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according to Lens Opacities Classification System III2) andaxial length of 23.06 mm had planned cataract surgery usingthe femtosecond laser (LenSx, Alcon Labs, Inc.) to create thecapsulotomy and corneal incisions and to perform lens frag-mentation. Following application of the patient interface andsuction, the anterior and posterior capsules were identifiedand marked under direct optical coherence tomography(OCT) imaging. The ellipsoid lens fragmentation patternwas programmed to be 1000 mm anterior to the posteriorcapsule and 500 mm posterior to the anterior capsule. Duringthe procedure, normal gas spread was observed posteriorto the fragmentation pattern, within the lens nucleus, andbehind the anterior capsulotomy (Figure 1). No errors ormalfunctions were noted during the laser procedure.

During the operative procedure, an ophthalmic visco-surgical device (OVD) was injected through the primaryincision, the anterior chamber deepened normally, andthe capsulotomy was removed without evidence of an an-terior capsule tear. A hydrodissection cannula was intro-duced and balanced salt solution injected. Immediatewrinkling and movement of the lens capsule and iriswere noted, and the lens shifted posteriorly at the superior

pole, suggestive of a posterior capsule tear. Because of lensdislocation, the eye was closed and a vitrectomy per-formed on the same day. The vitreoretinal surgeon notedthe crystalline lens intact on the retinal surface with the la-ser fragmentation pattern and residual gas within the sub-stance of the intact lens (Figure 2). The lens was removed,and a posterior chamber intraocular lens (IOL) wasinserted in the ciliary sulcus. An intact laser-cut capsuloto-my was confirmed on retroillumination (Figure 3). Depthand energy calibration checks performed on the femtosec-ond laser at the end of the surgical day were within spec-ifications. The postoperative course was uneventful, andfemtosecond laserassisted cataract surgery was per-formed in the fellow eye 8 weeks later. The hydrodissec-

tion technique was modified as described below, andsurgery was completed without complication. The cor-rected distance visual acuity in both eyes was 20/20.

Case 2

A 78-year-old manwith dense grade 4 nuclear sclerotic cat-aract (NO4, NC4, according to Lens Opacities Classification

Figure 1. Normal intracapsular gas bubble pattern following laserlens fragmentation and capsulotomy.

Figure 2. Residual gas bubble within the dislocated crystalline lens.

Figure 3. Retroilluminated view revealing intact laser-cutcapsulotomy.

Figure 4. Optical coherence tomography imaging following applica-tion of the patient interface showing a mature dense nucleus.

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System III2)andaxiallengthof24.14mmhadplannedcataractsurgery using the femtosecond laser to create the capsuloto-my, lens fragmentation, and corneal incisions. No posteriorspread of gas was noted during lens fragmentation, and thelaser procedure was completed without complication. TheOCT imaging confirmed a large dense nucleus (Figure 4).The initial intraoperative stages of surgery were identical to

those in Case 1, and the capsulotomy was removed normallywithout evidence of tear. Following hydrodissection, thephacoemulsification tip was inserted into the eye and irriga-tion commenced. The crystalline lens wasnotedto be unstableand subluxated 90 degrees into the vitreous. The eye wasclosed and a vitrectomy performed on the same day. Follow-ing removal of the lens, an IOL was placed in the sulcus.As reported in Case 1 (which was performed on the samesurgical day), depth and energy calibration checks on thefemtosecond laser were within specifications. The postopera-tive course was uneventful, and the CDVA was 20/20.

DISCUSSION

The 2 cases of posterior capsule rupture and lens dislo-cation following hydrodissection we describe are con-sistent with descriptions of intraoperative CBS in theliterature.1,35 Sudden wrinkling and movement ofthe lens capsule, tilting and instability of the lens fol-lowing hydrodissection, or unexpected dislocation ofthe lens into the vitreous at the commencement ofphacoemulsification suggest a posterior capsule rup-ture due to intraoperative CBS. Intraoperative pupil-lary block6 and subsequent rupture of the posteriorcapsule is thought to occur if the injected hydrodissec-tion fluid does not flow freely around the lens within

the capsular bag and out through the anterior capsu-lotomy and corneal incision. Rapid accumulation offluid behind the lenscapsule complex can mimica threatened expulsive hemorrhage.7,8 The eye be-comes especially vulnerable when a highly cohesiveOVD is injected into the anterior chamber prior tohydrodissection. The presence of a normal capsulepreoperatively strongly suggests intraoperative CBS;however, in cases of a weakened posterior capsule(eg, trauma, hypermature cataract, or congenital pos-terior polar cataract9), spontaneous posterior capsulerupture can occur without intraoperative CBS.

Both of the cases occurred in older patients with ma-ture cataracts, which are recognized risk factors forCBS. In addition, analogous to the increased incidenceof intraoperative CBS following capsulorhexis versuscan-opener style capsulotomy, the uniform capsuloto-my created with the femtosecond laser may increasethe potential for blockage of fluid egress by the ele-vated nucleus following hydrodissection. The pres-ence of intracapsular gas and laser-induced changesin the cortex are unique to femtosecond laserassistedcataract surgery and may represent additional risk fac-tors for intraoperative CBS in high-risk patients. The

underlying mechanism appears to be resistance tothe flow of injected fluid around the lens nucleus, add-ing to capsule distension, or increasing resistancearound the edge of the laser-cut capsulotomy.

Given these potential risk factors, we recommendthe following intraoperative procedures be performedduring laser-assisted cataract surgery:

1. Reduce the OVD fill prior to anterior capsule re-moval to avoid overinflating the anterior chamber.

2. Decompress the anterior chamber before andduring hydrodissection by exerting pressure onthe posterior lip of the corneal incision with theelbow of the cannula.

3. Decompress the lens capsule during hydrodissec-tion by elevating the anterior capsule with the tipof the hydrodissection cannula during injection.

4. Inject the hydrodissection fluid slowly and titrate

the volume based on the visible expanding fluidwave.5. Use a pre-chopper or blunt-tipped side-port instru-

ment to split the hemispheres prior to hydrodissec-tion to allow the gas and/or injected fluid to comeforward.

With awareness of the changed intraocular environ-ment following laser lens fragmentation and capsulot-omy and a modification of the surgical technique, asdescribed above, no additional cases of intraoperativeCBS have been seen in more than 600 laser-assistedcataract surgery procedures performed to date at our

facility.

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2070 CASE REPORT: CAPSULAR BLOCK SYNDROME AFTER FEMTOSECOND LASERASSISTED CATARACT SURGERY

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