IOL PLACEMENT FOLLOWING ANTERIOR OR POSTERIOR CAPSULE TEARS

David F. Chang, MD

Cataract surgeons must always be prepared to manage unexpected anterior or posterior capsule tears. In addition to completing removal of the nucleus and cortex, the surgeon must attempt to preserve as much capsular support as possible. The latter will determine the intraocular lens (IOL) fixation options, and this chapter will provide an overview of considerations with anterior or posterior capsule tears.

Anterior Capsule Tears

The incidence of anterior capsule tears reported from 4 contemporary studies varies from 0.8% to 5%.^1–4 The highest rate was from a resident series.² In Osher et al’s series of more than 2600 consecutive eyes, the overall rate of anterior capsule tears was 0.8%, and the incidence of tears occurring during the capsulorrhexis step was 0.5%.³ Forty-eight percent of these anterior capsule tears eventually extended into the posterior capsule, and 19% of cases with a torn capsulorrhexis required an anterior vitrectomy.

A series of 239 consecutive cases of anterior capsule tear were retrospectively evaluated at Moorfields Eye Hospital.⁵ Concurrent posterior capsule rupture developed in 24% of these eyes; 16% had vitreous loss and 5% had retained nuclear material. IOLs were placed within the capsular bag in 121 eyes (51%), in the ciliary sulcus in 108 eyes (45%), in the anterior chamber in 8 eyes (3%), and 1 eye remained aphakic. IOL exchange or repositioning surgery was performed in 5 eyes. Of 187 eyes with reported refractive outcomes, only 42.2% were within 0.50 diopters (D) of the target. The group with a ciliary sulcus IOL had worse refractive outcomes than those with capsular bag IOLs.

Following cortical clean-up, if the capsular bag is intact, it should be filled with ophthalmic viscosurgical device (OVD). A single radial tear will frequently cause the capsulorrhexis to take on a teardrop shape (Figure 16-1B). The goal is to implant and position the IOL without extending the radial anterior capsule tear into the posterior capsule. A wraparound tear will likely occur when enough pressure is applied against the capsular equator just beneath the radial tear. Injection and implantation of a hydrophobic, single-piece acrylic IOL can be performed while orienting the haptics 90 degrees away from the radial tear (Figure 16-1). The folded single-piece acrylic IOL is first injected into the capsular bag. The haptics open slowly enough to rotate the IOL without applying any force against the capsular equator (see Figures 16-1C and D). Toric single-piece acrylic IOLs pose a special challenge because the haptic-optic junction is located along the axis of cylinder correction (see Figure 16-1F). When deciding whether to implant a toric single-piece acrylic IOL following a radial anterior capsule tear, the surgeon must know where the haptics will need to be located to obtain the proper toric axis+ alignment.

If a single-piece acrylic IOL design is not available, a 3-piece IOL can also be safely placed inside the capsular bag with a single radial tear. The key is to avoid forcefully decentering the optic and haptic toward the quadrant where the capsulorrhexis is torn. One can accomplish this by first directing the lead haptic into the anterior chamber rather than into the capsular bag. This allows the surgeon to rotate the trailing haptic into the bag while all decentering forces are applied via the lead haptic against the opposite anterior chamber angle. The second haptic is rotated into the bag by decentering the optic away from the capsulorrhexis tear. The haptics are then oriented approximately 90 degrees away from the location of the radial tear. The advantage of completing phaco in the presence of a single capsulorrhexis tear is that the intended IOL can still be placed inside the capsular bag, with a low risk of postoperative decentration. Three-piece posterior chamber IOL (PCIOL) placement into the ciliary sulcus is also an acceptable option, but without the option of continuous curvilinear capsulorrhexis (CCC) optic capture. This increases the risk of a refractive surprise or postoperative decentration due to insufficient overall length.

As popularized by Howard Gimbel, a posterior capsulorrhexis can be considered if the capsule tear is localized without peripheral extension6 (Figures 16-2 and 16-3). A dispersive OVD should be placed anterior and posterior to the rent to help immobilize it and to displace the hyaloid face posteriorly. Because the retrocapsular OVD will not be aspirated out, a dispersive agent is less likely to cause a protracted intraocular pressure elevation. Locating and grasping a free capsule flap is not always possible. If not, capsule forceps can grasp one edge of the defect in an attempt to tear and round it off. Because the posterior capsule is so thin, it behaves with the characteristic elasticity of a pediatric anterior capsule. This makes it difficult to control the progression of the advancing tear unless the Little capsule rescue tear-out maneuver is employed.⁷ The advantage of a posterior capsulorrhexis is the ability to implant and securely fixate a single- or 3-piece IOL within the capsular bag without further enlarging the posterior capsule defect (see Figures 16-2G and 16-3K).

If the capsulorrhexis is intact and of an appropriate diameter, a 3-piece foldable or nonfoldable PCIOL should generally be placed in the ciliary sulcus (Figure 16-4). After the haptics are first positioned in the sulcus, the optic should be captured through a centered capsulorrhexis if possible.^6,8 CCC optic capture will ensure better centration if the ciliary sulcus diameter is larger than the IOL’s overall haptic length. First one side of the optic is tilted back and beneath the capsular rim before repeating the same maneuver for the other side of the optic (see Figures 16-4E through G). CCC optic capture may not be possible if the capsulorrhexis diameter is too large, too small, or decentered. It is also more challenging with significant zonulopathy or prior vitrectomy because of decreased peripheral anterior capsular countertraction. With CCC optic capture, the optic still rests behind the anterior capsule and there is generally no need to adjust the power of the IOL (see Figure 16-4G).

