MALYUGIN MODIFIED CAPSULAR TENSION RING
Boris Malyugin, MD, PhD
Cataract surgeons are not infrequently faced with compromised zonules of the natural lens. It may be anticipated but often is not. Trauma, pseudoexfoliation syndrome, glaucoma, high myopia, various hereditary diseases (Marfan and Weill-Marchesani syndromes, homocystinuria, etc) are among the most common reasons associated with significant lens zonulopathy.
Ocular surgery in eyes with generalized zonular weakness or localized zonular defects poses challenges for even the most experienced surgeons. These eyes are at increased risk of capsule rupture, vitreous loss, dislocation of the lens fragments into the vitreous cavity, intraocular lens (IOL) instability, and other complications.
Nowadays, a significant number of devices can facilitate cataract surgery in these patients. Specially designed capsule retractors may be made of metal, such as the capsule supporting system (Duckworth & Kent Ltd), or plastic, such as MST capsule retractors (MicroSurgical Technology). The latter comes in the original straight version and in the Chang modification, which has a more ergonomically curved tip design. The major advantages of capsular hooks over the conventional iris hooks are that the ends are elongated in order to support the capsular fornix and without greater local tension on the anterior capsulorrhexis edge. The latter is a factor in reducing the risk of anterior capsulorrhexis radialization.
The capsular tension segment (Morcher GmbH) designed by Ike Ahmed, AssiAnchor (Hanita Lenses) created by Ehud Assia, and hooks with T-shaped tips developed by Shigeo Yaguchi (Handaya Co Ltd) are all useful in supporting the capsular bag during surgery and preventing its dislocation postoperatively. All of these devices provide focal support of the capsular bag and in cases associated with generalized zonular laxity can be used in combination with a conventional or modified capsular tension ring (CTR).
Conventional CTRs maintain the circular contour of the capsular equator during surgery by stretching the capsular bag and distributing forces equally across the remaining zonules. They are also helpful for stabilizing the crystalline lens during phaco and reducing the likelihood of intraoperative complications. A CTR further prevents vitreous prolapse into the anterior chamber and capsular damage during irrigation/aspiration.
However, when implanted early during the case, a CTR entraps cortical material at the equator of the capsular bag, which makes its aspiration more difficult. Keeping this fact in mind, the surgeon should consider delaying CTR insertion until after the cortex has been completely removed. In some cases when early implantation of CTR is justified, it is possible to increase the efficiency of the cortex removal by using the bimanual irrigation/aspiration systems and tangential stripping maneuvers.
It is known that conventional CTRs are not able to prevent progressive zonular loss and subsequent capsular decentration. There is therefore some risk that the bag-IOL complex could dislocate later postoperatively. That is why a conventional CTR should be considered as a tool helping to avoid many intraoperative complications, but without guaranteeing the long-term stability of the capsular bag-IOL complex.
To address patients with extensive zonular defects or profound zonular weakness, Robert Cionni modified the standard CTR by attaching a fixation eyelet to the central portion of the ring. This eyelet allows the ring to be sutured to the sclera to provide both intraoperative support during phacoemulsification and long-term postoperative capsular support. The Cionni modified CTR (Morcher GmbH) is a useful tool and is recommended for patients with more than a 3 clock hour zonular dialysis. There are several variations of this device that feature 1 or 2 eyelets with differing positions.
Figure 7-1. (A) General view of the Malyugin CTR. Note the fixation element moved to the very tip of the device to allow its complete retraction inside the injector tube. (B, C) The injector hook captures the eyelet of the Malyugin CTR, and the device is retracted inside the injector.
Figure 7-2. (A-C) Schematic representation of injecting of the Malyugin CTR into the capsular bag.
Most surgeons use forceps to manually implant the Cionni CTR through the main cataract incision. The use of the injector is much less common. Using an injector is difficult because the fixation element is attached to a ring at a location that prevents the CTR from being fully retracted inside the injector lumen.
The Malyugin modified CTR (Type 10G, Morcher GmbH) is a capsular supporting device based on Cionni’s original concept. The basic principle of the Malyugin CTR is to create an injector-friendly device. This is achieved by moving the fixation element to the very tip of the CTR (Figure 7-1). As a result, the Malyugin modified CTR is completely retractable into the injector tube due to the elasticity of the polymethylmethacrylate material and the redesigned shape of fixation element. Using an injector to insert the ring is very controlled and friendly to the lens capsule. During insertion, the curved portion of the Malyugin CTR easily slides along the equator of the capsular bag (Figure 7-2). The risk of perforating the capsular fornix with the tip of the CTR hitting it at a more perpendicular angle is completely eliminated.
The Malyugin CTR can be implanted through a 2.2-mm cataract incision. Both the Cionni and Malyugin CTR modifications effectively address a large zonular dialysis or section of zonulopathy by centering the subluxated capsular bag and securing it to the scleral wall.
Surgical Technique
The initial steps of the Malyugin CTR surgical technique are not that different from other techniques employed for zonular laxity and/or dialysis. Specific maneuvers will vary according to the specific clinical scenario.
If present, vitreous strands should be first excised from the anterior chamber. To visualize the vitreous, triamcinolone acetonide suspension is injected into the anterior chamber followed by a dispersive ophthalmic viscosurgical device (OVD; Viscoat; Alcon Laboratories, Inc). The latter is not only used to fill the anterior chamber but also to at least partially reposit vitreous strands back into the posterior chamber. A dispersive OVD also helps to sequester and wall off vitreous in the area of the anterior chamber adjacent to the zonular defect.
My preference is to use a dry vitrectomy technique with small-gauge instrumentation (23 to 25 gauge). This prevents irrigation fluid from hydrating the vitreous and displacing it forward toward the anterior chamber (Figure 7-3). The anterior capsulotomy technique for these cases is very critical, because the lack of zonular tension will probably create capsule laxity and radial folds. I usually initiate the capsulotomy with the sharp bent needle before switching to microcapsulorrhexis forceps. If the lens is exceedingly mobile, I would consider stabilizing the capsulorrhexis edge with a metal hook or with an MST capsule retractor.
Figure 7-3. (A) Eye of a patient with dense cataract, microspherophakia, and generalized zonular weakness. (B) Anterior capsulotomy was already performed, and the capsular bag is suspended on 3 polymer capsular hooks. (C) Vitreous in the anterior chamber is stained with triamcinolone injection. (D) Dry vitrectomy is performed. (E-G) The Malyugin CTR is injected inside the capsular bag prior to the removal of the lens.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
