placing the capsular tension ring (CTR)

The capsular tension ring (CTR) is very useful.  Here I will discuss the use of the standard, unsutured CTR. 

Indications  The CTR is most commonly used when the zonules are weak in a limited area or together with a capsular tension segment (CTS) with more generalized zonular weakness.  The CTR can also be used to help prevent capsular phimosis or to allow suturing of the ring and capsule later in patients with progressive or more generalized zonular weakness.  Some surgeons have also suggested that the ring will help prevent posterior capsular opacification but I think that has not been proven.  

CTR variations  The CTR comes in many varieties that include standard rings in various sizes, CTR with one or two eyelets that allow one to suture them to the sclera (Cionni modification), and the Henderson CTR with waves that allow one to place the ring early and still remove cortical material (distributed by FCI in the US).  A close cousin of the CTR is the Ahmed capsular tension segment (CTS) which has a partial ring and an eyelet that can be used temporarly to hold the capsule with a hook or sutured permanently to the sclera.    The standard CTR comes in a variety of diameters -- in general i would suggest using the larger ring (eg 13 mm in the AMO/Ophtec ring).  

Injecting the CTR.    Several techniques that have been described to place the CTR.  The most simple and the technique that i use most often is to use an injector.  The injector is simply a cylinder which has a spring loaded hook that pulls the ring into the cylinder with a plunger to push it back out.   Here is a video showing how to load the CTR into the injector and inserting the CTR into the capsular bag filled with OVD. 



Here are is a video showing an example of a traumatic case using a CTR placed with an injector. 



Here is a video showing the use of an injected CTR in a patient with RP to help prevent phimosis.





Injecting the CTR does place some tension on the existing zonules and sometimes too much stress.  Here is a video showing a case where the placement of the CTR with the injector created too much stress on the zonules and actually made the situation worse. 



Little fish tail placement of the CTR. Angunawela and Little described a nice CTR insertion technique to use when the zonules are very weak.  In this fish tail technique the center of the ring is pushed through the wound and the eyelets remain outside the ring which looked to Little like a fish tail.  This insertion technique allows for much less tension on the zonules as the ring is inserted. The ring is bent a bit as it is placed through the 2.75mm wound, but it seems to snap back into position nicely.   Here is a video showing this technique.




Alternative fish tail #1.  Getting the central portion of the ring into the eye with the Little Fishtail technique is the trickiest part.  A variation of this technique is to use Duet micro forceps to place the central portion of the ring into the wound and the CTR into the capsular bag.  The remainder of the ring is then placed using forceps as described by Angunawela and Little.  This seems like a very nice way to place a ring to minimize the stress on the zonules during placement but it does seem to stress the central portion of the ring a bit.   Here is a video showing this technique.



Alternative Fishtail #2.  This fish tail modified technique uses a suture like a fish on a line to pull the injected eyelet back out of the eye to form the fish tail confguration. One of the issues with the little fish tail technique is getting the loop of the CTR into the eye without damaging the elasticity of the CTR.   In this modified technique you first insert the leading eyelet of the CTR into the anterior chamber with a suture through the eyelet and leave the trailing eyelet out of the eye.   You then use the suture and a hook to bring the leading eyelet back out of the eye keeping the loop in the anterior chamber which places the CTR into the familiar fish tail configuration.  Then use forceps to place the CTR as described by little.   Here is a video showing this technique.


References:
 

1. Price FW Jr, Mackool RJ, Miller KM, Koch P, Oetting TA, Johnson AT. Interim results of the United States investigational device study of the Ophtec capsular tension ring. Ophthalmology. 2005 Mar;112(3):460-5.
2. Angunawela RI, Little B. Fish-tail technique for capsular tension ring insertion. J Cataract Refract Surg. 2007 May;33(5):767-9.