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Management of Posterior Capsule Rent: Various Case Scenarios

  • Sudeep Das
  • Mathew Kurian
  • Purnima Raman Srivatsa
  • Nikhil Negalur
Chapter

Abstract

Posterior capsule rupture (PCR) along with corneal endothelial decompensation constitutes one of the commonest complications of cataract surgery with vision-threatening consequences [1]. Vitreous loss as a consequence of PCR is a dreaded intraoperative complication of cataract surgery. If not managed appropriately, it can have disastrous consequences such as endothelial decompensation, retinal detachment, endophthalmitis, recurrent uveitis, intractable glaucoma, and severe visual disability including blindness. According to various studies, the incidence of PCR varies from 0.5 to 7.5 % [2, 3] and has shown a progressive decline with the evolution of surgical techniques and technology used in cataract surgery. Owing to the surgical learning curve, PCRs are more common among beginner surgeons [4]. Cataract surgery has seen tremendous evolution since Susruta described couching, more than 3000 years ago [5]. Extracapsular cataract extraction (ECCE), first performed by Jacques Daviel in Paris in 1747, dominated till the early 1900s. Intracapsular cataract extraction (ICCE) was introduced by Smith in 1880 [6]. The subsequent decades saw the development of the classic sutured large-incision extracapsular cataract extraction, phacoemulsification, and manual small-incision cataract extraction [7].

Keywords

Anterior Chamber Cataract Surgery Cystoid Macular Edema Posterior Capsule Anterior Vitrectomy 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

11.1 Introduction and History

Posterior capsule rupture (PCR) along with corneal endothelial decompensation constitutes one of the commonest complications of cataract surgery with vision-threatening consequences [1]. Vitreous loss as a consequence of PCR is a dreaded intraoperative complication of cataract surgery. If not managed appropriately, it can have disastrous consequences such as endothelial decompensation, retinal detachment, endophthalmitis, recurrent uveitis, intractable glaucoma, and severe visual disability including blindness. According to various studies, the incidence of PCR varies from 0.5 to 7.5 % [2, 3] and has shown a progressive decline with the evolution of surgical techniques and technology used in cataract surgery. Owing to the surgical learning curve, PCRs are more common among beginner surgeons [4]. Cataract surgery has seen tremendous evolution since Susruta described couching, more than 3000 years ago [5]. Extracapsular cataract extraction (ECCE), first performed by Jacques Daviel in Paris in 1747, dominated till the early 1900s. Intracapsular cataract extraction (ICCE) was introduced by Smith in 1880 [6]. The subsequent decades saw the development of the classic sutured large-incision extracapsular cataract extraction, phacoemulsification, and manual small-incision cataract extraction [7].

Dr. Harold Ridley started the intraocular lens (IOL) era with a posterior chamber IOL implantation in 1949 [8]. Due to various design-related problems with that IOL, iris-fixated IOLs and anterior chamber IOLs were developed before well-designed posterior chamber intraocular lenses (PCIOL) became the standard. Once these lenses came into vogue, preserving the posterior capsule (PC) became of utmost importance. The biggest advance toward stable fixation of PCIOLs came when Howard V. Gimbel and Thomas Neuhann independently developed the continuous circular capsulorhexis (CCC) [9]. Gimbel further went on to develop the posterior continuous curvilinear capsulorhexis (PCCC) [10] to convert a PCR into a circular opening which allowed stable fixation of an intraocular lens, either in the bag or in the sulcus with an optic capture.

Vitreous as an anatomical entity was known to eye surgeons for centuries, but its importance during cataract surgery was not known till the mid-twentieth century. The management of vitreous disturbance during intracapsular cataract extraction was first described by Maumenee in 1957 [11, 12, 13]. This involved picking up vitreous strands and cutting them, followed by sweeping the wound clean with a spatula. Kasner in 1968 described “open-sky vitrectomy” using Weck-Cel sponges [11]. He was the first to show that the eye could survive the replacement of large amounts of vitreous with physiological saline. Machemer in 1971 introduced an instrument which could cut vitreous and simultaneously replace it with physiological saline [14, 15]. This cutter was the precursor to many similar “vitreous infusion suction cutters” (VISC). These were mostly coaxial systems which gradually gave way to the bimanual cutters of the present day in which the irrigation handpiece is separate from the cutting and aspirating handpiece. Most modern phacoemulsification systems nowadays come with a high-speed pneumatic or electric cutter with cut speeds varying from 2500 to 4000 cuts per minute.

11.2 Recognition of PCR

There are numerous predisposing factors [16] for the development of PCR, and these are discussed elsewhere in this book. The commonest ones among the numerous factors are posterior polar cataract, brunescent cataracts, mature cataracts, soft cataracts, high myopia, and nondilating pupils including “intraoperative floppy iris syndrome (IFIS)” [17]. Prevention is better than cure. Hence, a detailed history, meticulous slit-lamp examination, and specialized imaging techniques such as anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM) will serve to detect many of these conditions prior to surgery.

Early recognition of PCR and proper management can provide the patient with an outcome that is as good as one with an uncomplicated surgery. The earliest and most definitive way of recognizing a PCR is seeing the margins of the PCR (Fig. 11.1). This sign along with the sudden appearance of a brilliant red glow are seen even before there is disturbance of the anterior hyaloid face. All the other signs follow vitreous prolapse into the anterior chamber. Signs of a posterior capsule rent include the following [18]:
Fig. 11.1

A small PCR (denoted by an arrow) is seen as an area with bright red glow and demarcated by the darker margins of intact PC

  • Recognizing the edges of the posterior capsule tear (Video 11.4).

