(USA)
INTRODUCTION
It is amazing to look back and see the progress we have made in cataract surgical techniques over the past 50 years. It is difficult to imagine another procedure that has advanced so rapidly toward minimal tissue trauma and resultant rapid recovery. We are the beneficiaries of some very ingenious and courageous surgeons and scientists such as Sir Harold Ridley and Dr Charles Kelman. In turn, our successors will hopefully benefit from our continued diligence and reap the benefits that the bimanual technique offers.
When Dr Kelman invented phacoemulsification he obviously encountered significant heat generation at the phaco needle. He wisely dealt with this problem by placing a sleeve over it for cool fluid to flow through and dissipate the heat. It also allowed for fluid to enter the eye to counterbalance the fluid being removed from the eye by the phaco probe. Some surgeons speculate that a bimanual separate irrigation sleeveless phaco technique may have been the preferred technique for Dr Kelman and other early phaco pioneers if the phaco probe had not required cooling and irrigation could have been placed through a separate wound.
EARLY WORK
The History of MICS likely dates back farther, but some of the earliest known work began with Dr Steven Shearing in 1985. Its usefulness for dense nuclear removal with ultrasonic emulsification was limited do to heat generation by the phaco probe causing thermal injury to the corneal wound and eye interior. In 1989 Dr Tsutoma Hara from Japan published an article in Ophthalmic Surgery touting the advantages of an endocapsular bimanual technique. Do to the limited interest fueled by heat generation at the phaco tip and the larger wound necessary for lens insertion, the technique lay dormant until the late 1990's.
PIONEERING DEVELOPMENT
In 1998, Dr Amar Agarwal, in India, conceived the idea of using a bent needle as an irrigation and chopping instrument and removing the sleeve from the phaco needle to perform cataract surgery. The same issue arose with regard to wound burn which was partially solved by dripping cool BBS on the wound as phaco was being performed. Dr Agarwal was also involved in the early instrument design and refinement of the technique.
Simultaneously in Spain, Jorge Alio began his work with the separation of irrigation and phaco/aspiration and its usefulness in cataract removal. He and Dr Agarwal both realized early on that if the wound could be protected from heat generation and burns, the fluid dynamics, safety and efficiency of the technique was superior to their conventional coaxial technique.
In the year 2000, another visionary surgeon, Dr Kanalleopoulos performed bimanual sleeveless microincisional cataract surgery using the ARC Dodick Laser Photolysis System. This technology does not generate heat and therefore does not require a cooling irrigation sleeve on the ND:YAG laser probe. A cataract 4can be removed through two 1.4 mm incisions however the technology has been limited by its inability to remove anything other than a soft nucleus.
IMPROVEMENTS IN TECHNOLOGY
The early instrumentation for MICS, especially the irrigation instruments were rudimentary and often did not allow for adequate passive fluid infusion into the eye leading to an unstable anterior chamber. This led to the invention of an air infusion pump in 1999 by Sunita Agarwal of India. The device infused air into the irrigation bottle to pressurize it and force irrigation into the eye. This led to improved irrigation and a more stable chamber. Improved irrigating choppers with thinner walls that allowed for greater flow were eventually created and reduced the need for forced infusion.
With the obstacle of thermal wound damage to the fragile ocular tissue impeding the success of a sleeveless phaco procedure, attention was drawn to heat generation during cataract surgery and how to reduce it. In the year 2000, Dr Hiroshi Tsuneoka from Japan began to intensely study the nature of wound burns in animal eyes. He concluded that by creating a clear corneal wound slightly larger than the phaco needle, fluid could escape the eye around the needle and cool the tip as it flowed around it. This would reduce the risk of thermal injury. At the same time in the United States Dr William Soscia and Dr Randall Olson were studying heat generation with new generation micropulse phaco software. They clearly demonstrated that with the newly released AMO Sovereign phaco machine with Whitestar software it was possible to remove cataracts without any tissue damaging heat generation by the phaco needle. They showed data for both sleeved and unsleeved phaco whereby the improved Whitestar microburst software generated less phaco energy and heat generation than standard pulsed or continuous phaco.
EARLY ADOPTION
In 2002, once word spread of the capability and safety of the new micropulse software, forward thinking surgeons across the globe began to embrace the concept of bimanual separate infusion sleeveless phaco. (It is not actually completely sleeveless because a short cut sleeve is usually place on the phaco needle to prevent spray at the hub of the needle.)
By 2003, much had been learned about the fluidics and advantages of MICS. New instruments were being designed and refined specifically for the microphaco surgeon. Mr. Larry Laks and his colleagues at Microsurgical Technologies (MST) designed and perfected thin walled titanium irrigating choppers and aspiration instruments for the procedure. The newer designs matched inflow to outflow and the earlier issues with chamber stability were eliminated. Other pioneering companies such as ASICO, Rhein, Surgical Specialties and Storz also began to create instrument sets and keratomes for MICS.
