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Cataract Surgery | Mar 2009

Posterior Capsular Rupture: Prevention and Management

Rupture may occur suddenly and unexpectedly, even during the best planned and executed surgeries.

Posterior capsular rupture is one of the most significant complications of cataract surgery. Because vitreous is usually involved, the chance of placing an IOL in the posterior chamber is jeopardized. It is difficult for the surgeon to visualize the posterior capsule, which may be seen only by reflexes of its surface, unless there is an opacity of the capsule. This demands comfort with the particular operation, gained only by performing many surgeries.

In this article, I offer my surgical techniques for cases of sudden posterior capsular rupture. Any technique should begin with the preoperative assessment. Proper assessment of the eye preoperatively will prepare you for possible eventualities, including posterior capsular rupture.

PREOP ASSESSMENT
A standard preoperative cataract assessment includes slit-lamp examination of the capsule with a dilated pupil. Some things to look for during this assessment include a fibrotic anterior capsule, pseudoexfoliation (PXF), and vitreous hemorrhage. If the other eye has had cataract surgery with capsular rupture, it may well occur in the second eye.

If the anterior capsule is fibrotic, which is common in patients with a long-standing cataract, the continuous curvilinear capsulorrhexis (CCC) or anterior capsulotomy may be difficult to achieve. In these cases, the capsule may have to be cut with scissors. Additionally, hypermature cataractous lenses in these circumstances may develop zonular dialysis. A tear of the anterior capsular CCC extending posteriorly may result.

If PXF is present, lens subluxation, raised intraocular pressure (IOP), and fragility of the capsule may occur. Subluxed crystalline lenses make lens extraction more difficult to achieve. The surgeon must take care to preserve as much capsule as possible to allow placement of a posterior chamber IOL. The use of a capsular tension ring may be helpful.

Any trauma to the anterior capsule causing a cataract may have penetrated far enough to involve the posterior capsule, which will only be seen after lens matter is removed. Additionally, vitreous hemorrhage makes it difficult to get a red reflex, and therefore, the reflexes from the posterior capsule can be more difficult to pick up.

DIAGNOSIS
As a surgeon, you must continually assess the situation intraoperatively. It is imperative to know when you may have ruptured the capsule. The following are indicators: (1) the rim of the hole in the capsule is visible, (2) it becomes difficult to aspirate the remaining lens matter, which is mixed up with the vitreous, (3) the anterior chamber is deep, despite aspiration with no infusion, because vitreous is filling the chamber, (4) air injected into the anterior chamber does not form a single bubble but rather multiple bubbles, (5) there is no reflex from the posterior chamber when palpated with the instruments, such as the chopper, (6) sticky vitreous is found in the wound—a Weck-cell swab wiped past the wound will pick up strands of vitreous, and (7) the nucleus can drop into the posterior segment.

There are several things you can do during cataract surgery to avoid posterior capsular rupture. After peribulbar anesthesia, apply pressure to the eye. I typically use a weight or pinky ball or ask the patient to apply pressure to the eye by pressing with their hand. This pressure exerted on the eye will reduce the pressure of the vitreous pushing forward. Applying pressure is unnecessary when using anesthetic eye drops only and would cause a dangerous vagal reaction. Additionally, the weight of the eye speculum increases vitreous pressure on the posterior capsule.

The closed chamber phaco technique keeps the capsule bowed backward and unlikely to herniate through the pupil. With this technique, applying pressure to the eye prior to surgery is also unnecessary.

The size of the CCC should be smaller than the optic of the IOL. If the CCC should tear, it can extend into the posterior capsule. To avoid a posterior capsular tear, keep the instruments away from the posterior capsule. Instruments placed behind the nucleus can keep the tip of the phacoemusifier away from the capsule. The nucleus should be sucked out of the posterior chamber and emulsified in the iris plane. Care must be taken not to groove the nucleus too deep, thus rupturing the capsule. The red reflex seen at the bottom of the groove is a good indicator of current depth. In aspiration mode, the tip of the phaco probe may be used to shovel soft lens matter from the bottom of the groove and uncover the posterior capsule. If this is unsuccessful, there is more hard nucleus that needs emulsification.

MANAGEMENT
Even in the best planned and executed surgery, capsular rupture may occur. When it happens, the rupture is sudden and unexpected. As mentioned above, good effective anesthesia will reduce the likelihood of this complication; using topical anesthesia requires a closed chamber technique.

The diagnosis of posterior capsular rupture should be made as early as possible to limit the extent of the rupture and the amount of damage to the eye. In the event that the CCC tears, consider converting to an extracapsular cataract extraction technique. If the hole in the posterior capsule is small, pushing back with an ophthalmic viscosurgical device may control the vitreous.

An anterior vitrectomy through the capsular hole can prevent enlargement of the hole. It is necessary to clear all vitreous out of the anterior chamber and the wound. At the end of the anterior vitrectomy, the pupil should be round and all vitreous removed from the corneoscleral incision. Vitreous should be swept from the surface of the iris, where it tends to be slightly adherent. Triamcinolone acetonide injected into the eye will pick up vitreous strands; it has the added effect of being antiinflammatory. Pilocarpine injected intracamerally at the end of surgery, when the IOL is in place, will pick up any distortions of the pupil due to vitreous on the surface of the iris or in the wound.

After the vitrectomy, the amount of remaining capsule can be assessed to decide whether it is possible to safely place a posterior chamber IOL. If there is any doubt, it is best to close and implant a secondary posterior chamber IOL later, after you have looked at the situation at the slit lamp. Iridectomy should also be considered.

In the event of a posterior capsular rupture, there maybe enough anterior capsule to support the IOL. The posterior chamber IOL may then be placed in the sulcus. A hard PMMA lens with as large an optic as possible should be used. This will mean enlarging the incision to accommodate the IOL. The incision must then be sutured. If there is enough anterior or posterior capsule to support the IOL inferiorly, stitch the superior haptic of the scleral fixation IOL to the iris at the 12-o'clock position. (This should be done as a secondary procedure because it will not be possible through the tunnel or corneal incision.)

A posterior lens implant may be impossible if the rupture is too large or the zonules rupture with loss of the capsular bag, as may occur in PXF cases. In these situations, an anterior chamber lens may be inserted with two iridectomies in a separate procedure. Other optical corrections are possible if the eye is at risk of more complications with further operations. Contact lenses or aphakic spectacles are safe ways to correct vision; however, they are not as acceptable due to the high expectations of the patient.

COMPLICATIONS
As with any surgical procedure, complications may result during cataract surgery in cases in which posterior capsular rupture occurs. In certain circumstances, complications are more likely, including: (1) failure to implant a posterior chamber IOL that provides the best optical correction, (2) vitreous loss, after which retinal detachment occurs more frequently, (3) cystoid macula edema, (4) wound leakage if the vitreous wick keeps the wound open, (5) progression of diabetic retinopathy, which may lead to rubeosis, (6) end-ophthalmitis, and (7) migration of previously injected silicone oil has into the anterior chamber.

CONCLUSION
If capsular rupture is diagnosed early and proper management is carried out, the results of the surgery can be the same as if the complication had never occurred.

Mark Wood, MD, practices with the CCBRT Hospital, Dar es Salaam, Tanzania. Dr. Wood states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: markwood@cats-net.com.

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