Acute posterior segment complications
Late posterior segment complications
Dislocated lens fragments
Malpositioned IOLs
Endophthalmitis
Retinal detachment
Cystoid macular edema
Occurrence of PCR during cataract surgery also has a significant short-term impact on the patient in terms of postoperative reviews for follow-up, additional topical and oral medications, and additional procedures [8, 9].
29.2 Dislocated Lens Fragment
The reported incidence of nuclear fragments in vitreous cavity following a PCR is 0.3 % (2–3/1000 operations/year) [12, 13] to 1.1 % [14] and is reported to be inversely proportional to the surgeons’ experience and surgical volume. PCRs in phacoemulsification are more central than that in ECCE and are hence more conducive to posterior migration of the nuclear fragment [15].
The complications of a dropped nucleus may include elevated intraocular pressure, uveitis, corneal edema, cystoid macular edema, and retinal detachment. Hence, proper management of vitreous loss and retained lens fragments is the most important factor influencing the chances of an excellent visual outcome. This ensures reduction in the risk for developing further complications and also ensures a final corrected visual acuity ≥6/12 as reported by von Lany et al. [16] in 2009 in the report of the British Ophthalmological Surveillance Unit (BOSU) and also by various other authors in several retrospective case series [17–19].
29.2.1 Intraoperative Management by the Cataract Surgeon
Following a PCR, the primary goal of the cataract surgeon is to remove as much of the remaining nucleus as possible if it is visible and in an accessible position in the anterior vitreous. A dispersive ophthalmic viscosurgical device (OVD) can be injected into the anterior chamber to tamponade the vitreous and to support the nuclear fragment [20]. This maneuver ensures safe withdrawal of the phaco needle without aggravating further vitreous prolapse. The surgical procedure is thus “frozen-in-time,” allowing the surgeon adequate time to think and plan the immediate surgical strategy. There are certain intraoperative maneuvers which aggravate the risk of vitreous traction and should be avoided. A few of these are mentioned below and will also be discussed in detail by other authors.
PAL (posterior-assisted levitation) was recommended by Packard and Kinnear [21] in 1991 to raise the dropped nucleus into the anterior chamber for safe removal. However, this maneuver is associated with the risk of aggravating vitreous traction. Furthermore, it is technically difficult to cause a purely axial displacement of the lens fragment by injecting OVD behind the dislocating lens fragment. When placing the OVD in the posterior segment, it is often impossible to place it reliably between the vitreous and the dropped nucleus, and in many cases the OVD may push the nuclear fragment peripherally under the iris and out of the surgeon’s view.
Inserting a spatula through the pars plana creates unpredictable and disastrous vitreous traction and can also predispose to the development of a suprachoroidal hemorrhage in a soft eye [22]. Use of irrigation to the vitreous to “flush” the nucleus up into the pupillary space has the high risk of creating retinal tears and is hence not advisable [23]. There are “scores of reports” in literature, documenting the dangers of fishing for lens fragments [24–27]. In the presence of vitreous, it is dangerous to continue to use phacoemulsification to remove nuclear fragments. The phaco tip cannot cut the vitreous gel, but would instead aspirate the vitreous, leading to significant vitreoretinal traction and a high risk of developing a retinal tear [28]. The fluid flow into the vitreous through the capsular rent, if phacoemulsification is continued, will aggravate vitreous prolapse and also enlarge the PCR.
If the Nucleus Has Drifted out of Reach, No Attempt Should Be Made to Retrieve It via the Anterior Route
So, even if the nucleus drops into the vitreous cavity, unless optimal three-port pars plana vitrectomy capability is immediately accessible, the cataract surgeon should focus on minimizing collateral damage by safe management of anterior vitreous (by adequate bimanual anterior vitrectomy), cortical cleanup, a stable IOL implantation wherever possible, and assured incision integrity [29].
