The transition from can-opener capsulotomy to capsulorrhexis was an epiphany that redefined phacoemulsification surgery and significantly improved postoperative outcomes. The continuous curvilinear capsulorrhexis (CCC), first described by Gimbel1 in 1985 and then Neuhann2 in 1987, has since come a long way. It is no longer just a smooth, round opening in the anterior capsule. Consistently achieving a centered, perfectly circular, optimally sized capsulorrhexis is a challenge for even the most experienced surgeon.
WHAT IS IDEAL?
An ideal capsulorrhexis is defined by its contour, centration, and dimensions (Figure 1). It is pupil-centric, uniformly circular, and void of any free edges. It should be approximately 5.5 mm in size when the planned IOL optic diameter is 6 mm.
Contour. A smooth contour, without any free edges, is the most important attribute of a capsulorrhexis. This is because the V-shaped edges of an irregular capsulorrhexis can snag on the phaco probe during aspiration. Likewise, the mechanical stress of chopping can cause peripheral extension of the capsulorrhexis from the V.
Centration. The use of premium (aspheric, toric, accommodating, and multifocal) IOLs has increased profoundly in recent years. To achieve the best results with these IOLs, a pupil-centric IOL is important, as a poorly centered lens can significantly hamper functional visual acuity.
Dimensions. Long-term prevention of posterior capsular opacification (PCO) requires intimate contact between the capsular bag and the IOL. Achieving a 360º overlap of the IOL edge with the anterior capsule is a prerequisite to prevent the migration of lens epithelial cells (LECs) into the visual axis. An oversized capsulorrhexis will prevent overlap; a too-small one will predispose the eye to anterior capsular contraction, eventual phimosis, anterior movement of the foldable lens, and late myopic shift. Most posterior chamber IOLs are available with optic diameters of 6 mm. The target capsulorrhexis size for nonaccommodating IOLs is therefore 5.0 to 5.5 mm, achieving an overlap of 0.25 to 0.5 mm.
Any deviation from the above characteristics can be considered an inadequacy in modern cataract surgery.
PRINCIPLE AND TECHNIQUE
Use of continuous force. A circle can be created in the anterior capsule by exerting continuous force tangential to an initial linear cut. Because the capsule has intrinsic elasticity, and because centrifugal forces from the zonules act around 360º, there is a tendency for the capsulorrhexis to extend peripherally. The capsulorrhexis can be performed by using shearing and tearing forces to counterbalance the elasticity and centrifugal forces.3 A high-viscosity ophthalmic viscosurgical device (OVD) is preferable to maintain anterior chamber stability. If the anterior chamber becomes shallow, additional OVD can be injected.
Cystotome-assisted capsulorrhexis. A 26-gauge needle is bent 90º at its bevel and then bent 120º at 6 mm away from the tip to fashion a cystotome. A 2.5-mm linear puncture (the radius of the circle) extending from the center to the periphery of the capsule is initiated using the sharp edge of the cystotome. A capsular flap is then fashioned by initiating tangential force at this point. The capsular flap is turned over itself, so that the inner epithelial surface faces outward. The capsulorrhexis is completed circumferentially by applying the appropriate vectors of tangential and centripetal forces.1
Forceps-assisted capsulorrhexis. This method is performed through the main incision. An initial capsular puncture is initiated in the manner described above. The flap is then grasped with the capsulorrhexis forceps, and traction is applied tangentially. The flap is regrasped every 3 to 4 clock hours. To complete the capsulorrhexis, the final flap is rotated inward with centripetal force. Forceps give better control over the capsulorrhexis; microcapsulorrhexis forceps or Utrata forceps may be used.2
Breach prior to initiating the CCC. It is somewhat common for the keratome to accidently nick the anterior capsule as the main and sideport incisions are being made in eyes with shallow anterior chambers. In these cases, the breach is usually within the limits of the capsulorrhexis, and routine initiation of the CCC can be accomplished.4
Argentinian flag sign. In intumescent cataracts and silicone– oil-filled eyes, the initial puncture can extend radially and rapidly in opposite directions, resulting in the Argentinian flag sign. The tear extends to the capsular periphery and, rarely, to the posterior capsule eyetube.net/?v=urewo; Figure 2)
In these eyes, it is best to plan a dye-assisted capsulorrhexis. A high-viscosity OVD, such as 1.4% sodium hyaluronate (Healon GV; Abbott Medical Optics), should be used to flatten the anterior capsule and maintain anterior chamber stability. Once the capsule is radially breached, most of the tension in the bag is relieved. Intravitreal scissors or angled Vannas scissors can be used to place small nicks in the mid-periphery of the capsule, and a forcepsassisted hemi-capsulorrhexis can be performed on each side to provide an opening shaped like a wrist watch.3,4
Lost capsulorrhexis margin. This can occur when performing the capsulorrhexis over an area of cortical cataract that obscures the retroillumination. Trypan blue dye (0.06%) can be injected under the OVD to stain the capsulorrhexis margin and then gently washed off.
