Modern cataract surgery performed with phacoemulsification allows meticulous intraocular control and minimal incision size. However, inherent risks of capsular rupture exist. Therefore, surgeons performing cataract surgery will inevitably face the complication of a torn posterior capsule. Torn posterior capsules are reported to occur in 0.3% to 6% of cases. Surgeons must manage this complication in a way that will provide the patient with the best surgical and visual outcome.
Predisposing Factors (Table 1)
Hand Position
The relationship of the surgeon's hand position to the patient's brow can be a factor that predisposes a patient for a torn
posterior capsule. Construction of a superior incision may lead to visibility problems, irrigation fluid pooling, and torsion
of the globe. The surgeon must attempt to minimize torsion of the globe during surgery as this impedes adequate visibility.
Temporal incisions are prudent, especially if the brow is prominent (i.e., a deep-set eye). If pooling of fluid occurs, the
head should be turned temporally, which will allow fluid to drain. The speculum should allow easy access to the globe without
interfering with the phacoemulsification step. Some surgeons prefer to place their incision over the axis of the plus cylinder.
However, this cannot be done with the plus cylinder at 90º in a patient with a prominent brow and a deep-set eye. It is preferred
that a surgeon forego addressing the issue of astigmatism and operate temporally, for access and exposure, rather than risk poor visualization
and a capsular tear.
Microscope Alignment
Poor microscope illumination or alignment is another cause of poor visualization. Once recognized, this should be simple to remedy.
Other factors that impede visibility include dense arcus senilus, dense nasal or temporal pterygia, severe Fuch corneal dystrophy,
with or without associated corneal edema, band keratopathy, old corneal scars, and interstitial keratitis. Faced with these challenges
of visualization, the surgeon should slow down, pay more attention to detail, and allow visualization of the anterior segment. To
minimize the risk of a torn capsule during phaco, the nucleus should be elevated to the plane of the iris early in the procedure.
This is accomplished by using a stop and chop or phaco chop procedure. As soon as the nucleus is split, the fragments are elevated
to the plane of the iris so they are not close to the poorly visualized posterior capsule during the application of phaco power.
Dispersive viscoelastic or Healon 5 (sodium hyaluronate) may be placed above and below the fragments to isolate them for
emulsification. Therefore, the risk of rupturing the posterior capsule is diminished.
Axial Length
Eyes with unusually long or short axial lengths present other predisposing factors for torn capsules. In high myopia, the anterior
chamber is deeper with more trampolining of the posterior capsule, due to the thinner, more pliant tissues. Eyes that have previously
undergone vitrectomy behave in a similar manner. Lowering the infusion bottle lessens this tendency. In high hyperopia, the crowded anterior
chamber brings the posterior capsule closer to the phaco tip, thereby increasing the risk of a torn capsule. In these situations, the early
use of pulsed phaco will assist in deepening the anterior chamber. Other causes of a shallow anterior chamber are discussed later in this tutorial.
Pseudoexfoliation
Pseudoexfoliation is known to cause weak zonules and poor dilation secondary to fibrosis of the pupillary sphincter. These
problems lead to an increased incidence of torn posterior capsules due to poor visualization, as well as dehiscence of the zonules
from routine manipulation of the nucleus during the procedure.
Table 1. Predisposing Factors for a Torn Posterior Capsule
|
Poor visibility secondary to physical problems |
|
Hand position, brow, fluid pooling |
|
Poor visibility secondary to pathology |
|
Sense arcus, pterygium, band keratopathy |
|
Corneal scars |
|
Long and short axial length |
|
Pseudoexfoliation |
|
Black cataract |
|
White cataract |
|
Dense asteroid hyalosis |
|
Small pupil |
|
Previous trauma |
Mature Cataract
Mature cataracts with brunescent or black nuclei, as well as cortically mature white cataracts, cause poor visualization and
subsequently hinder capsulorrhexis. In the presence of a poor capsulorrhexis and a hard cataract, the chance of tearing the
capsulorrhexis peripherally increases significantly. Samuel Masket, MD, has proposed using a retinal light probe held near the
limbus to provide "side light" illumination while lowering the coaxial microscope and room illumination. This improves visibility
of the tearing edge of the capsule in these difficult situations. Other solutions include the use of vital stains, which have
dramatically improved surgeons' ability to visualize the tearing anterior capsule. Staining the anterior capsule with indocyanine
green (ICG) or Vision Blue (trypan blue dye, DORC, The Netherlands) has become
invaluable. ICG is the only capsular dye presently
available in the United States.
