Capsular tension rings (CTRs) and specialized capsular hooks are two of many devices available to improve diffuse zonular weakness or localized zonular dehiscence during complex cataract surgery. These tools can also be used alone or in conjunction with a Malyugin Ring (MicroSurgical Technology) or another pupil expansion device when manual dilation is required.
Regardless of the surgeon’s chosen management strategy, there are three objectives in addressing zonular weakness: (1) avoiding or minimizing intraoperative complications, (2) providing long-term IOL stability, and (3) preventing postoperative decentration. Although both CTRs and capsular hooks are helpful in achieving these goals, they each have limitations.
If they are inserted prior to irrigation and aspiration, CTRs can impede the removal of soft lens matter and lead to further zonular stress due to the increased force required for its removal. Despite how easy specialized capsular hooks are to use, they can complicate the surgical environment if they become dislodged during phacoemulsification. Capsular hooks can also give rise to anterior capsular tears, which, if allowed to propagate, can run beyond the equator and lead to dropped nuclear material, vitreous loss, and the inability to place an IOL in the capsular bag or even in the sulcus.
A NEW DEVICE
We have been experimenting with a semicircular plastic cuff that is designed to engage the anterior capsular edge in an effort to counteract zonular weakness (Figure 1). Each segment, housing three plastic cuffs located 45º apart and angled 54º from the support edge, provides 120º of support. This novel device can be inserted through the phaco wound with a pair of standard or angled forceps (Figure 2A). Once inside the anterior chamber, it can be maneuvered to the relevant area of zonular laxity (Figure 2B) and secured with iris hooks. A surgical demonstration of segment placement can be viewed at eyetube.net/?v=funur.
In eyes with extensive zonular laxity, more than one device can be implanted to evenly distribute the force on the zonules. The bottom supporting edge of the device is 2.02 mm, and the total height is 0.76 mm. Compared with the insertion of iris hooks alone, its larger size is responsible for increasing capsular stability and decreasing the chance for it to dislodge unexpectedly during surgery. The plastic cuff can be anchored in up to three places, securing its position in the capsular bag.
Similar to a CTR, the device provides support to the bag equator; however, it also supports the anterior capsule. Additionally, whereas insertion of a CTR is done blindly—potentially leading to malposition of the device and capsular tears—ours is continuously visible and can be inserted in a controlled manner.
Once cataract surgery is completed, the device can be removed or sutured into place to improve postoperative stability and minimize the risk of anterior capsular phimosis.
Insertion of our novel semicircular plastic cuff has two benefits in the presence of zonular weakness or dehiscence. First, it provides capsular support. Second, it can facilitate iris retraction simultaneously when required.
Because this device can be inserted through a phaco incision and requires no specialized instruments or techniques, it lends itself to use by less experienced surgeons who may be faced with capsular complications.
Allon Barsam, MD, MA, FRCOphth, is a Consultant Ophthalmic Surgeon at Luton & Dunstable University, The Western Eye Hospital, Imperial College Healthcare NHS Trust, and Focus Clinics in London. Dr. Barsam is a member of the CRST Europe firstname.lastname@example.org.
Rebecca Davie, MBBS, BSc, is an Ophthalmology Registrar at Addenbrooke’s Hospital, Cambridge, United Kingdom. Dr. Davie states that she has no financial interest in the products or companies mentioned. She may be reached at e-mail: email@example.com.
Eric D. Donnenfeld, MD, is a Professor of Ophthalmology at New York University and a trustee of Dartmouth Medical School in Hanover, New Hampshire. Dr. Donnenfeld is a member of the CRST Europe Global Advisory Board. He states that he has no financial interest in the products or companies mentioned. Dr. Donnenfeld may be reached at tel: +1 516 766 2519; e-mail: firstname.lastname@example.org.