HENDERSON CAPSULAR TENSION RING

Brett P. Bielory, MD and Bonnie An Henderson, MD

Background (Capsular Tension Ring Modifications)

Capsular tension rings (CTRs) are curvilinear, horseshoe-shaped, polymethylmethacrylate or silicone rings with eyelets on each end (Figure 5-1). The unique design of a CTR is a ring diameter that is larger than the capsular bag diameter. When secured in its final intracapsular position, a CTR sustains the capsule contour in the setting of zonular dehiscence, such as with pseudoexfoliation and other causes of zonular compromise. The main mechanism of CTR action is to distribute the capsular forces circumferentially by recruiting tension from stronger zonules to buttress areas of weaker or absent zonules, thereby stabilizing the entire capsular complex. The device is used to help prevent early and late intraocular lens (IOL) decentration by maintaining the equatorial expansion of the lens capsule in a fully distended circle of 360 degrees. Indications and contraindications for CTRs are listed in Table 5-1.

One of the main drawbacks of using a CTR is the difficulty of removing residual lenticular or cortical material after the implantation. Because the CTR expands and compresses the bag, any lens material caught between the CTR and the capsular equator becomes trapped. The expansive force of the CTR against the bag inhibits easy cortical removal. To combat this difficulty, a modified CTR was created. The Henderson Capsular Tension Ring Type 10C (HCTR; Morcher GmbH, distributed in the United States by FCI Ophthalmics) features 8 equally spaced indentations of 0.15 mm spanning the circumference of the ring, creating a sinusoidal shape (Figure 5-2).¹ The total external expanded diameter is 12.29 mm, with an inner compressed diameter of 11 mm. This open modified C-shape design received the CE Mark and was approved by the Food and Drug Administration in 2009. The indentations create space between the CTR and the capsular bag equator, which facilitates nuclear and cortical material removal while still maintaining the desired stretch and support of the capsular bag.

The HCTR was constructed with the same force parameters and spring constants as the standard CTR to maintain the same effectiveness in capsular bag stabilization. The HCTR was compared to the traditional nonindented CTR in a single blind prospective study and found to improve outcomes such as mean surgical time, effective phacoemulsification time, and mean irrigating balanced salt solution volume compared to the traditional CTR group (P = .06, .34, and .03, respectively).²

Timing of Placement

The timing for placing a traditional CTR is usually as late in the procedure as possible but as early as necessary. When zonular weakness is discovered, the early CTR placement provides additional capsular support in order to continue with the remainder of the surgery. For example, if zonular weakness is evident during the opening of the anterior capsule, insertion of a CTR can stabilize the crystalline lens during phacoemulsification and prevent vitreous prolapse. However, as stated previously, CTR implantation may inhibit the removal of residual lens material by compressing it against the capsular fornices. This is especially true in eyes with pseudoexfoliation because the zonulopathy may be more generalized rather than focal.³

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