- CHIEF MEDICAL EDITOR’S PAGE
- Live From the 2011 AAO Meeting
- Corneal Inlays for the Surgical Treatment of Presbyopia
- IOL Calculations After Refractive Surgery
- Dosing Antibiotic Drops: a Closer Analysis
- Corneal Applications for Anti-VEGF Agents
- Visual Function in Older Adults
- Careful Pterygium Surgery Speeds Healing and Reduces Recurrence
- New Procedures in Corneal Transplantation
- Topography-Guided Refractive Surgery
- Novel Procedure for Blepharitis
- Innovations in Cataract Surgery Are Aimed at Improving Patients’ Vision and Satisfaction
- Update on New Glaucoma Surgical Devices
- Surgical Options for the Back of the Eye
- Educate Patients With a Loaded iPad
- INDUSTRY NEWS AND INNOVATIONS
- One-Year Results Reported for the Infant Aphakia Treatment Study
Meeting patients’ expectations has always been an important component of ocular surgery. It is not always good enough to perform a technically flawless procedure if the patient’s final visual acuity does not allow him or her adequate function. The importance of quality of life is receiving growing recognition in the realm of surgery, especially cataract surgery.
Simply put, modern cataract patients want to see well after their procedure. Often, they expect to have a noticeable improvement on day 1 postoperatively. Cataract surgery itself has evolved tremendously since it was first performed, and that evolution has always been driven by innovations that push the boundaries of what is possible. With the introduction of femtosecond laser technology and an ever-increasing array of IOLs, I believe that cataract surgery is again undergoing a transformation for the better.
LASER REFRACTIVE CATARACT SURGERY
Versus Manual Techniques
To me, the use of a femtosecond laser represents a natural progression in cataract surgery. Just as phacoemulsification improved outcomes compared with extracapsular cataract extraction (and extracapsular techniques improved on intracapsular surgery), so, too, does a laser offer an opportunity to better meet patients’ expectations. In short, a femtosecond laser has the potential to improve the predictability of the capsulotomy, arcuate and cataract incisions, and the effective lens position as well as to reduce the amount of energy used inside the eye to fragment the lens.
With current technology, only about 45% of patients achieve within 0.50 D of their intended refraction after cataract surgery, 72% are within 1.00 D, and about 6% fall outside 2.00 D of the intended target.1 These are successful outcomes, and they represent an improvement over what patients typically achieved with older surgical techniques. Current results may fall short, however, of what modern cataract patients expect in part due to the success of femtosecond lasers in refractive surgery.
Importance of the Capsulorhexis
One way in which femtosecond lasers may help ophthalmologists meet patients’ expectations for postsurgical vision is that the technology can create a predictable and reproducible capsulorhexis. Whether the capsulorhexis is perfectly centered on axis is a crucial determinant of the effective lens position, which, in turn, will affect the performance of the IOL.2 For instance, a 0.5-mm deviation in the effective lens position will yield a refractive error of 1.00 D.3 In addition, studies have demonstrated that posterior capsular opacification may be associated with an insufficiently sized capsulorhexis.4
A decentered or irregularly shaped capsulorhexis can affect the suitability of placing a multifocal implant. In addition, capsular tears, although infrequent, increase the risk of vitreous loss and can make the cataract procedure more challenging. I would argue that, in essence, performing the capsulorhexis manually can take a premium procedure back to the level of the standard operation.
Early reports and presentations indicate that femtosecond laser technology improves surgeons’ ability to increase their odds of achieving the intended refractive outcome via a more precise capsulorhexis.5 In early studies with the LenSx Laser (Alcon Laboratories, Inc., Fort Worth, TX), surgeons achieved a capsulotomy within 0.25 mm of the intended accuracy in 100% of their cases performed with the platform.6 These results compared favorably with those of surgeries performed using manual techniques, for which only about 10% of cases in the study fell within the target noted earlier.
In addition to the capsulotomy, the LenSx platform is also approved for liquefaction and/or fragmentation of the lens and for the creation of corneal or astigmatic incisions. The FDA approved the LensAR Laser System (LensAR Inc., Orlando, FL) for use in creating the anterior capsulotomy and fragmentation of the lens. Although this platform is not currently approved for use in creating incisions, several presentations at the recent meetings have shown that it can perform this function.
Other companies are developing femtosecond laser cataract platforms specifically for fragmenting the lens and creating a capsulotomy and corneal incisions. They include OptiMedica (Santa Clara, CA; Catalys Precision Laser System) and Bausch + Lomb (Rochester, NY; formerly Technolas Perfect Vision; Victus). These devices have been studied in Europe but have not received FDA approval.
The femtosecond laser can be used for fragmenting the nucleus prior to extraction. In theory, this application should result in more efficient, safer surgery compared with manual removal of the lens. In a recent study involving the LenSx laser, the liquefaction of cataracts of 2+ density resulted in a 46% reduction in the phacoemulsification power required to perform the procedure and a 28% decrease in endothelial cell loss at the 1-month follow-up visit compared with patients undergoing a similar operation but with manual techniques (data on file with Alcon Laboratories, Inc.).6-8
A femtosecond laser can be combined with optical coherence tomography. Real-time imaging allows the surgeon to use femtosecond laser technology to create accurate, predictable, and reproducible corneal incisions and limbal relaxing incisions.
Femtosecond lasers can also be used to cut incisions intended for astigmatic correction, an important consideration given that a large portion of the cataract population has between 0.50 to 0.75 D of corneal astigmatism or more.5 If left uncorrected, astigmatic defocus can alter the performance of the implanted IOL and decrease the patient’s satisfaction. Unlike with classic limbal relaxing incisions cut with a manual knife, however, surgeons have the option of making intracorneal laser arcuate incisions at the time of cataract surgery and opening them only if needed during the postoperative healing period.
Innovations and improvements in IOL technology have expanded cataract surgeons’ armamentariums and continue to improve their ability to meet patients’ demands. A number of IOLs are either in the late stages of clinical development or are already available outside the United States and rumored to be moving toward domestic availability.
Already available to US surgeons is an expanded catalog of AcrySof IQ Toric IOLs (Alcon Laboratories Inc.) specifically for the correction of 3.75 to 6.00 D of astigmatism. This wider array of options means the surgeon can place the correction closer to the nodal point of the eye, which makes a significant difference in outcomes in terms of visual quantity and quality.
Another relatively recent innovation in cataract surgery that pertains to the use of toric lenses is the availability of the ORA System (WaveTec Vision, Aliso Viejo, CA). With this wavefront technology, a surgeon can intraoperatively verify placement of a toric lens along the axis or adjust its location as needed before finalizing the case. Even outside the context of astigmatism-correcting lenses, I believe that the ability to check the lens’ power intraoperatively against data from the IOLMaster (Carl Zeiss Meditec, Inc., Dublin, CA) and preoperative biometry is a real boon to surgeons.
Recent innovations in cataract surgery are improving the procedure’s outcomes and surgeons’ ability to meet patients’ rising expectations. This is an exciting time, as the field makes the leap into true refractive cataract surgery. As femtosecond laser platforms reach cataract surgeons’ practices, more information will become available on how best to use this technology.
Karl G. Stonecipher, MD, is the director of refractive surgery at TLC in Greensboro, North Carolina. He is a consultant to Abbott Medical Optics Inc.; Alcon Laboratories, Inc.; Bausch + Lomb; and Nidek, Inc. Dr. Stonecipher may be reached at (336) 288-8523; firstname.lastname@example.org.