To prepare ICG, 25 mg of ICG is dissolved in 0.5 mL of the aqueous solvent supplied. Then 4.5 mL of BSS Plus (Alcon) is added. The resulting solution will have a concentration of 0.5% and an osmolarity of 270 mOsm. With a TB syringe, 0.1 cc of the ICG stain is injected under an air bubble in the anterior chamber. After a few seconds, the stain is washed out. Finally, the anterior chamber is filled with viscoelastic and the capsulorrhexis is continued.
To use Vision Blue, the dye is removed directly from the supplied container and injected into the anterior capsule under air, as noted above. With this technique, the anterior capsule is fully visible.1 It is useful to stain both white and black cataracts. Vision Blue offers more versatility than ICG, as ICG will only stain white cataracts.
Methylene blue should never be used for this application as toxicity to the endothelium has been demonstrated. Currently, no dye is approved by the U.S. Food and Drug Adminstration for capsular staining.
Asteroid Hyalosis
Dense asteroid hyalosis, which results from glistening asteroids, make seeing the posterior capsule difficult. The surgeon must
again use caution and, if necessary, viscoelastics to elevate the nuclear fragments to provide a safe distance between the phaco tip
and the posterior capsule.
Small Pupil
Small pupils are a significant predisposing factor that may cause posterior capsule tearing during surgery. Many regimens
provide adequate pharmacologic dilation in most patients, for example, cyclopentolate 1%, neosynephrine 2.5%, and ketorolac
tromethamine 0.5%, are given every 5 minutes four times prior to surgery. Recently, the use of pledgets soaked in topical anesthetic
and dilating medications in the inferior cul-de-sac has become popular.
Patients with poorly dilated pupils need an additional dose of neosynepherine 10% gel. Neosynepherine 10% solution is avoided because there have been reports of the development of recalcitrant cardiac arrhythmias in some patients.
If the pupil does not dilate adequately pharmacologically, it can be further enlarged surgically. This can be accomplished by stretching the pupil with the Beehler dilator (Moria), performing multiple sphincterotomies with microscissors, using iris retractors, or using the Graether pupil expander.
Stretching the pupil can be accomplished with a Beehler dilator. This instrument will quickly enlarge the pupil to an adequate size for phaco by creating microtears of the fibrotic pupillary sphincter. Large, uneven tears that can cause permanent pupil distortion postoperatively are avoided with this procedure. This fast, simple procedure is usually sufficient to allow phacoemulsification to be performed safely. Beehler dilators are available with a three-spline instrument for incisions greater than 3 mm or a two-spline instrument for 2.5-mm to 3-mm incisions. If, after using the Beehler dilator, the pupil still remains too small, micro iris retractors should be used. These small hooks should consistently provide adequate room for phacoemulsification. However, iris retractors are too time-consuming and complex to use routinely. If placed too anteriorly, they may pull the iris forward creating the illusion of performing phaco in a "hole".
Miscellaneous Factors
Additional predisposing factors for a torn posterior capsule include:
Small Capsulorrhexis
If a capsulorrhexis is too small, the potential to create a zonulolysis exists by catching the subincisional capsule with the phaco
tip or by pulling on the capsule with aspiration opposite the incision. Removal of subincisional cortex may be considerably more difficult.
The additional instrument manipulation may be a precursor to zonular disruption. During hydrodissection, resistance to flow created by the
small rhexis may lead to fluid accumulation deep in the nucleus and precipitate a posterior capsular tear. This is especially risky in
the presence of a mature nuclear cataract.
Large Capsulorrhexis
A large capsulorrhexis may incorporate zonules, which predisposes a patient to zonular unzipping. Occasionally, when the capsulorrhexis is
large, the tearing capsule may run into an anteriorly attached zonule. This may redirect the tear and cause the tear to turn radially, with
an abrupt tear into the equator. If the capsulorrhexis is large, there is little residual room to redirect the radially tearing capsule
before the tear extends into the equator.