An adequate bimanual anterior vitrectomy should be performed through the two paracenteses, avoiding the use of the main incision. Using a low bottle height, high cut rate, and low suction, the anterior chamber should be cleared of vitreous [30]. Triamcinolone acetonide usage for visualization [31] ensures thorough vitrectomy and adequate anterior vitreous removal and may be helpful in decreasing postoperative inflammation (Fig. 29.1). The cutter is first passed through the rent in the posterior capsule to remove an adequate amount of anterior vitreous [32]. This will ensure removal of all the prolapsed vitreous in the anterior chamber and prevent further vitreous prolapse and enlargement of the PCR. The anterior vitrectomy can also be performed through the pars plana either directly through a sclerotomy or by placement of a valved trocar 3 mm posterior to the limbus using MIVS [33, 34]. If the PCR is small and there is only a small amount of vitreous prolapse into the anterior chamber, a “dry” vitrectomy can be performed, taking care to maintain the anterior chamber by injecting OVD (Fig. 29.2a, b). Residual soft cortical lens matter in the anterior vitreous can be removed using the vitreous cutter. The intraoperative strategies to be adopted by the primary surgeon in the event of PCR will be elaborated in the other chapters of this book.
Fig. 29.1
Preservative-free triamcinolone acetonide is used to visualize vitreous strands
Fig. 29.2
(a) Dry vitrectomy can be performed if the vitreous prolapse is small, using a vitrectomy cutter. (b) Intraoperative hypotony is countered by injecting OVD into the anterior chamber intermittently
After performing an adequate bimanual anterior vitrectomy, the location and status of residual lens matter should be reassessed and an attempt made to prevent it from dislocating into the posterior segment. Remaining lens matter can be maneuvered mechanically with the use of OVD and brought to the pupillary area, from where it can be removed by resuming phacoemulsification over a temporary scaffold (Sheet’s glide [35] or Agarwal’s [36] three-piece IOL scaffold technique or by converting to a large-incision manual ECCE or manual small-incision cataract surgery. These techniques are described in detail in previous chapters.
29.2.1.1 IOL Implantation Options for the Cataract Surgeon
The decision to implant an IOL during the primary surgery is usually made by the cataract surgeon, taking into account the integrity of the capsular bag and capsulorhexis margin, location, and size of the PCR, the degree of visibility permitting an accurate assessment of the capsular integrity, as well as the size and hardness of the dislocated lens fragment.
- 1.
It is not advisable to place an IOL if visibility is too poor to assess capsular support or hard nuclear fragments that have dislocated posteriorly. In such situations, postponing the IOL implantation to a later date will give time for fibrosis of the residual capsular bag and may permit secondary IOL implantation in the sulcus.
- 2.
If the visibility is good and PCR is small, conversion into a posterior continuous curvilinear capsulorhexis (PCCC) is feasible. A single-piece PC IOL can be placed in the bag in this situation.
- 3.
If the PCR is large and/or peripheral, a PCCC is not feasible. In this situation, if the visibility is good and if the capsulorhexis margin is intact, after adequate vitrectomy, a three-piece PC IOL can be implanted in the sulcus with optic capture through the capsulorhexis margin.
- 4.
However, if the capsular bag can be assessed and the capsular support is found to be grossly inadequate, options include implanting an AC IOL, or fixating a PC IOL to iris or sclera.
In general, a silicone IOL should be avoided, particularly in eyes with high risk of developing retinal detachment and possible need for silicone oil tamponade. This is because silicon oil–silicone IOL [37] interaction causes visual aberration for both the patient and the operating retinal surgeon.
29.2.2 Medical Management
Medical management of retained lens material in the interim period before the definitive surgery is aimed at treating its secondary complications including intraocular inflammation and glaucoma. Topical steroids and nonsteroidal anti-inflammatory drugs (NSAIDS) are used to control inflammation along with cycloplegic agents. Topical antiglaucoma medications and oral carbonic anhydrase inhibitors may be necessary to bring the IOP under control.
29.2.3 Definitive Surgery
29.2.3.1 Timing of Definitive Surgery
Timing of definitive surgery to retrieve the dropped nucleus is determined on an individual case basis [38–41]. Delayed vitrectomy can result in the development of glaucoma and corneal edema. Blodi et al. [42] reported glaucoma (elevated IOP) in 60 % of eyes undergoing vitrectomy for removal of retained lens matter after 3 weeks. Margherio et al. [22] found an increased incidence of retinal detachment associated with delayed vitrectomy due to persistent vitreous traction aggravated by prolonged inflammation.
