Ophthalmic Pearls EXTRA CATARACT CONTENT AVAILABLE Phacoemulsification After Pars Plana Vitrectomy: Pearls for the Cataract Surgeon by robert van der vaart, md, and kenneth l. cohen, md edited by sharon fekrat, md, and ingrid u. scott, md, mph ars plana vitrectomy (PPV) capsulorrhexis more difficult. Because 1A is now a frequently per- of decreased resistance, the surgeon formed vitreoretinal surgery needs to exert more pressure with the that, with improvements cystotome or the point of the capsulor- over the last decade, gen- rhexis forceps. However, occult zonu- Perally provides excellent anatomic, lar instability and/or posterior capsule visual, and safety outcomes. The damage may be present after PPV, and indications for PPV are numerous greater pressure against the capsule and include rhegmatogenous or trac- may exacerbate the situation. tional retinal detachment, proliferative Removal of the nucleus, epinucleus, diabetic retinopathy, macular hole, and cortex is complicated by the lack epiretinal membrane, trauma, vitreous of vitreous support, compromise of the hemorrhage, and endophthalmitis. supporting structures of the lens, and Although patients are commonly large fluctuations in anterior cham- referred to a vitreoretinal specialist for ber depth. These factors also make it PPV, the comprehensive ophthalmolo- more difficult to place the IOL in the 1B gist is likely to participate in the long- capsular bag. The incidence of periop- term care of postvitrectomy patients. erative complications, including iris For example, the ophthalmologist trauma, choroidal hemorrhage, and will probably be faced with making nuclear fragment loss, may be as high decisions about cataract surgery, as as 12.5%.2 cataract develops and progresses in up to 70% of patients within 2 years after Preoperative Considerations PREOPERATIVE DISCOVERY. (1A) The PPV.1 The cataract surgeon needs to PPV changes the structure of the eye, arrows indicate a posterior capsule understand the unique challenges of and the cataract surgeon’s preoperative hole identified in preoperative evalu- cataract surgery in post-PPV eyes. evaluation should take into account ation for cataract surgery in a patient the effect of these changes. who had previously undergone PPV. Why Is Phaco After PPV Challenging? Biometry. Optical biometry is more (1B) In this anterior segment OCT Eyes that have undergone PPV have a accurate than ultrasound biometry in taken in the same patient, the arrows higher risk of intraoperative and post- vitrectomized eyes for several reasons. indicate the area of posterior capsule operative complications; this is a result First, myopia is a risk factor for many injury with incomplete healing. of both the original disease that led to of the vitreoretinal conditions that are the PPV and the consequences of the treated with PPV; therefore, these eyes If the cataract is too dense for opti- vitrectomy procedure. The cataracts are often highly myopic or have poste- cal biometry, then immersion ultra- that occur most commonly after PPV rior staphylomas. Second, if silicone oil sound is preferred. are the denser nuclear sclerotic and is present, axial length measurement Assessing the need for cataract posterior subcapsular types, rather will be incorrect unless a compensat- surgery. It can be difficult to confirm than senile cataracts. 2,3 ing factor is used (see “Compensating that the cataract—rather than coex- The lack of posterior support for the for Silicone Oil,” with this article at isting vitreoretinal disease or prior debra k. cantrell, coa, unc kittner eye center cataractous lens makes performing the www.eyenet.org). treatment—is the primary cause of eyenet 33 Ophthalmic Pearls visual deficit in post-PPV eyes. Careful capsular and zonular compromise. into either the capsular bag or the cili- review of the medical record, including During this process, the surgeon ary sulcus. If there is zonular compro- tracking visual acuity changes before should allow for egress of ophthalmic mise, a 1-piece or a 3-piece IOL can be and after vitrectomy, as well as use of viscoelastic device so as to prevent pos- placed into the capsular bag with the instrumentation such as the potential terior dislocation of the lens through haptics in the meridian of the zonular acuity meter, can assist in making this an occult injury to the posterior cap- compromise. decision. sule and/or zonules. If posterior cap- If there is compromise of the pos- Preparing for possible compli- sule damage is known to be present, terior capsule, a 3-piece IOL may be cations. It is vital for the cataract hydrodissection may be omitted. placed in the ciliary sulcus. A 1-piece surgeon to carefully evaluate for the Phacoemulsification. Post-PPV IOL should never be placed into the presence