  • Sudden localized brightening of the fundal glow.

  • Pupillary snap sign [19] where the pupil dilates and then suddenly constricts during hydrodissection. This has been described in detail later in this chapter [19] (Fig. 11.2).
    Fig. 11.2

    (a) Peaking of the pupil superiorly due to vitreous incarceration in the wound. (b) The pupil is round after vitrectomy

  • Sudden deepening of the anterior chamber (AC) due to vitreous prolapse into the AC.

  • Peaking of the pupil due to vitreous incarceration in the wound.

  • Wiping the wound with a Weck-Cell sponge will pick up strands of vitreous.

  • An air-bubble injected into the AC forms multiple bubbles instead of a single large one.

  • Failure of aspiration and loss of followability (Video 11.5) due to vitreous clogging the aspiration port.

  • Paradoxical movement of lens matter away from the aspiration port and lateral movement of the nucleus caused by hydration of vitreous surrounding the phaco needle.

  • Failure of rotation of a previously mobile nucleus due to vitreous entrapment and lack of capsular support.

  • Turbulence of the nuclear pieces during phacoemulsification due to traction on vitreous.

  • Tilting of a pole of the nucleus.

  • Sinking of the nucleus (Video 11.6) or nuclear pieces into the vitreous cavity. This can be dramatic in vitrectomized eyes where the nucleus literally drops like a stone on to the retina.

  • Feeling of “give way” or snap of the PC with loss of resistance.

  • It is important to trust one’s intuition during surgery. If there is even a suspicion of a PCR, it is prudent to verify the integrity of the posterior capsule before proceeding with the surgery.

11.3 Stages at Which PCR Is Common and Its Prevention

PCRs can happen at any stage of the surgery, right from creation of the wounds at the start of the surgery to the hydration of the wounds at the close of surgery. One of the authors had a PCR when the assisting nurse accidentally knocked his operating hand during the capsulorhexis. As a consequence, the needle perforated the entire lens and ruptured the posterior capsule! We have also encountered a PCR during hydrodissection when the cannula dislodged from the syringe, bounced off the angle, caused an iridodialysis and then ruptured the posterior capsule. Mercifully, the zonules remained intact in both cases. The highest incidence of PCR is seen during emulsification of the last nuclear fragment, especially in hard cataracts. The next most common occurrence is during posterior capsule polishing followed by cortical aspiration [20].

Here, we will deal with the surgical steps during which PCR is seen and the precautions to be taken.

11.3.1 Wound Construction

Careful construction of the incisions is often neglected by beginner surgeons. The keratomes used should be accurately matched with the diameter of the phaco needle and sleeve. A tight wound pinches the sleeve and reduces the flow of fluid into the eye, while the vacuum remains the same. This leads to an unstable AC and severe surge, increasing the chances of PCR. A tight wound is recognized by the difficulty in maneuvering the phaco tip, corneal striae, and, if not recognized early, by wound burn (Fig. 11.3). Once recognized, the tight wound can easily be increased to the right size with a keratome, and the problem is resolved. A large wound leaks (Fig. 11.4), and unless sutured or the bottle height increased, it causes shallowing of the AC, increasing the probability of PCR. When suturing the wound does not help, the wound is closed with sutures, and a fresh one is created at a new location. Side ports that are leaky either due to large size, short length, or tears of the roof should be sutured before continuing with phacoemulsification.
Fig. 11.3

Wound burn seen as an area of intense whitening of the cornea (a) and retraction (shrinkage) of the outer lip of the phaco wound (b). This is usually a consequence of a tight wound leading to constriction of the sleeve with reduced irrigation. This can lead to shallow AC, surge, and PCR

Fig. 11.4

A large leaking wound with BSS pouring out by the side of the phaco probe (a), and later, the iris prolapsing out (b). This can cause a shallow and unstable AC leading to a PCR. (c, d) The wound being sutured

11.3.2 Capsulorhexis

Improperly made or incomplete anterior capsulorhexis can lead to a host of intraoperative and postoperative complications. A small capsulorhexis is easily damaged during phacoemulsification either with the phaco needle or with the second instrument. A runaway capsulorhexis which could not be rescued could have an extension up to the equator at that point. A capsulorhexis that has been completed with a notch pointing to the outside (Fig. 11.5) is weak and can tear at this point. All these scenarios could, during phacoemulsification, lead to the anterior capsule tear extending across the equator into the posterior capsule causing a PCR. A less experienced surgeon would be better off converting to a manual small-incision cataract surgery (MSICS) or a standard extracapsular cataract extraction. A more experienced surgeon would be able to continue with phacoemulsification using a direct chop technique with minimal rotation and lateral stress on the capsule to try and avoid the tear from extending. It is important to prevent collapse of the AC by adjusting the fluidics parameters and by filling the AC with Ophthalmic Viscosurgical Device (OVD) before stopping irrigation.
Fig. 11.5

(a) Correct termination of the capsulorhexis with the notch pointing to the center. (b) Incorrect termination with the notch pointing outward. The latter can lead to an anterior capsule tear at this point which could extend into the PC

11.3.3 Hydrodissection

Hydrodissection is potentially fraught with danger for a beginner surgeon, and at times even the experienced ones. All of us have at some point or the other experienced that sinking feeling seeing the nucleus sink into the vitreous following hydrodissection. A small capsulorhexis adds to the risk of posterior capsule blow out. The ideal capsulorhexis should be around 5–5.5 mm so that it allows the escape of the fluid injected during hydrodissection, at the same time providing 360° coverage of the optic of the IOL by the anterior capsule margin. For a beginning surgeon, it is prudent to create a capsulorhexis which is around 6 mm in diameter. This makes the hydroprocedures safer and the nucleus removal maneuvers easier.

