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May 28, 2006
The Modified CTR
CRS Today May 2006
Robert J. Cionni, MD
The Modified Capsular Tension Ring (CTR) (Morcher GmbH, Stuttgart, Germany; distributed in the US by FCI Ophthalmics, Inc., Marshfield Hills, MA) is much like a standard CTR except for the fixation hook attached to the PMMA ring filament. As the device lies inside the capsular bag, this hook rests at a plane anterior to that of the ring so that the hook courses around the capsulorhexis' edge. Passing a suture through an eyelet located at the edge of the fixation hook fixes the ring to the scleral wall. The Modified CTR is indicated when a standard CTR will not provide sufficient stability to allow phacoemulsification and/or the long-term stability and centration of an IOL implant in the bag. Specifically, the device is appropriate in eyes with more than 180¼ of zonular dialysis and in cases of marked lens decentration (eg, from trauma or Marfan's syndrome). My advice for success with the Modified CTR follows.
INSERTING THE RING
After nuclear removal, I like to create a space for the Modified CTR by viscodissecting all of the cortex away from the periphery of the capsular bag. I prefer a dispersive viscoelastic for this maneuver, because some of the agent can ooze from the incision versus the expulsion of a cohesive glob. Before I place the ring in the bag, I preload the fixation hook's eyelet with a suture. I would recommend 9–0 Prolene .
The Modified CTR is available in three versions. Model 1-L (Figure 1) must be inserted manually, so I use a tying forceps to feed the device into the bag so that the part closest to the fixation hook goes in last. During the insertion of the ring, the fixation hook should catch naturally anterior to the capsulorhexis' edge. If not, the surgeon must manipulate it anteriorly.
The model 2-C is a mirror image of the 1-L, so it may be inserted with an injector .
The 2-L model has two fixation hooks and is indicated for extremely loose lenses. This is the most difficult version of the Modified CTR to use. I would recommend that surgeons first become familiar with suturing a one-hook model in a few less difficult cases before attempting to use the 2-L.
CONCLUSION
The availability of the CTR and now the Modified CTR has greatly enhanced cataract surgeons' ability to manage challenging cases. Videos demonstrating the use of the Modified CTR may be found at the AAO's Web site as well as at http://www.fci-ophthalmics.com/videos/cionni_ctr_video.htm.
Posted by aman at May 28, 2006 10:38 PM