The FDA's recent approval of presbyopia-correcting IOLs has increased patients' demand for refractive lens exchange. Compared with individuals undergoing cataract surgery, these patients tend to be younger and more active, to possess higher disposable incomes, and often to have higher levels of education and more questions. Because the procedure is elective, the expectations of patients undergoing refractive lens exchange are higher. Avoiding complications and optimizing their visual outcomes are therefore top priorities.
Lens removal with the Aqualase Liquefaction Device (Alcon Laboratories, Inc., Fort Worth, TX) is safer than with ultrasound, and safety is a key component of successful refractive lens exchange procedures. For this reason, I use Aqualase for all such cases.
Aqualase is gentler to the eye than ultrasound in several respects. It employs energetic pulses of warmed fluid deflected from the phaco tip to impact the lens, and the device allows the surgeon to aspirate softened nuclear material safely and efficiently. The pulses of fluid emerge from a smooth, rounded polymer tip that is gentler to the capsule than a metal tip. With the polymer tip, surgeons are able to aspirate safely along the posterior capsule and within the capsular bag.
Aqualase is probably equally efficient as phacoemulsification on moderately dense cataracts, but, in my opinion, it is more efficient and safer than ultrasound for lens-based refractive surgery. This device uses little energy, and surgeons work almost entirely within the capsular bag and away from the cornea. They may go more deeply into the capsular bag than with ultrasound. As a result, corneas are remarkably clear postoperatively, and patients may reasonably expect to recover their vision rapidly.
The surgeon cannot simply remove with I/A the lens of a 55-year-old refractive lens exchange patient, because it has become rigid with age. In these cases, the minimal energy needed with AquaLase is an advantage. With ultrasound, the phaco tip is somewhat cumbersome within the confines of the capsule and is more likely to cause a capsular break if it contacts the capsule during times of high vacuum and aspiration.
Another benefit of Aqualase is the absence of thermal issues, a potential problem in eyes with lenses of medium density. There is no vibration of the tip to create friction in the incision, as occurs with ultrasound. The Microsmooth Irrigation Sleeve that comes with the Infiniti Vision System (Alcon Laboratories, Inc.) reduces friction within the incision, thus increasing surgical control by providing easy entry into the wound, more freedom of movement within the incision, and less mechanically induced movement of the eye as the tip shifts in the incision.
It is naïve to presume that it is easier to remove clear versus cataractous lenses. These procedures present the same risks. The Aqualase Liquefaction Device and the Infiniti's fluidic design ensure a stable anterior chamber during lens removal and thus reduce the likelihood of complications to the posterior capsule or the cornea.
There is a learning curve, although short, with the Aqualase Liquefaction Device. Additionally, it has a higher cost compared with ultrasound, but that can be recovered as part of the additional fees that surgeons can charge refractive patients.
Aqualase is less effective for dense nuclei and is only capable of efficiently liquefying cataracts of up to grade 3+ in combination with prechopping. I find ultrasound to be a better choice for denser cataracts.
I begin surgery in the same fashion as for ultrasound phacoemulsification. I use a 1-mm diamond knife to create the sideport incision and then instill Viscoat (Alcon Laboratories, Inc.). Next, I make a 3-mm groove at the posterior margin of the cornea, and I enter the anterior chamber with a trifacet diamond or metal keratome. After performing the capsulorhexis with a Utrata forceps, I perform cortical cleaving hydrodissection to ensure that the nucleus and cortical attachments are freed.
In young patients with soft nuclei, I pass a Bechert nucleus rotator through the sideport incision and insert the Aqualase tip. The lens can usually be safely and efficiently removed with power levels of 20% or less, aspiration of 40mL/min, and a vacuum level of 200mmHg. All flow and manipulation occur within the confines of the capsular bag. Cortical cleanup is usually minimal, and I polish the capsule with an angled, silicone I/A tip.
For nuclei that are somewhat firm, I routinely use the Salvitti Akahoshi prechopper (Duckworth & Kent USA, St. Louis, MO), which greatly enhances the speed and efficiency of nuclear removal. Predividing the nucleus allows me to use quadrant-removal settings immediately and to avoid the slow, deliberate delamination necessary to success with a bimanual cracking or divide-and-conquer approach. In addition, prechopping allows me to determine in advance if Aqualase will efficiently liquefy and remove a cataract (those so hard that I cannot prechop the posterior plate are often more efficiently removed with ultrasound). I use a rise time of 3, a vacuum level of 400mmHg, and an aspiration flow rate of 45mL/min. Although they are more aggressive than some of my colleagues', I find these settings to be safe and efficient. Nevertheless, I recommend caution and care when developing personal settings.
Aqualase offers ophthalmologists an especially gentle means of removing the lens. Currently, the technology's design limits the surgeon's access to all aspects of the posterior capsule. Future designs of the device, however, may prove useful for power-washing the capsular recesses and removing the residual capsular epithelium that is responsible for posterior capsular opacification.
Robert P. Lehmann, MD, is Clinical Associate Professor of Ophthalmology at Baylor College of Medicine in Houston, and he is in private practice in Nacogdoches, Texas. Dr. Lehmann is a consultant to Alcon Laboratories, Inc., but states that he holds no financial interest in the products mentioned herein. Dr. Lehmann may be reached at (936) 569-8278; firstname.lastname@example.org.