The eye can tolerate small amounts of soft cortical matter, and hence these patients can be safely observed with a vigilant watch for development of raised IOP or evidence of intraocular inflammation. In all other situations, the chance of chronic intraocular inflammation and raised IOP is very high. A vitreoretinal specialist’s availability to team up with the anterior segment surgeon at the same surgery or on the same day is ideal, both emotionally for the patient and structurally for the eye. For the patient, it avoids going through two postoperative periods for achieving the final best visual result. However, if vitreoretinal facility is not immediately available, an honest communication with the patient, good counseling, and appropriate referral to a vitreoretinal facility will almost always ensure a happy patient outcome. Vitrectomy for removal of dislocated nuclear fragments can be delayed up to 3 weeks without significant difference in the visual and functional results. However, delaying vitrectomy for removal of dislocated nuclear fragments indefinitely will almost always result in limited visual recovery and a higher incidence of recalcitrant glaucoma and retinal detachment.
Some cases may have to be delayed to permit clearing of corneal edema for adequate visualization for vitrectomy. However, in cases with markedly elevated IOP refractory to medical management, urgent surgical intervention is necessary.
The following information should be included while referring the patient for vitreoretinal intervention.
Amount/type/hardness of retained lens material
Presence/absence of IOL implant
Assessment of capsular support
Calculated IOL power
The vitreoretinal surgeon should assess the patient thoroughly prior to taking up the case and make his own judgments about the amount and hardness of the nucleus fragment and the urgency with which the intervention should be performed. The following factors should also be assessed:
- a.
Integrity of cataract wound should be verified.
- b.
Slit-lamp evaluation to assess corneal clarity, grade the degree of anterior chamber inflammation, and check the applanation IOP.
- c.
Indirect ophthalmoscopy should be performed to assess the nuclear fragment as well as to exclude peripheral retinal tears, retinal detachment, or choroidal detachment.
- d.
In eyes where presence of media haze (corneal edema, anterior soft cortical matter in pupillary area, or associated vitreous hemorrhage) precludes fundus visualization, a B- scan ultrasonography should be performed to evaluate the integrity of the posterior segment and rule out the presence of retinal detachment or choroidal detachment. The dislocated lens fragment may appear hyperechoic and show acoustic shadowing.
29.2.3.2 Surgical Procedure
A three-port pars plana vitrectomy is the procedure of choice and is today the standard of care for patients with posterior dislocated lens fragments. Hybrid or mixed gauge vitrectomy is performed with the active 20 G port for introduction of the larg-bore fragmatome [37–39]. A fragmatome is similar to a phaco probe without an infusion sleeve, and it cannot cut the vitreous. Hence, a complete vitrectomy should be performed before using the fragmatome for nucleus removal. This can be aided by the use of triamcinolone acetonide to delineate the posterior hyaloid face and for the induction of a posterior vitreous detachment (PVD) [40–42].
Soft nuclear or fluffy cortical fragments can be cut and aspirated with the vitreous cutter. The endoilluminator can be used to crush the fragments against the cutter and feed them into the cutting port [43–45].
For harder nuclear material, the fragmatome is used. Prior to phacofragmentation, majority of surgeons will introduce a small amount of perfluorocarbon liquid (PFCL) into the vitreous cavity to cover the macula and float the fragments away from the retinal surface [46]. This helps to protect the macula from fragments that tend to fall back during phacofragmentation. The settings for the fragmatome include a pulse mode with 10–20 pulses/min, 20–50 % power depending on the hardness of the nucleus, and a vacuum of 150–200 mmHg, as well as a high bottle height to prevent hypotony as higher flow rates are necessary to meet the demands of aspiration through the wider-bore fragmatome. Small fragments stuck to the retinal surface or entrapped in the vitreous base should be removed. Any residual vitreous at the vitreous base should be excised to eliminate traction, and the retinal periphery should be scrutinized in detail for any retinal tears or detachment (Fig. 29.3a–d).
Fig. 29.3
(a) Intraoperative still photograph showing a large chunk of hard nucleus in the pupillary space in the process of descending into vitreous cavity. Note that a small pupil has been enlarged with iris hooks. (b) Pars plana vitrectomy performed in the same sitting. A thorough vitrectomy is essential. (c) Injection of a small amount of perfluorocarbon liquid into the vitreous cavity to protect the retina from dropping fragments during phacofragmentation. (d) Phacofragmentation in progress
In cases with dislocated black cataract where a prolonged and difficult phacofragmentation is anticipated or when visualization is impaired by corneal edema, the nucleus can be floated up to the pupillary space using PFCL and delivered out through the enlarged phaco incision [46].
