|Year : 2002 | Volume
| Issue : 4 | Page : 333-337
Use of capsular tension ring in phacoemulsification. indications and technique
P Lanzetta, Raffaella Gortana Chiodini, A Polito, F Bandello
Department of Ophthalmology, University of Udine, Viale Venezia, 410, 33100 Udine, Italy
Department of Ophthalmology, University of Udine, Viale Venezia, 410, 33100 Udine
The capsular tension ring (CTR) was originally introduced to reinforce the zonule in eyes with zonular dehiscence and to prevent capsular phimosis in eyes at risk for postoperative capsular shrinkage. Since then, other designs and applications have been developed and described. Modified CTRs with shields can be used in eyes with iris coloboma. A CTR with loops is intended for scleral fixation. Studies are underway to determine if the presence of the CTR helps avoid or limit capsular opacification. A number of different insertion techniques with the aid of manipulators, injectors and traction sutures have been described. We have developed a technique that is particularly effective in cases of zonular dehiscence due to its low solicitation to the damaged bag.
Keywords: Capsular tension ring, traumatic cataract
|How to cite this article:|
Lanzetta P, Chiodini RG, Polito A, Bandello F. Use of capsular tension ring in phacoemulsification. indications and technique. Indian J Ophthalmol 2002;50:333-7
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Lanzetta P, Chiodini RG, Polito A, Bandello F. Use of capsular tension ring in phacoemulsification. indications and technique. Indian J Ophthalmol [serial online] 2002 [cited 2015 Apr 1];50:333-7. Available from: http://www.ijo.in/text.asp?2002/50/4/333/14752
Capsular tension rings (CTRs) are polymethyl methacrylate (PMMA) intraocular implantation devices introduced in 1993 by Withschel and Legler [Figure - 1]. The original CTR was introduced into the market by Morcher. Since 1993 similar products have been marketed by a number of other manufacturers. None of these products, to our knowledge, is currently approved by the U.S. Food and Drug Administration.
| Indications|| |
Designed to maintain the capsule's contour (equator ring) and to stretch the posterior capsule (tension ring), CTRs were originally used for zonular reinforcement in eyes with a weak zonular apparatus, such as in pseudoexfoliation and Marfan's syndrome, and when zonular rupture or dehiscence occurs after blunt or surgical trauma. Other possible applications include the prevention of postoperative shrinkage of the anterior capsular opening as a result of fibrosis (capsulorhexis phimosis, capsule contraction syndrome) and, hopefully, the inhibition of posterior capsule opacification due to cell proliferation and migration. Modified CTRs with integrated iris shields have also been used to protect against glare or monocular diplopia in cases of aniridia, iris coloboma and uveal tumours involving the anterior segment that may require resection of the iris and ciliary body [Figure - 2]. The ring is also used to control primary posterior capsulorhexis and prevent postoperative oval distortion along the lens axis, and to quantify in vivo capsular bag circumference and postoperative capsular shrinkage. In addition, during combined cataract and vitreous surgery, a CTR prevents capsule damage and provides undisturbed peripheral visualisation before IOL implantation. Some surgeons routinely use CTRs in all cataract procedures. The professed aims are to stretch the capsular bag circularly in order to obtain fewer capsular stretch folds, and maintain IOL centration.
| Designs|| |
The rings come in various sizes: the 12.3/10.0 mm diameter ring (Morcher type 14TM) and the 12.0/10.0 mm diameter ring (Ophtec type PC 275 TM) are mostly used for routine cases. In cases of high myopia, 14.5/ 12.0 mm diameter rings (Morcher type 14A TM) are preferred. Standard rings have expanded ends that contain positioning holes to facilitate surgical manipulation. The modifications, all introduced by Morcher, include models with integrated iris shields of 60 and 90 degrees (types L, G and 50 C- [Figure - 3]), models of capsular bending edge rings (types E and F) designed to reduce secondary cataract and prevent capsular fibrosis, and models with one or two adjunctive loops intended for transcleral fixation of the bag without distorting the capsulorhexis opening (Cionni ring, type 1L - [Figure - 4]). The main characteristic of the Ophtec ring is a ski-tip-like apical bend, that allows easy implantation and avoids the entanglement of the capsule during the operation [Figure - 5].