Howard Fine first described cortex-cleaving hydrodissection in 1992 [21]. A 26-gauge blunt cannula is inserted under the edge of the capsulorhexis, and the anterior capsule is tented up to lift it up from the underlying cortex. Fluid is now gently injected till a fluid wave is seen passing between the posterior capsule and the overlying cortex. At the same time, the entire lens bulges forward. At this point, the central part of the lens is depressed backward with the cannula; the trapped fluid is forced out cleaving the cortical-capsular adhesions at the capsular equator and under the anterior capsule. This maneuver can be repeated 6 clock hours away. Instead of performing a decompression, if more fluid is injected at this stage, either the edge of the lens prolapses out of the bag, or, more disastrously, the posterior capsule ruptures backward. I (SD) use an alternate technique (Fig. 11.6, Video 11.7), where I perform hydrodissection in one quadrant alone. On seeing the fluid wave crossing the midpoint of the lens, I move the cannula to the opposite pole of the lens, and gently nudge the nucleus backward and toward the site of injection. This creates more space for the fluid to escape out of the bag, thus making the procedure safer. In posterior polar cataract (PPC) and in cases of suspected preexisting PC dehiscence, hydrodissection should be abandoned altogether in favor of hydrodelineation, (Fig. 11.7 e) which preserves the cushion of the epinucleus.
Fig. 11.6

Cortex-Cleaving Hydrodissection. (ac) Injection of BSS under the anterior capsule. The advancing fluid wave between the posterior capsule and cortex is demarcated by arrows. (d) Release of the trapped fluid by pushing the lens backward and toward the site of fluid injection. The fluid escapes anteriorly from all sides, cleaving the cortex from the capsule. (e) Hydrodelineation by injecting BSS between the soft epinucleus and harder endonucleus denoted by the formation of a golden ring

The PC blow out is seen as a “pupillary snap sign,” [19] (Video 11.1) seen as dilatation of the pupil followed by a sudden and brisk constriction. The dilatation is caused by forward movement of the nucleus against the iris caused by the fluid trapped between the nucleus and the PC. The sudden constriction of the pupil happens at the exact time that the PC ruptures, allowing the nucleus to move backward into the vitreous. If this sign is overlooked, the nucleus is highly likely to drop into the vitreous cavity the moment phacoemulsification is started. If the nucleus is still in the patellar fossa or anterior vitreous, one can use a vectis or posterior-assisted levitation (described elsewhere in the book) to retrieve the nucleus into the anterior chamber. The wound is now extended and the nucleus prolapsed out. If the nucleus is in the midvitreous or beyond, it is best handled by a vitreoretinal specialist.

11.3.4 Nucleus Removal

The commonest cause of PCR during phacoemulsification of the nucleus is due to aspiration of the posterior capsule, often the equatorial part, with the phaco tip while removing the last bit of nucleus (Fig. 11.7 and Video 11.4). The second more common cause is due to the capsulorhexis margin getting accidentally cut by the second instrument or with the phaco tip itself [22]. This goes unnoticed most of the time, resulting in the tear extending beyond the equator into the posterior capsule. The former is prevented by reducing the fluidics parameters and injecting a dispersive OVD into the bag before removing the last nuclear fragment. The latter is prevented by staining the anterior capsule with trypan blue before the capsulorhexis, so that the capsulorhexis margin is clearly visible throughout the phacoemulsification, reducing the chances of inadvertent damage to it. If a capsulorhexis tear is noticed early, the tag is torn to complete it into a capsulorhexis again, preventing extensions during further maneuvers. While performing a vertical chop, one should stay within the capsulorhexis. While performing a horizontal chop which necessitates an excursion of the chopper up to the equator of the lens, it is necessary to scrape the surface of the lens while traversing distal to the capsulorhexis margin so as to not cut it.
Fig. 11.7

(a, b) A small round central PCR produced during emulsification of the last nuclear fragment. Vitreous prolapse can be prevented with the use of a dispersive OVD to plug the PC opening

11.3.5 Cortex Aspiration

Iatrogenic PCRs during irrigation-aspiration (IA) and PC polishing (Fig. 11.8 and Video 11.9) can be caused by poor-quality instruments with sharp edges. Hence, it is prudent to check the IA cannulae under the microscope before using them. The PC can get engaged in the aspiration port if high vacuum is used during PC polishing. This can be avoided by using low-to-moderate vacuum and aspiration flow rate (AFR) and by avoiding random movements while aspirating the cortex. Using silicone-tipped irrigation-aspiration handpieces reduces the incidence of PCR during cortex aspiration and PC polishing [23].
Fig. 11.8

(ac) Polishing the PC with instruments that have sharp edges can produce PCRs. They can also be produced if high vacuum is used during PC polishing and the capsule gets engaged in the aspiration port.