The posterior capsule may also tear during the injection and implantation of a single-piece acrylic IOL. Particularly if there is no vitreous prolapse, the surgeon may be reluctant to rotate or exchange the IOL at this point. If so, one option is to perform reverse optic capture, where the haptics are left within the equatorial capsular bag behind the CCC, but the optic is prolapsed forward through the capsulorrhexis (Figure 16-5). Because the thicker single-piece haptics remain behind the anterior capsule, the risk of iris chafing is low in this situation. Posterior capsule rupture is particularly problematic when the patient had selected a toric, multifocal, or extended depth of focus IOL. Reverse optic capture is often an option for implanting a single-piece acrylic refractive IOL when the posterior capsule is torn. It may be possible to achieve reverse optic capture with a 3-piece PCIOL as well, but the posterior angulation of the haptics makes it difficult. Finally, the torn anterior and posterior capsular remnants may fuse postoperatively to provide a continuous opening through which the optic can be captured secondarily (Figure 16-6).

IOL SELECTION FOR CILIARY SULCUS PLACEMENT WITHOUT OPTIC CAPTURE

There are situations in which both the anterior and posterior capsules are torn, but sufficient capsular support remains to support a PCIOL in the ciliary sulcus without CCC optic capture. A wraparound anterior capsule tear that extends into the posterior capsule is an example (Figure 16-7). Amidst the stress of managing an unexpected complication, it may be tempting to use the same foldable PCIOL that was planned for the capsular bag. This is not recommended for several reasons.

Moving the axial IOL position slightly forward changes the effective power of the lens. Therefore, the IOL power should be decreased by approximately 0.5 D to 1.0 D to compensate for this change in position.^9–11 The refractive change from any axial shift is proportional to the dioptric power of the IOL optic. The higher the IOL dioptric power, the greater the compensatory reduction in sulcus placement power should be. Therefore, for IOL powers in the low to high 20s, 1.0 D should be subtracted for an IOL placed in the sulcus.

Single-piece acrylic IOLs should never be placed into the ciliary sulcus.¹² The overall length of this IOL is too short for sulcus placement, and the thicker, sharp-edged haptics can cause posterior iris chafing, pigment dispersion, and iris transillumination defects. Chronic uveitis-glaucoma-hyphema syndrome and cystoid macular edema may result until the offending IOL is removed.12–16 In the largest published retrospective study of complications of single-piece acrylic IOLs in the ciliary sulcus, the most common complication was lens decentration, which frequently resulted in symptomatic edge glare.¹²

In contrast, 3-piece PCIOLs have the advantage of thin, posteriorly angulated C-shaped haptics. Ideally, the anterior optic surface should be smooth and have rounded edges to prevent iris chafing should any posterior iris contact occur. In the absence of suturing or capsulorrhexis capture, proper IOL centration requires adequate capsular support and lateral stability within the ciliary sulcus, and IOLs shorter than 13.0 mm should not be used. Polymethylmethacrylate (PMMA) PCIOLs with 6.5-mm optics and a 14-mm overall length fulfill these criteria but require a much larger incision.

Among foldable, 3-piece hydrophobic acrylic IOLs, the MA50 model by Alcon Laboratories, Inc has a 6.5-mm diameter optic, but has a square anterior optic edge and an overall haptic length of 13.0 mm. This IOL has been associated with pigment dispersion following piggyback implantation in the sulcus, and the sharp anterior edge of this optic is therefore undesirable in this location.^17–21 One potential disadvantage of silicone IOLs is the compromise in surgical visibility should silicone oil or expansile gas ever be required for vitreoretinal surgery.22,23

Negatively aspheric IOLs have become popular as a means of reducing overall ocular spherical aberration and improving contrast sensitivity. However, because these IOLs have higher amounts of negative spherical aberration (to offset the positive spherical aberration from the cornea), they will actually induce more unwanted higher-order aberrations if they become tilted or decentered by more than 0.5 mm.^24–26 For this reason, based on the potential induction of spherical and other higher-order aberrations, it is inadvisable to implant a negatively aspheric IOL in the sulcus if centration within +0.5 to 0.8 mm cannot be achieved. The Johnson & Johnson Vision Sensar AR40 has a rounded anterior optic edge and is an excellent 3-piece hydrophobic acrylic IOL for sulcus placement. It also has close to zero spherical aberration, which means that slight tilt or decentration are unlikely to result in higher-order aberrations from the IOL.

PREVENTING AND MANAGING SUBLUXATION OF A POSTERIOR CHAMBER IOL IN THE SULCUS

Nearly all foldable lenses are 13.0 mm or longer, which may be too short for the ciliary sulcus in some eyes. Studies by Werner and others have also shown that there is no reliable way to gauge the sulcus diameter according to external landmarks.27–30 Using the Artemis UBM to measure the sulcus in autopsy eyes, Werner found that the diameter of the sulcus can vary from one meridian to another.²⁷ In other words, the sulcus plane may be more oval rather than circular. Therefore, although the IOL may center well in the operating room, if it is too short it can eventually rotate into the longest diameter meridian, causing it to become decentered.

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