One way to safely and effectively manage zonular dehiscence during cataract surgery and IOL implantation is to use a capsular tension ring (CTR). Hara et al1 introduced this technology to maintain the circular contour of the capsular bag, which in turn supports sectors of missing zonules. This assists in the even distribution of stress on the remaining zonules. Additionally, CTRs aid in the prevention of lens decentration, and their use may also reduce the risk of vitreous prolapse.1,2 Patients with pseudoexfoliation syndrome have a higher risk for zonular weakness.3
A CTR may be inserted either with a freehand bimanual technique or by using an injector system. Both methods start by placing the leading end of the ring under the rim of the capsulorrhexis. The remainder of the ring is then pushed from behind (compressing the device and dialing it in), and the trailing end is dropped under the edge of the rhexis. Finally, the surgeon releases the CTR from the instrument used to deliver this trailing end (ie, forceps or right-angle hook).
Inserting the CTR becomes increasingly challenging when the cataract is more dense or during the later stages of surgery (ie, when the capsular bag is either empty/flaccid with little zonular support or when the IOL is already in place). In such circumstances, the risk of tearing through the capsule or exerting additional shearing and tractional stress on the zonules is increased because of the high probability that any dialing technique will snag the leading end of the CTR on the equatorial bag (Figure 1) or IOL. Our new method—the fish-tail technique—helps to safely and effectively deliver the CTR into the correct position during such challenging cases without the need to dial it in. We chose this name due to the shape that the over-compressed CTR conforms to in preparation for insertion.
FISH-TAIL TECHNIQUE
Fill the bag. As in other CTR insertion techniques, an ophthalmic viscosurgical device (OVD) should be used to fully expand the capsular bag as well as the anterior chamber. This will guarantee that the capsule is under tension and free from folds. We prefer a cohesive OVD for this purpose.
Compress the ring. Grasp the C-shaped open ring symmetrically, on either side, with two pairs of forceps. The forceps should be positioned approximately one-third of the way down the ring on each side. Next, push the forceps toward each other to tightly compress the ring, the apex of which will deform into the head of the fish, while the ends overlap each other, forming the tail. The apex of the ring is flexed sufficiently to pass readily through an unenlarged incision (2.8 mm) with minimal resistance (Figure 2). We have found that CTRs from Morcher GmbH (Stuttgart, Germany), John Weiss & Son, Ltd. (Buckinghamshire, UK), and Advanced Medical Optics, Inc. (Santa Ana, California), do not crimp and remain within their elastic limit, even under the degree of flexion placed upon them during the fish-tail technique.
Unfolding of the ring. Once the girth of the rounded head of the fish-like shape is through the internal opening of the tunnel, the CTR will begin to expand and self-deliver under its own elastic recoil. As this occurs, position the apex under the rhexis' distal edge, which is diametrically opposite from the main incision (Figure 3). We recommend first inserting the under-riding arm into the eye in order to avoid pressing down from above to insert the over-riding arm. Next, flex the leading end of the CTR and deliver it under the capsule's edge with the aid of the forceps. It is essential to continue holding the trailing end with the second pair of forceps (Figure 4).
Placement. Finally, guide the trailing end of the CTR through the incision. It should lie central to the edge of the subincisional rhexis. This maneuver is best managed with a Sinskey hook placed through the eyelet, which induces less incisional gape and distortion. It also helps to flex the ring with ease and allows good directional control (Figure 5). Alternatively, forceps may be used.
Expansion of the ring. As the flexion is relaxed, the ring should expand, causing it to move under the rhexis. The Sinskey hook may be difficult to release from the eyelet; we recommend pushing the ring down with a cyclodialysis spatula through the sideport incision (Figure 6), causing it to disengage (Figure 7). Another trick is to lift the eyelet against the undersurface of an adjacent iris hook being used to stabilize the capsule to achieve disengagement.
In our experience, the fish-tail technique is a safe and effective CTR insertion strategy that minimizes radial and circumferential zonular stresses. This straightforward method is especially relevant in patients with extensive diffuse zonular loss or when inserting a CTR into an empty capsular bag or one already containing a lens implant. However, with a little practice, this technique works well under all circumstances. We have found it to be a more efficient and zonule-friendly method than dialing the CTR into the capsular bag with conventional linear feed. The fish-tail technique uses the ring's own compression and elastic recoil to minimize or eliminate the need for dialing, due to the wide elastic limits of the PMMA used in current CTRs.
Romesh I. Angunawela, MRCOphth, is in the resident program at Moorfields Eye Hospital, London. Dr. Angunawela states that he has no financial interest in the products or companies mentioned. He may be reached at romeshi@hotmail.com.
Brian Little, MA, DO, FRCS, FRCOphth, is an ophthalmologist at the Royal Free Hospital, London. He states that he has no financial interest in the products or companies mentioned. Dr. Little may be reached at brianlittle@blueyonder.co.uk.
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