11.3.6 IOL Implantation

Most PCRs during IOL implantation occur due to a sudden uncontrolled ejection of the IOL from the cartridge (Fig. 11.9 and Video 11.10). The anterior chamber should be kept deep with OVD before IOL implantation. If the plunger of the IOL injector is anything but smooth at any stage of IOL implantation, it should be withdrawn from the eye, the IOL reloaded, and implantation re-attempted. An IOL shooting through the equatorial capsule into the vitreous can have serious consequences. Utmost care is needed while implanting three-piece IOLs. Wait for the optic to open fully after inserting the leading haptic into the bag, before dialing in the trailing haptic. The tip of the leading haptic points backward toward the PC before the optic opens, and if the IOL is implanted in a hurry, the tip may pierce the PC (Videos 11.11 and 11.12).
Fig. 11.9

(a, b) PCR seen due to inadvertent forceful ejection of the IOL from the cartridge during implantation.

11.3.7 Wound Hydration

This last step is not without risks. The cannula detaching from the syringe can enter the eye with considerable force, causing complications such as Descemet’s membrane detachment, PCR, IOL dislocation, and iridodialysis. This is avoided by using a properly fixed cannula on a Luer-locked syringe, and if not available, the hub of the cannula should be grasped firmly between the thumb and forefinger of one hand before injecting saline into the wound margins and the anterior chamber. Even if the cannula was to detach itself, it would still be held between these two fingers and not shoot into the eye.

Even after taking these precautions, surgeons will encounter a PCR sometime, and the next section will deal with its management.

11.4 Management of PCR

The surgical strategy to be followed depends on the stage at which the PCR occurs. If the PCR occurs right at the beginning of nucleus management, while sculpting or while performing the first chop, it is prudent to convert to a sutured ECCE at the same site or a sutureless manual small-incision cataract surgery (MSICS) at a different location. When the PCR occurs during the later stages of nucleus emulsification, an experienced phacosurgeon may still be able to continue with phaco, with the use of appropriate OVDs, but a less-experienced surgeon will have to convert.

The normal reaction on noticing a PCR is to immediately withdraw the instruments from the eye. As the irrigation suddenly stops, the AC collapses and the vitreous moves forward through the PCR, thereby enlarging its size. The sequence to be followed (Fig. 11.10 and Video 11.14) on realizing that there is a PCR is as follows:
Fig. 11.10

Sequence to follow on recognizing a PCR during phacoemulsification. (a) Stop phacoemulsification, but keep the irrigation on. (b) Withdraw the second instrument and inject a dispersive OVD through the same paracentesis. (c) Complete emulsification of the remaining nuclear fragment under cover of OVD. (d) Inject more OVD into the AC before withdrawing the phaco tip from the eye.

  • Stop phacoemulsification and aspiration immediately, but continue with the irrigation. In other words, one should move to position 1 on the foot pedal. The only situation when one keeps the aspiration on (remain on position 2) is when the PC opens up with a nuclear fragment held with vacuum at the phacoemulsification needle. Releasing the vacuum at this stage will cause the fragment to drop through the PCR. In these situations, the foot pedal should be kept in position 2 and OVD injected beneath the fragment, before releasing the foot pedal.

  • Take an OVD (preferably a dispersive one, but practically any one that is immediately at hand) in the nondominant hand and form the anterior chamber through the paracentesis. If possible, inject the OVD below the nuclear fragment before filling up the anterior chamber.

  • Once the anterior chamber has been stabilized, the phaco probe can be withdrawn from the eye.

  • Using the second instrument, move the nuclear fragments into a safe area that is away from the PCR. This would mean moving the pieces to an area of intact capsule or even in front of the iris.

  • Do not panic and say anything which may increase the anxiety or discomfort to the patient. Words like “rent” and vitreous “loss” are best avoided. Any negative interjection at this stage can also be detrimental.

  • Take stock of the situation. Check the position and extent of the PCR and at what stage of surgery it has happened. One should make a realistic assessment of one’s ability to manage the situation. One has to decide on whether to continue or seek help of a senior consultant if available. If one is able to continue, one should decide on which route one is comfortable with, that is, to continue with phacoemulsification or convert, type of vitrectomy, choice of IOL, etc.

  • Perform anterior vitrectomy if needed, complete the cataract surgery, and implant the correct choice of IOL.

  • The wounds will often require to be closed with sutures to prevent postoperative wound leak which would further compromise an already compromised outcome.

  • One cannot overemphasize the importance of protecting the corneal endothelium while trying to rescue the lens and performing anterior vitrectomy. Often, the delicate cornea is forgotten in the attempt to retrieve the lens leading to early or late surgery-induced corneal decompensation.

11.5 Posterior Capsule Rent Without Vitreous Prolapse

The steps taken to prevent enlargement of the PCR are as follows. The phacoemulsification and aspiration should be stopped immediately, but the irrigation is kept on (foot pedal position 1). It is important to stabilize the anterior chamber with a dispersive OVD before shutting off the irrigation and removing the phaco probe from the eye. This maintains positive pressure and prevents collapse of the AC, prolapse of vitreous, and enlargement of the PCR. A cohesive OVD is of no use in this situation. If there is a risk of the nuclear fragment falling through the PCR, the phacoemulsification is stopped, but the aspiration is kept on (foot pedal position 2) to hold the fragment at the tip, till OVD is injected below the nuclear fragment.

