The Perfect Capsulorrhexis This Step in Cataract Surgery Dwarfs Many Other Steps in Importance

cover story eyetube.net The Perfect Capsulorrhexis This step in cataract surgery dwarfs many other steps in importance.

By David F. Chang, MD

he capsulorrhexis, or continuous curvilinear cap- IOL position from case to case. Being able to accurately sulotomy (CCC), is generally considered the single predict this effective lens position is a crucial factor in most important step in cataract surgery and pro- calculating the proper IOL power for emmetropia. vides numerous surgical advantages. First, a continu- Achieving these advantages is all the more crucial for ousT capsular edge renders the capsular bag more resistant multifocal and presbyopia-correcting IOLs. to tearing during surgery. Like an elastic waistband, the It follows that a capsulorrhexis with a diameter that capsulorrhexis will stretch in response to mechanical surgical extends beyond the optic edge in some or all areas forfeits forces rather than tear. Second, not only is a continuous edge these advantages. Posterior LEC migration occurs in any necessary to perform cortical cleaving hydrodissection, but it region where the posterior capsule is not kinked by the optic also facilitates cortical cleanup and placement of both hap- edge,3 and slight optic decentration may result from asym- tics into the capsular bag. Third, it converts the anterior cap- metric capsular contractile forces over time. Furthermore, as sule into a contingency platform for IOL support should the the posterior capsule tenses postoperatively, it may displace posterior capsule tear. Fourth, because the overall length of the optic slightly more anteriorly wherever it is not restrained many foldable IOLs is too short for the ciliary sulcus, captur- by a taut capsulorrhexis edge, resulting in a myopic shift. ing the optic of a three-piece IOL with the capsulorrhexis is the best way to assure good IOL centration in this situation. DISADVANTAGES OF A SMALL-DIAMETER Failure to achieve an intact capsulorrhexis not only CAPSULORRHEXIS precludes these benefits but also increases the risk of During phacoemulsification, a smaller capsulorrhexis posterior capsular rupture due to a wraparound tear. is much more likely than an adequately sized one to be torn by the chopper tip or shaft or incised with the properly sized CAPSULORRHEXIS phaco tip. Surgeons should take a mental snapshot of The postoperative advantages of a properly sized cap- the capsulorrhexis shape and diameter upon its comple- sulorrhexis are equally important. First, as the capsular tion, because its visibility will be subsequently lost fol- bag contracts, a continuous capsulotomy edge prevents lowing hydrodissection and nuclear rotation. This allows pea-podding, or escape of either haptic.1 Second, asym- the surgeon to mentally picture the edges of the capsu- metric capsular forces resulting from an eccentric CCC lorrhexis during emulsification. Aspirating the anterior can cause delayed optic decentration. Third, continuous epinucleus prior to phacoemulsification also facilitates circumferential overlap of the IOL optic edge produces this. Using bimanual instrumentation for cortical cleanup a capsular shrink-wrap effect, whereby the posterior may overcome the specific hurdle of aspirating the sub- capsule is kinked by the optic edge—a major factor in incisional cortex with a small-diameter capsulotomy. the prevention of posterior capsular opacification.2 That In addition to impeding surgical steps, a CCC with a is, by sharply indenting the posterior capsule, the optic small diameter may create problems postoperatively. The edge creates a mechanical barrier that blocks lens epi- increased load of LECs on the back of the anterior capsule thelial cells (LECs) from migrating behind the lens optic.3 can increase inflammation, cause anterior capsular fibro- Capsulorrhexis overlap may also help to reduce positive sis and opacification, and produce excessive contraction optic edge dysphotopsias as the anterior capsule opaci- of the capsulorrhexis and capsular bag.4 This can lead to fies over time. Finally, such continuous overlap of the zonular damage or dehiscence and optic decentration.5 optic edge is the only way to attain consistency in axial Anterior capsular fibrosis and contraction are more likely

54 Cataract & Refractive Surgery Today europe May 2014 cover story

A B

C D

E F

G H

Figure 1. Secondary enlargement of the capsulorrhexis: The primary capsulorrhexis diameter is kept small to avoid a peripheral radial tear (A). After IOL implantation, the capsulorrhexis diameter is seen to be too small (B). An oblique cut in the edge is made with curved capsule scissors (C). Capsule forceps are used to retear the capsulotomy to increase its diameter while still overlapping the optic edge (D-H). with silicone optic material than with hydrophobic acrylic Given the importance of attaining a proper capsulorrhexis materials.6 With weakened zonules, visually significant capsular diameter, it is ironic that, until recently, this is one of the only phimosis or subluxation of the bag-IOL complex can occur.7,8 steps that had not been improved through the use of new Besides secondary capsulorrhexis enlargement (Figure 1), technology. Most of us continue to employ the low-tech as described below, other techniques to reduce capsular method of a manual tear performed with a needle and/or contraction include aspiration of LECs from beneath the forceps with an intended diameter that is estimated visually. anterior capsule and creation of relaxing incisions in the a However, individual variability in corneal magnification anterior capsule with an Nd:YAG laser.9 Excessive anterior and in anterior segment and pupil diameter makes it dif- capsular opacification can impair ophthalmoscopic visual- ficult to precisely size the capsulorrhexis. Parallax occurring ization of the peripheral retina and become visually signifi- with eye movement makes it difficult to judge the sym- cant for the patient. Finally, excessive overlap of the nasal metry and centration of the evolving capsulotomy. One of optic edge with a capsulorrhexis may be a cause of tempo- the most appealing advantages of a femtosecond laser cap- ral pseudophakic negative dysphotopsia.10 sulotomy is the ability to reproducibly create a centered

