Laser cataract surgery, something that patients assume we have been performing regularly for years, has now become reality with the advent of femtosecond lasers designed specifically for this purpose. It is interesting to see how the paradigm has completely changed from approximately 8 years ago, when laser flap creation in LASIK was considered to have little chance of being accepted because of the cost and unnecessary level of sophistication involved. At that time, there was really only one contender in the arena of femtosecond lasers for refractive surgery. Now, the introduction of laser cataract surgery is accompanied by greater enthusiasm, with technologies from several manufacturers either in place or in the pipeline.
The Victus femtosecond laser (Figure 1) received the Conformité Européenne Mark following the announcement of a joint venture arrangement between Bausch + Lomb and Technolas Perfect Vision. The laser is approved for the performance of LASIK flap, astigmatic keratotomy (AK), Intracor, capsulotomy, and lens fragmentation procedures in countries in the European Economic Area. It is the only platform that is capable of both refractive and cataract applications, according to the manufacturer; corneal therapeutic applications such as corneal transplantation with geometric trephination are also possible using the Victus.
This solid-state, 1,028-nm femtosecond laser operates at 160 kHz. Incorporation of optical coherence tomography (OCT) in laser cataract surgery has led to an improvement in surgical precision. Real-time, high-resolution OCT is used to visualize the anterior segment, ensuring and verifying the performance of precise surgery as laser fragmentation occurs (Figure 2). Although it is not yet possible to use the real-time OCT in flap creation and corneal therapeutics, this feature would help accurately verify flap depths and intrastromal corneal tunnel depths in advance of laser delivery.
The Victus laser is equipped with a high-resolution video microscope, but an external microscope can be added if desired. The laser interfaces with the eye using a suction ring and a curved, intelligent-sensor interface (Figure 3), and sensors are used to ensure that vacuum causes little (if any) corneal deformation.
REFRACTIVE SURGERY OPTIONS
The Victus can be used to perform LASIK and as a standalone device to correct astigmatism and presbyopia (Figure 4). LASIK flaps at user-defined depth, diameter, and sidecut angle can be created with the laser positioned alongside an excimer laser. Astigmatism can be corrected with AK or limbal relaxing incisions (LRIs) with user-defined angles, diameters, and depths, and these can be made subepithelial or sub-Bowman layer. The Victus can also perform Intracor, a presbyopia treatment consisting of a series of intrastromal cylindrical cuts surrounding the visual axis that leads to slight elevation of the central cornea, an increase in asphericity, and an improvement in depth of focus and visual quality.
Capsulotomy and lens fragmentation are the most significant elements of laser cataract surgery. In more than 500 cases completed to date with the Victus at various surgical centers, capsulotomy has been performed without any adverse events. Femtosecond-assisted lens fragmentation is an area that has been evolving, and a variety of patterns are possible depending on lens density, including ring cuts, radial cuts, and a combination cut that includes a sectoral quadrant cut (Figure 5). The quadrant cut is useful in hard cataracts, as it allows rapid removal of the initial quadrant, making room for dismantling of the remaining lens. Reduction of phaco times has been demonstrated using femtosecond lens fragmentation (personal communication, Reddy et al, Hyderabad, India).
Corneal incisions such as geometric-shaped tunnels can be performed at the same time as capsulotomy and lens fragmentation. As noted in the previous section, the dimensions of LRIs and AK incisions can be personalized to the cornea. The use of sub-Bowman (50 to 60 μm under the surface) LRIs and AK incisions may help to ensure wound and astigmatic stability, and nomograms for these types of incisions will undoubtedly be developed.
In less than 30 seconds, the Victus laser can create paracenteses and tunnel incisions, correct astigmatism, and perform capsulotomy and lens fragmentation with an exceptional level of accuracy. In time, as surgeons get used to docking and real-time OCT, surgical efficiency is expected to improve significantly.
In corneal transplantation surgery, the use of geometric incisions such as the mushroom (regular and modified) and tongue-and-groove (top hat, zig-zag, and zig square) have been found to increase wound stability and decrease healing time.1,2 The Victus is also capable of performing decahedral (10-sided) trephination on donor and host, which can help to ensure good graft centration.
These geometric incisions can be used to perform penetrating keratoplasty and deep anterior lamellar keratoplasty. Future use of real-time, high-resolution OCT in corneal surgery may pave the way for highly accurate tectonic procedures such as wedge resections and transplants to improve corneal shape.
The inclusion of refractive, cataract, and therapeutic applications in one laser platform has considerable advantages. From an economic standpoint, there is no need to have multiple lasers with multiple service fees and vendor relationships. For individual surgeons or small group practices that have had a femtosecond laser on their wish list, with the larger catalogue of procedures that can be achieved a viable business case for acquisition can be made. Additionally, there is no requirement for increased surgical space, and a new era of ambulatory ophthalmic surgery is now possible through minimal adaptation of existing practice facilities and increasing use of disposable instrumentation.
Other advantages of the Victus include its real-time OCT, which can be used to improve accuracy and safety for various cataract surgery procedures. In LASIK, OCT can be used to confirm flap depth and residual bed pachymetry.
The ability to do so much on one platform paves the way for considerable innovation, and there is no telling what suite of new applications will be available through use of this all-around anterior segment workstation.
- The Victus is capable of cataract, refractive, and therapeutic applications.
- Real-time, high-resolution OCT can be used to improve accuracy and safety in cataract surgery.
Sheraz M. Daya, MD, FACP, FACS, FRCS(Ed), FRCOphth, is Director and Consultant of Centre for Sight, East Grinstead, United Kingdom. Dr. Daya is a Co-Chief Medical Editor of CRST Europe. He states that he is a consultant to Bausch + Lomb. He may be reached at e-mail: email@example.com.
- Bahar I, Kaiserman I, McAllum P, Rootman D.Femtosecond laser-assisted penetrating keratoplasty:stability evaluation of different wound configurations.Cornea.2008;27(2):209-211.
- Farid M, Steinert RF, Gaster RN, Chamberlain W, Lin A.Comparison of penetrating keratoplasty performed with a femtosecond laser zig-zag incision versus conventional blade trephination.Ophthalmology.2009;116(9):1638-1643.