In many cases, necessity truly is the mother of invention. When faced with cataract cases with weak zonular support that couldn't be helped with a traditional Cionni capsular tension ring, Toronto ophthalmologist Ike Ahmed decided to modify a Cionni ring to suit his needs. Now, 11 cases later, his Capsular Tension Segment (Morcher, Stuttgart, Germany) seems to be working well, and is useful even in cases in which a Cionni ring would be contraindicated. Here's what it can do, and how you may be able to obtain one yourself even though it's not yet for sale in the United States.
The CTS is a partial ring with a 5-mm radius of curvature and holes for suture fixation. "The idea for it came about as a way to deal with severely dislocated cataracts, rather than just a small zonular dialysis," says Dr. Ahmed. "This is for 3 to 4 clock hours or more of dialysis no matter how severe it is or where it's located. The dialysis can be from trauma, pseudoexfoliation or Marfans." The segment is designed for scleral suture fixation.
Dr. Ahmed says that, unlike the full Cionni ring that's most easily placed after phaco, a CTS can be placed after the anterior capsulotomy but before phaco without inducing significant capsular bag torque and zonular stress like a full ring can. Dr. Ahmed says the CTS can also be used in the setting of an anterior capsular tear or posterior capsular rent, which are usually contraindications for the use of a tension ring.
Another feature that makes the CTS different from a Cionni ring is that it's removable, allowing a surgeon to have capsular support during the procedure to implant a posterior chamber IOL, then be able to remove the segment. A surgeon can also place multiple segments, or remove a CTS and replace it with a full ring after phaco.
Salt Lake City surgeon Alan Crandall has used the CTS three times. "I was beginning a case on a patient with pseudoexfoliation, and it was obvious his lens was becoming very loose," he recalls. "I made a stab incision, put the CTS in the bag and put a Grieshaber iris hook onto the segment to hold the lens up so I could do phaco. I didn't lose the nucleus and was able to phaco the whole thing."
Dr. Ahmed has studied 11 patients with conditions ranging from ocular trauma to aniridia who received either a CTS alone or CTS in combination with other capsular support devices. At around seven-months follow-up, the average best-corrected acuity has gone from 20/250 preop to 20/40, and their intraocular lenses have remained centered.
Donna Lochner, branch chief of intraocular and corneal implants in the U.S. Food and Drug Administration's Office of Device Evaluation, says that, if a surgeon has a patient whom he thinks would benefit from the use of a CTS during surgery, the physician can send a letter to the FDA's Office of Compliance (Harold Pellerite, FDA Compliance, 2094 Gaither Rd., HFZ-300, Rockville, MD 20850). The letter should explain what the CTS is and why he needs to use it. If the request is approved, the surgeon can then send the subsequent FDA approval letter to Morcher (Kapuzinerweg 12, 70374 Stuttgart, Germany), and the company will be able to send the surgeon the segments.