At this time, among surgeons, opinions varied on lens insertion. Some surgeons preferred to enlarge one of the existing microwounds and others liked to create a fresh third incision for the lens to go through between the other two smaller incisions. Regardless of technique, committed surgeons were enjoying the advantages of controlled fluid dynamics and intraoperative control seen with bimanual cataract surgery.
In 2003, the first official MICS course in the United States was held in Eugene, Oregon.
This revolutionary symposium, hosted by Dr Howard Fine, Dr Richard Hoffman, and Dr Mark Packer, gave attending surgeons all the tools and knowledge needed for success with microphaco. In 2004, the second course was given at the Eye Institute of West Florida in Largo, Florida.
It was not long before Bausch and Lomb as well as Alcon developed similar micropulse software for the Millenium and Legacy to allow surgeons who used these machines to perform bimanual phaco. By 2004 MICS was being performed on a regular basis across the globe. Surgeons that committed themselves to go through the learning curve usually wound up preferring the technique and continue to use it. However, the vast majority of cataract surgeons, especially in the United States, refrained from transitioning over to MICS. When asked why they did not want to try MICS, most surgeons stated that they were waiting for a lens that could be injected through a microwound to be approved. In Europe and Asia the bimanual procedure was more accepted and embraced. Many surgeons transitioned to the technique. This may be partly due to the fact that new implants had been approved in Europe and Asia that could be injected through the microwounds.5
MICROINCISION IMPLANT DEVELOPMENT
Paralleling the advancements in MICS has been IOL technology capable of being inserted through a wound of less than 2 mm. One of the earliest implants available was the Thinoptx Ultra Choice 1.0 lens. This lens was first implanted by Dr Amar Agarwal in late 2001. This implant has a 5.0 mm optic and due to its thin design, can be rolled up and injected through an incision less than 2 mm. Its fresnel prism design allows for a very thin profile of approximately 100 um.
Another company that has pioneered microincision implants is Acritec. With their Acrismart plate haptic style lens and proprietary injection system, surgeons are able to perform MICS without the need to enlarge the wound for lens implantation at the end of the procedure. Its first human implantation was performed in 2000 and since then, thousands have been implanted worldwide.
Currently no implants capable of being injected through a wound less than 2 mm are available in the United States. Bausch and Lomb is working on a microincisional implant called the Akreos MI which may be approved by the FDA in 2008. It is quite possible that once this and other MICS lenses are available in the US, many surgeons will embrace and convert to a sleeveless bimanual technique. This would follow suit with what has happened internationally with the availability of MICS implants and improved instruments and phaco machines.
We are probably still in the early stages of the evolution toward microincision cataract surgery. This trend toward smaller wounds has persisted throughout the history of cataract surgery and it is destined to continue. With upcoming improvements in phacoemulsification machines, instruments, and intraocular implants the next decade will likely show a gradual movement toward this more controlled and precise procedure.
BIBLIOGRAPHY
- Agarwal A, Agarwal S, Agarwal AT. Phakonit and Laser Phakonit: lens surgery through a .9 mm incision. In Agarwal S, et al. Phacoemulsification, Laser Cataract Surgery and Foldable IOL's. 2nd ed. Jaypee Brothers New Delhi, India: 1998:204–16.
- Agarwal A, Agarwal S, Agarwal AT. The Phakonit Thinoptx IOL. In Agarwal A. Presbyopia. SLACK Inc Thorofare, NJ: 2002:187–94.
- Pandey S, Wener L, Agarwal A, Agarwal S, Agarwal AT, Hoyos L. Phakonit: cataract removal through a sub 1.0 mm incision with implantation of the Thinoptx rollable IOL. J Cataract Refract Surg 2002;28: 1710.
- Agarwal A, Agarwal S, Agarwal AT Phakonit: phacoemulsification through a .9 mm incision. J Cataract Refract Surg 2001;27:1548–52.
- Soscia W, Howard JG, Olson RJ. Bimanual phacoemulsification through 2 stab incisions: a wound-temperature study. J Cataract Refract Surg 2002: 28:1039–43.
- Soscia W, Howard JG, Olson RJ. Microphacoemulsification with Whitestar: a wound-temperature study. J Cataract Refract Surg 2002;28:1044–46.
- Tsuneoka H. Thermal Burn Studies in Animal Eyes. In Agarwal A. Bimanual Phaco. SLACK, inc Thorofare, NJ: 2005:17–22.
- Alio JL, Rodriguez JL, Galal A. MICS:Microincisional Cataract Surgery. Eldorado, Panama: Highlights of Ophthalmology International 2004.
- Garg A, Fine IH, Alio JL, Chang DF, et al. Mastering the Phacodynamics. Jaypee Brothers New Delhi, India: 2007.