: The Essentials. New York: Thieme; 1999:572. Reprinted by permission.)

Iris fixation sutures were initially described for the use of dislocated AC IOLs.⁷⁵ Their use has been modified for fixation of dislocated posterior chamber implants using a limbal or a pars plana approach.^72,76 Iris claw IOL implants are another option, with both anterior and posterior types available. This technique requires that a suture pass through the cornea and iris, around the IOL haptic, and back out through the iris and cornea. Because accurate placement of the needle is difficult, it is challenging to optimize IOL centration. In addition, concern regarding iris-mediated chronic inflammation, chronic pupillary miosis, chronic macular edema, and the technical difficulty encountered during suture placement have led to the development of other techniques.^29–47

Scleral fixation sutures were first introduced for implantation of secondary IOLs and for primary IOL placement in the absence of satisfactory peripheral capsular support in a limbal or pars plana approach.^29–40 Early reports described pulling the haptic to or externally through^77–79 a sclerotomy to position a suture on the haptic before suturing to the deep part of the sclerotomy wound. Subsequently, IOL repositioning using transscleral fixation sutures via a pars plana approach mimicking the techniques of secondary IOL fixation was described. Components common to all scleral suture fixation techniques include (1) retrieving the IOL, (2) introducing a suture loop through the ciliary sulcus region into the vitreous cavity, (3) passing the suture loop around the IOL haptic, (4) securing the suture to the sclera, and (5) covering or burying the scleral suture knot. A wide variety of techniques have been described to achieve these goals.^{29–47,76–79}

Most proposed techniques modify how the suture loop is introduced and attached to the IOL haptic. Such techniques have included imbricating the IOL haptic into the sutures used to close the sclerotomy, externalizing the haptics to attach a suture, using a needle guide to thread the suture around the haptic, introducing a small needle intraocularly to capture the haptic, suturing through IOL optic positioning holes, backing a large needle into the eye to introduce a suture loop, grasping a loop by intraocular forceps, and introducing the suture from a third sclerotomy. Other proposed variation techniques include achieving three- or four-point fixation to lessen lens torsion, using speciallydesigned small-gauge forceps to aid in maneuvering the loop around the haptic, and using perfluorocarbon liquids to place the implant in a convenient position for suturing. Most posterior segment surgeons find the use of perfluorocarbon liquids unnecessary.^{29–47,76–95}

Anatomy of Scleral Suture Fixation

Histopathological and ultrasound biomicroscopic studies have shown that little or no fibrosis occurs around sutured PC IOL haptics,⁹⁶ but one study has shown cicatrization around the haptics.⁹⁷ Either way, it is vital to use a nondissolving suture material because it may provide the sole means of support at the ciliary sulcus.

Intraocular lens torsion and decentration can be avoided by accurate ciliary sulcus placement and by adequate excision of bulky capsular and cortical remnants. It may be necessary to exchange some IOLs that are too short from haptic to haptic for sulcus fixation. Anatomic studies have located the sulcus ~ 1 mm posterior to the limbus.⁹⁸ Consequently, suture placement more posteriorly may cause IOL optic torsion by forcing the circumferentially oriented haptic over radially oriented ciliary processes. The sutures must be placed 180 degrees apart for proper centration. In addition, the IOL must be rotated minimally and cautiously to the center at the end of the operation.

Outcomes of Surgery for Dislocated Posterior Chamber Intraocular Lenses

The final visual acuity probably depends on not only preoperative macular function, but also complications from the original cataract surgery, such as CME and retinal detachment. Despite the possibility of complicating factors, a final visual acuity ≥ 20/40 in more than 90% of eyes has been reported in some series (Table 22.2). Surgical series are difficult to compare accurately due to nonhomogeneity and the variety of management techniques.

Table 22.2 Visual Acuity Outcomes of Pars Plana Vitrectomy for Dislocated Intraocular Lens

An intraoperative or postoperative vitreous hemorrhage commonly occurs, given that sutures are placed through the vascular ciliary body, but are almost always self-limited and of little clinical significance. Bacterial migration along the transscleral suture tract has been described as being the possible route for infection in cases of delayed-onset endophthalmitis.^60,99,100 Rotating the suture knot or the use of a partial-thickness scleral flap to cover the scleral suture knot should reduce the risk of this complication. However, the suture knot can erode through the flap.