At the end of the procedure, the PFCL introduced into the vitreous cavity should be aspirated, and laser retinopexy should be performed to any retinal tears detected intraoperatively
29.2.3.3 The IOL Options
The IOL options are reassessed at the completion of lens removal. If adequate capsular integrity/support is present, a three-piece PC IOL can be implanted into the sulcus with optic capture through the capsulorhexis [47, 48]. The options available in the absence of capsulozonular support include:
- 1.
AC IOL implant [49, 50] in the eyes of older patient with normal anterior segment and angle anatomy as well as normal endothelial count. The surgical procedure is short, simple, and avoids placement of complicated scleral sutures and the risk of suture erosion at a later date. New generation open-loop, quadriflex design of AC IOLs, if properly handled, are rarely associated with complications such as pseudophakic bullous keratopathy (PBK), uveitis glaucoma hyphema (UGH) syndrome, etc.
- 2.
- 3.
Scleral-fixated PC IOLs are a good option in younger patients, and their use lessens future corneal endothelial damage and iris irritation. Sutured scleral fixation by the four-point technique using the nonbiodegradable gore-tex suture [53], with the externalized knot securely placed within the dissected Hoffman’s pouch [54], ensures stable fixation with lesser chance of suture erosion and associated complications. Sutureless scleral fixation technique, popularized by Gabor Scharioth [55] and modified as “glued IOL” surgery by Agarwal et al. [56], is also a good option in the hands of an experienced surgeon (Fig. 29.4a–c). These techniques are described in detail in another chapter.
Fig. 29.4
(a–c) Intraoperative still photograph during vitrectomy to reposit a dislocated PC IOL by the sutureless intrascleral haptic fixation technique. (a) Dislocated PC IOL lying on the retinal surface after vitrectomy. (b) Exteriorizing the haptics of the PC IOL by “handshake” method. (c) Haptic tuck into a groove made using a 26-gauge needle
29.2.3.4 Management of Associated Complications
- a.
Intraocular inflammation: The lens protein causes severe intraocular reaction when exposed to the ocular environment, as it is an immunologically protected protein, meant to be confined within the lens capsule. The severity of the reaction is usually directly proportional to the volume of lens matter retained in the vitreous cavity, the extent of intraoperative manipulations, and also to the individuals’ inflammatory response [57]. Topical steroids and NSAIDs are used to combat inflammation along with cycloplegics.
- b.
Glaucoma: Nearly 50 % of patients undergoing pars plana vitrectomy for retained lens matter have elevated IOP [42]. Patients in whom vitrectomy for removal of retained nuclear fragments was delayed for more than 3 weeks for various reasons have shown a higher incidence of elevated IOP on long-term follow-up. The presumed mechanism for development of elevated IOP in eyes undergoing delayed vitrectomy could be due to clogging of trabecular meshwork with lens protein, macrophages, and other inflammatory cells. Even though removal of retained lens material will control IOP in majority of cases, it is not uncommon that some eyes will require long-term glaucoma medications and/or glaucoma procedures. It is noteworthy that elevated IOP occurs despite attempted prophylaxis with slow-release acetazolamide. Other factors contributing to elevated IOP are retained OVD and increased release of inflammatory mediators due to extrasurgical manipulations [6]. There have been reports of recalcitrant secondary glaucoma due to retained OVD in vitreous after its usage to tamponade posterior capsular rupture [7].
Hence, it is important to ensure that as much of the residual viscoelastic and soft lens matter is cleared from the anterior chamber during the primary surgery. The importance of reviewing patients with PCR on postoperative day 1 and anticipating IOP rise is highlighted by these reports.
Other causes of ocular hypertension after cataract surgery include pigment dispersion secondary to sulcus placement of the IOL, particularly if a single-piece acrylic lens is used, and also steroid responders who develop raised IOP secondary to postoperative steroid eyedrops. The rise in IOP in the steroid responders will settle after discontinuation of topical steroids, but those in the former group will often require antiglaucoma medication or even surgery in more extreme cases.