May 2014 Cataract & Refractive Surgery Today europe 55 cover story

capsulotomy of a precise diameter. Other methods include a Malyugin Ring (MicroSurgical Technology). the use of corneal markers and capsule forceps with etched Timing. The safest time to enlarge the capsulorrhexis millimeter markings to assist in gauging size, such as the is after IOL insertion. This is true regardless of whether Seibel Rhexis Ruler (MicroSurgical Technology). a capsular tension ring (CTR) is inserted. Executing the second-stage enlargement is generally easier than the SECONDARY ENLARGEMENT primary capsulotomy for several reasons. First, following Strategy. When performing a manual capsulotomy, my removal of the cataract, the red reflex is improved and strategy is to plan on performing a two-stage capsulor- there is no convexity to the anterior capsule to promote rhexis as needed. As I make the primary capsulorrhexis, I err downhill radial extension of the tear. Second, the optic on the small side (Figure 1A). This is because the diameter provides a perfect visual template for resizing the CCC can always be enlarged, but not reduced. diameter. Third, in eyes with weak zonules, the presence I take a moment to assess the appropriateness of the of stiff three-piece IOL PMMA haptics or a CTR increases CCC diameter after IOL implantation. Frequently, the outward tension on the capsular bag and improves con- size and centration are fine; however, it is surprising how trol over the direction of the anterior capsular tear. It is often the CCC is slightly eccentric to the optic center. reassuring that, should the tear escape peripherally, the Sometimes, a perfectly round CCC becomes ovoid follow- risk of a posterior wraparound tear is negligible because all ing IOL implantation due to the directional stretch of stiff of the most forceful surgical steps have been completed. three-piece IOL haptics. Significant ovalization may indicate However, the IOL should not be rotated in the presence of zonular laxity and insufficient centrifugal tension in the a single anterior capsular tear because of this risk. areas perpendicular to the haptic axis. Advantages. Although enlargement of a small-diameter In either of these situations, or if the overall diameter is capsulorrhexis is not absolutely necessary in most cases, I too small (Figure 1B), I enlarge the capsulorrhexis by first encourage the mastery of this technique. With multifocal making an oblique cut with scissors (Figure 1C) and then IOLs, achieving a symmetric capsulorrhexis that completely grasping the resulting flap with capsule forceps (Figure overlaps the optic edge is particularly important. There 1D). The cut should be oblique, rather than radial, to is even less margin for CCC diameter error with accom- better incline the resulting flap to tear circumferentially. modating IOLs, such as the Crystalens (Bausch + Lomb). The flap is then maneuvered with capsule forceps Excessive variability in CCC diameter has a greater effect on under a generous amount of ophthalmic viscosurgical effective lens position for a hinged IOL design. Initially err- device (OVD; Figures 1D through 1H). Curved Uthoff-Gills ing on the small side, with the option to enlarge when and capsulotomy scissors with blunt tips (K4-5126; Katena where necessary, is a reliable way to consistently manually Products) have the perfect shape for creating an initial obtain a perfectly sized capsulorrhexis diameter. curved cut to either side of the phaco incision. In some Comfort with the secondary enlargement maneuver is cases, I trim only a part of the remaining anterior capsular important if one is having difficulty steering the flap during rim where it is excessively wide. Other times, I may retear the primary capsulorrhexis. Whether the cause is poor vis- the entire 360º circumference of the opening (Figure 1). If ibility, patient movement, a shallow anterior chamber, or the pupil is small enough to conceal the optic edge, it can weak zonules, one can make a smaller-diameter opening in be locally retracted with a Lester hook or by maneuvering order to increase control and reduce the risk of a peripheral extension. The capsule tear-out rescue maneuver Take-Home Message described by Brian C. Little, MA, FRCS, FRCOphth, can be • Failure to achieve an intact capsulorrhexis not only used to improve control or rescue an escaping tear.11 precludes multiple benefits but also increases the Because of the long-term impor- et risk of posterior capsular rupture. tance of a properly sized capsular • Surgeons should take a mental snapshot of the be .n

opening, the surgeon should sec- tu capsulorrhexis shape and diameter upon its e

ondarily enlarge a small-diameter ey completion because its visibility will be lost capsulorrhexis following IOL inser- following hydrodissection and nuclear rotation. tion, when the surgical conditions are eyetube.net/?v=itote • A two-stage capsulorrhexis technique ensures that more favorable. For a video depiction the CCC is never too large; err on the small side of my technique, visit eyetube.net/?v=itote. and enlarge it if necessary after IOL implantation. Special indications. There are two clinical situations • In eyes with uveitis or weak zonules, it may be in which it may be advantageous to enlarge the capsu- advantageous to enlarge the capsulorrhexis lorrhexis diameter out to or beyond the IOL optic edge diameter out to or beyond the IOL optic edge. (known as all off).

