Why Laser Cataract Surgery?
Phacoemulsification cataract surgery has been around since invented by Charles Kelman, MD in 1967. This technology pioneered the way to small incision surgery that has made cataract surgery one of the safest and most successful procedures in medicine today. Although phacoemulsification is considered to be the current state of the art cataract removal technique, many steps in the cataract procedure are still performed manually with either a surgical blade, a bent needle or forceps. Laser cataract surgery with the femtosecond laser can now perform these steps adding a greater amount of precision and improved visual outcome to the entire cataract procedure.
In addition to using the laser to create a stair-stepped, self sealing incision to begin the procedure, an opening in the thin membrane bag-like structure that surrounds the natural lens can now be made with the laser. This step, the capsulorhexis, is one of the most delicate steps in cataract surgery and is critical to the safety and efficacy of the procedure. In fact, your replacement Intra-Ocular Lens (IOL) is placed through the capsulorhexis into the membrane, so it is critical to a good refractive outcome.
The capsulorhexis also provides your surgeon with an opening to begin the removal of the cataract. Once the cataract is removed, the remaining capsular bag serves as a platform to hold the IOL. The round capsulorhexis is usually about 5 millimeters in diameter and will hold a 6 millimeter or larger IOL. If the capsulorhexis is not made uniformly it may cause the IOL to tilt or move as the capsular bag contracts around the IOL during the healing process. If the capsulorhexis is torn during the manual process, it could prevent the insertion of certain types of IOLs, thus compromising the desired outcome.
During clinical studies of the LenSx laser, 120 eyes were studied with 60 eyes having a manual capsulorhexis made with a bent or shaped needle and 60 having the capsulorhexis performed by the femtosecond laser. The study found that the laser achieved accuracy of + or – 0.25 millimeters in diameter on all 60 procedures while only 10% of the manual capsulorhexis achieved a similar result and in the manual group the error was a much as 1.6 millimeters. The consistently precise capsulorhexis contribute to better lens positioning and therefore more predictable visual outcomes.
One of the advantages of laser cataract surgery is the way it prepares the eye for the lens implant. This shows a beautifully centered and positioned Tecnis® Multifocal IOL in a patient the day after laser cataract surgery. One can actually see the multiple focal rings on the lens.
In traditional cataract surgery, once the capsulorhexis is made manually, the lens has to be separated from the surrounding capsular bag and chopped into pieces with the ultrasonic power of the phacoemulsification instrument. Certain complications could be induced during this step such as rupturing the posterior of the capsular bag and causing traumatic injury to the delicate zonular fibers that hold the capsular bag in place and help the natural lens change its shape. In order for the new technology multifocal and accommodating IOLs to function at peak performance, the integrity of the zonular fibers must not be compromised.
In order to prevent injury to the zonular fibers, the femtosecond laser can be used to gently break apart or even liquefy the cataractous lens. Surgeons can then choose to use the phacoemulsification instrument to remove the liquefied cataract at a much lower power and in less time or they may even be able to vacuum it out using a simple aspiration instrument with no ultrasonic power at all.
Again, clinical studies of the LenSx laser showed significantly reduced ultrasonic power was needed to remove the lens when it was liquefied with the femtosecond laser. It also demonstrated that the lens could be sufficiently liquefied by the laser to allow it to be aspirated without the use of ultrasound.