Noncontinuous Capsulorrhexis
Noncontinuous capsulorrhexis occurs when the tear progresses peripherally under the iris and is no longer visualized. Once this occurs,
the reason for the extension must be determined. Generally, there is positive posterior pressure pushing the lens nucleus anteriorly. This
creates vector forces on the tearing capsular bag, which cause it to tear outward. Therefore, the speculum must be loosened, any drape
pressure should be relieved, and the anterior chamber should be deepened with dispersive viscoelastic. The objective is to deepen
the anterior chamber enough so that the anterior lens surface is flattened. This should reverse the tendency for the tear to deviate
peripherally. If the tear can be visualized, it can be completed by pulling the flap directly toward the center of the pupil.
Redirecting the tear vector away from the periphery should maintain a continuous capsulotomy. If the tear cannot be visualized,
it can be completed from the opposite direction. In this situation, when the capsulorrhexis is completed, it should be made large
enough to allow prolapse of the nucleus. Because there is no longer a continuous capsulorrhexis, the nucleus should be gently
hydrodissected or viscodissected into the anterior chamber. Emulsification is then performed in the anterior chamber. There
should be no pressure exerted on the posterior capsule, as this might cause the capsulorrhexis tear to extend peripherally around
the equator into the posterior capsule and lead to vitreous loss and/or a dropped nucleus.
Nucleus Rotational Complications
Modern phacoemulsification techniques require free rotation of the lens nucleus to reach nuclear material. Persistent equatorial
nuclear/capsular connections will impede nuclear rotation and, during the ensuing excessive rotational effort, zonular and/or capsular
tears may occur.
When the lens nucleus will not rotate, additional hydrodissection should be performed in all four quadrants. Gentle retropulsion of the nucleus is helpful to force fluid trapped behind the posterior pole of the nucleus around the equator. This will hopefully lyse any remaining nuclear/cortical connect ions at the equator. If the lens nucleus still does not rotate freely, a two-handed rotational maneuver can be performed under viscoelastic. A lens manipulator can be placed through the paracentesis and across the nucleus to the opposite side. The phaco tip is then placed in the eye and in position engaging the nucleus opposite the manipulator. In foot pedal position 0, as the vitreous comes forward to support the lens nucleus, gentle rotational movement of both instruments is performed in unison. This will usually produce free rotation of the nucleus.
Anterior Chamber Shallowing
During surgery, if it is difficult to maintain the anterior chamber, the probability of a torn posterior capsule increases. It is difficult
to perform phacoemulsification in the presence of a shallow anterior chamber as posterior capsule forward movement and/or significant
pressure on the posterior capsule may result in capsule rupture. In this situation, the surgeon must determine the cause of the chamber
shallowing. Causes for a shallow anterior chamber include:
If the paracentesis or main incision is leaking as a result of poor wound construction, sutures should be placed. If inflow is too high, the infusion bottle should be lowered. If the inflow is inadequate, the incision should be enlarged or the bottle should be raised. The use of a dispersive rather than cohesive viscoelastic may be of assistance once the cause of chamber shallowing has been determined.
If posterior positive pressure and a shallow anterior chamber persist, the cause must be determined. Posterior pressure may be caused by physical forces such as a tight speculum, tight drapes, or a retrobulbar hemorrhage. Other possible causes include fluid misdirection syndrome or a suprachoroidal effusion/hemorrhage.
If physical forces and a retrobulbar hemorrhage are ruled out and the chamber remains shallow, either fluid misdirection or a suprachoroidal effusion is developing. A globe that is firm to touch indicates elevated pressure.
Fluid misdirection syndrome occurs when irrigating fluid passes through intact zonules or a zonular tear into the vitreous. This causes vitreous hydration, expansion of vitreous volume, and subsequent elevated posterior segment pressure. Fluid misdirection will usually respond to treatment, allowing surgery to be completed.
