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CTR has many indications
Among other benefits, the capsular tension ring can reduce the incidence of intraoperative complications.
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In two issues earlier this year, Drs. Nishanth Patel, Vikas Lal et al shared their insights on the use of capsular tension rings. Dr. Patel et al deserve congratulations for their gifts of clear language and wonderful illustrations, which make their publications excellent teaching tools.
The capsular tension ring (CTR) is an essential part of our armamentarium, as the discovery of significant zonular laxity and partial zonulolysis cannot always be predicted preoperatively. This device can reduce the incidence of intraoperative complications, as well as promote a routine postoperative course in patients with subclinical changes recognized at the time of capsule puncture and the more overt subluxated lens patients. I have had the privilege of being a part of the FDA investigational device exemption trials for the Morcher CTR over the last few years and eagerly await its availability to all American surgeons. My experience leads me to make the following observations and recommendations as an addendum to the excellent article by Dr. Patel and colleagues.
Harvey Lincoff, MD, published data conclusively demonstrating the safety of nonpreserved intraocular lidocaine for the retinal neuroreceptors. Without a doubt there is a transient amaurosis when it is instilled with an open capsule or zonular apparatus. This is associated with suppression of electrical signals caused by lidocaine’s anesthetic effect, but there is no detectable deleterious short- or long-term effect on neuroreceptor structure or function. The sudden transient blindness can, however, be frightening to patient and doctor and prevent fixation and voluntary akinesia. Therefore I also avoid it in these cases.
Two-handed technique
Capsulorrhhexis can be facilitated by a two-handed technique. A paracentesis is made in a convenient location to allow a small hook to give artificial support to the capsulorhhexis edge in the area of zonular weakness or absence, while shearing forces are applied with forceps to propagate the tear in the usual fashion.
The CTR can be placed at any stage after the capsulorhhexis and hydrodissection. In more subtle zonular damage, without true subluxation, it can be placed before, during or after phaco or irrigation and aspiration or even after the IOL is positioned. In cases of severe subluxation (more than 4 clock hours) capsule retention hooks (designed by Richard J. Mackool and manufactured by Grieshaber) or pupil expansion hooks can be used to aid centration and support the bag until the Cionni-modified CTR with the 3-D eyelet for scleral fixation can be placed after irrigation and aspiration. This cannot be easily placed earlier because of the prior threading of suture through the eyelet.
The use of capsular dyes such as indocyanine green or trypan blue can be very helpful, especially for the neophyte. This maneuver facilitates visualization of the capsulorhhexis edge to avoid the undesirable blunder of accidental placement of the CTR anterior to the anterior capsule flap.
Tiddlywinking
The current packaging of the Morcher CTR is challenging to open without tiddlywinking the device. Similarly, this frustration can add time and expense when trying to engage the eyelet of the CTR with the hook of the insertion device. I recommend opening the package and loading the inserter under the microscope over the bag of the sterile drape for maximal visualization and a safety net. If an inserter is not available, an Osher “Y” hook is invaluable for bimanual manipulation to assure entry of the trailing end of the ring into the capsular fornix.
Dr. Patel rightly points out that radial forces on cortex can be undesirable. Creating a good potential space between the anterior capsule and cortex with viscoelastic before CTR placement can minimize trapped cortex. Particularly if good cortical cleaving hydrodissection has been performed (à la Dr. Fine), little cortex may be trapped. In the presence of significant cortex radial forces are ineffective, though I haven’t found there is any harm done, as the ring is just pulled centrally into view and then springs back into the equator on aspiration of cortex or elimination of vacuum. It can be effective, however, to drag cortex circumferentially to the CTR opening. This will allow the cortical wedge to freely come out through the area of the CTR discontinuity. This trick sequentially removes cortex from proximal to distal in both directions. Consider manual “dry” cortical aspiration under viscoelastic in place of automated irrigation and aspiration to prevent vitreous hydration if the CTR does not perfectly tamponade the vitreous face.
Capsular fibrosis
Capsular fibrosis and phimosis resulting in late implant decentration or even lens-bag dislocation is our most vexing long-term postop complication in these patients. Logic then dictates that the most capsule-biocompatible lens material and design should be used. The early generation silicone plate haptic lens is the least desirable choice. Acrylic is the best choice of material for its documented low propensity to cause capsular fibrosis and reaction.
My design of choice is the one-piece acrylic Alcon SA60 AT, for several reasons. Placement of this lens is the least traumatic, with no energy release on extrusion from the cartridge of optic or haptic. It is easily placed without dialing and rotational forces. Although a three-piece lens can be placed with a bimanual technique, significant zonular forces are not similarly entirely eliminated. Additionally, the one piece can be gently nudged aside for thorough evacuation of the posterior chamber without the cantilevering forces required to tip up a three-piece lens for this maneuver.
Once the IOL is in place, initial asymmetric forces in the plane of the three-piece haptics cause ovaling of the capsulorhhexis and striae in the posterior capsule, which may not resolve over time. This is not seen in even the weakest zonules cases with the one-piece, with which forces are more evenly distributed. Lastly, it has been proven that the acrylic haptics maintain their memory with virtually no decay, whereas PMMA or polypropylene haptics have rapid decay of memory over a 2-week period, negating any helpful effect that might be gained from haptic placement in the meridian of zonular weakness or absence.
It remains to be seen whether the CTR’s more widespread use as the FDA completes its deliberations will reduce the incidence of late decentration and dislocation. It is clear that the device allows those unfortunate patients with abnormal anatomy to reap the early benefits of bag fixation and small-incision surgery enjoyed by our more routine patients.
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For Your Information:Reference:
- Lisa Arbisser, MD, is a private practitioner in Iowa and Illinois and is president of the American College of Eye Surgeons. She can be reached at (563) 323-8888; fax: (563) 328-5699; e-mail: l-arbisser@usa.net. Dr. Arbisser has no direct financial interest in any of the products mentioned in this article, nor is she a paid consultant for any company mentioned.
- Lincoff H, Zweifach P, et al. Intraocular injection of lidocaine. Ophthalmology. 1985;92(11):1587-91.