IC-96 Stabilizing the Subluxated Lens: A Medley of Rings, Segments, Suture Techniques
The Capsular Anchor – concept and clinical experience
Ehud I. Assia, MD
Subluxation of the crystalline lens usually occurs because of a large dehiscence or weakness of the zonular fibers. Etiologies include: blunt ocular trauma, pseudoexfolition, high myopia and congenial diseases such as Marfan syndrome, homocystinuria and others (1). Optical aberrations such as partial aphakia, high myopia, astigmatism and monocular diplopia are associated with significant impairment of vision. Surgical correction of lens subluxation usually includes complete lens removal (lensesctomy / ICCE) and implantation of an anterior chamber lens (angle or iris supported), or suturing of a posterior chamber IOL to the sclera or the iris. In recent years devices and techniques were developed to preserve the capsular bag and maintain the capsular diaphragm between the anterior and posterior segments of the eye. Small zonular defects (up to 3 clock hours) can be treated using a capsular tension ring (CTR), however large defects require suture fixation of the capsular bag to the scleral wall. Modified endocapsular rings were developed, such as Cionni's ring (modified capsular tension ring, MCTR) (2,3), Malyugin-Cionni ring and Ahmed's Segment (capsular tension segment, CTS) (4) (both manufactured by Morcher GmbH, Stuttgart, Germany). The modified rings support the entire (MCTR) or a part (CTS) of the capsular equator and are sutured to the scleral wall through an extension of the ring passing through the anterior capsulorhexis.
We have developed an alternative device to fixate the intact lens capsule to the scleral wall based on a different concept (5,6). The Capsular Anchor (Hanita lenses, Kibbutz Hanita, Israel) is a poly methyl methacrylate (PMMA) intra-ocular, uni-planer implant, inserted into the capsular bag after capsulorrhexis is performed. The Anchor clips the anterior capsule, and supports a localized segment of the lens equator. The two lateral arms of the device are inserted behind the anterior lens capsule whereas the central rod is placed in front of the capsule (figure 1). A 10-0, or preferably 9-0, prolene suture is used to fixate the Anchor to the scleral wall. After lens removal by phacoemulsification a conventional PC-IOL is inserted into the capsular bag. The capsular Anchor recently gained the CE mark and permit for use in Europe and is in use in several countries.
My Personal experience includes surgery in 21 patients using 22 Anchors. In one patient with large zonular defects on 2 separate locations, 2 Anchors were used. Also the capsular Anchor was used to repositioned two eyes with subluxated PC-IOLs while still in the bag in eyes with pseudoexfoliation and primary zonular weakness.
The following surgical pearls are based on the cumulative clinical experience:
Significant subluxation occurs if at least 3-4 hours of zonules are missing or weakened. Lens removal is then often technically difficult because of the instability of the crystalline lens. It is therefore advisable to stabilize the lens capsule using the Anchor prior to lens removal.
Intact anterior capsulorhexis is a pre-requisite for using the Anchor. The dimensions of the Anchor are designed for a 5 mm ACCC. A rim of capsule of at lest 2 mm should be maintained to provide sufficient contact with the anchoring device.
After anterior capsulorhexis is made, localized hydrodissection and viscodissection is done to separate the lens material and the capsule, to create a "pocket" for the comfortable placement of the Anchor.
The fixation suture can either wrap around the central rod (figure 2a) or be threaded though a hole at the Anchor's base (figure 2b).
If the surgeon prefers wrapping the suture around the neck of the central rod, a safety suture may help preventing the device from falling through a large zonular defect during implantation. A temporary safety suture is inserted through the second, proximal hole and is easily removed after the Anchor is secured to the sclera. This is especially relevant after vitrectomy.
Since the fixation suture is not tied to the device it is possible to bury the knot in the scleral tissue. No scleral flaps are, therefore, required.
Phacoemulsification is done in the regular (but cautious) manner. Hydrodissection should be carefully completed to release adhesions of the lens material from the capsule and minimize the stress on the capsule and zonules
A conventional capsular tension ring can be used in conjunction with the Anchor to reform and maintain the round contour of the capsular equator. CTR often interferes with removal of peripheral cortical fibers therefore it is advisable to insert the ring only after cleaning of the capsular bag is completed.
It is sometimes better to secure the Anchor with a temporary suture prior to lens removal. Final permanent fixation is done only after IOL is implanted in the bag to assure a central position of the optic.
In cases of very large zonular dehiscence or if zonules are ruptured at two separate locations - two Anchors (and more) can be used.
The capsular Anchor can be utilized also to refixate subluxated capsular PC-IOLs. A small "pocket" is done between the fibrosed anterior capsule and the IOL using a lens spatula.
Clinical experience with the Anchor is, so far, very encouraging and with a follow up of more than 3 years all the IOLs are central and stable (figures 3-5). No adverse effects related to the device were recorded.
In summary, the clinical experience using the capsular Anchor supports its safety and efficacy for reposition and fixation of subluxated lenses.
Figure 1: Schematic illustration of the capsular Anchor. The 2 lateral arms are located behind the anterior capsule. The anterior central rod is placed in front of the capsule.
Figure 2: Options for suture fixation
The suture wraps around the neck of the central rod