No Need to Compromise With the Best of Both Worlds
Phacoemulsification is experiencing a period of significant transition. Two techniques (ie, standard coaxial phaco and bimanual phaco) are divergent, as standard coaxial is considered, for the majority of us, the method of choice and bimanual by microincision (ie, sub-2.0 mm) is another viable option. Both techniques have significant advantages and drawbacks.
Standard coaxial phacoemulsification. The main advantage of this technique is that it is perfectly standardized. Although the majority of surgeons consider it secure and efficient, standard coaxial phaco is somewhat limited due to a corneal incision size of 2.8 mm to 3.2 mm, which is needed to successfully perform the ultrasound phase of the phacoemulsification. In fact, we may now reliably inject high-quality IOLs — respecting all necessary gold standard specifications — through incisions of only 2.0 mm to 2.2 mm. Contrary to our prior habits, during the ultrasound phase of IOL implantation, we regretfully have to create a superior-sized incision compared with the necessary size.
Bimanual phacoemulsification by microincision. This surgical technique has been widely developed and promoted for the last 3 years. It is promoted as an efficient technique, but its use is still controversial; only an estimated 5% of cataract surgeries in Europe are performed with this technique.
The main advantage of bimanual phacoemulsification is that it is less invasive, thanks to a smaller-sized corneal incision compared with standard coaxial phacoemulsification incisions. Despite the technique's slow spread, it is considerably efficient and certainly safe in the hands of expert surgeons who regularly practice. Certain drawbacks of this technique, however, remain undeniable for a majority of surgeons:
• A delicate and long learning curve;
• The necessity to learn new surgical gestures and to modify surgical habits;
• Particular instrumentation, which is often fragile and onerous;
• The fluid balance during surgery is difficult to obtain and requires the right compromise between (1) tiny and watertight incisions that allow excellent anterior chamber stability maintenance but risk burnings or corneal stretching and (2) if the incisions are not as tiny, the mechanical risks may be smaller but also jeopardize anterior chamber stability and security during surgery; and
• IOL injection through a sub–2-mm incision, if possible, is most often made at the detriment of lens quality (optic diameter <6 mm, and/or overall diameter <13 mm). At the end of bimanual surgery, the incision is often widened for IOL insertion, which respects the gold standard criteria generally approved by all.
My colleague Khiun F. Tjia, MD, and I are proposing an innovative concept that, in our opinion, is benefited by the advantages of standard coaxial phacoemulsification and microincisional bimanual phacoemulsification, while in parallel minimizes the respective drawbacks of each technique. Our technique, coaxial microincision phacoemulsification surgery, is easily performed through mini incisions (≤2.2 mm). After 12 months of evaluation and 260 eyes in 192 patients, we consider this as the most safe and efficient technique for our daily surgeries. More results will be presented at the 2006 European Society of Cataract and Refractive Surgeons meeting in London. An explanation for its superiority is that development was based on two widely tested and approved main ideas: (1) benefit from a coaxial technique and (2) injecting an IOL that respects all security criteria.1 With regard to coaxial benefits, keeping the infusion sleeve around the phaco needle prevents the risk of corneal burning and allows for watertight incisions, which ensures preoperative anterior chamber stability. Furthermore, structure of the incision is kept intact to guarantee a good postoperative tightness. Security criterion includes vision quality (thanks to precise optic refraction), postoperative stability (thanks to a new patented design of IOL haptics) and low occurrence of posterior capsular opacification (thanks to an appropriate IOL behavior during capsular contraction and an innovative double square-edge technology). Development of a new phaco kit (Kit Phaco Mini Incision [21 gauge]; Xcelens SA, Geneva, Switzerland) concept — including a mini disposable phaco needle and its appropriate infusion sleeve that enables full phacoemulsification by an incision ≤2.2 mm (Figure 1) — allowed for the adaptation of the two aforementioned principles to create coaxial microincision cataract surgery.
We use the specifically designed mini flared phaco tip (21 gauge) combined with a thinner infusion sleeve (20 gauge) to achieve coaxial microincision cataract surgery, which enables maintenance of excellent infusion flow by increasing the used volume between tip and sleeve (20% to 40% more infusion, in my experience depending on the compared products).2 Additionally, we noted a significant increase in ultrasound efficiency due to a more concentrated cavitation effect of the Xcelens phaco tip. Moreover, we can work with higher vacuum levels (450 mm Hg to 500 mm Hg) than those currently used with standard 19-gauge and 20-gauge tips because of the diminution of the phaco tip's internal diameter. We still maintain a minimized surge effect; surgeries then become safer and more efficient.
The Innovative Double Edge Angulated Lens (IDEA; Xcelens SA) — a new IOL raw material combined with a reliable IOL design conferring specific properties to a new generation of lens for microincision surgery — is a 25% water content hydrophilic acrylic IOL (Figure 2). The specificity of the used raw material results from a copolymerisation of two monomers, a hydrophilic acrylic monomer (hydroxyethyl methacrylate) and a hydrophobic acrylic monomer (ethoxyethyl methacrylate). This copolymerization is the basis of the superior pseudoplasticity of the IDEA lens, enabling injection of this IOL (6-mm optic and 13-mm overall diameter) through a 1-mm internal diameter cartridge without any damage, whatever the IOL power used between -10.00 D and +35.00 D (Figure 3).
Additionally, this large IOL benefits from an innovative concept of double square edges, which when combined with IOL angulations of 9º and with its postoperative anteroposterior movement (Figure 4), give the IDEA lens the capacity to offer all necessary security items (ie, prevention of secondary posterior capsular opacification).
After 12 months of feedback and more than 250 procedures with coaxial microincision cataract surgery, in my opinion, this technique appears to be particularly interesting for 10 reasons:
•There are practically no learning curves: Gestures are the same as with standard coaxial phacoemulsification.
•Only phaco machine parameters should be modified according to a slightly different fluidic dynamic and an increased efficiency of the ultrasounds.
•No specific instrumentation is needed.
•Incisions at the end of surgery are perfectly watertight.
•The anterior chamber is perfectly stable throughout surgery.
•There is diminution of the necessary quantity of efficient ultrasounds. Phenomena increased with hard nucleus (greater than or equal to grade 3) minimize postoperative cornea edema in case of hard nucleus.
•Diminution of the induced astigmatism by more than one-third when compared with standard coaxial phacoemulsification through a
3-mm incision.
•Regardless of eye morphology, the IDEA lens has excellent stability in the capsular bag; at 18 months, posterior capsule opacification rate seems to compare with that obtained from other popular IOL models.
•No increased complication rate.
•Spherical aberration rate is low after surgery.
Phacoemulsification by coaxial microincision — shown in this article — appears to be a potential technique of choice for a large number of surgeons in their daily practice. Today, coaxial microincision cataract surgery combines the efficiency, the security and the reproducibility of standard coaxial phacoemulsification and significantly diminishes the corneal incision size without compromising the quality of the IOL used.
Pierre Lévy, MD, is from the Polyclinique Saint-Roch, in Montpellier, France. Dr. Lévy states that he is a paid consultant for Xcelens SA regarding new product developments, however, he said he does not hold any financial interest in the mentioned products. He may be reached at levy.34@free.fr.
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