If the nucleus is soft and most of it has been removed, one can proceed with emulsification after moving the nuclear pieces to an area remote from the PCR. Copious amounts of a dispersive OVD are used to tamponade the vitreous and plug the PCR. As the emulsification proceeds, the OVD may need to be replenished to prevent the vitreous from prolapsing out. The bottle height or intraocular pressure (IOP), vacuum, and AFR have to be reduced during phacoemulsification in the presence of a PCR. This reduces turbulence in the AC, keeps the fragments close to the phaco tip, and reduces the probability of vitreous hydration. If there is still a large amount of nucleus left or it is hard, conversion to a manual ECCE procedure should be considered. An OVD is used to prolapse the nuclear pieces out of the eye. Once the nuclear pieces have been either emulsified or prolapsed out, the cortex is aspirated with bimanual IA handpieces with reduced parameters. By separating the irrigation from aspiration, one can keep the irrigation away from the PCR, but at the same time keep the AC under constant pressure, thus keeping the vitreous face behind the PC. Every time one removes either the phaco probe or the irrigation handpiece out of the eye, the AC should first be filled up with an OVD. Once the cortex has been aspirated, one should check for vitreous herniation by injecting a small amount of diluted triamcinolone acetonide [24] (40 mg in 1 ml). Anterior vitrectomy is done if needed, and an appropriate IOL is implanted. If vitreous prolapses into the anterior chamber at any stage, it should be removed before continuing with nucleus or cortex removal. This prevents traction on vitreous base with potentially disastrous consequences.

PCR during cortex removal can usually be managed without vitreous prolapse with judicious use of a dispersive OVD to plug the PCR. The same principle as above is used. Once the cortex has been removed, an appropriate IOL is implanted.

11.6 Posterior Continuous Curvilinear Capsulorhexis

A central or paracentral PCR with a tag can often be converted into a posterior continuous curvilinear capsulorhexis (PCCC) [10] as described by Gimbel. For this step, it is important to fill up the AC with just enough OVD to maintain a flat configuration of the PC. Overfilling the AC will result in the tag of PC being pushed into the vitreous cavity from where it will be difficult to retrieve. The microcapsulorhexis forceps are passed through the paracentesis, and the PC tag is held and torn to convert the PCR into the smallest circular opening possible (Fig. 11.11, Video 11.13). This is impossible if the PCR is close to the equator. The PCCC, like an anterior capsule capsulorhexis, is more resistant to tearing and allows IOLs to be safely implanted in the bag even in the presence of a PCR.
Fig. 11.11

(ae) Conversion of a central PCR into a PCCC using microrhexis forceps under cover of a dispersive OVD. (f, g) An IOL implanted in the bag following the PCCC.

11.7 Posterior Capsule Rent with Vitreous Prolapse

In a PCR with vitreous prolapse, a dispersive OVD is first injected before removing the phaco probe from the eye. The nuclear fragments are moved to a safe area with OVD. Bimanual vitrectomy is performed to remove the vitreous from the wounds and anterior chamber. Following vitrectomy, the management is the same as in the previous section. PCRs with vitreous prolapse are usually larger than ones without vitreous prolapse. A few may still be converted into PCCC following vitrectomy. Vitreous cannot be emulsified, and it will only result in traction on the vitreous base, which can lead to large retinal tears.

When the PCR happens early in surgery with most of the nuclear material present, it is safer to convert to a large-incision surgery such as ECCE or MSICS [25] to prevent the lens matter from dropping into the vitreous cavity. If the nucleus has already been divided into multiple pieces, they are best expressed out of the eye with an OVD. If there are one or two large nuclear pieces in the lens plane, an OVD is injected, and these pieces are removed with a wire vectis. One should resist the urge to fish for lens fragments from the vitreous cavity as this causes traction on the vitreous with serious retinal consequences. Nuclear pieces in the vitreous cavity are best removed in a posterior vitrectomy setup. Anterior chamber phacoemulsification can lead to permanent corneal endothelial decompensation and should not be performed.

11.8 Converting to Manual Small-Incision Cataract Surgery

MSICS is an elegant method of performing cataract surgery. Knowledge of MSICS can be of immense help in complicated situations such as following a PCR. The other option is to convert the phaco incision into a large sutured ECCE wound, but this tends to produce a more irregular wound and unpredictable postoperative astigmatism. An MSICS wound is sutureless, secure, easy to learn, reproducible, and produces predictable postoperative astigmatism. A more detailed description is included in another chapter in this book.

11.9 Mastering Anterior Vitrectomy

Before going on to the method of performing an anterior vitrectomy, it is important to understand the basic anatomy of the vitreous, the instrumentation, and the machine parameters.

11.9.1 Anatomy of Vitreous [26] (Fig. 11.12)

Fig. 11.12

Anatomy of the vitreous with the attachment to the vitreous base

The vitreous is composed of 98–99 % water, with a network of fine collagen fibrils and coils of the mucopolysaccharide acid. The vitreous is adherent to the margins of the optic nerve head, the macula, and the vitreous base which extends approximately 2 mm anterior and 4 mm posterior to the ora serrata. Thus, traction on the vitreous can lead to macular edema and retinal tears.