Suprachoroidal effusion is caused by rupture of the short posterior ciliary vessels with subsequent outpouring of plasma and blood into the suprachoroidal space. The amount of extravasation is ultimately limited by the elevation of the intraocular pressure (IOP), which effectively tamponades further hemorrhage. If the wound is opened, the resulting hypotony permits further hemorrhage and eventual expulsion of the intraocular contents. Suprachoroidal effusion will often be unresponsive to treatment and will cause persistent high IOP and marked shallowing of the anterior chamber.
The recommended treatment for fluid misdirection syndrome and suprachoroidal effusion is:
A surgeon must never convert to an extracapsular cataract extraction (ECCE) as enlargement of the wound will destabilize the eye and allow a suprachoroidal effusion to become an expulsive hemorrhage.
Most tears of the posterior capsule occur during phaco and involve many factors (Table 2). In the presence of inadequate hydrodelineation, resultant fragments of nucleus are literally stuck to cortex; they are immobile. This will force the surgeon to perform phaco toward the equator, beyond the delimiting hyrodelineation plane, leading to equatorial tears. Additionally, adherence of the nucleus to the capsular bag may cause an equatorial capsular tear or zonular dehiscence while attempting to rotate the nucleus. Inadequate hydrodissection resulting in cortex adherent to the posterior capsule may cause tears during irrigation and aspiration (I&A).
Table 2. Time of PC Tear.
Surge
Many believe that the sharp edges of a hard nuclear fragment may tear the posterior capsule. This is most likely to occur during an episode
of postocclusion surge.
A principal limiting factor in the selection of high levels of vacuum or flow is the development of postocclusion surge. When the phaco tip is occluded, flow is interrupted and vacuum builds to its preset level. Emulsification of the occluding fragment then clears the occlusion. Flow immediately begins at the preset level in the presence of the high vacuum level. In addition, if the aspiration line tubing is not reinforced to prevent collapse (decreased tubing compliance) the tubing will have constricted during the occlusion. It then expands upon occlusion break. The expansion is an additional source of vacuum production. These factors cause a rush of fluid from the anterior segment into the phaco tip. The fluid in the anterior capsule may not be replaced rapidly enough by infusion to prevent shallowing of the anterior chamber. There is a rapid, anterior displacement of the posterior capsule. This abrupt and forceful tensing of the posterior capsule around nuclear fragments may be a cause of capsular tears. In addition, the posterior capsule can be torn by its being sucked into the phaco tip. The magnitude of the surge is determined by the presurge settings of aspiration flow rate and vacuum.
These problems can be avoided by
Another technique is to perform I&A after the intraocular lens has been inserted. In this way, the optic holds the posterior capsule back from the I&A tip as the cortex is aspirated.
Recognition
During emulsification, there are four cardinal signs of a torn posterior capsule (Table 3). The first is a
sudden deepening of the anterior chamber. This occurs instantaneously as a rent appears in the capsule. Second, the hammock-like
posterior capsular support is lost, so that the nucleus begins to fall back. As this occurs, the pupil will dilate in response to the
deepening anterior chamber. Finally, during emulsification, the nucleus falls away from and will not move toward the phaco tip. The
reason behind this third sign is that the flow dynamics in the anterior chamber have been altered by the posterior capsule tear.
The fourth sign is when vitreous may become preferentially aspirated by the phaco tip. This will literally push the nucleus away from the phaco tip.
The posterior capsule can tear during the following steps: hydrodissection, rotation, cracking, removal of the last quadrant when small fragments of nucleus and cortex remain, I&A, capsular polishing, lens insertion, and viscoelastic removal. Management of a torn posterior capsule depends on when the tear occurs and the amount and density of the remaining nucleus.
Table 3. Recognition of a Torn Posterior Capsule
|
Sudden deepening of the anterior chamber |
|
Momentary pupillary dilatation |
|
Nucleus does not follow toward the phaco tip |
|
Nucleus falls away from the Phaco tip |
Once a surgeon recognizes a tear in the posterior capsule, two questions must be asked. First, is there vitreous present in the anterior chamber? Second, is conversion to a standard ECCE procedure indicated? The decision to convert depends on multiple factors including the density and size of the nuclear material in the anterior segment, the size of the pupil, the ability to maintain an adequately deep anterior chamber, and the ease of access to the anterior segment. The level of surgical experience and the extent of the posterior capsular rent must also be considered.
