Cataract surgery has undergone significant developments through new technologies and new operative strategies. During more than the first half of the twentieth century, cataract surgery was highly invasive, with a large limbal incision, zonulolysis and the extraction of the entire crystalline lens and its capsule. As a rule, the patient remained in hospital for a week, and functional recovery included significant astigmatism and a high rate of complications with numerous post-operative infections.
The arrival of extra-capsular extraction towards the end of the ’60s and of phacoemulsification in the early ’70s enabled improvements in these functional results by means of a reduction in surgery time and infection rates, smaller incisions and the intact preservation of a posterior capsule of the crystalline lens.
Bimanual microincision phacoemulsification is a new development in cataract surgery. It makes it possible to separate irrigation from the ultrasound probe to emulsify the crystalline lens as it is now possible to maintain the higher temperature of the ultrasound probe below the threshold that results in corneal burns at the incision site. Now coaxial infusion was no longer logical, and its relocation to a separate instrument prevents antagonistic phenomena between irrigation pushing away, and aspiration bringing back pieces of crystalline lens to the tip of the probe. In bimanual phaco, irrigation is provided by a separate irrigation probe, and the ultrasound tip is no longer surrounded by a silicone sleeve. Surgery can be performed by means of two micro-incisions of less than 1.5 mm which induce less astigmatism and improve perioperative visualisation.
The first description of bimanual phacoemulsification with two 1 mm incisions was provided by SHEARING in 1985. However, the variability of results due to a not insignificant rate of corneal burns and the use of 6 mm PMMA implants caused this technique to be of only limited interest.
On the other hand, over the last five years, technological advances enabling better US power management, a better understanding of fluid dynamics and the advent of implants for microincisions have reawakened interest in bimanual phacoemulsification. No reference work would be complete without citing some of the pioneers of bimanual phaco as it is practiced today:
- Amar Agarwal in India who, in 1999, performed the first 0.9 mm bimanual phacos, called PHAKONIT, N for needle, I for incision, T for tip. The first bimanual phacos were therefore carried out with an infusion needle passed through a micro-incision. He received assistance from his sister Sunita Agarwal who perfected the system with an air pump connected to the irrigation bottle to increase the flow of the intracameral infusion and to prevent perioperative collapse events.
- At the same time, in Japan, Hiroshi Tsuneoka performed the first large-scale series of 637 bimanual phaco procedures with microincisions of less than 1.5 mm; an overview was published in the Journal of Cataract and Refractive Surgery in 2002.
- Starting in 1999, Randall Olson began researching ways to control ultrasound emissions to reduce the thermal effects of the probe and to make non-coaxial phacoemulsion possible. In 2001 he demonstrated the feasibility of 1 mm bimanual phaco.
- In Spain, Jorge Alio created the term MICS for Micro Incision Cataract Surgery, and his important work was instrumental in popularising the technique in Europe.
- In Germany, Christine Kreiner developed the first implant for microincisions. Their first lens was implanted in Greece through the work of Kanellopoulos in 2000.
- In the US, Scott et Waine Callahan developed an ultra-thin, foldable and injectable implant to use with incisions of less than 1.8 mm, with one of the first implantations being carried out by Alio in Spain in 2001.
To put the evolution towards bimanual phaco into perspective, a parallel could be established between the current developments in bimanual crystalline lens phacoemulsification and those in the area of vitrectomy. Vitrectomy was also in its beginnings a technique in which irrigation was coaxial to the vitreotome. Kloti’s vitreotome model is an example of this arrangement. It gradually changed into two angles of approach, with a separation of the infusion and the cutting action of the vitreotome, then into a three-port-system with the introduction of an cold light source for intraocular use. Today, it would be unthinkable to return to coaxial vitrectomy. And what will be the future of phacoemulsification ? Time will tell.