Other postoperative complications are difficult to separate from those that would be expected with complicated cataract surgery. Both CME and retinal detachment have been described after IOL repositioning surgery. Retinal detachment occurs in combination with dislocated PC IOL in ~ 2 to 3% of cases, and may be less frequent than with retained lens fragments^{13,59,60,62,63,81} (Table 22.3). Possible reasons for the disparity include less inflammation with IOL dislocation relative to lens nuclear and cortical materials. Also, primary vitrectomy is often performed from the limbus at the time the lens fragment is lost, whereas with the dislocated IOL this is usually less aggressively performed. The surgical approach typically involves standard vitreoretinal surgical techniques, but perfluorocarbon liquids may be useful in selected cases to better manipulate the IOL while avoiding retinal trauma. A final issue to consider in IOL suture fixation is the long-term stability of the suture material. Although published reports are limited, it has been shown that 10-0 polypropylene suture material can break down, resulting in the need for secondary intervention as early as 2 years following original surgery, and up to 16 years later within a pediatric study population. Although some surgeons prefer the use of 9-0 Prolene, there is limited published information as to the exact difference in breakdown as compared with a 10-0 Prolene suture.¹⁰¹

Recommendation for Management of Dislocated Intraocular Lens

Infectious endophthalmitis following ocular surgery is an uncommon clinical entity often causing severe vision loss.^102,103 As previous estimates have indicated that at least 1.35 million cataract operations are performed each year in the United States,¹ pseudophakic endophthalmitis is the most frequently encountered category in reported series. This complication is not specific to phacoemulsification or cataract surgery. Other categories of intraocular surgery may also lead to endophthalmitis but are less frequent in reported clinical series. Endophthalmitis after secondary IOL implantation, corneal transplant, pars plana vitrectomy, and glaucoma filtering surgery is reported less often in large series.^104–109

Table 22.4 Incidence of Endophthalmitis at the Bascom Palmer Eye Institute (1984–1994)¹¹⁰ and (2002–2009)¹¹¹

*Reported cumulative rate of endophthalmitis from 1995–2001 reported to be 0.05%.¹¹¹

Incidence

In surveys of postoperative endophthalmitis at the Bascom Palmer Eye Institute from 1984 to 1994 and again from 2002 to 2009, the incidence of nosocomial endophthalmitis was reported to be low, with a continued trend toward a lower overall rate over a 25-year period^110,111 (Table 22.4). The incidence of endophthalmitis after penetrating ocular trauma (3 to 30% of patients in reported trauma series) is much higher than in the postoperative categories.^112–115 Even in the era of advanced modern surgical techniques, prevention of postoperative endophthalmitis must be considered. In fact, some authors have provided study results suggesting that postoperative endophthalmitis may be a result of sutureless corneal wounds now commonly used in cataract surgery, thus making postoperative endophthalmitis a continuing concern.¹⁰³

Clinical factors associated with a higher frequency of endophthalmitis include vitreous loss (cataract surgery), repeat incisions in the surgical limbus with potential poor wound healing (secondary IOL), and use of adjunctive antimetabolites (glaucoma filtering surgery).

Clinical Diagnosis and Microbiological Confirmation

The diagnosis of postoperative endophthalmitis is made by recognition of clinical features and by microbiological confirmation. The clinical features of post–cataract surgery endophthalmitis include marked intraocular inflammation and fibrin in the anterior chamber (Fig. 22.4) often with hypopyon.¹⁰² In addition, conjunctival congestion, corneal edema, and lid edema are traditional signs associated with intraocular infection. Symptoms often include pain and marked loss of vision. Although endophthalmitis caused by less virulent organisms may have minimal or no pain, some degree of pain is still present in the majority of postoperative endophthalmitis patients. The loss of vision is usually profound and out of proportion to the typical postoperative vision measured during the first days or weeks after intraocular surgery.

An attempt is made to confirm the clinical diagnosis by microbiological growth from intraocular specimens. Vitreous specimens are more likely to yield a positive culture result than simultaneously obtained aqueous specimens.¹¹⁶ Many different techniques have been described for obtaining these specimens. The anterior chamber specimen is typically obtained using a syringe with a 30-gauge needle. The vitreous specimen can be obtained either by a needle tap or by a vitrectomy instrument. The needle tap technique generally employs a 23- or 25-gauge needle (although some surgeons may use a 27- or 30-gauge needle, such small bore needles may limit efficacy and sample yield) introduced through the pars plana and directed toward the midvitreous cavity. Neither a conjunctival incision nor a suture closure is necessary for the needle entry site. A small specimen (0.2 to 0.5 mL) is obtained and is directly inoculated into culture media or delivered to the laboratory without delay. If a vitrectomy instrument is utilized, the specimen may be passed through a membrane filter system to concentrate the microorganisms on the filter paper. Using sterile techniques, the filter paper sections are placed on appropriate culture media. Alternatively, freshly collected vitrectomy specimen can be injected directly into blood culture bottles for analysis by the microbiology department as growth occurs. In a reported study comparing membrane filter cultures versus blood culture bottles, similar rates of positive cultures were obtained from both culture techniques.¹¹⁷ At night or on the weekends when the microbiological staff is not available to process the vitrectomy specimen, the blood culture bottles are particularly useful.

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