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Femtosecond lasers represent a paradigm shift in modern cataract surgery
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Phacoemulsification with implantation of an IOL is a safe and effective standard ocular intervention in cataract surgery and one of the most frequently performed ophthalmic procedures. In recent years, the new microincisional, coaxial and bimanual phacoemulsification techniques together with new IOL designs have made cataract surgery more predictable and accurate, and able to equal the results of refractive procedures. Modern cataract surgery with premium and advanced technology IOLs has also raised the expectations of patients, who can now aim at spectacle independence. To achieve this goal, a perfect and standardized surgery is required.
Just a few years ago, femtosecond lasers stepped into cataract surgery. They provide consistent surgical results in three crucial steps of the procedure: corneal wound creation, central continuous curvilinear capsulorrhexis (CCC) and pre-fragmentation of the crystalline lens. Femtosecond laser technology also offers a solution for preoperative corneal astigmatism. Arcuate keratotomies of the desired depth and length can be performed in the peripheral cornea. New femtosecond laser platforms can also be used simultaneously for cataract and corneal refractive surgery.
I performed the first worldwide femtosecond cataract surgery procedure in August 2008. The alpha-machine had arrived just a couple of days earlier. Previously, a great amount of time was spent doing all the necessary paperwork for official authorizations and drafting a specific patient consent form. By August, everything was ready for the start of a brand-new procedure in ophthalmology. From the very first moment, I felt I was dealing with something new and revolutionary that could make a real difference for both ophthalmologists and patients. It was not something that would replace good surgeons, but something that could help good surgeons be even better. I also felt that the method would be debated for a long time.
The first step was central CCC. The alpha-model had no inbuilt OCT to show with micrometer precision where we were within the eye. Measurements had to be worked out before surgery using ultrasound (A- and B-scan), Lenstar (Haag-Streit) and Pentacam (Oculus) technology. Extreme caution was needed because the patient interface, which slightly flattened the eye, could modify all parameters.
The next step was lens fragmentation and liquefaction. We tried the cylindrical (concentric) pattern of liquefaction first and the cross pattern fragmentation later. The cross pattern fragmentation lines helped to chop the cataractous lens with a special thin, sharp edge chopper. A dedicated chopper was later made available by ASICO.
The last step was corneal wound creation. I thought at first that it was going to be the easiest part of femtosecond laser-assisted cataract surgery because femtosecond lasers were used before for corneal lamellar surgery. On the contrary, the wound came out more central than expected. The solution came from a new patient interface and a special soft contact lens that was inserted between the patient eye and the curved patient interface. In this way, the cornea was not applanated, there were no folds, and a free-floating capsulotomy was achieved in 97% to 98% of the cases.
The LenSx team always listened to our observations and assisted us during our early surgical sessions. Dedication, sound software and hardware knowledge, good dexterity, surgical imagination, listening, performing, continuous evaluation, teamwork and team thinking were key to our success and something we learned and consolidated together during this long-term project.
A number of reports published in peer-reviewed journals show that the use of the femtosecond laser in cataract surgery allows for a more reproducible and properly sized and centered central CCC. This results in a better overlap between the capsulorrhexis and the IOL, enhancing IOL centration and stability. As a consequence, predictability of postoperative refraction and quality of vision is optimized. To ensure IOL prediction accuracy, the capsulorrhexis should be round, central and smaller than the IOL optic.
Optimal wound creation and geometry result in self-sealing corneal wounds, less induced postoperative astigmatism and fewer higher-order aberrations. Corneal wounds may be customized in number, size and location. Preoperative corneal astigmatism is also treatable and titratable by the new technology.
What does the future hold? New technologies always take time to be accepted by the public, but patients tend to quickly and well accept laser procedures.
I foresee a femtosecond laser that can switch from corneal to lens applications and maybe to other treatment modalities involving the sclera and the vitreous. Future machines should have an inbuilt phacoemulsification platform, so that patients do not have to be transported from one operating theater to another. Price should also be lowered. A multiple-use piece of equipment with femtosecond technology is bound to gain a primary role in the armamentarium of ophthalmologists in the near future.
- For more information:
- Zoltan Z. Nagy, MD, PhD, DSc, can be reached at can be reached at Semmelweis University, Maria u. 39, H-1085 Budapest, Hungary; email: zoltan.nagy100@gmail.com.
Disclosure: Nagy reports he is a consultant to Alcon Europe and Alcon/LenSx.