Posterior capsule tear with vitreous loss occurs in 1% to 2% of all cataract operations, causing additional morbidity if ineffectively managed. Thus, anterior vitrectomy techniques are an essential skill for all cataract surgeons. Posterior capsule tear is an unplanned occurrence; the surgeon may use unfamiliar instruments and surgical approaches in an already difficult situation. This article highlights the techniques used to manage vitreous presentation, emphasizing a step-by-step approach.

It is best to familiarize yourself with available instrumentation, especially if operating in a new environment. Even in one's regular operating theater, it is advisable to ensure that the entire team—including the scrub team, who needs to know how to set up for the anterior vitrectomy—is trained to deal with this occurrence. The team should know (1) where the anterior vitrectomy kit is physically kept, (2) how it needs to be connected, and (3) what settings will be used. I often find it reassuring to ask my scrub nurse, "What would you do if I asked for [fill-in-the-blank?]," during a routine uncomplicated case. This gives the entire team a chance to rehearse, at least verbally, what needs to be done when the complication does occur.

Many commercially available anterior vitrectomy probes take a full function approach (ie, irrigation, aspiration, and cutting are combined into one instrument). I mention this, only to dismiss it. In this type of probe, the irrigation port is placed adjacent to the cutting port. When the tip is placed through a capsular tear into the anterior vitreous, the flow of fluid may further tear the capsule. More vitreous comes forward—due to local turbulent flow—and vitreous volume expansion from hydration occurs. It is more advantageous to use a separate infusion line, with the active instrument cutting and removing the vitreous. When a separate irrigation line is used, it is placed through a sideport incision with the flow directed toward the anterior chamber angle, reducing turbulence at the site of cutting.

Many techniques have been described, however, I find it useful to employ a standardized approach, applicable to most situations. (See Vitreous Management and Surgical Principles for the aims of vitreous management and the surgical principles.)

BIMANUAL ANTERIOR VITRECTOMY
Identify the problem. The first step to managing a problem is the need to recognize it early. The classic signs of capsular tear are (1) sudden deepening of the anterior chamber and (2) pupil dilation, occurring due to abrupt equalization of hydrostatic pressure between the anterior and posterior segments. Nuclear material may also move posteriorly through the capsular tear. Early signs of trouble are noted when the nucleus moves less readily than expected, as the fluid currents no longer move smoothly in the enclosed bag, or vitreous blocks the phaco tip. Generally, if the surgeon suspects that a capsule tear has occurred, it probably has, and immediate steps must be taken to minimize further damage.

Immediate actions. Phacoemulsification and aspiration should be stopped immediately. The foot pedal should move to position one (ie, irrigation only), thus maintaining inflow to stabilize the anterior chamber. Continuing with ultrasound use or aspiration will draw in more vitreous. Avoid any maneuver that pulls on vitreous, which may cause retinal traction and retinal tear.

The phaco probe is kept stable with one hand, the second instrument is removed, and viscoelsatic is injected through the sideport. As the anterior chamber is stabilized, the bottle height is lowered between 20 cm to 40 cm. Irrigation is then eased off. The phaco probe may now be withdrawn, without collapsing the anterior chamber. You have now bought yourself thinking time!

Assess the situation. Most capsular tears occur during the last stages of nuclear emulsification. The capsular bag is more prone to collapse at this stage, because a majority of the nuclear material is gone, and the bag is no longer held open. At this stage, assess the remaining nuclear segments, the site, and the extent of the capsular tear and presenting vitreous.

Management of remaining nuclear fragments. If small nuclear fragments remain, move them away from the site of the tear with gentle injection of viscoelastic. Guide them out of the wound, which may be extended slightly, if needed. Any nucleus segments that are dislodging posteriorly through the capsular opening should never be chased with instruments behind the capsule. It is much safer to manage the anterior segment and leave any posteriorly dislocated nuclear fragments for a vitreoretinal specialist to manage later. Although not essential, I advise injecting a small amount of triamcinolone into the anterior chamber at this stage. The triamcinolone (Kenalog; Bristol-Myers Squibb Company, New York, New York) crystals adhere to any vitreous that has presented, thus greatly facilitating visualization. (See Triamcinolone Stain of Vitreous.)

Anterior vitrectomy. A second sideport incision is created at the 9-o'clock position (ie, for a superior main incision) or the 6-o'clock position (ie, for a temporal incision). Do not use the cutter through the larger phaco incision, as it encourages fluid leakage that leads to intermittent anterior chamber shallowing. If the main incision seals securely, it may be left alone. An unstable wound (eg, in a case involving prolonged ultrasound use and extensive manipulation) should be closed with a suture.

The infusion line is placed through the first sideport with a low bottle height, and the fluid flow is directed toward the anterior chamber angle. The cutter is now inserted through the second sideport, establishing a stable closed system and allowing for a controlled environment. A high cut rate and low flow are advisable; the cutting rate should be set at 600 cuts/min to 700 cuts/min, with a vacuum of 150 mm Hg to 200 mm Hg (Figure 2). The high cut rate minimizes the risk of retinal traction while the vitreous is cut and removed. The cutter is placed through the tear, pointing toward the optic nerve. The cutting port is positioned behind the posterior capsule to minimize the risk of engaging the capsule during the vitrectomy.