11.9.2 Instrumentation

Vitrectomy cutters are available as coaxial or bimanual irrigating and cutting systems. Coaxial cutters predate the bimanual ones (Fig. 11.13), are easy to set up, and use. Separating the irrigation from the vitrector has numerous advantages, and most modern machines allow only bimanual vitrectomy. As the irrigation is very close to the cutter in coaxial systems, the vitreous is pushed away from the cutter and more importantly gets hydrated. This can cause enlargement of the PCR and results in a large amount of vitreous being removed. In bimanual anterior vitrectomy (Fig. 11.14), the irrigation and cutting handpieces are introduced through separate paracenteses at the limbus. The irrigation maintains a positive-pressure tamponade on the vitreous, while the cutter can be introduced through the PCR cutting off the attachment of the prolapsed vitreous from the vitreous body with minimal vitrectomy. Bimanual cutters are available in different sizes from 20–25 Gauge. The smaller the cutter, the higher is the cut rate and the vacuum that can be used and the more precise is the cutting.
Fig. 11.13

Bimanual vitrectomy cutter

Fig. 11.14

Diagrammatic representation of bimanual vitrectomy with separate handpieces for irrigation and vitrectomy-aspiration

11.9.3 Machine Settings

Modern phacoemulsification systems allow almost the same degree of customization and control as posterior vitrectomy systems. The functions that can be programmed are the cut rate, IOP (bottle height), vacuum, AFR, and the vitrectomy mode (Fig. 11.15). Most machines nowadays allow two vitrectomy modes, the irrigation-cut-aspiration (ICA) or irrigation-aspiration-cut (IAC) modes. The foot pedal cycles through irrigation-cut-aspiration in the former or irrigation-aspiration-cut in the latter mode. The former is the only mode used for anterior vitrectomy, and the latter is used after anterior vitrectomy has been completed.
Fig. 11.15

Settings used for anterior vitrectomy on new-generation phacomachines. The cut rate is kept at the highest possible, while the bottle height (or IOP), vacuum, and aspiration flow are kept fairly low

The rule of the thumb in setting up a machine for anterior vitrectomy is that the cut rate is the highest that the machine allows, while the vacuum, intraocular pressure, and AFR are kept low. The low intraocular pressure, vacuum, and AFR reduce turbulence in the AC, hydration of the vitreous, and traction on the vitreous base. It also prevents residual lens matter from swirling into the vitreous cavity. The high cut rate has the effect of rapidly cutting the vitreous strands before they exert traction due to the vacuum. The absolute settings would depend on the size of the cutter. A 20 gauge cutter would require a bottle height of 50–60 cm, a vacuum of 100–120 mmHg, and an AFR of 15–20 cc/min. A 23 gauge cutter on the other hand would require a bottle height of 75 cm, a vacuum of 150–200 mmHg, and an AFR of 10–15 cc/min. The cut rate on modern-day phacoemulsification machines varies from 1500 to 2500 cuts/min, and in the latest generation machines such as the Centurion Vision System (Alcon Laboratories, Fort Worth, Texas), the maximum cut rate is 4000 cuts/min. This machine has active fluidics which allows very precise control of the intraocular pressure during surgery. The indicative settings for anterior vitrectomy on this machine would be 4000 cuts/min, IOP of 30–40 mmHg, vacuum of 150 mmHg, and an AFR of 10 mmHg.

Once the vitreous has been cleared from the wounds and anterior chamber in the ICA mode, the IAC mode can be used to complete the cortex aspiration shifting between position 1 and 2 of the foot pedal. If a small strand of vitreous is found to engage the aspiration port during cortex removal, one can momentarily go to position 3 of the foot pedal to cut it off before continuing. The other situation where the IAC mode is used is to remove the OVD from behind the IOL after completion of vitrectomy and IOL implantation.

11.9.4 Technique of Performing Anterior Vitrectomy

The three basic principles in performing anterior vitrectomy are (1) use bimanual vitrectomy cutters, (2) use a closed chamber with sutures if necessary, and (3) keep the irrigation anterior to the vitrectomy cutter [27]. The advantages of using a bimanual vitrectomy cutter over a coaxial one have been covered earlier. Many of the phacoemulsification systems come with 20-gauge cutters that require the paracentesis to be enlarged with a 15° keratome before it can be used for vitrectomy. A 23-gauge cutter does not require enlargement of the paracentesis.

A closed chamber reduces turbulence and maintains the positive pressure needed to tamponade the vitreous behind the iris plane. Leaky wounds will allow fluid and vitreous to stream out; hence these should be sutured close before performing vitrectomy. The main wound cannot be used for vitrectomy for this very reason that vitreous will leak out from around the cutter. Ideally, the fluid entering the AC through the irrigation handpiece should leave the eye through the cutter alone. This creates a laminar flow and prevents any vitreous from getting incarcerated in the wounds. The amount of vitreous needed to be removed is minimal, reducing vitreodonesis and thus the incidence of retinal detachment and cystoid macular edema.

During bimanual vitrectomy, the irrigation should be kept above (anterior to) the cutter, preventing hydration of the vitreous. The vitreous strands in the wounds are swept into the anterior chamber to make them taut, so that they are easily cut by the vitrector. A constant dilemma for surgeons is visualizing a transparent structure like the vitreous. The telltale clues given are the distortion of the pupil and more importantly the margins of the PCR. Injection of dilute triamcinolone acetonide [24] stains the vitreous and makes it much easier to remove this otherwise clear structure. Sweeping the anterior chamber with a spatula to find vitreous strands had earlier been advocated, but this step has been rendered superfluous with the use of triamcinolone.

11.10 Management in Common Scenarios During Which PCR Occurs

PCR While Removing the Last Nuclear Fragment

A dispersive OVD such as Viscoat (Alcon Laboratories) or a viscoadaptive one such as Healon-5 (Abbott Medical Optics Inc.) is used to plug the PCR. Using low-flow settings, the nuclear bit is emulsified over an area of intact PC. A cannula of OVD can be used as the second instrument in the nondominant hand, constantly replenishing OVD as the emulsification proceeds. A limited vitrectomy is done if there is any prolapse into the AC and the IOL is implanted. A small PCR can be converted to a PCCC (Video 11.13) before the IOL implantation.

