Professor Kuhn: Kuhn 45° Power Forceps

Turning ideas into innovations - The Kuhn 45° Power Forceps!

Vitreq’s new Kuhn 45° Power Forceps was developed in collaboration with Professor Ferenc Kuhn - one of the world`s most ‘outside-the-box’ thinkers in VR surgery. Professor Kuhn explains more about the development of the unique, all-purpose forceps.


What motivated you to design and develop the Kuhn 45° Power Forceps?

I started vitreoretinal surgery 32 years ago. Surgical techniques and equipment were just being developed, together, back then. In certain procedures, however, surgeons have had to learn to work with what was available. And within this, I have discovered gaps in the market. By this, I mean that it is not just that certain instruments are not exactly tuned to my own preference, but that they are simply not offered by any company. An all-purpose forceps that reduces the number of instruments required in VR surgery was one of these ‘missing’ products.

My idea was a forceps with a tip that enables exceptional visualization during grasping maneuvers, with a 45°crocodile design inner surface that enables selective and strong grasping of the target tissue, regardless of its rigidity, size, orientation, or surface texture. 

The resultant design, the Kuhn 45° Power Forceps, enables the surgeon to achieve optimal contact with membranes in all membrane positions, because the teeth at the tip of the forceps can be used as demanded by the individual situation. With all other forceps designs, the area of contact with the tip may be very small when the serrations are perpendicular to the axis of the forceps and the membrane is located so that its axis is parallel with the teeth, since only one tooth grasps the membrane (the membrane is parallel to the retina). Conversely, the area of contact with the tip is large with the 45° alignment, and the surgeon can achieve optimal contact with the membranes in all positions, because more teeth grasp the membrane.

Design and development have required calculating precisely the right dimensions for the forceps to achieve optimal functionality.

Why was Vitreq the right company to develop the new forceps with?

While bigger companies have obvious advantages of more resources and more people, they also have a severe disadvantage in the multiple layers of decision-making within these companies. In my experience, the physical turnover of staff at large companies is far greater than in a smaller entity. In smaller companies, you can work with the same people over an extended period of time. And the relationship that develops from that not only strengthens professionally, but becomes personal. This is beneficial in developing surgical innovations, and was a big plus that I have found at Vitreq.

How has the collaboration with Vitreq been?

I have worked with a lot of companies in the past. I find it very rare that they truly listen to you, and I have had some very disappointing experiences around developing instruments that I feel would really help surgeons. It is not that I have received negative feedback from these companies, but simply that the original idea for an improved instrument has ‘died’ en route to development. So, it was a very uplifting experience to work with Vitreq, specifically with Frank Ruseler, Vitreq’s CEO, and Vitreq’s Chief Engineer. While neither individual is actually a qualified surgeon, I found that when I explained something, they put their mind directly into the shoes of the surgeon, which is not easy to do. They were able to immediately realize the benefits that my proposed design offered.

How has the Kuhn 45° Power Forceps proved in testing and use so far?

Vitreq developed two initial prototypes of the Kuhn 45° Power Forceps, both of which worked, with one proving more promising. We have tested and worked with both prototypes of the forceps. In my experience, the first prototype of a new instrument is rarely exactly perfect. This is a normal phenomenon for several reasons. However, I was very surprised that the first prototypes of the forceps were not only as good as I had hoped, but way beyond my expectations. I was extremely pleased with the prototypes. They were exactly what I needed. I did not expect that first time.

Our goal was to create a forceps that would allow surgeons to achieve things that they could not do before. I tested the forceps and I was able to securely grab preretinal, subretinal, and intravitreal membranes, thin and thick, without any difficulty and without tissue-loss from the jaws, via adjusting the orientation of the tip, if necessary. A secure grab means that several of the teeth on the tip of the forceps must catch the membrane, not just the most proximal one. I also used the forceps successfully on the lens capsule, iris, intraocular cataract lens, to remove small intraocular foreign bodies, fibrinous membranes and to detach the posterior hyaloid – a procedure that typically requires aspiration. Finally, I tried both prototype forceps for most delicate tissue any surgeon could operate on – to grab, lift and peel the ILM - they both worked flawlessly! This was the most positive surprise. The unique shape of tip of the Kuhn 45° Power Forceps enables the instrument to be pushed down, causing the delicate ILM to ‘jump up’ between jaws of the forceps, so that it can be grabbed and peeled easily.

I have not come across any relevant task in the eye that I am not able to accomplish with the Kuhn 45 Power Forceps. It is a truly multifunctional tool.

The Kuhn 45° Power Forceps enables a very secure grab with the specially designed inner surface of the tip. The surface area that is in contact with the membrane is far larger than with the end-gripping forceps. Therefore, the chance of tearing membrane due to insufficient grasping is much, much smaller.

When you have an instrument in your hand, it must meet a number of criteria. Firstly, the handle of the instrument that you use to actuate the tip must be optimal. I had looked closely at the handle of existing Vitreq instruments that I had previously used and found it to be excellent. With Vitreq’s ergonomically designed instrument handles, the surgeon doesn’t need to use too much or too little force, and the travel distance from the point that you start squeezing to the point of actuation is precisely enough. When this brilliantly balanced handle was used for the Kuhn 45° Power Forceps, it clicked perfectly into place.

Secondly, the instrument must offer some extra benefit over the existing armamentarium. One major advantage of the new forceps is that multiple tasks can be accomplished with the same instrument – in other words, there is less of a need to continually remove and reintroduce instruments, which not only shortens the duration of the operation but, more importantly, lowers the risk of retinal detachment for the patient. In addition, since surgical instruments require significant investments, the fewer tools a surgeon has to have, the more economically efficient the procedure is.

What were the challenges of realizing the design?

The Kuhn 45° Power Forceps was a lot more difficult to manufacture than the traditional serrated forceps with 90° to the axis, because the tip has more than one tooth. For improved grip, the more teeth the tip of the forceps has, the better; however, this involves a more complicated manufacturing process. As mentioned already, the two prototype forceps that Vitreq developed were already beyond my expectations: there were no challenges that Vitreq couldn’t solve in realizing the design. Furthermore, one important element related to the unique 45° design of the forceps that we had to consider, was to include a design feature that enables the surgeon to check the internal alignment of the teeth of the forceps during surgery. With a standard 90° forceps, the tip is symmetrical, severely restricting the alignment-potential of the forceps by the surgeon. With the Kuhn 45° Power Forceps, the surgeon must know how the teeth of the forceps are orientated, while it is in position within the eye, for optimal placement. We have developed a special external marking on the instrument close to the tip, which enables the surgeon to easily see the internal position of the teeth.

Can you summarize what the Kuhn 45° Power Forceps will offer VR surgeons?

I am not aware of any other forceps currently available that offers the VR surgeon such a wide range of functionality, from the very front of the eye to the very back. Minimal instrument exchange in VR surgery is the optimal benefit of the new forceps.

Professor Ferenc Kuhn

Professor Ferenc Kuhn is one of the world`s top experts in vitreoretinal surgery and the treatment of eye injuries. He is a Professor of Ophthalmology at the University of Alabama in the United States (US), Immediate Past President of the American Society of Ocular Trauma, President of the International Society of Ocular Trauma, Director of Clinical Research at the Helen Keller Foundation in the US, and Chief of Vitreoretinal Surgery at various institutions in several European countries. He has received numerous prestigious international awards.