Once a tear in the posterior capsule is recognized, the goal is to prevent enlargement of the tear and damage to the intact anterior capsulorrhexis and minimize the size of the vitrectomy.
While assessing the situation, a surgeon should not abruptly remove the phaco tip; this will cause the anterior chamber to depressurize. The resultant sudden loss of anterior capsule fluid will allow the positive vitreous pressure to push the posterior capsule forward. The tear will enlarge and, as the vitreous face ruptures, vitreous will prolapse into the anterior capsule. To prevent this, the surgeon should pressurize the anterior capsule with viscoelastic or air before removing the phaco tip.
When in doubt, the surgeon should convert to a standard ECCE instead of proceeding with phaco. The goal is to avoid dropping some or all of the nucleus posteriorly. A key factor in this decision is whether vitreous is ensnarled with the nucleus in the anterior or posterior chamber. Vitreous present immediately after a capsular tear generally indicates a large capsular tear and a syneretic (AU: Please confrm syneretic) vitreous. This would further argue in favor of converting to a standard, large incision ECCE.
Conversion to ECCE
To convert to a standard, large incision ECCE, the surgeon must first secure the nucleus with a dispersive viscoelastic to prevent loss of nuclear
fragments into the vitreous. Viscoelastic should be injected underneath the nucleus to support it. It may be necessary to create a
paracentesis opposite the incision, through which a hook can loosen and manipulate nuclear fragments into the proper position. A clear corneal
incision may be sutured and abandoned. In contrast, a corneoscleral incision can be extended. A well-constructed limbal incision should be
fashioned after a conjunctival peritomy has been performed. The size of this incision depends on the size of the nuclear fragments remaining.
Generally, the surgeon should err on the side of an overly generous incision size. Once the incision has been created, the wound should be
opened to its full extent and a lens loop should be used to extrude the lens nucleus. No external pressure should be applied to the
opposite limbus to prevent vitreous from being expelled. Alternatively, the clear corneal incision can be enlarged for extracapsular
extrusion of nuclear material and implantation of a PMMA, foldable, small-diameter IOL. Once the lens nucleus has been removed, further
anterior segment surgery should proceed as described below. The choice of IOL depends on the amount of residual anterior capsule
remaining. Suturing of the wound is accomplished with interrupted or running 10-0 nylon radial sutures. Conjunctival closure is
accomplished with the same suture and a buried knot.
If the surgeon believes that continued phacoemulsification is appropriate, a dispersive viscoelastic should be placed below the lens nucleus to elevate it into the anterior chamber. Bottle height, vacuum, and aspiration flow should be lowered to create a low flow system (e.g., bottle height should be decreased from 65 mm to 55 mm, flow should be decreased to 18 cc/min, and vacuum lowered to 100 mm Hg).
The nucleus should then be emulsified in the anterior chamber in one piece while using two instruments. The second instrument is used to feed the edge of the nuclear fragment into the phaco tip. Foot pedal positions 2 and 3 should be used only when the nucleus is adjacent to the phaco tip to avoid aspirating vitreous. It is best to avoid creating multiple nuclear fragments that might fall through the posterior capsule rent into the posterior segment.
If the rent appears too large to safely continue phacoemulsification, a "pseudo-posterior capsule" can be created using a Sheets glide. Narrow glides are available from Visitec or can be manually fashioned to the appropriate width for a small incision. The narrow glide is placed through the incision after the anterior chamber has been filled with viscoelastic. The glide is manipulated behind the nuclear fragment (a second instrument may be helpful) and, if possible, into the opposite residual capsular bag equator or ciliary sulcus. Phacoemulsification is then performed over the Sheets glide. It may be necessary to enlarge the incision slightly to accommodate both the phaco tip and Sheets glide. The glide can remain in place during emulsification of the remaining nucleus, as well as during I&A of any residual cortex.
If the capsular tear occurs when only a small fragment of nucleus remains, the fragment can be emulsified by manipulating it toward the phaco tip. Upon aspiration, the fragment should block the phaco tip so it prevents unwanted aspiration of vitreous.
