February 2010

 

CATARACT / IOL

 

Life in the innovator’s ring


by Bonnie A. Henderson, M.D.

 

Cataract surgery in challenging cases has been associated with a higher rate of intraoperative and postoperative complications. Adjunctive devices such as pupil expansion rings, iris hooks, capsular tension rings, and capsular dyes have greatly enhanced our ability to approach difficult cases with greater safety for the patient and less stress for the surgeon. Can you remember performing cataract surgery on mature white cataracts, small pupils, or dialyzed capsular bags without these tools? In this month’s column, Bonnie Henderson describes her challenges with the standard capsular tension ring and her desire to improve this device with an innovative modification that has enhanced its utility. Insertion techniques and contradictions for its use are briefly reviewed. The next great idea in ophthalmology is waiting to be discovered by addressing limitations in our current intraoperative techniques and devices and learning to think outside of the box.

Richard Hoffman, M.D., Column Editor

 

The HTCR makes cortical cleanup easier while stabilizing the capsule

The unique design of the HCTR eases the cortical removal process Source: Morcher

Capsular tension rings are of course a very common part of the armamentarium, which are imperative for those pseudoexfoliation or traumatic cataract cases where the capsular bag is unstable. Such standard rings have come to the rescue and helped me on many occasions. It was while using such a traditional ring in one case, in which it was particularly difficult to remove cortical material, however, that I decided to try on the hat of innovator. This case prompted me to think about how the device could be possibly modified to assist with cortical cleanup. In that specific instance I found that I was really struggling to remove residual cortical material and I was worried that I was doing more damage to the capsule and the weakened zonules in my efforts to clear this remaining debris away than I would if I hadn’t even been using a capsular tension ring in the first place.

The initial idea

The problem was that the snug fitting ring was pushing that residual material against the capsular bag. It occurred to me that in such cases there had to be a better way and I began to think about how that might be possible. With this in mind, I developed a prototype for what later became known as the Henderson capsular tension ring (Hcapsular tension ring, HCTR, Morcher, Stuttgart, Germany). Unlike the continuous c-shaped configuration of a traditional capsular tension ring, the HCTR, has eight equally spaced indentations. The idea behind the indentation was that if there was material trapped between the ring and the capsular bag it would allow a little extra space so that it would be easier to remove this debris without pulling on the patient’s potentially already weakened zonules. In short, I hoped that this modified ring would continue to stabilize the bag while easing cortical cleanup.

Capsular tension rings can of course be placed at any time during the cataract procedure. These are helpful for people who either have pseudoexfoliation or traumatic cataracts where the capsular bag is not stable. They work by redistributing the pressure 360-degrees around the capsule rather than in just the locations where the zonules are intact. The HTCR modified ring accomplishes this as well, however, the design modification is meant to also ease cortical cleanup. As a result, the HTCR can be of benefit for those instances when it is necessary to place the ring in the bag early in surgery before the cortical material can be swept away.

Successful usage

This modified capsular tension ring can be inserted either using a commercially available injector system or, even manually. It’s actually very easy to do manually: you just dial this into the capsular bag. The one caveat here is that it is sometimes a little tricky to place that last trailing end in such cases. For those who would prefer to proceed manually I recommend using a bimanual approach, using either a Sinskey or a Kuglen hook to actually push that remaining eyelet into place in the capsular bag. The HTCR should not be used in any eyes in where there is a break in the posterior capsule or a disruption of the anterior capsulorrhexis because often times it can cause a further rip in the capsular bag if this is attempted.

As I had hoped, the HTCR, can prove immensely helpful in those cases where the bag is intact and you need to stabilize this early in the process. I find that it helps to decrease the stress on the zonules while making it easier to remove the cortical material. The modified ring also does still bring with it the same ability to enhance stability as the original. Engineers at Morcher investigated the modified ring and found that the spring constant was the same as the continuous ring. Both of these rings are in effect equivalent in terms of the strength and the ability to stay open and redistribute the pressure.

In 2009 I was gratified to see that the HTCR received Food and Drug Administration approval. It has been an enormously rewarding process to have started with an idea, pursued it, and then watched it come to fruition. I am of course far from alone here. It is satisfying to know that ophthalmologists in this country are able to take an idea that think would benefit others, produce something, test this to make sure it works and then ultimately have this available to many. I definitely encourage others who have unique ideas to pursue these. Even if this does take a little bit of effort I do think that it’s worthwhile and does help all of the ophthalmologists around the world.

Contact information

Henderson: bahenderson@eyeboston.com

Life in the innovator’s ring Life in the innovator’s ring
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