Today, cataract surgery is the most frequently performed surgical intervention in ophthalmology, and it is becoming even more important due to the aging of the population. Phacoemulsification at present is the gold standard of cataract surgery, and the combination of premium IOLs, microincision surgery, and outpatient treatment can lead to rapid rehabilitation. High patient expectations increase pressure on surgeons to provide optimum treatment. Patients’ requests for perfect visual acuity without additional correction make modern cataract surgery similar to a refractive surgical treatment.
AT A GLANCE
• Immediate sequential bilateral LACS appears to be a promising application of femtosecond laser technology.
• Patients must be given additional informed consent before bilateral cataract treatment because visual acuity after bilateral lens fragmentation is temporarily markedly reduced.
• In the author’s series of 146 immediate sequential bilateral LACS cases, no contraindications or complications were observed.
Femtosecond lasers have added a new step in this process. The first laser-assisted cataract surgery (LACS) procedure was performed in 2008,1 and surgeons at the University Eye Clinic of the Paracelsus Medical University, where I practice, began performing LACS in October 2012. Since that time, we have gained a large amount of experience with the procedure, which I describe in this article.
We now use the Catalys femtosecond laser system (Abbott Medical Optics). In our university clinic, LACS can be offered to every patient without additional fees.
In the beginning, the laser system was placed inside the operating room (OR). Due to our high volume of patients, it became necessary to place the system outside the OR, in a separate room, allowing us to prepare patients for three ORs simultaneously. Precise logistics are essential to prevent delays in workflow. The laser pretreatment is done by one of 12 trained femtosecond laser operators.
From October 2012 to November 2015, we performed 2,891 LACS treatments. Of these cases, 2,774 (96%) were fully completed as planned using two to four of the LACS steps listed in the accompanying graphic, Features of LACS. There was a short learning curve, and most problems encountered initially have been solved.
One must differentiate between technical (n=13) and patient-related problems (n=104) during the learning curve. In the former category, temperature fluctuations inside the OR were the most frequent cause of laser treatment interruptions. In the latter, the leading cause of problems was rapid unexpected eye movement during laser treatment (n=83). These problems almost disappear with growing experience. Incomplete treatments were also related to narrow pupils and special anatomic situations such as extremely narrow palpebral fissures. The only contraindication for femtosecond laser treatment in our setting is a small nondilating pupil.
In the series reported here, we observed a rate of 99.7% perfectly and completely cut anterior capsules, floating in the anterior chamber at the time of surgery. Lens fragmentation was performed successfully in 97.1% of cases. Even when the lens is not completely fragmented, the laser pretreatment still leads to significant reduction of phacoemulsification energy use. As noted above, during lens fragmentation, the laser system creates a safety margin from the posterior capsule—a useful feature for surgeons.
To correct preoperative corneal astigmatism of 0.75 to 2.50 D, we performed nonpenetrating intrastromal arcuate keratotomy in 1,249 eyes. With the femtosecond laser, the precision and reproducibility of this technique is higher than with manually performed anterior penetrating stromal incisions. With aid of the laser, these corneal incisions can be customized for each surgeon and for different surgical techniques.
FEATURES OF LACS
Crucial steps of cataract surgery can be performed with a femtosecond laser using photodisruption induced by ultrashort laser pulses. During surgery, the steps of femtosecond laser treatment are guided by live intraoperative OCT images, allowing the surgeon to follow the progress of the treatment through real-time infrared video.
Step No. 1: Capsulotomy
Capsulorrhexis has always been considered a technically difficult step of cataract surgery, and, until the advent of LACS, it was performed manually. Using the laser, one can create a perfectly customized circular capsulotomy in less than 1.2 seconds. It has been postulated that patient safety is increased due to the high degree of precision and repeatability of the laser. The precision of circularity and the ability to place the center of the opening on the optical axis results in better centration and capsule-IOL overlap, as compared with manual capsulorrhexis. This supposedly leads to less anterior tilt of the implanted posterior chamber IOL.
Step No. 2: Lens fragmentation
Femtosecond lasers also offer multiple patterns for fragmentation of the lens nucleus. In our experience, lens fragmentation has shown good results in soft and medium-hard lenses. Additionally, this process creates a safety margin of 500 µm from the posterior capsule, resulting in a higher margin of error for the surgeon and fewer capsular ruptures.
Step No. 3: Arcuate corneal incisions (anterior, penetrating, or intrastromal)
Surgeons using the laser have options for cutting the cornea. Arcuate incisions can be performed to reduce postoperative astigmatism.
Step No. 4: Corneal incisions
The laser can also create the main and sideport incisions, although more research will be required before surgeons can finally deliver the highest level of precision with these functions.
At present, cataract surgery in patients with bilateral significant lens opacification is usually performed with at least 2 weeks between the two surgeries. For some indications, such as high myopia or refractive lens exchange, immediate sequential bilateral cataract surgery (ISBCS) is preferable. This approach can result in fast visual rehabilitation, and patients often choose this option at the surgeon’s recommendation.
The greatest concerns with ISBCS are postoperative endophthalmitis and refractive deviations due to errors of biometry. Studies have shown that, since the introduction of intracameral antibiotics at the end of surgery, the risk of the former in ISBCS is comparable with that in unilateral surgery. Likewise, advances in intraoperative measurements with OCT and highly reliable IOL power calculations have nearly eliminated the latter risk. Moreover, the advantages, such as reduced numbers of patient visits, prevention of anisometropia, and savings in health care and patient-related costs, must be considered.
Because of our excellent results with LACS, we have begun to perform immediate sequential bilateral LACS. So far, we have performed 146 of these cases—a total of 292 eyes treated. Of these eyes, 192 were refractive lens exchange (65.8%) and 100 were cataract procedures (34.2%).
As with single-eye LACS, the femtosecond laser system is placed outside the OR in a separate room to facilitate use by three surgeons in three ORs at the same time. Precise logistics are essential to prevent delays in workflow.
Patients must be given additional informed consent before treatment because visual acuity after bilateral lens fragmentation is temporarily markedly reduced. Otherwise, patients may express concerns between the laser treatment and the lens implantation portions of the procedure. Also, we prefer to patch both eyes postoperatively for about 1 hour, which can cause stress in some patients unless they are well informed beforehand.
In this series, we have not observed any contraindications for or complications of immediate sequential bilateral LACS, such as endopthalmitis or anisometropia.
Due to the high level of precision and increased safety of LACS, and the convenience and other benefits of immediate sequential bilateral surgery, this appears to be just the beginning of a promising application of femtosecond laser technology. n
1. Nagy Z, Takacs A, Filkorn T, et al. Initial clinical evaluation of an intraocular femtosecond laser in cataract surgery. J Refract Surg. 2009;25:1053-1060.
Günther Grabner, MD
• Professor and Director, University Eye Clinic, Paracelsus Medical University, Salzburg, Austria
• Financial disclosure: None acknowledged