Irrigation and Aspiration
To remove cortex in the presence of a capsular tear, the remaining cortex should be stripped toward the capsular tear. To avoid aspirating
vitreous, the 0.3-mm I&A tip opening should be fully embedded in the cortex before vacuum is activated. Lowering the infusion bottle will
decrease inflow. This should reduce any associated turbulence that may enlarge the capsular rent and force more vitreous forward. The surgeon
should avoid working directly above the capsular tear. Cortex should never be stripped directly away from the capsular tear, as this will
enlarge the tear.
Bimanual I&A is beneficial in this setting as it is easier to manipulate the smaller instruments. Additionally, the chamber is more stable due to the tight paracentesis incisions. Manual cortex removal techniques may also be used. Small amounts of cortical material that is too difficult to remove can be left behind.
If vitreous is present immediately after the capsular tear, it should not be removed until after the nucleus or nuclear fragments are emulsified, because it may provide support to keep the nucleus from falling posteriorly. Once emulsification is completed, a bimanual vitrectomy should be performed. This is accomplished by establishing irrigation through a separate 23-gauge cannula through the paracentesis. The irrigation bottle is positioned at the appropriate height to maintain the anterior chamber during vitrectomy. An occutome-type vitrectomy cutter is then placed through a newly created paracentesis and through the rent in the posterior capsule to draw vitreous back through the rent toward the posterior segment. It is better if the vitrectomy is not performed through the main incision. Because this incision is much larger than the vitrectomy instrument, the fluid outflow may cause vitreous to wash out of the wound. Vitrectomy should be performed with a high cutting rate (250 to 300 cuts per minute), an aspiration flow rate of 20 cc/min, and a vacuum of 200 mm Hg. The vitrectomy is continued until no vitreous remains anterior to the plane of the posterior capsule. Bimanual vitrectomy is used to prevent enlargement of the capsular tear. If only a small amount of vitreous remains in the presence of a small capsular rent, a dry vitrectomy can be performed. In this case, a dispersive viscoelastic is first used to fill the anterior chamber. Without an irrigation sleeve, the vitrector is placed through the posterior capsule rent and into the vitreous. A limited vitrectomy is performed using the above parameters. Viscoelastic volume is augmented as is necessary, so no irrigation is necessary.
Pars plana vitrectomy can also be performed. One should first measure 3 mm to 4 mm posterior to the limbus in the inferotemporal quadrant. After performing a small conjunctival peritomy, vitreous cavity is entered with an MVR blade pointed toward the center of the globe. A vitrector with the irrigation sleeve removed is then placed into the vitreous until it is visualized through the pupil. With separate irrigation through a limbal port, the vitrectomy is then performed utilizing the above parameters.
Posterior Assisted Levitation
In certain situations it may be impossible to stabilize the nucleus. This is most likely to occur when the phaco tip creates a large zonular
dehiscence opposite from the incision. In such a circumstance, zonules are present subincisionally so that the distal pole of the nucleus
falls into the vitreous. The subincisional attachments prevent the entire nucleus from disappearing. In this unique setting, a pars plana
stab incision should be made 3.5 mm posterior to the limbus. Alternatively, the pars plana incision can be moved to wherever the zonular
hinge occurs. As described by Charles Kelman, MD, a cyclodialysis spatula is then used to lever the nucleus into the anterior chamber
through the pars plana approach.
Once the nucleus is secured within the anterior chamber, it can be removed either by emulsification over a Sheets glide, or by extracting it through an ECCE approach.
In any case where the full extent of the posterior capsular tear can be visualized, a posterior capsulorrhexis can be attempted. If the vitreous face is intact, a posterior capsulorrhexis is performed by first placing viscoelastic above and below the tear to push the vitreous face back. This creates enough room to grasp the posterior capsular flap with a capsule forceps. If the vitreous face is already broken, viscoelastic is necessary only to stabilize the anterior capsule and make room for the forceps. A capsulorrhexis forceps is used to create a 360º posterior capsulorrhexis. As the posterior capsule is more fragile than the anterior capsule, frequent grasping of the capsular flap is necessary to provide adequate control of the tear. A Masket-modified Utrata Forceps is useful, as the curved blades provide for easier access to the posteriorly positioned capsular flap. This step is difficult because of poor visibility of the capsular flap and poor instrument access. Failed attempts may result in extension of the tear and initial or increased vitreous loss.