Peripheral extension of CCC. Timely identification of a peripheral extension is crucial (Figure 3). The anterior chamber should be re-formed with OVD to relieve excessive centrifugal forces acting on the rhexis margin and to promote viscomydriasis, enabling visualization of the edge of the peripheral extension. Little et al5 described a technique for capsulorrhexis rescue in which the flap is regrasped near the root of the tear and directed toward the opposite clock meridian plus 1 clock hour. For example, a tear at the 5-o’clock position should be redirected toward the 12-o’clock position (11 + 1 = 12). One warning: A centripetal pull in the exactly opposite direction can further extend the tear. Traction should always be applied in a horizontal direction with no vertical vector eyetube. net?/v=amopi. At times, the tear may extend beyond the zonular attachments on the anterior capsule. It is important to frequently regrasp the flap, as the attachments may continually redirect the edge of the flap.
With smaller pupils or when the tear extends into the equatorial area, the edge of the tear may not be visible. In this event, the capsulorrhexis should be reinitiated in the opposite direction from the initial linear capsular puncture. As there is no sharp edge in these cases, intravitreal scissors can be used to form a small nick in the opposite direction. If the initial flap was rotated counterclockwise, a flap is formed to rotate the tear clockwise.
Small capsulorrhexis. Although the contour may be right, a small capsulorrhexis makes maneuvering in the capsular bag and chopping the nucleus difficult (Figure 4). Excessive manipulation may cause zonular stress and subsequent iatrogenic intraoperative subluxation, especially in eyes with advanced nuclear sclerosis. There is also risk for an inadvertent nick of the anterior capsule margin and for postoperative anterior capsular contraction.6
If the under-sizing of the CCC is recognized halfway through its construction, the capsulorrhexis can be extended in a spiral pattern, making two circular turns instead of one to obtain the optimal size. If the CCC has already been completed, a small nick can be placed on the edge of the CCC with intravitreal scissors, Vannas scissors, or a cystotome. A flap is then fashioned and rotated with forceps to enlarge the CCC eyetube.net/?v=isulu Figure 5). Often the same process may have to be repeated on the opposite side, as achieving a 360º turn with a small flap is difficult.
CAPSULORRHEXIS IN DIFFICULT SITUATIONS
Small pupil. A pupil diameter of less than 4.5 mm will prevent an adequately sized CCC. Intraoperative epinephrine; viscomydriasis with a high-viscosity OVD; or placement of a Malyugin Ring (MicroSurgical Technology), pupil expander system, or iris hooks can be considered before a dye-assisted capsulorrhexis is attempted. Synechiolysis is mandatory if posterior synechiae are present.
Intumescent cataract. A dye-assisted capsulorrhexis under a high-viscosity OVD is preferred in intumescent cataracts. After the initial puncture, aspiration of the liquefied milky cortex can be performed to decompress the capsular bag. A smaller-than-normal capsulorrhexis can be attempted initially and then spiraled to form a normal-size capsulorrhexis. Use of capsulorrhexis forceps is recommended.
Subluxated lens. When the lens is decentered, the tendency is to make a pupil-centric rhexis instead of a capsulorrhexis centered on the capsular bag. Once the bag is centered after insertion of a capsular support or bag fixation device, the rhexis then becomes eccentric. It is therefore important to plan a capsulorrhexis that will eventually be centered on the bag. A high-viscosity OVD and capsulorrhexis forceps are required.
