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Managing compromised capsules and weak zonules
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This issue’s cover story discusses approaches for managing compromised capsules and weak zonules, which occasionally occur even though cataract surgery techniques have advanced a lot in recent years. These situations can be challenging, especially when they happen unexpectedly during surgery. However, if managed properly, good surgical outcomes are possible even in the case of a compromised capsule or weak zonules.
When facing situations with a compromised capsule, the first and foremost thing that should go through a surgeon’s mind is “don’t panic” and “keep calm.” There is a natural tendency for surgeons to quickly withdraw all instruments from the eye once realizing such a complication has happened, especially when he or she is panicked. This is, however, adding trouble to the already compromised situation because once instruments are withdrawn without precautions, the underlying vitreous will have a much higher chance to prolapse into the anterior chamber or even through the wounds. It is highly desirable to stabilize the anterior chamber and tamponade the underlying vitreous with viscoelastic agents before withdrawing instruments.
After stabilizing the anterior chamber, a careful evaluation of the situation should follow. If nuclear or cortical fragments remain inside, a choice exists between continuing with phacoemulsification under a closed chamber or converting to manual expression through an enlarged wound. Generally speaking, if the chance of dropping the nucleus is low (eg, small fragments, relatively intact capsule, good viscoelastic tamponade), phacoemulsification can be carefully continued with special settings (eg, low bottle height, high energy level, low vacuum). On the other hand, if the chance of dropping the nucleus is high, it will be more desirable to enlarge the main wound and express the nucleus out manually with the help of either viscoelastic agents or instruments.
Anterior vitrectomy is sometimes necessary if there is vitreous prolapsed into the anterior chamber or through the wounds. Mechanical vitrectomy with a sponge and scissors is generally obsolete due to its potential traction to the underlying retina. An automated anterior vitrector, preferably 23 gauge inserted through side ports, is preferred. During anterior vitrectomy, the anterior chamber should be maintained with either repeated filling of viscoelastic agents or fluid infusion. The infusion port should be above the iris plane, so as to avoid disturbance of the vitreous in the posterior chamber. Intracameral triamcinolone is helpful in identifying vitreous in difficult cases.
After delivering all the remaining nuclear or cortical fragments and clearing any prolapsed vitreous by anterior vitrectomy, placement of an IOL may be considered. This depends on the extent of capsular damage and the expertise of the surgeon. The ideal place for IOL implantation is always the capsular bag, if intact and safe. If this is not possible, sulcus or scleral fixation and an anterior chamber IOL may be considered. Moreover, if nucleus drop happened, prompt referral to a vitreoretinal specialist is highly desirable.
If weak zonules are noticed during cataract surgeries, we fully echo that a capsular tension ring (CTR) is indeed a great potential rescue to a difficult situation. It improves both stability and centration of the capsular bag-IOL-CTR complex. If, however, the zonular loss is too extensive, centration of the complex may not be good, even if stability can be maintained. Two options are available in this scenario: suturing a CTR with an eyelet (eg, a Cionni ring) during the surgery, or using a two-stage approach of implanting the CTR and IOL first, followed by scleral fixating the capsular bag-IOL-CTR complex at a second surgery after capsular fibrosis has occurred. The second option is less technically challenging, has more predictable outcomes and can be performed even if a Cionni ring is not available.
References:
Kumar DA, et al. J Refract Surg. 2012;doi:10.3928/1081597X-20120413-01.
Sparrow JM, et al. Eye (Lond). 2011;doi:10.1038/eye.2011.103.
Vajpayee RB, et al. Surv Ophthalmol. 2001;45(6):473-488.
For more information:
Dennis S.C. Lam, MD, FRCOphth, can be reached at State Key Laboratory in Ophthalmology, Sun Yat-Yen University, 54 South Xianlie Road, Guangzhou 510060, People’s Republic of China; +852-3997-3266; fax: +852-3996-8212; email: dennislam.gm@gmail.com.