Lost Nucleus and/or Cortical Nuclear Fragments
If the posterior capsule is torn during phaco, small pieces of lens material may fall into the vitreous. If the piece is large (including the entire nucleus) and/or hard, the likelihood of vitritis, macular edema, and/or secondary glaucoma is high. If vitritis or elevated IOP develops, it is advisable to retrieve the lens fragments within 2 weeks of the original surgery. If the pieces are soft and more cortical in nature, they are likely to be more readily reabsorbed and better tolerated. One should never attempt to irrigate or aspirate pieces of material from the posterior segment, via an anterior approach. Rather, if removal of intravitreal nucleus becomes necessary, it is preferable to have a vitreoretinal specialist later perform a three-post pars plana vitrectomy. A lens implant may be placed into the ciliary sulcus and the original incision should be closed.
Retinal surgeons may have different preferences regarding IOL implantation in this setting. It may be prudent to discuss these preferences with the designated vitreoretinal specialist in advance.
Zonular Dialysis: Recognition and Management
A discussion of the complete scope of preoperative zonular dialysis is beyond the scope of this tutorial. It should be noted that zonular dialysis significantly increases the risk of both vitreous loss and nuclear fragments dislocating into the vitreous. IOL implantation may be more difficult. The surgeon's ability to perform phacoemulsification depends on the number of clock hours involved with the zonular dialysis. New techniques such as the capsular tension ring and new viscoelastic techniques have increased the successful outcome of phaco in these challenging situations.
Following a vitrectomy, subconjunctival triamcinolone 20 mg may be indicated. Follow-up visits should be performed frequently. Prednisolone sodium acetate and a nonsteroidal anti-inflammatory are given four times a day. A subconjuntival triamcinalone injection is repeated at 3 weeks if cystoid macular edema (CME) is diagnosed.
Posterior capsule rupture worsens the visual outcome of cataract surgery. When the posterior capsule is torn without vitreous loss and a posterior chamber IOL is implanted in the capsular bag or ciliary sulcus, there is still an increased risk of CME, vitreous prolapse into the anterior chamber, and psuedophakic retinal detachment. Although recommended, a peripheral iridectomy may increase the risk of hyphema.
Vitreous loss appears to be the crucial factor influencing clinical outcome. Once vitreous is lost, the postoperative course is complicated in 30% of patients, with an increased number of visits due to hyphema, retained cortex, corneal edema, blurred vision, and vitreous strands. Long-term retinal problems include chronic CME, macular holes, and retinal detachment, which occur in 25% of patients who undergo unplanned vitrectomy. (Table 4) represents the postoperative outcome in the experience of different surgeons.
Table 4. Postoperative Complications Based on the Experience of Three Surgeons
| Osher-Cionni 2 | Fishkind 3 | Powe et al4 | |
| Vitrectomy | 1% | 1.25% | 0.8% |
| Vision >20/40 | 89% | 80% | 90% |
| Early Complications | |||
| Endophthalmitis | 0% | 0% | 0.13% |
| Hyphema | 0% | 0% | 0.2% |
| Vitreous in anterior chamber | 10.4% | 5% | not reported |
| Elevated IOP | 0% | 0% | 0.2% |
| Late complications | |||
| Cystoid macular edema | 2% | 0.27% | 1.5% |
| Retinal detachment | 0% | 0.1% | 0.7% |
Recognition and appropriate adjustment of the surgical plan in the presence of predisposing factors for a torn posterior capsule should help to decrease the incidence of this problem. Also, prompt recognition and treatment of torn capsules and vitreous loss should help prevent serious complications and improve surgical outcomes. Slow, methodical analysis and nuclear and cortical removal, preservation of as much posterior capsule as possible, careful vitrectomy, and appropriate IOL selection and insertion should improve outcome. Increased use of postoperative subconjunctival and topical steroids and nonsteriodal anti-inflammatory drugs further improve the postoperative course. Careful office follow-up is justified.