Sr. No
Condition
Mechanism
Morphology
1.
Posterior polar cataract
Inherent weakness and thinning of posterior capsule with enlargement of opacification [18]
Central, vertically oval defect, thick fibrosed margin [5]
2.
Congenital cataract
Anomalous attachment of Weiger’s hyaloidocapsular ligament to posterior lens capsule
Central, large (8–9 mm) defect with attached ligament
Posterior lenticonus
Central, thin margins, associated with lens abnormality
Intrauterine trauma
Irregular, thin margins, associated with vitreous prolapse
Persistent hyperplastic primary vitreous (PHPV)
Central, thick margins, fibrovascular attachment of a stalk from the optic disk [19]
Idiopathic
Central, thick margins, chalky white spots on the capsule and floating in vitreous (fish-tail sign) [20]
3.
Trauma
Penetrating ocular trauma (direct effect)
Type 1: Thin cataract, irregular, thick margins; size does not change [12]
Type 2: Thin, transparent margins; rapidly enlarge during surgery [12]
Blunt ocular trauma (equatorial expansion)
Central, oval/circular, thick, fibrosed edges [5]
6.3 Recognition of Preexisting PCR
6.3.1 Clues in the Clinic
Often, careful slit-lamp biomicroscopy can help in the identification of a preexisting posterior capsular defect. Every patient with irregular posterior capsule must be carefully examined for any discontinuity in the posterior capsule or signs of vitreous prolapse in the anterior chamber.
In a patient with PPC, careful observation of the central posterior opacity can provide clues to the integrity of the posterior capsule (Fig. 6.1). In a patient with PCR, a horizontal or vertical oval defect will be seen posterior to the onion-skinned central opacity in the lens. There may be tiny refractile lens particles floating in the anterior vitreous [21, 22].
Fig. 6.1
Slit-lamp biomicroscopy examination of a patient with posterior polar cataract demonstrates a well-defined central defect in the posterior capsule before surgery. The posterior slit beam is seen to bend posteriorly, and discontinuity of the beam is evident
In patients with traumatic cataract, due to the nonvisualization of the posterior capsule, it may not be possible to detect the tear in the posterior capsule prior to surgical intervention. These tears largely remain underdiagnosed until during surgery. Traumatic cataracts may be associated with the rupture of the hyaloid face and luxation of nuclear material into the vitreous cavity. Clues such as presence of intraocular inflammation, vitreous prolapse into the anterior chamber, and rise in intraocular pressure can guide further investigations to diagnose PCR prior to surgery [5].
6.3.2 Imaging to Detect PCR Before Surgery
6.3.2.1 Ultrasound B-Scan and Ultrasound Biomicroscopy
In cases where the view of the posterior capsule is obscured, imaging with ultrasound (USG) B-scan or water immersion ultrasound biomicroscopy (UBM) can help in the diagnosis of posterior capsular tears [9]. Often, trauma may result in distortion or appearance of discontinuity of the posterior lens capsule. This can be confirmed with UBM or USG B-scan. Various probes have been used for this purpose, including 10, 20, 35, and 50 MHz probes [9, 23–25]. With higher frequencies, the penetration of the ultrasound waves diminishes, though better resolution images may be obtained. In such a situation, 20 or 35 MHz probes may be suited to determine the presence of discontinuity in the posterior capsule. Tabatabaei et al [24] have shown a sensitivity of 93 % and specificity of 86 % for the evaluation of posterior capsular tear using 20 MHz ultrasonography. Ultrasonography can also be used to detect the presence of dislocated nuclear fragments in the vitreous cavity.
The drawbacks of ultrasound imaging include the need for topical anesthesia and a coupling fluid to ease the contact of the probe with the eye. UBM requires an immersion technique and patient cooperation. These techniques may not be possible in children or immediately following trauma. Due to lower resolution of ultrasound technology, smaller capsular defects may not be identified. Recognition of defects in the posterior capsule and finer details, including its size and location, requires expertise [9].