of sequelae from the PPV eyes have deep and unstable anterior ciliary sulcus due to the risk of iris procedure; these may include zonular chambers compared with nonvitrecto- chafe and chronic uveitis. instability, phacodonesis, and posteri- mized eyes.3,4 If intraoperative fluctua- In the case of anterior capsule com- or capsule compromise. Such findings tion of anterior chamber depth occurs, promise, an anterior chamber IOL require the surgeon to adapt his or her the bottle height should be lowered should be considered, and the calcu- operative techniques. and the irrigation maintained to help lations should be available for that For example, during a preoperative stabilize the anterior chamber. scenario. When an anterior chamber evaluation on one of our patients, we Eyes with compromised zonules or IOL is used, it is advisable to perform identified the posterior capsular hole posterior capsule damage are at risk for a peripheral iridectomy to avoid pupil- shown in Figure 1. Accordingly, we fluid misdirection syndrome, which is lary block. IOL placement may be con- altered our surgical approach to elimi- indicated by narrowing of the anterior firmed with intraoperative aerial go- nate hydrodissection, use less vigorous chamber, a hard eye, and iris prolapse. nioscopy, as described by Dr. Charles nuclear manipulation, and employ In this condition, fluid flows into the Kelman. dispersive OVD more liberally. These posterior segment, and the ciliary body Zonular weakness or loss dur- adaptations produced an excellent out- rotates anteriorly, blocking flow from ing cataract surgery may necessitate come for the patient. posterior to anterior. Thus, raising the the use of a capsular tension ring to Informed consent. The consent bottle will, paradoxically, cause more provide stable support for placing the process for the postvitrectomy eye fluid to flow posteriorly, further shal- IOL. The ring should be placed with its should be customized to take into lowing the anterior segment and hard- opening 180 degrees from the area of account the higher degree of risk as- ening the eye. zonular weakness. sociated with cataract surgery in this Fluid misdirection is managed by The cataract surgeon should pre- setting. It is essential for the patient to halting irrigation and putting external pare for these possibilities and make understand the increased risk for ad- pressure on the incision to stop leak- sure that the appropriate instruments verse events. age. This anterior pressure counteracts and supplies are readily available. the posterior pressure; the anterior However, complications may still oc- Perioperative Steps chamber will deepen, and the eye will cur despite precautions. Such instances Wound construction. It may be dif- soften as the fluid equilibrates. emphasize the need for careful patient ficult to create a sclerocorneal tunnel Techniques for dismantling the preparation and consent in the preop- incision in the presence of conjunctival cataractous lens must be considered erative period. scarring. A clear corneal incision is carefully. Both nuclear sclerotic and recommended in such eyes. posterior subcapsular cataracts are Postoperative Considerations Capsulorrhexis. As discussed above, common after PPV. Nuclear sclerotic Whether the cataract surgery was capsulorrhexis may be difficult due cataracts are hard. In this situation, complicated or uneventful, there are to a lack of posterior support. In ad- the surgeon should consider a vertical important considerations for the post- dition, visualization may be hindered chop technique, which puts less stress operative care of these patients. by a poor red reflex caused by a dense on the zonules and creates less torque Short-term care. In eyes with cataract and capsular fibrosis. The use than does a horizontal chop technique. capsular or zonular complications, of Trypan blue should be considered to Because posterior subcapsular cata- complete removal of the viscoelastic is improve visualization of the anterior racts tend to be dense and adherent, rarely possible. Thus, it is our practice capsule. However, the surgeon should it may be safer to place the IOL in the to treat these patients prophylactically be aware that Trypan blue changes the capsular bag and perform a YAG cap- with oral or intravenous acetazolamide elastic property of the capsule, which sulotomy after the eye is healed. in the recovery area to avoid IOP eleva- becomes more fragile and less elastic. tion in the immediate postop period. Hydrodissection. Hydrodissection IOL Selection and Placement The cataract surgeon should consid- should be slow and gentle because of The surgeon should have calculations er performing dilated ophthalmoscopy the possibility of preexisting posterior available for a 3-piece