The capsulorrhexis is started in an area with intact zonules and advanced to an area with zonular dialysis or weakness. It is then terminated in another area with intact zonules so that the affected area lies sandwiched in-between. The extent of centripetal force should be minimal to avoid iatrogenic extension in the subluxated area. Iris hooks or capsular support hooks may be used to stabilize the bag. Caution: If tension on the bag is excessive, the hooks may rip the capsulorrhexis margin.
Calcified and fibrosed capsule. Rotating the capsulorrhexis flap in an area of calcification or fibrosis is difficult, and excessive force can lead to irregular extension. A Fugo Plasma Blade (Medisurg Research & Management), vitrector, or high-frequency diathermy can be used to create an opening of the desired size.7 If a manual capsulorrhexis is undertaken, the calcified or fibrosed portion of the capsule can be cut with intravitreal scissors and a flap created to complete the rhexis.
It is difficult to repeatedly achieve a well-centered capsulorrhexis of 5.5 mm. The demand for precision has led many surgeons to use a femtosecond laser for capsulorrhexis creation (Figure 1). The exact targeted size and pupil-centric rhexis is easily achieved with this system. After docking the patient interface, the capsulorrhexis size and position are set according to the pupillary aperture aperture and surgeon preference using real-time anterior segment optical coherence tomography (AS-OCT). The capsulorrhexis leaf is then gently pulled centripetally with a cystotome or forceps, separating it from the underlying cortex and surrounding anterior capsule.8
In some cases, photodisruption may not be complete in all areas of the capsule. The gas bubbles entrapped underneath help to identify areas with inadequate photodisruption. Instead of simply pulling the capsule centripetally, a flap is fashioned in the area with no adhesions. It is then rotated—similar to routine capsulorrhexis— to bring the rhexis margin from the outer to the inner side, rather than the inner to outer side. This prevents any sharp edges. These steps are completed under a high-viscosity OVD.
Case selection for laser-assisted capsulorrhexis is important. Patients with small pupils, corneal opacity, glaucoma, or previous retinal detachments are not suitable candidates.
The capsulorrhexis has evolved significantly over the past 2 decades. The technologies recently developed for this crucial step in cataract surgery are promising, but they have their own unique complications. With that said, the basic principles for managing these complications, as described above, remain the same.
Tushar Agarwal, MD, practices at the Dr. Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi. Dr. Agarwal states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail:firstname.lastname@example.org.
Pooja Bandivadekar, MD, practices at the Dr. Rajendra Prasad Centre for Ophthalmic Sciences, AIIMS, New Delhi. Dr. Bandivadekar states that she has no financial interest in the products or companies mentioned. She may be reached at e-mail: email@example.com.
Rasik B. Vajpayee, MS, FRCS(Edin), FRANZCO, practices at the Royal Victorian Eye and Ear Hospital, University of Melbourne in Australia. Dr. Vajpayee states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: firstname.lastname@example.org.
- Gimbel HV. Capsulotomy method eases in-the-bag PCL. Ocular Surgery News. 1985;3:13:2-3.
- Neuhann T. Theorie und operationstechnik der kapsulorhexis. Klin Monatsbl Augenheilkd. 1987;190:542-545.
- Arshinoff S. Mechanics of capsulorrhexis. J Cataract Refract Surg. 1992;18(6):623-628.
- Vajpayee RB. Phacoemulsification Surgery. Jaypee Brothers; 2005.
- Little BC. Little capsulorrhexis tear-out rescue. J Cataract Refract Surg. 2006;32(9):1420-1422.
- Gimbel HV. Two-stage capsulorrhexis for endocapsular phacoemulsification. J Cataract Refract Surg. 1990;16:246- 249.
- Fugo RJ. Fugo blade to enlarge phimotic capsulorrhexis [letter]. J Cataract Refract Surg. 2006;32:1900.
- Dick HB, Gerste RD. Capsulotomy or capsulorrhexis in femtosecond laser-assisted cataract surgery? J Cataract Refract Surg. 2013;39(9):1442.