56 Cataract & Refractive Surgery Today europe May 2014 cover story

Eyes with uveitis. Uveitic eyes with preoperative posterior enhanced control and visibility cited earlier. In pseudoexfolia- synechiae have a strong tendency to develop iris adhesions tion eyes where a CTR is not deemed necessary, I secondarily to the anterior capsular edge postoperatively. Iris bombé, enlarge the capsulorrhexis diameter to reduce the zonular with full circumferential pupil seclusion and secondary weakening potential of capsular contraction over time. n angle-closure glaucoma, can occur and be refractory to Nd:YAG or surgical iridectomy. Some have suggested plac- David F. Chang, MD, is a Clinical Professor at ing the IOL in the ciliary sulcus in uveitic patients so that the University of California, San Francisco and in the optic will prevent posterior synechiae from developing private practice in Los Altos, California. Dr. Chang to the capsulorrhexis edge.12 As a better alternative, sec- states that he has no financial interest in any ondarily widening the capsulorrhexis following IOL inser- instrument or technique described. He may be tion should achieve this goal and preserve the immunologic reached at e-mail: [email protected]. advantages of sequestration of the lens in the capsular bag. 1. Ram J, Apple DJ, Peng Q, et al. Update on fixation of rigid and foldable posterior chamber intraocular lenses. Part I: Elimination of Eyes with weak zonules. A second situation in which a fixation-induced decentration to achieve precise optical correction and visual rehabilitation. Ophthalmology. 1999;106:883-890. larger-than-usual capsulorrhexis is advantageous is with 2. Hollick EJ, Spalton DJ, Meacock WR. The effect of capsulorhexis size on posterior capsular opacification: one-year results of a randomized prospective trial. Am J Ophthalmol. 1999;128:271-279. weakened zonules. Because capsulorrhexis contracture 3. Nishi O, Nishi K, Wickstrom K. Preventing lens epithelial cell migration using intraocular lenses with sharp is countered by centrifugal zonular tension, significant rectangular edges. J Cataract Refract Surg. 2000;26:1543-1549. 4. Joo CK, Shin JA, Kim JH. Capsular opening contraction after continuous curvilinear capsulorhexis and intraocular capsular phimosis always indicates severe zonular laxity. lens implantation. J Cataract Refract Surg. 1996;22:585-590. 5. Hayashi H, Hayashi K, Nakao F, Hayashi F. Anterior capsule contraction and intraocular lens dislocation in eyes Capsulorrhexis contracture, in turn, further dehisces and with pseudoexfoliation syndrome. Br J Ophthalmol. 1998;82:1429-1432. weakens the zonules and increases the risk of late bag-IOL 6. Werner L, Pandey SK, Escobar-Gomez M, et al. Anterior capsule opacification: A histopathological study compar- 5,7,8 ing different IOL styles. Ophthalmology. 2000;107:463-471. dislocation with pseudoexfoliation. Therefore, leaving 7. Jehan FS, Mamalis N, Crandall AS. Spontaneous late dislocation of intraocular lens within the capsular bag in a small-diameter capsulorrhexis in an eye with weakened psuedoexfoliation patients. Ophthalmology. 2001;108:1727-1731. 8. Chang DF. Prevention of bag-fixated IOL dislocation in pseudoexfoliation. Ophthalmology. 2002;109:1951-1952. zonules is particularly objectionable. 9. Hayashi K, Yoshida M, Nakao F, Hayashi H. Prevention of anterior capsule contraction by anterior capsule relaxing Because a larger-diameter capsulorrhexis has far less ten- incisions with neodymium:yttrium-aluminum-garnet laser. Am J Ophthalmol. 2008;146:23-30. 10. Masket S, Fram NR. Pseudophakic negative dysphotopsia: Surgical management and new theory of etiology. J dency to contract, my preference is to secondarily enlarge the Cataract Refract Surg. 2011;37:1199-1207. 11. Little BC, Smith JH, Packer M. Little capsulorhexis tear-out rescue. J Cataract Refract Surg. 2006;32:1420-1422. capsulorrhexis diameter out to the optic edge in eyes with 12. Holland GN, Van Horn SD, Margolis TP. Cataract surgery with ciliary sulcus fixation of intraocular lenses in weak zonules. This is done after IOL insertion because of the patients with uveitis. Am J Ophthalmol. 1999;128:21-30.