In the setting of severe and widespread zonular weakness, ring suturing may be necessary.
David F. Chang, MD, provided his practical tips for using CTRs during cataract surgery at the fourth annual San Francisco Cornea, Cataract, and Refractive Surgery Symposium.
Weak zonules can result from a number of different problems, notably, ocular trauma, aging, pseudoexfoliation, or Marfan's syndrome; however, weak zonules can also be associated with retinopathy of prematurity, prior trabeculectomy or vitrectomy, or an ultra-brunescent cataract.
The devices do have disadvantages, however, in that their insertion can cause zonular trauma, they impede cortical clean-up, and they can become dislocated if the posterior chamber ruptures, pointed out Dr. Chang, clinical professor, University of California, San Francisco, and in private practice in Los Altos, CA.
Insertion of CTRs is contraindicated in the presence of a torn capsulorhexis or posterior capsule, or when one cannot adequately visualize the capsulorhexis. The device is inserted using either forceps or an injector.
When to insert
Dr. Chang first demonstrated insertion of the CTR with the injector prior to IOL implantation in a case in which the cataract had already been extracted. To reduce the risk of perforating a lax posterior capsule with the ring, a generous amount of viscoelastic should be used to inflate the capsular bag. He uses a Lester hook to help bend the CTR into place as it is injected into the bag. This, he explained, allows the brunt of the bending forces to be borne by the hook instead of the capsulorhexis or the bag.
"This is the easiest situation in which to insert a capsular tension ring. It is ideal for surgeons just learning the procedure, because the capsular bag is empty," he said.