A number of important technical advances facilitated the evolution from extracapsular cataract extraction with manual expression of the lens nucleus to small incision phacoemulsification. Lens removal by ultrasonic phacoemulsification was the main advancement, but other developments such as viscoelastics, foldable intraocular lenses (IOLs), and capsulorrhexis were also important. Viscoelastics, interchangeably known as ophthalmic viscosurgical devices (OVDs), coat and protect the corneal endothelium, iris, and lens capsule during surgery while maintaining space for the critical steps of surgery such as IOL implantation. Foldable IOLs allow the cataract incision to remain as small as the phacoemulsification needle. Capsulorrhexis ensures centration of the IOL within the capsular bag as the bag fibroses and contracts around the lens postoperatively. Arguably, other advances such as sutureless incision closure and topical anesthesia also played important roles in the evolution to small incision cataract surgery.
This chapter will review the rationale for capsulorrhexis, describe my method for performing it, and present solutions on how to avoid and handle problems. Special situations will also be discussed such as surgery in infants and children, posterior capsulorrhexis, optic capture, bimanual phacoemulsification, and the use of capsule stains. The reader should note that the accepted spelling of the word capsulorrhexis has evolved from one “r” to 2 rs. Older literature should be searched using the spelling capsulorhexis.
II. HISTORICAL OVERVIEW OF CAPSULORRHEXIS
The first IOL manufactured in the laboratory phase of foldable IOL development had a silicone plate-haptic design. The STAAR Surgical model AA4203 is the commercial version of this early lens. As a side note, the first foldable IOL actually sold in the United States was the Advanced Medical Optics SI18NB. This lens is a 3-piece foldable silicone lens with Prolene haptics. Plate-haptic IOLs were attractive to the early designers because they could be implanted through very small incisions. However, plate-haptic IOLs had to be implanted and remain inside the capsular bag because of their short overall length. If implanted in the ciliary sulcus, these IOLs would uniformly decenter. The dilemma facing the developers of the new foldable plate-haptic lens technology was how to confine the IOL to the capsular bag when the predominant anterior capsule opening at that time was a can-opener capsulotomy.
In the days when extracapsular surgery with manual expression of the nu- cleus was the norm, surgeons were often polled as to where they thought they placed the IOL. Invariably, most surgeons felt they placed the optic and both haptics inside the capsular bag, even though they performed a can-opener capsulotomy. Ninety percent or more of the time the surgeons would be sure the lens was in the capsular bag. Many of these eyes were subsequently au- topsied and a different perspective emerged. Pathologists found that one or both haptics were in the ciliary sulcus 50% of the time. Is it possible to reconcile these 2 perspectives or explain what happens to an IOL to change its position after implantation? The answer is yes. As the capsular bag contracts around an IOL after surgery, one of the haptics often pops out when there is a can-opener capsulotomy in the anterior capsule. One or more of the radial relaxing incisions in the anterior capsule splits open as the capsule fibroses. With plate haptic lenses, it is critical that they remain confined to the capsular bag for all time. The continuous tear of a capsulorrhexis ensures that any IOL implanted within the confines of the capsular bag will remain there forever.
III. HOW TO PERFORM A CAPSULORRHEXIS
This section describes my technique for performing a manual capsulorrhexis. Throughout the chapter, I will use the term capsulorrhexis instead of anterior capsulorrhexis, but these two are interchangeable. Posterior capsulorrhexis is described in Section VIII on p. 96. My capsulorrhexis technique is suitable for most types of cataracts.
- It is important to fill the anterior chamber with plenty of OVD. I inject enough that the anterior dome of the lens is flattened and OVD begins spilling out of the incision.
- The capsulotomy is begun by puncturing the anterior capsule with a bent 30-gauge needle. Either the surgeon or a scrub technician can bend the needle using a needle holder. Prebent needles are available commercially, but I do not generally like the gauge or design of the needles currently available. I find that a 30-gauge needle gives maximum maneuverability inside the eye and excellent cutting power (Figure 9-1). Larger needles can be used, but the larger the gauge, the more trouble the surgeon will have avoiding contact with the corneal endothelium. Some surgeons like to use sharp-tipped capsulorrhexis forceps to make the initial capsule puncture. I find that the tips dull after a few uses.
- I prefer to make the initial puncture small and central. I am right- handed, so I start the puncture just right of center and slice the needle through the capsule to just left of center so that the initial tear is approximately 3 to 3.5 mm in length. The needle should be pushed in only as far as necessary to cut the capsule. Pushing too far in will stir up the cortex and force it up into the viscoelastic, obscuring the surgeon’s view. This problem is particularly evident with milky white cortical cataracts. With the needle on the far left side of the tear, the capsule is elevated and pulled toward the incision, creating an edge that flops over toward the incision. A bent needle is much better for pulling the capsule toward the incision than pushing it away from the incision. The capsule flap should be left high in the OVD so that it can be grasped easily (Figure 9-2). It should not be pushed onto the capsule where it will be harder to engage.
- Next, the capsule flap is grasped with capsulorrhexis forceps. Many different types of capsulorrhexis forceps are available. Direct-action Utrata forceps are popular. I now prefer cross-action Inamura forceps (Figure 9-3). They work nicely through sub 2.4-mm incisions. It is important to keep the capsulorrhexis forceps in the middle of the phacoemulsification incision at all times so that the eye remains centered in the field of the microscope and the OVD remains inside the eye. The capsule should be torn with a shearing motion (ie, the capsule should be folded over and pulled tangentially in a spiral fashion until the desired diameter is reached). The tear beneath the incision is the hardest to make (Figure 9-4).
- After achieving the desired diameter, it is important to tear tangentially all the way around (Figure 9-5), maintaining a constant distance from the pupil margin. The distance to maintain depends on the diameter of the pupil. With most IOLs, it is appropriate to make the capsulorrhexis 0.5 to 1 mm smaller than the diameter of the optic. For a 6-mm optic, I make the capsulorrhexis 5 to 5.5 mm in diameter. The surgeon should regrasp the capsule whenever necessary. As a right- handed surgeon, I tear the capsulorrhexis in the counterclockwise direction. It might be easier for left-handed surgeons to tear in the clockwise direction.
- I usually find it necessary to regrasp the capsule flap 4 or 5 times to tear it all the way around. The surgeon should not be embarrassed to let go and regrasp. When letting go, the capsulorrhexis forceps should be released high up in the middle of the anterior chamber so the capsule will be easier to regrasp. When regrasping, never do so close to the cut edge. If the eye suddenly moves, the capsulorrhexis may quickly radialize. Always grasp 1 to 3 mm upstream from the cut edge. The importance of tearing tangentially all the way around cannot be overemphasized. The capsulorrhexis is completed on the left side of the pupil in the surgeon’s view (Figure 9-6). For a left-handed surgeon, the capsulorrhexis is completed on the right side of the pupil. I like to pull the capsule out of the eye using the capsulorrhexis forceps, but it is not entirely necessary. If left in, it will come out during the hydrodissection or phacoemulsification step.
*Dikutip dari Buku Essentials Of Cataract Surgery 2nd Ed, halaman 87-91