PCR While Sculpting

If the PC is accidentally sculpted along with the nucleus (Video 11.3), there is no option but to convert to an ECCE or MSICS. The lens matter is visco-expressed out of the AC. Vitrectomy is performed, the cortex is aspirated out, and an IOL implanted.

PCR During Cortex Removal

This is more often seen while polishing the PC. Using dispersive OVDs as mentioned earlier, vitreous prolapse can usually be prevented. The PCR is converted to a PCCC whenever possible, the cortex aspiration is completed, and an IOL implanted.

PCR While Implanting Foldable IOLs

This is usually seen in two situations. The first is when a single-piece IOL shoots out of a push-type injector and goes through the PC (Fig. 11.9, Video 11.10). This is usually associated with vitreous prolapse. The IOL has to be explanted, vitrectomy completed, and a three-piece IOL implanted in the sulcus, ideally with the optic captured in the capsulorhexis. If the IOL has sunk into the vitreous, the patient should be referred to a vitreoretinal consultant for further management. The second scenario of PCR during IOL implantation is caused by the leading haptic of an IOL, more commonly the three-piece variety (Videos 11.11 and 11.12). All three-piece IOLs are made of a hydrophobic material and open slowly after injection into the AC. Before the optic unfolds fully, the tip of the leading haptic points posteriorly at the PC. If the IOL is dialed forcefully at this stage without adequate OVD in the bag, this haptic can tear the PC. This is usually not associated with vitreous prolapse. With the trailing haptic in the wound or supported on the iris, the leading haptic can carefully be dialed out of the area with the PCR into an area with intact PC. If the IOL is not stable, the optic can be prolapsed out of the capsulorhexis to do a reverse optic capture (optic in sulcus with haptics in bag). If the capsulorhexis is larger than that of the optic, the optic and haptics can be brought anterior to the anterior capsule, so that the IOL now rests in the sulcus. Triamcinolone is injected, and vitrectomy is done if needed.

PCR During Hydrodissection

The only option to prevent a nucleus drop after seeing the pupil snap sign [19] (Video 11.8) is to dial the nucleus above the anterior capsule or the iris under cover of an OVD. It is not possible to continue with phacoemulsification, and one has to convert to an ECCE or MSICS and express the nucleus out with OVD. The rest of the surgery is as mentioned in earlier sections.

11.11 IOL Implantation After PCR

The choice of IOL to be used following a PCR depends on the amount of residual capsule left after completion of anterior vitrectomy. An IOL should under no circumstance be implanted before completing the anterior vitrectomy. The following are the common situations encountered.

Small Central PCR

This is the easiest to manage. Injecting a cohesive OVD into the AC, a single-piece hydrophobic IOL can be implanted in the bag. As these IOLs open slowly, the haptics open gently within the bag, causing the least distortion to the bag or capsulorhexis. If the PCR has been converted into a PCCC, any IOL can be implanted in the bag (Fig. 11.16 and Video 11.4) as it will resist extension. The cohesive OVD easily comes out as a single bolus on aspiration.
Fig. 11.16

The IOL has been implanted in the bag between the larger anterior and smaller posterior capsulorhexes

Small Peripheral PCR

These also allow careful implantation of single-piece IOLs in the bag if there is sufficient space to allow both the haptics to stay in an area where the bag is intact. It may on occasion be possible to convert a peripheral PCR into a PCCC unless it has extended up to the equator.

Large PCR with Adequate Anterior Capsule Support

A three-piece foldable IOL can be implanted in the sulcus with the optic captured in the capsulorhexis (Fig. 11.17 and Video 11.15). A single-piece foldable IOL should never be implanted in the sulcus [28, 29, 30]. The haptics and the optic-haptic junctions are thick, and there is no angulation of the haptics. This leads to constant chaffing of the posterior pigment epithelium of the iris, with pigment dispersion, recurrent uveitis, and “uveitis glaucoma hyphema” or UGH syndrome. An optic captured in the anterior capsulorhexis allows the optic to remain closer to its intended position in the bag, thus maintaining its effective power. The IOL is fixed in place and does not move or rotate. By forming an artificial PC between the vitreous cavity and the anterior chamber, it reduces vitreodonesis, vitreous prolapse, and migration of the OVD forward into the AC, thus decreasing the severity of the postoperative OVD-induced glaucoma and the incidence of retinal detachment and cystoid macular edema.
Fig. 11.17

The haptics of the three-piece IOL are in the sulcus. The inferior haptic is visible. The optic is seen behind the rhexis in the bag

PCR with Insufficient Anterior and Posterior Capsule Support

The only option here is an anterior chamber IOL (ACIOL), an iris-fixated IOL, or a scleral-fixated IOL (SFIOL). If the surgery has been fairly atraumatic and the preoperative endothelial counts were good, one could extend the wound and implant an appropriately sized, modern flexible ACIOL. Following more complex surgeries, and when the endothelial cell counts are not good, the patient can be left aphakic after vitrectomy. When the eye has quietened down in 4–8 weeks, a second procedure can be undertaken, and an iris-fixated or scleral-fixated IOL implanted.