6.3.2.2 Anterior Segment Optical Coherence Tomography (OCT)
Newer imaging technologies such as anterior segment OCT provide us with improved image resolution and details for studying various intraocular structures such as cornea, angles, and iris. However, imaging of the posterior capsule of the lens may be limited due to poor penetration of the incident waves, especially in cataractous eyes. Good-quality imaging of the anterior capsule is possible with this technique, but images of the posterior capsule and zonules are largely nongradable [26]. In recent case series [27, 28], the authors have observed that a limitation of OCT was the inability to detect “true” capsular defects, as false-positive results can be obtained by overlaying dense lens opacity.
6.3.2.3 Scheimpflug Imaging
Scheimpflug imaging involving a rotating camera (Pentacam, Oculus, Germany) has been used in studying the crystalline lens [29, 30]. Using this technique, study of the lens thickness, posterior capsule, and its integrity is possible [31, 32]. However, in more than half of the patients with dense cataract, visualization of the posterior capsule may not be possible using this technique.
Since both OCT and Scheimpflug imaging are based on the optical principle, it is expected that their use in determination of integrity of posterior capsule may be limited, especially in cases where the cataract is dense. In a recent study comparing the three techniques, 20 MHz ultrasonography was found to be more accurate than AS-OCT and Scheimpflug imaging in predicting PCR preoperatively [33]. Figure 6.2 represents the techniques available to diagnose preexisting PCR.
Fig. 6.2
The flowchart represents various imaging techniques available to diagnose preoperative posterior capsular rupture. Analysis of images obtained by these techniques can help detect and characterize posterior capsular rupture prior to taking up the patient for surgery
6.4 Preoperative Surgical Considerations
A successful outcome in patients with complicated eyes due to PCR is likely in cases where adequate preoperative assessments are performed. It is important for the operating surgeon to take out time to carefully analyze the posterior capsule, presence, location and size of the PCR, if any, weakness or dialysis of zonules, and other ocular complications. Signs of comorbid ocular conditions such as posterior lenticonus (Fig. 6.3) and polar cataracts must be noted. The surgeon must make a note of the stability of the capsulozonular complex and presence of any lens matter floating in the vitreous [34]. Examination under dilatation using topical tropicamide and phenylephrine is essential. Indirect ophthalmoscopy and intraocular pressure evaluation must be performed. Careful consideration of intraocular lens implantation in the primary setting can be made at this stage.
Fig. 6.3
Two cases of posterior lenticonus. Panel (a) shows the slit-lamp examination of a patient with posterior lenticonus with protrusion of the posterior capsule into the vitreous cavity. Panel (b) shows slit-lamp examination of another case with posterior lenticonus, and the posterior capsule can be clearly identified
Adequate counseling and patient information are necessary. It must be advised to the patient that the surgery may be complicated, possibly requiring a vitreoretinal intervention and that intraocular lens (IOL) placement may not be possible until next surgical sitting [5].
6.5 Surgical Strategies for Management of Preexisting PCR
6.5.1 Extracapsular Cataract Extraction
With increasing surgical skills among surgeons performing phacoemulsification, the use of extracapsular cataract extraction (ECCE) technique is used much less frequently [35]. Phacoemulsification can be converted into ECCE at any stage during the surgery, especially if there is dislocation of nuclear fragments in the early stages of surgery, that is, capsulorhexis or nuclear sculpting [36]. The incisions can be enlarged, and the nucleus can be delivered using assisted techniques. In cases with vitreous prolapse, this step must be followed by adequate anterior vitrectomy through the limbal approach.
In patients with coexisting subluxation of the lens or severe zonulopathy, the surgeon may plan ECCE rather than phacoemulsification, depending on the surgeon comfort and experience [37]. ECCE can be also used in pediatric traumatic cataracts with good visual results [38]. A well-done ECCE can provide better results than a shabby phacoemulsification in these complicated eyes, especially following severe trauma [39]. Table 6.2 summarizes the situations that possibly favor ECCE over phacoemulsification.