The vitrectomy. Most of the anterior vitreous is drawn backward and efficiently removed. This is continued until the anterior segment is free of vitreous. Once accomplished, the cutter is moved forward into the capsular bag. Remaining lens matter is removed with the cutter, reducing the cut rate to 300 cuts/min. The vacuum is increased to draw the firmer lens material into the cutting port and allowing it to engage sufficiently to permit cutting. The cortex is then engaged, using the vacuum-only setting of the cutter and stripped off the capsule. The cortex is freed and drawn into the center, and the cutting action is activated to remove it. If vitreous strands remain, they will be highlighted by the triamcinolone, allowing easy identification and removal. The cutter is now withdrawn, and the anterior chamber is refilled with viscoelastic as the infusion is withdrawn. This maintains a stable anterior chamber. The stage is now set for IOL implantation.

IOL implantation. In most cases, there is adequate capsular support to implant an IOL into the ciliary sulcus. The overall diameter of the chosen IOL should be at least 13 mm. There are two optional maneuvers to consider at this stage: (1) If the tear in the posterior capsule is small and central, it may be possible to grasp the torn flap of capsule with an Utrata (Duckworth & Kent Ltd., Hertfordshire, England) or similar forceps and convert the opening into a posterior capsulorrhexis. If this is achieved, then in-the-bag IOL implantation is safe. If this is impossible, plan a sulcus implantation. (2) If the anterior capsulorrhexis is intact and central, place the IOL into the sulcus, and push the optic through the rhexis. The haptics remain in the sulcus, but the optic is positioned behind the anterior capsule captured by the capsulorhexis (Figure 3), achieving a stable IOL position. If the anterior capsulorrhexis is split or if zonular loss resulting in an eccentric rhexis is suspected, implant the lens into the sulcus. If the IOL is to be sited in the sulcus, adjust the IOL power for the changed lens position. A rule of thumb is to reduce the lens power by 0.50 D from that calculated for in-the-bag implantation. On the rare occasion of extensive capsule loss, an open-loop anterior chamber lens or an iris claw lens should be used.

Finishing steps. Once the IOL has been placed, the viscoelastic should be removed from the anterior chamber, with no attempt being made to remove it from behind the IOL. The pupil is then constricted with an agent such as acetylcholine (Miochol; Novartis Pharmaceutical, Basel, Switzerland). This will help identify any persistent vitreous strands that extend to the wound and cause a peaked pupil. If acetylcholine is injected with a blunt cannula through a sideport, the cannula may be used to confirm the absence of vitreous extending to the wound by placing it into the anterior chamber, near the angle under the incision and sweeping it centrally toward the pupil. My threshold for putting a suture into the wound to ensure closure is quite low.

DRY ANTERIOR VITRECTOMY
An alternative approach is to use a dry technique, whereby the vitreous is cut and removed without an infusion. This is especially useful for small amounts of vitreous presenting toward the end of a procedure (eg, if a strand of vitreous presents through a small area of zonular loss toward the end of cortical clean-up or after IOL implantation). In this setting, it is efficient to refill the anterior chamber with a viscolelastic and cut and remove the strand of vitreous with the cutter (Figure 4). As minimal maneuvering is required, and only a small volume is removed, the anterior chamber will not collapse, and the surgical goal is rapidly achieved. A dispersive viscoelastic will tamponade the vitreous and is preferred in this setting.

SINGLE PARS PLANA INCISION
A conceptually attractive alternative to bimanual anterior vitrectomy is to use infusion through the sideport and make a single pars plana incision 3.5 mm behind the limbus. The cutter is then placed into the vitreous cavity. This is done after reflecting the conjunctiva with an MVR blade for a 20-gauge cutter or transconjunctivally for a 25-gauge trocar cannula system for a high-speed 25-gauge cutter. This allows the flow to move in one direction—from anterior to posterior—making removal of vitreous more efficient. Many anterior segment surgeons may not be familiar or comfortable with pars plana incisions, and a bimanual anterior approach as detailed above will therefore be preferred.

POSTOPERATIVE CARE
There are some important issues that must be managed in the postoperative period.

Frequent topical steroids are useful postoperatively, as the increased manipulation involved often causes a higher level of inflammatory response than after uncomplicated surgery.

Intraocular pressure (IOP) may be elevated, because of any remaining viscoelastic and postoperative inflammation. This must be monitored and medically managed. The oft-employed technique of depressing the posterior lip of the sideport to release some aqueous when raised IOP is found after uncomplicated surgery should not be used after surgery complicated by capsular or vitreous loss.

If intraocular triamcinolone is used, some will invariably remain in the eye. The crystals may be seen as particles floating in the aqueous or unusually may collect in the anterior chamber, giving the false impression of a hypopyon. A clue to its benign nature is that the eye is not significantly inflamed. Also, under high magnification, the granular nature of the material is obvious. Triamcinolone may also raise the IOP, because of a steroid response, which should be treated medically. If a steroid response occurs, IOP-lowering medication should be continued 4 months to 6 months after surgery, but the raised IOP usually normalizes afterward.

Finally, a detailed fundus and full peripheral examinations must be obtained before the patient is discharged. This may be done a few days or even weeks after the surgery to allow time for any postoperative inflammation to settle and the wound to be secure. Effective management with good surgical technique and postoperative care will, in most cases, ensure excellent visual outcomes—even when vitreous loss occurs in cataract surgery.

Som Prasad, MS, FRCS(Ed), FRCOphth, is Consultant Ophthalmologist with special interests in cataract and vitreoretinal surgery, at Arrowe Park Hospital, in Wirral, UK. Dr. Prasad states that he has no financial interest in the products or companies mentioned. He receives travel reimbursement from Bausch & Lomb (Rochester, New York). He may be reached at sprasad@rcsed.ac.uk.