11.12 Case Scenarios

In a recent phacoemulsification on a patient (Video 11.4) with a dense brown cataract, everything seemed to be going picture perfect, and with the aid of the long sharp chopper that I use for chopping hard nuclei, I had removed most of the nucleus. I was about to remove the last nuclear piece when I noticed a small central tear in the PC. I had the presence of mind to not stop my irrigation. I asked for a cannula of Viscoat (Alcon Labs), and taking it in my left (nondominant) hand injected it through the paracentesis over the area of the PCR. With the PCR blocked by the OVD, I completed emulsifying the last nuclear bit. I injected some more OVD into the AC and withdrew the phaco needle from the eye. Introducing a pair of 23-gauge microrhexis forceps through the paracentesis, I proceeded to convert the linear PC tear into a small circular capsulorhexis, so that it would not extend with surgical manipulation. The cortex was aspirated out with bimanual IA cannulae. A single-piece hydrophobic IOL was safely implanted in the bag. Though there was no vitreous prolapse into the AC, a bimanual vitrectomy cutter was used to remove the OVD from behind the IOL to reduce the chances of developing postoperative glaucoma. This would cut off any vitreous strands that came into the port along with the OVD. The patient was started on acetazolamide tablets to prevent postoperative glaucoma which could be caused by the residual OVD. The next day, the patient had a quiet eye, the intraocular pressure was normal, had a well-centered IOL in the bag, had a clear vitreous, and was reading 20/20 without correction.

In another instance, we had a young female patient who came to our OPD with bilateral large posterior polar cataracts (PPCs). She insisted on multifocal IOLs as she hated wearing glasses. Neither an ASOCT nor a UBM could reveal any space between the PPC and the PC. Knowing that there was a real risk of a PC dehiscence, we planned on using a three-piece foldable multifocal IOL. During surgery, we took all precautions that are taken for PPCs. We did a 5 mm anterior capsulorhexis followed by hydrodelineation without hydrodissection. We proceeded to remove the nucleus without rotating it, and being soft it was achieved without a struggle. As we were about to remove the epinucleus, the PC opened up and widely so (Video 11.16). With the epinucleus being held at the phaco tip, we kept shut the phaco power, but kept the vacuum on (foot pedal position 2), so that the piece would not drop into the vitreous cavity. Taking a syringe of OVD with the left hand, we injected it into the AC between the epinucleus and the PCR. The phaco needle was only then withdrawn from the eye. As the remaining epinucleus was soft, we could visco-express it out of the AC. We proceeded with a thorough anterior vitrectomy with a 20-gauge cutter. This surgery was performed before 23-gauge cutters became available on anterior segment phacoemulsification machines. Once the vitreous had been removed from the AC and the wounds, we aspirated the considerable cortex which was still present. The three-piece multifocal IOL was then implanted in the sulcus and the optic captured behind the anterior capsulorhexis. The next day, the patient had an unaided vision of 20/20 for distance and N6 for near. As an optic capture had been done, the effective lens position and power of the IOL remained the same. We had to go through this all over again a month later for the other eye, fortunately with equally good results.

11.13 Postoperative Management Following PCR

There is slightly exaggerated postoperative uveitis due to the increased surgical manipulation. There is also a much higher incidence of postoperative glaucoma due to retained OVD and pigment release. One would need to prescribe more frequent topical corticosteroids, cycloplegic, and antiglaucoma drugs in these patients. Topical nonsteroidal anti-inflammatory drugs which are routinely used in cataract patients would be needed for a longer duration of up to 3 months postoperatively. There is a higher incidence of endophthalmitis following PCR, and there is a strong case for intracameral antibiotics [31] in these patients at the conclusion of surgery.

All these patients need to have a vitreoretina consultation as soon as the media are clear. This would detect any significant amount of lens matter in the vitreous requiring a posterior vitrectomy. One would have to actively look for cystoid macular edema and peripheral retinal breaks that would require treatment. Small amounts of cortex in the vitreous or anterior chamber will get absorbed and do not require surgical intervention. In our setup, the patient would be seen on the first postoperative day, and then 7 days, 28 days, and 3 months after surgery. The subsequent visits would depend on the results of that examination. Sutures if applied would have to be removed between 4 and 6 weeks before the final refraction and glass prescription.

11.14 Consequences of PCR

The long-term outcome of a well-managed PCR is almost as good as a routine phacoemulsification. A badly managed PCR can give rise to one of many of the following: corneal endothelial decompensation, severe postoperative uveitis, prolonged glaucoma, intractable cystoid macular edema, retinal breaks including giant retinal tear, hyphema, vitreous hemorrhage, epiretinal membrane, and endophthalmitis.

There are nonmedical consequences. One has to explain to the patient in simple and nonalarming terms as to what happened. If an IOL other than the intended one was used, this has to be explained to the patient. I tell the patients that there is an extremely thin layer which holds the natural lens, and after a cataract surgery, the IOL. This was damaged during surgery due to certain reasons, and a more suitable IOL was implanted, or the eye was left without an IOL so that a more appropriate IOL could be fixed later. It is of utmost importance that one deals with the anxiety of the patient by reassuring the patient and his attendants that the best possible treatment was given to the patient, that he would be looked after, and that given time, he would do extremely well.

Notes

Financial Interests

None of the authors have any financial interests in any company or product mentioned in the text.

Supplementary material

Videos 11.1–11.16

(MPG 1860760 kb)

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Copyright information

© Springer India 2017

Authors and Affiliations

  • Sudeep Das
    • 1
  • Mathew Kurian
    • 1
  • Purnima Raman Srivatsa
    • 1
  • Nikhil Negalur
    • 1
  1. 1.Cataract and Refractive SurgeryNarayana NethralayaBangaloreIndia

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