In September's Point/Counterpoint article, Dr. Mackool stated that microphaco had nothing to add
27 years ago, has nothing to add today, and should be declared dead. Pronouncements such as that do not leave much hope for this procedure; however, I would like to suggest that there may be a few reasons not to declare this subject dead.
Twenty-seven years ago, foldable lenses were not available and 6-mm PMMA was the standard lens material. We do not need to wait for injectable lenses to take advantage of microphaco wounds. Even today, NEOPTYX has lenses that have been inserted in eyes through 1.5-mm wounds. Hiroshi Tsuneoka, MD, has reported that, with a special customized insertion device for the Acrysof SA-30 IOL, wound sizes in microphaco measure 2.2-mm after insertion—a size that is probably impossible to attain with coaxial phaco. There are hydrophilic acrylic lenses available that can be inserted in the sub–2-mm range. None of these lenses or these approaches may be superior to present-day technology; however, general acceptance of lenses through such small incisions will dramatically change the level of interest in microphaco.
Dr. Mackool is convinced that microphaco is only for surgeons who work slowly. Phaco chop dissembles lenses very quickly and has routinely provided this opportunity with flow rates of 25 to 30 mL per minute. Microphaco with 21-gauge technology, with which I am currently working, adds between 30 seconds and 1 min-ute to the nucleus removal time, which still routinely averages less than 4 minutes. With chop, it takes just seconds to cut pieces into smaller and smaller bite-sized chunks, and so readers must decide if this difference in time is enough to “put surgeons to sleep,” as Dr. Mackool says, or relegate this technology to only “slow surgeons.”
As far as infusion issues are concerned, many of the phaco sleeves and instruments I have seen allow a great deal of flow to exit straight out of the sleeve more often than out of either of the side openings when I turn them on the outside of the eye. Any flow coming straight down around the needle opening is mostly aspirated without any work or is directly pushing nuclear fragments away. I am sure that some sleeve and phaco needle combinations minimize this issue; however, look at your own machines and observe this flow prior to inserting the instrument in the eye. You may be surprised.
As far as whether there are irrigation advantages for microphaco, interestingly, many surgeons have already voted on this with bimanual I/A. Coaxial phaco using two stab incisions is popular with many surgeons because separating irrigation during cortical removal provides clear advantages. Dr. Mackool is right in that this can be a positive or a negative feature depending on how you use it; however, to have that separate irrigating stream to fluff the cortex, open the capsular fornix, and switch instruments exemplifies why surgeons have felt that this is a superior approach. You do not have to use microphaco to see that separating irrigation from aspiration may have distinct advantages. Furthermore, those who are now experimenting with microphaco have clearly found that separated irrigation can offer distinct advantages, and yes, you can clearly see a directed stream move a particle without approaching it and then watch that particle pop toward your phaco tip. This is distinctly different from coaxial phaco. A single opening on the irrigating instrument end accomplishes this best. We are not talking about a comparison of absolutes here—the advantages may not be enough for you to leave coaxial phaco.
Flow rates depend upon whether thin-walled tubing is used, which it must be because infusion is a problem. Furthermore, you need to raise the bottle on either an IV pole or extension pole so that you can obtain additional flow. Getting 50 mL/min or more flow by using well-designed irrigating instruments and elevating the irrigation bottle go a long way in stabilizing the chamber. There is already equipment available that can put positive pressure on the system that can both maintain the IOP and see that we have the additional flow necessary. Such systems in the future could surpass gravity flow with present-day coaxial equipment. Flow issues alone certainly are neither going to make or break the differences between these two approaches.
The equipment needed to try microphaco is truly minimal. Certainly with phaco chop, buying an irrigating chopper, which is available at minimal expense, and then using a bare phaco needle with regular equipment is a very easy way to get started. I am encouraged by the number of individuals who have become interested and expressed their enthusiasm in bimanual phaco. I do not know where this is all going, so I feel that it is a mistake to try to predict what the future may bring. I remember a lot of experts 25 years ago predicting that phacoemulsification was just a fad, and times have shown that they were dead wrong. Microphaco may not be important in 25 years, but then it is possible that coaxial phaco will not be, either. All I can ask is, keep an open mind, and may the superior procedure win in the end.
Randall J. Olson, MDSalt Lake City, Utah