Table 6.2
Guide to choosing extracapsular cataract extraction over phacoemulsification in eyes with preexisting posterior capsular tear
Inadequate surgeon experience |
Large subluxation of the lens (>9 clock h) |
Early dislocation of nuclear fragments into vitreous cavity during phacoemulsification |
Pediatric traumatic cataract |
Camp settings; unavailability of sophisticated instrumentation Hard cataract |
6.5.2 Posterior Approach: Pars Plana Surgery
In cases of trauma complicated by vitreous prolapse, dense cataract, possible dislocation of lens matter into the vitreous cavity, and vitreoretinal complications, such as hemorrhage, retinal detachment, or intraocular foreign bodies, initial posterior approach through the pars plana is probably the best [40–42]. Such cases are best left to vitreoretinal surgeons who can perform complete pars plana lensectomy and vitrectomy and treat the ocular complications. Implantation of IOL may not be possible in such circumstances at primary surgery. However, if other complications are taken care of, trans-scleral fixation of IOL may be possible once the eye is quiet [43].
In selected cases, anterior approach can be used to perform anterior capsulotomy and dry aspiration of the lens matter. This can be followed by vitrectomy either through the anterior or pars plana approach. Table 6.3 summarizes clinical scenarios where posterior approach may be the first choice for surgical approach.
Table 6.3
Examples of case scenarios where pars plana vitrectomy may be the first surgical choice in eyes with preexisting posterior capsular tear
Dislocation of >75 % nuclear fragment into the vitreous cavity |
Retinal detachment |
Intraocular foreign body |
Vitreous hemorrhage |
Choroidal detachment |
Large, vascularized persistent hyperplastic primary vitreous |
6.5.3 Anterior Approach: Phacoemulsification
Advances in surgical techniques, better understanding of phacodynamics, and operative devices with much improved software to handle surge during phacoemulsification by optimizing duty cycle have resulted in better results with this surgical modality. Phacoemulsification is the most commonly performed and preferred procedure to handle eyes with complicated cataracts.
The goal of performing phacoemulsification is to cause minimal disturbance of the anterior vitreous face and to successfully implant the IOL in the same sitting. The aim of the surgeon is to salvage the integrity of the capsulo-zonular complex as much as possible to minimize postoperative complications [5, 21].
The techniques and strategies of phacoemulsification with preexisting PCR depend on the etiology and morphological characteristics of the cataract, which can be highly variable from case-to-case. The surgeon must be prepared to modify the surgical technique based on the situation at the time of surgery [44–46].
6.5.3.1 Management of Anterior Chamber Configuration
The cornerstone of achieving a successful visual outcome in complicated eyes with PCR is maintenance of deep anterior chamber during phacoemulsification. Excessive billowing of the torn posterior capsule can lead to increase in the size of the tear by tractional forces. A cohesive viscoelastic can provide stability to the anterior chamber and prevent forward movement of the iris-lens diaphragm [47].
The maintenance of the anterior chamber depth is aided to a great extent by creating a triplanar self-sealing clear corneal incision. A valvular incision prevents leakage of anterior chamber contents during surgical manipulation [48]. In children, the preferred incision, however, is a valvular sclerocorneal incision, though often surgeons may create clear corneal incisions in older children due to less risk of bleeding and increased surgical ease [49, 50].
6.5.3.2 Hydroprocedures
In eyes with preexisting PCR, the surgeon must take precautions while performing hydroprocedures. There are several considerations before performing hydrodissection in the absence of integrity of posterior capsule. Cortical-cleaving hydrodissection must be avoided to prevent further extension of the tear in the posterior capsule [18, 22, 51]. In experienced hands, limited hydrodissection may be performed [47].