- c.
Corneal Edema: It is seen in almost 33–85 % of patients with retained nuclear fragments [17, 22, 42, 58, 59]. Increased intraoperative manipulation, postoperative intraocular inflammation, and elevated IOP are the three important factors contributing to the development of corneal edema. With appropriate management of the postoperative inflammation and measures to control the elevated IOP, the corneal edema usually clears.
- d.
Retinal Tears and Retinal Detachment (RD): The incidence of RD increases from ≤1 % in uncomplicated cataract surgery to 6.8–8 % after a complicated cataract surgery with PCR [60]. The incidence of RD associated with retained nuclear fragments is even higher and has been reported to vary from 4 to 16 % [60–62]. RD can develop intraoperatively at the time of cataract surgery or in the early postoperative period. It can also develop after pars plana vitrectomy to remove dislocated nuclear fragments. In a series which reported the highest rates of RD (16 %), 40 % of the RD were seen during and 60 % after pars plana vitrectomy [63]. Attempts to retrieve the dropping nuclear fragment using lens loop or trying to flush it out by irrigating into the vitreous cavity can cause traction on the vitreous base and development of retinal tears at the periphery or a giant retinal tear intraoperatively [22, 58] (Fig. 29.5). In a series published by Margheiro et al., 43 % of the detachments occurred after vitrectomy, among which 75 % were diagnosed within 1 month after surgery and 50 % were diagnosed after 3 months [22]. After a thorough pars plana vitrectomy with excision of vitreous base, PFCL is injected to float up the dislocated nuclear fragments and flatten the retina mechanically. The dislocated nuclear fragments can be removed using phacofragmentation in the anterior vitreous. The responsible retinal tear is lasered, and a PFCL-air exchange with nonexpansile mixture of air-C3F8 tamponade or PFCL-SO exchange is performed.
Fig. 29.5
Fundus photograph of a patient with pseudophakic rhegmatogenous retinal detachment caused by a large irregular tear. This patient had a complicated cataract surgery with PCR and dropped nucleus
- e.
Vitreous Hemorrhage: It has been reported with attempts to flush out the dislocated nuclear fragments by posterior irrigation into the vitreous cavity [64].
- f.
- g.
Dislocated IOL with Retained Lens Material: Posteriorly dislocated IOL along with retained nuclear material can occur if the surgeon fails to recognize the presence of a rent in the posterior capsule or if the PC IOL is incorrectly positioned. The IOL removal or repositioning is performed after fragmentation and removal of the dislocated nuclear fragments. A three-piece IOL can be grasped with the vitreous forceps and manipulated into the ciliary sulcus, if adequate capsular support is present. In the absence of adequate capsular support, the haptics can be exteriorized and placed in a scleral tunnel in the bed of a partial thickness scleral flap to achieve sutureless scleral fixation. Prior dissection of the scleral flaps is necessary for this procedure. Single-piece IOLs or IOLs with broken haptics and plate-haptic IOLs are generally explanted and replaced with an appropriate IOL as previously described.
29.2.3.5 Visual Outcomes
In eyes with retained lens fragments, a final visual acuity of 20/40 or better is achieved in 56–72 % and is increased to 80 % when preexisting vision-limiting ocular pathology is excluded [60, 65]. Eyes with softer nonnuclear retained lens fragments have better outcomes than eyes with harder retained nuclear fragments. Vanner et al. [41] have reported that 78 % of eyes with nonnuclear fragments obtain 20/40 or better vision, compared to only 39 % of eyes with retained nuclear fragments.
29.3 Dislocated Posterior Chamber Intraocular Lens
Early postoperative dislocation is caused by placing part or all of the IOL through the PCR into the anterior vitreous. When dislocation occurs more than a few days or weeks after surgery, it is attributed to spontaneous IOL haptic rotation away from the meridian of posterior capsular remnants. The severity of visual symptoms depend on the degree of decentration and can vary from mild glare to gross visual loss with aphakic pupil and a large floater-like symptom in eyes with a mobile dislocated PC IOL. Preoperatively, prior to the definitive surgery for management of dislocated IOLs, it is absolutely essential to assess the degree of intraocular inflammation and judge if ≥6 clock hours of capsular support, half of which is in the inferior quadrant, is present for PC IOL implantation. The decision to explant or reposition the dislocated IOL is influenced by the presence or absence of adequate capsule-zonular support. The IOL options available to the surgeon have already been discussed (Sect. 29.2.3.3).
