There have been few procedures in cataract surgery that have been so thoroughly promoted as bimanual sleeveless microphacoemulsification. Despite headlines about this method in every tabloid and 3 years of media saturation, however, only a tiny fragment of cataract surgeons has bought into this technique. The reasons are quite obvious.
First, the fluidics of bimanual sleeveless microphacoemulsification are downright unfavorable. A 22-gauge (Agarwal), 21-gauge (Olson), 20-gauge (Fine), or 19-gauge (Steinert) irrigating chopper does not allow enough infusion to stabilize the anterior chamber. Even when the bottle height is elevated “to the roof,” the surgeon cannot work at his usual vacuum levels and aspiration rates without experiencing surge. The consequences of working at lower levels of vacuum with a 0.9-mm phaco tip create a trade-off in purchasing power and overall efficiency. Contrary to vociferous claims, bimanual microphacoemulsification is by no means a quick operation.
The second drawback of this technique deals with the integrity of the incision. When a round metal tube is manipulated through a tight linear incision, the opening changes architecturally. Microincisions leak, further compromising the chamber's stability, and several studies have confirmed wound damage. In fact, excellent surgeons such as I. Howard Fine, MD, of Eugene, Oregon, routinely make a third incision for the IOL, because they cannot depend upon the competency of the primary incisions. Renowned surgeon Richard L. Lindstrom, MD, of Minneapolis solved chamber instability with an additional incision for an anterior chamber maintainer to improve chamber stability. However, when one adds up the incisions (1.2mm + 1.2mm + 2.7mm), the sum total is more than 5mm—not microphacoemulsification, but rather “macrophacoemulsification!”
SAFETY ISSUES WITH BARE NEEDLES
Additional safety issues of sleeveless microphacoemulsification must also be addressed. For example, there is almost no margin of safety against a thermal injury when a bare phaco needle is within a tight corneal incision. Fortunately, Advanced Medical Optics, Inc. (Santa Ana, CA), introduced the Whitestar phaco innovation, which uses hyperpulse with a duty cycle for a thermoprotective effect. Nevertheless, the system's primary source of cooling is aspiration through the needle, and a 0.9-mm needle being plugged with a viscoelastic material at low vacuum spells trouble.
PROBLEMS WITH IOLs
The IOL issue is also a disadvantage at the present time. In the US, there is no IOL approved for microincisional surgery, which means that the American surgeon must enlarge the incision anyway. Surgeons outside the US may have the advantage of implanting an IOL through a tiny incision, but is it wise to sacrifice all of the sophisticated advances in IOL technology just to get through a smaller incision? Compromising a superior material, a low rate of posterior capsular opacification, macular protection, aberration reduction, toric correction, and multifocality, which are all available at the present time, simply does not make sense.
A final reason why bimanual sleeveless microphacoemulsification has not been embraced by the vast majority of cataract surgeons is its learning curve. This operation is definitely different than a routine phacoemulsification technique. In fact, nearly every step is different, including the capsulorhexis, the emulsification, and the bimanual cortical removal. Although an experienced surgeon is capable of performing this procedure, my patients did not enjoy the excellent UCVA and the consistent corneal clarity that was published by three of my fellows in the Journal of Cataract and Refractive Surgery last year.3 I honestly admit that I could not duplicate my coaxial results with a bimanual technique, despite my best efforts and many trips to the practice lab.
TESTING OTHER TECHNOLOGIES
The drawbacks of bimanual sleeveless microphacoemulsification have motivated the industry to develop microincisional cataract technology with improved criteria for efficacy, safety, and IOL facility. It was with great excitement that I accepted an invitation from Alcon Laboratories, Inc. (Fort Worth, TX), to investigate a new generation of phaco sleeve technologies. The Ultra Sleeve was developed for coaxial phacoemulsification using a 1.1-mm flare tip through a 2.2-mm incision (Figure 1). The laboratory evaluation my colleagues and I conducted yielded outstanding results. We found infusion flow rates to be approximately 60% greater than those measured with irrigating choppers, and we recorded the temperatures in the incision as 20% lower when comparing the same parameters using sleeveless bimanual phacoemulsification. We found the incisions to be consistently more competent (Figure 2), and we measured approximately seven times less wound leakage than during bimanual sleeveless microphacoemulsification. Also, surge testing confirmed greater chamber stability with the Ultra Sleeve during coaxial phacoemulsification.
Fortified with such positive laboratory results, I began using coaxial microphacoemulsification just before the April 2005 ASCRS meeting in Washington, DC, and I have continued to use this technique in the majority of my patients. It has virtually no learning curve and features marvelous fluidics. The only modification it requires is a slightly higher bottle height and an altered technique for inserting the IOL. I use the same chopping method within the capsular bag to disassemble the nucleus. I also remove the cortex with the silicone I/A tip. I can inject a full-sized 6-mm Acrysof SN60 WF or Restor IOL ( Alcon Laboratories, Inc.) through a 2.2-mm incision by using a second instrument to provide countertraction in the stab incision (Figure 3). Instead of loading the lens in the opposite way to that shown in the picture on the cartridge and injecting it bevel-up to allow the haptics to open from beneath the optic inside the bag, this modified technique requires loading the lens as shown in Figure 3 for bevel-down insertion within the incision. The lens, confidently injected with a plunger, will open like a book within the ophthalmic viscoelastic device. The haptics are easily positioned within the capsular bag using an Osher Y-hook (MP205; Duckworth & Kent Ltd., Hertfordshire, England). The incision may spread to 2.3mm after IOL insertion, but after hydration, it remains consistently competent at the end of the operation (Figure 4).
Coaxial microphacoemulsification is an excellent approach to small-incision surgery and will represent the next major step in the evolution of cataract surgery. Surgeons will transition from their current technique to coaxial microphacoemulsification easily, and the procedure's fluidics are almost identical to the safe intraocular environment to which we have become accustomed. Best of all, it allows the injection of a superior IOL with superb centration without either enlarging the incision or making a separate one. Furthermore, patients' UCVAs and corneal clarity on the first postoperative day are enormously satisfying to both the surgeon and patient alike. Unlike bimanual sleeveless microphacoemulsification, I anticipate rapid acceptance of this technique, and I am proud to have the opportunity to share the laboratory science and the clinical results with my colleagues.
Robert H. Osher, MD, is a professor in the Department of Ophthalmology at the University of Cincinnati College of Medicine and is Medical Director Emeritus of the Cincinnati Eye Institute. He is also the founder and editor of the Video Journal of Cataract and Refractive Surgery. He is a paid consultant with Alcon Laboratories, Inc. Dr. Osher may be reached at (513) 984-5133; firstname.lastname@example.org.
1. Vasavada, AR. Phaco tips and corneal tissue. Cataract & Refractive Surgery Today. 2005;5(suppl):9-10.
2. Weikert MP, Koch DD. Phaco wounds study. Cataract & Refractive Surgery Today. 2005;5(suppl):11-13.
3. Osher RH, Barros MG, Marques DM, et al. Early uncorrected visual acuity as a measurement of the visual outcomes of contemporary cataract surgery. J Cataract Refract Surg. 2004;30:9:1917-1920.