Hydrodelineation can be performed to separate the cortex from the epinuclear sheet [22, 47]. The epinucleus can act as a barrier preventing prolapse of the vitreous from the posterior segment. The mechanical cushion created by the epinuclear sheet allows phacoemulsification to proceed with minimal anterior hyaloid face disturbance. In eyes with traumatic posterior capsular dehiscence, controlled hydroprocedures using Simcoe cannula have been described [15]. In congenital cataracts, hydroprocedures can be avoided and the lens material aspiration can be performed without delineating the cortex from the epinucleus in very young children [52, 53]. The technique of “inside-out delineation” can be performed in eyes with posterior polar cataracts [54].
6.5.3.3 Division of the Nucleus
In the presence of a ruptured posterior capsule, the phacoemulsification must begin with low-flow parameters. The bottle height is usually maintained at 30–40 cm above the patient’s head, and flow rate is maintained at 10–15 cc/min [55]. Insertion and removal of intraocular instruments must be smooth, without allowing excessive fluctuations in the anterior chamber depth or distortion of the corneal incision.
It is imperative to avoid rotation of the nucleus in cataracts with preexisting PCR. The management of nucleus depends on the age of the patient and the etiology of the cataract. For adult patients, there must be an effective strategy to divide the nucleus to proceed with the surgery.
Management Strategies in Posterior Polar and Traumatic Cataract
The division of nucleus in cases with torn posterior capsule must avoid excessive capsular stress. There may be a tendency of the nucleus to slip into the posterior segment through the PCR if accurate and precise surgical maneuvers are not performed. Prior to beginning the phacoemulsification, a dispersive viscoelastic, such as VISCOAT, may be used to coat the defect in the posterior capsule [56]. This may allow temporary plugging of the PCR [5]. If there is significant vitreous bulge, the authors suggest initiating two-port anterior vitrectomy prior to inserting the phaco probe. Phacoemulsification should be performed in the absence of vitreous in the anterior chamber to avoid tractional forces on the retina.
Minimal stress may be achieved by dividing the nucleus with the phaco-chop technique. Direct chop techniques are more suitable than stop-and-chop, which require more nuclear fragment manipulation and rotation. Various other nuclear fracture techniques include Gimbel’s nucleofractis [57], bevel-down phacoemulsification [58], and V-style phacoemulsification [59]. It is important to use a second instrument, such as a manipulating “y” instrument, to prevent the drop of the nuclear fragments into the vitreous cavity. Alternatively, Sheet’s glide may also be used. In the experience of the authors, many cases with trauma may present with a soft cataract that may not be amenable to conventional division techniques. These can be directly emulsified with the phaco probe. The cannula of the viscoelastic agent may be used to separate partially cleaved nuclear fragments with a bimanual technique. Vajpayee et al. [60] have described a technique of layer-by-layer phacoemulsification in eyes with preexisting PCR, secondary to posterior polar cataract. Table 6.4 provides clinical pearls in the management of the nucleus in preexisting PCR.
Table 6.4
Clinical pearls in the management of nucleus in eyes with preoperative posterior capsular dehiscence
Choose more advanced phacoemulsification device and operating microscope with superior optics |
Have the setup ready for anterior vitrectomy |
Choose peribulbar anesthesia |
Create a valvular, self-sealing corneal incision |
Avoid hydroprocedures |
Surgery to begin with low-flow parameters |
Perform in situ phacoemulsification |
Use nuclear fracture techniques that minimize stress on capsule |
Adequate and timely use of dispersive and cohesive viscoelastic material |
Use of second instrument to prevent nuclear dislocation |
Avoid chasing the nucleus with the phaco probe |
Do not panic, and do not hesitate to seek help |
Management Strategies in Congenital Cataract
The challenge of pediatric cataract surgery is further compounded by the presence of a preexisting PCR. Preoperative assessment may not resemble intraoperative findings due to difficulty in imaging the posterior capsule. The surgeon must approach each case of congenital cataract where the density of the cataract does not allow adequate visualization of the posterior capsule with precaution, similar to that exercised with a torn posterior capsule.