A dislocated IOL can produce complications such as corneal edema, recurrent intraocular inflammation, retinal detachment, cystoid macular edema, and glaucoma, all of which form relative indications for vitreous surgery. It is important to perform a total vitrectomy after inducing a PVD. All vitreous adhesions to the dislocated IOL should be removed. It is necessary to ensure that the IOL is freely mobile and lying on the retinal surface before attempting its removal. Use of PFCL injection is rarely necessary unless the dislocation is associated with retinal detachment. In this situation, PFCL ensures mechanical flattening of retina, and hence the maneuvers within the vitreous cavity can be accomplished with ease without traumatizing the retina and also with no risk of the IOL falling back on to the retinal surface.
The final visual outcome in these eyes depends to a great extent on the preoperative macular function and on the presence of complications associated with previous surgery such as CME and RD. A final visual outcome ≥6/12, varying from 59 to 94 % of cases, has been reported in various studies [66–70].
29.4 Pseudophakic Cystoid Macular Edema (PCME)
PCME is the commonest cause for unexpected visual loss after cataract surgery. The incidence of PCME has declined with the advent of phacoemulsification, but is still a prevalent morbidity due to the sheer volumes of cataract surgeries performed each year. Intraocular surgery, even an uneventful one, is a powerful proinflammatory event. The incidence of clinical PCME in uncomplicated cases varies from 0.1 to 4 %, and the incidence varies when the diagnosis of PCME is made by OCT evaluation (4–11 %) or by fluorescein fundus angiography (9–19 %) (Fig. 29.6) [71–74].
Fig. 29.6
(a) Fluorescein fundus angiographic appearance in PCME showing the classic “flower petalloid” appearance, (b) OCT image demonstrating cysts
A complicated cataract surgery with additional tissue manipulations and prolonged operating time is associated with increased intraocular inflammation and CME risk. The incidence of PCME in eyes with PCR and vitreous loss has been reported as 21–46 % [71, 72]. The pathogenesis of PCME [73–76] is multifactorial, and the three core proposed etiological factors include inflammation, vitreous traction, and hypotony. Surgically induced anterior segment inflammation results in the release of endogenous inflammatory mediators such as prostaglandins, cytokines, and other vasopermeability factors that disrupt the perifoveal retinal capillaries, resulting in fluid accumulation.
Presence of PCR, iris trauma, vitreous loss, retained lens fragments, and prolonged operating time are all predispositions which result in multiple insults to the vascular permeability and retinal homeostatic mechanisms, resulting in an increased risk of developing PCME [71]. Selection of intraocular lens also plays a role in PCME development. Iris-fixated IOLs have a highest reported rate of PCME, and AC IOLs have a higher rate than PC IOLs [71].
29.4.1 Diagnosis and Clinical Course
PCME peaks at 4–6 weeks postoperatively. The most common presentation is as blurry vision after having enjoyed good vision for 4–6 weeks postoperatively. Symptoms may manifest as early as 2 weeks postoperatively. The patient may complain of a “washed-out” appearance in poor contrast situations. Less common presentation is as central scotoma, metamorphopsia, or mild photophobia. The diagnosis of PCME [77] can be confirmed by slit-lamp biomicroscopic examination with fundus contact lens and red free light (cystic changes, retinal thickening, loss of foveal depression, and optic disk swelling in rare cases), fluorescein fundus angiography (typical flower petalloid appearance), or OCT evaluation. The treatment response can be conveniently monitored by biomicroscopy, visual acuity, and OCT. OCT also helps in identifying other predisposing macular factors such as presence of vitreomacular traction, presence of epiretinal membrane (ERM), or a lamellar macular hole [78]. Spectral domain OCT has emerged as a sensitive tool for detecting and monitoring PCME. OCT usually demonstrates cystic spaces in the outer nuclear and outer plexiform layers. Sometimes, intraretinal thickening is present on OCT that lacks the distinct intraretinal cystic pattern. Detachment of neurosensory retina with the presence of subretinal fluid is also seen.
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