| Applications|| |
CTRs can be inserted with forceps or injectors through the tunnel or paracentesis. A micromanipulator can assist the manoeuvre. Depending on the stability of the capsular bag, a CTR may be inserted at any stage of the cataract procedure: before phacoemulsification after capsulorhexis has been performed, or after phacoemulsification, either before cortical aspiration or before IOL implantation. In the former case, the ring is slipped through the side port incision and fed under the capsulorhexis with a needle-holder, while the second hand glides it with a Lester hook through the tunnel. Once the ring is in place, cortical cleaving hydrodissection is performed, followed by hydrodelineation. When residual cortex is aspirated with the ring in place, additional forces are needed with the I/ A handpiece as the cortex is pressed up against the capsular fornices. Tangential traction on the cortex with the I/A tip, rather than stripping centrally, is recommended in cases of zonular dehiscence [Figure - 6]. In general, CTRs are easily inserted in a capsular bag that is well expanded with viscoelastic material. However, the leading end of large or rigid CTRs, such as those designed for myopic eyes or to block capsule opacification, may entangle with the bag fornix. This is indicated by traction folds in the posterior capsule. Such entanglement can be avoided with adequate capsulorhexis sizing. The capsulorhexis should be slightly smaller than the IOL optic for standard CTRs, and it should be as large as possible for capsular bending rings. Entanglement can also be avoided with further precautions such as selecting an acute angle of attack when inserting the leading end of the CTR into the bag fornix and the use of high-viscosity viscoelastic substances. In cases of unclear settlement, the position of the CTR and its eyelets can be verified by gonioscopy and, if necessary, by ultrasound biomicroscopy.
In our technique the ring is inserted through the side port with the needle-holder in the other hand (i.e., side port on the left side and needle-holder in the right hand) [Figure - 7]a. This manoeuvre usually prevents any solicitation of the capsular bag and the zonular fibres because all the forces used in the insertion are discharged on the side of the paracentesis [Figure - 7]b. The distal end of the ring is then forced with the tip of the needle-holder by placing it through the paracentesis under the capsulorhexis [Figure - 7]c. A Lester hook positioned into the distal eyelet may help drive the end of the ring under the anterior capsulorhexis into the capsular bag [Figure - 7]d.
We verified the safety of standard CTRs in selected cases of phacoemulsification. The rings were implanted using our own technique. Twenty-seven eyes scheduled for phacoemulsification and IOL implantation received a CTR. Three eyes had a traumatic zonular dehiscence of up to 120° and subluxated lens; 3 had intraoperative zonular compromise; 6 had pseudoexfoliation; 3 high myopia; 3 complicated cataract with posterior synechiae; and 9 had a small-sized capsulorhexis. CTRs were implanted before phacoemulsification in the subluxated lenses while, in the remaining eyes, they were implanted after phacoemulsification and cortical aspiration but before IOL implantation. In all cases, CTRs were inserted through the paracentesis with a needle-holder as already described.
The CTR was implanted successfully in all eyes. The placement in the ring allowed the completion of surgery and IOL implantation without complications in the eyes with zonular dehiscence. With our technique we did not face any case of entanglement of the ring with the capsular bag or damage of the zonular fibres. After a mean follow-up of 8 months (range 2-19), we did not notice signs of IOL decentration, capsular contraction syndrome, or extrusion of the ring through the bag. The use of CTR facilitated safe surgery in cases with zonular dehiscence or in eyes prone to IOL decentration and capsule contraction syndrome. The CTR is a relatively new device that eases surgery of difficult cases that are prone to intraoperative complications. Also, it may be useful in preventing shrinkage of the bag and capsular opacification. It can be used as a prosthesis in cases of traumatic or congenital colobomata of the iris. An adequate insertion technique is the key to success.
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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8], [Figure - 9], [Figure - 10]
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