The lens matter must be carefully and slowly aspirated using bimanual irrigation and aspiration (I/A) using low-flow parameters. We recommend a bottle height of no more than 70–80 cm above the head of the patient. The vitrector must be handy to perform “cut-I/A” in the presence of vitreous strands in the anterior chamber. The aspiration of lens matter must be completed, usually requiring periodic insertion of the vitrector in the chamber using the “I/A-cut” mode.
6.5.3.4 Management of Epinucleus, Cortex, and Posterior Capsule
Usually, the epinuclear plate separates on its own from the posterior capsule after removal of the nucleus. In case the epinucleus is not separated, the technique of viscodissection [47] may be used. Slow separation of the epinucleus prevents vitreous herniation through the PCR. Viscoelastic material (Healon GV®) acts as a cushion beneath the epinucleus and must be generously used. In posterior polar cataracts, the central epinucleus should be the last to separate. If the surgeon is comfortable, multiquadrant hydrodissection can be performed at this stage to separate the epinucleus circumferentially.
The cortex can be removed with the anterior vitrector. The surgeon can shift from cut-I/A to I/A-cut settings, performing one step after another, that is, vitrectomy followed by cortex removal and shifting back to vitrectomy as and when required. This technique is very useful in pediatric cataracts.
In most cases of trauma, the posterior capsule is likely to be torn in an irregular fashion. These tears can have leading edges that can progressively widen, resulting in the enlargement of the dehiscence. Converting PCR into posterior continuous curvilinear capsulorhexis (PCCC) using Utrata forceps minimizes radial forces and stabilizes the posterior capsule [61]. For tears with thick, fibrosed margins (e.g., type 1 tear following trauma), capsulotomy can be performed with the vitrector. Type 2 posterior capsular tear can be converted into PCCC using forceps alone, after flattening the capsule with high-viscosity viscoelastic such as Healon GV [5]. A similar approach is possible in posterior polar cataracts.
PCCC in children improves postoperative visual acuity by preventing development of posterior capsular opacification. We perform PCCC routinely in children under 6 years of age [62, 63]. In children with preexisting PCR, PCCC may act in a similar manner, apart from preventing intraoperative increase in size of the tear. Either Utrata forceps or anterior vitrector [64, 65] may be used to create the PCCC. In eyes with PHPV, the retrolental tissue may be removed using vitrector along with a trocar, taking care to aspirate the bleeding encountered [66].
6.5.3.5 Management in Cases with Luxation of Nuclear Material
If large nuclear fragments are dislocated into the vitreous cavity with vitreoretinal complications, pars plana vitrectomy and phacofragmentation of the nuclear material appear to be the most suitable surgical approaches [67].
There can be dislocation of nuclear fragments into the vitreous cavity before the beginning of phacoemulsification, intraoperatively. A sinking nucleus may be managed by posterior assisted levitation, by inserting a spatula through a pars plana incision, placing it behind the nucleus [68]. In case a large chunk of the nucleus is lost into the posterior segment, it is not advisable to chase the piece with the phaco probe [69]. The surgeon must keep in mind that the phaco probe does not replace the action of a guillotine vitrector required for this purpose. The remaining cortical matter can be removed, followed by implantation of IOL, and three-port pars plana vitrectomy by a vitreoretinal surgeon can be performed in the same setting if possible [70]. If it is not possible to perform vitrectomy at the same sitting, a secondary procedure may be planned without much delay to prevent glaucoma and cystoid macular edema [71].
6.5.3.6 Management of Vitreous
In eyes with preoperative PCR, the anterior hyaloid face could be ruptured, and there could be a significant amount of vitreous in the anterior chamber. The surgeon may use intraoperative stains such as preservative-free triamcinolone acetonide to identify the vitreous strands and possibly decrease postoperative inflammation [72]. Therefore, the management of vitreous in such cases is a continuous, dynamic process and may begin soon after entering the anterior chamber.
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