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Up Front | May 2005

Assessing Current Laser Platforms

Surgeons evaluate the pros and cons of the available systems

Bausch & Lomb Technolas 217/Zyoptix System

Over the past 13 years, I have used all of the excimer laser platforms available in the US. I considered all laser options when I opened my laser center, and the variety of excellent choices made the decision challenging. Overall, I felt that my patients achieved the best results, the quickest recovery, and the fewest side effects with the Technolas 217z Zyoptix System for Personalized Vision Correction (Bausch & Lomb, Rochester, NY) (Figure 1). I prefer its small scanning-spot platform for accuracy, and its blended treatment zones, which are the largest in the industry, minimize nighttime vision problems.

Six months ago, my main complaints with the Zyoptix system were related to cumbersome data acquisition and processing, excessive laser pulses with lengthy treatment times, overcorrections, and unpredictability. My colleagues and I were performing customized treatments for only approximately 20% of our cases. However, we recently received the 2.38 software upgrade for the Zyoptix system and now average closer to 40% customized treatments. This upgrade incorporates enhancements for both the Zywave wavefront data capture as well as for the laser algorithm. To the company's credit, its engineers listened to surgeons' complaints when improving the Zyoptix system. My technicians love its greatly simplified data capture and conversion to treatment files. That fewer patients require dilation for wavefront capture has enhanced accuracy and made clinical flow more efficient. In the laser suite, our treatment times are shortening with dramatically reduced treatment pulses, by approximately 40% in some cases. So far, this has enhanced the accuracy of our outcomes.


No laser system is perfect. Although the capturing step has improved with Bausch & Lomb's new software, many patients still have to be dilated in order to capture their wavefront data. For Zywave-treatment data capture, the pupil has to be at least 6mm in diameter so that higher-order aberrations can be treated in a large enough critical zone. The previous illuminated fixation target has been replaced by a lower illumination target. It was changed from a distant landscape target to a Maltese cross, which not only allows capture of data in the undilated state, but also promotes more accurate refractions by better controlling accommodation. With the new software, most surgeons have to dilate between 20% and 25% of their patients. Once the dilating drop is administered, it is difficult to know the rate and symmetry at which individuals' pupils will dilate. We strive to capture data while the pupil is 6.5mm, but some pupils will be 7 or 8mm if they dilate very quickly. This variability increases the potential of capturing extraneous data and heightens the risk of overcorrection. The inability to capture without dilation also prohibits same-day treatments, because pupils cannot be dilated for the surgery.

With all lasers, accurate nomograms are essential to enhancing outcomes. Bausch & Lomb asks surgeons to send their Zyoptix data to the company for analysis by scientists in Munich, Germany, who in turn produce a recommended nomogram adjustment for the spherical component. I have not found their recommendations to be as accurate as desired. With the new software, accuracy has greatly improved, but my staff and I are fine-tuning our nomogram once again.

One of my most significant complaints is that the Zyoptix platform is not approved for hyperopic customized wavefront treatments or mixed astigmatism in either standard or customized procedures. At my practice, we have been impressed with the excellent results of Planoscan hyperopic LASIK (Bausch & Lomb), but it would be nice to have the option to perform customized hyperopic and mixed treatments, especially in complicated cases such as retreatments. Along those lines, we have also found the Zywave data capture unpredictable in surgically altered corneas.

Unfortunately, surgeons cannot achieve monovision with any of the current wavefront-guided excimer laser systems. Most presbyopic LASIK patients in my practice desire “blended vision” or a slight bit of monovision. The Zyoptix system will allow for a maximum of 25% sphere offset, up to 0.75D at most. This does not allow for enough residual myopia for reading in most cases. Presently, presbyopic patients are opting for Planoscan or standard laser treatment in their nondominant reading eye and customized wavefront treatment in their dominant eye. This is frustrating if the patient has significant higher-order aberrations in his nondominant eye. The system should allow the surgeon to select the target.

A minor inconvenience is that the Zyoptix platform provides single-use treatment cards. The lasers' operator must calibrate the laser and perform a beam alignment and fluence test on the laser between bilateral treatments. The patient is forced to rise from the table and sit in a chair adjacent to the laser between ablations. This not only wastes valuable time in the laser suite, but it adds to the patient's apprehension as he sits idle and watches the laser being tested. Bausch & Lomb has indicated that it will soon debut a multitreatment card that will eliminate that step and allow for seamless bilateral treatments.

Finally, the Technolas 217z laser consumes more tissue than other platforms. Although this issue has also improved dramatically with the new software, it is still a concern. The large blend zone is nice, but I feel that some changes could be made in the application of peripheral pulses to minimize tissue consumption. However, this issue has not precluded me from treating patients whose corneas are too thin for LASIK. For these eyes, I will perform advanced surface ablation or implant a phakic lens such as the Verisyse IOL (Advanced Medical Optics, Inc., Santa Ana, CA). Overall, I have been pleased with the outcomes from the Zyoptix system but look forward to the enhanced ease of use and predictability that comes with the continued refinement of all new technology.

Wavelight's Allegretto Wave

In my hands, refractive surgery with the Allegretto Wave excimer laser (Wavelight Laser Technologie AG, Erlangen, Germany) has consistently produced quality-of-vision outcomes better than what patients achieved preoperatively with their glasses or contact lenses. I have performed more than 2,000 treatments with this laser, which I acquired in January 2004 (Figure 2). My patients rarely report glare or halos postoperatively, no matter what their pupil size, because this laser's wavefront-optimized profile addresses spherical aberrations. The system's phenomenal eye tracker monitors the eye's fine saccadic movements to provide a more precise and centered ablation.

Although I am delighted with the predictable and consistent outcomes of this 200-Hz laser, I would like to see a few improvements incorporated in future platforms. I would prefer a brighter fixation light, because patients can become anxious when they are unable to fixate on it. In addition, the current platform's direct illumination makes it difficult for me to visualize the pupil in patients with incredibly dark eyes. Regarding ergonomics, the Iris Registration satellites used to illuminate the eye during surgery can become obstructed on patients with larger upper frames and thus prevent my moving the slit lamp into and out of place. The slit lamp is a wonderful intraoperative tool that allows me to create and examine the corneal flap. In addition, it would be nice if the bed could move faster. Lastly, it would also be useful to have a split screen on the monitor so that I could see the eye-tracking image and the microscope's view at the same time.


The pros of the laser certainly outweigh the minor ergonomic and mechanical issues I have described. My enhancement rate with the Allegretto Wave is only approximately 1%, a priceless benefit to my practice in terms of reducing technician time, chair time, card costs, and the loss of potential referrals. My outcomes and patients' satisfaction are even better than what I achieved with wavefront-guided technology.

Nidek EC-5000

I have been using the EC-5000 laser platform (Nidek, Inc., Fremont, CA) (Figure 3) for the past 5 years with superb, reproducible surgical outcomes. I underwent LASIK on my own eyes with the EC-5000 more than 8 years ago, and my UCVA is still 20/15. I have shown that conventional EC-5000 treatments do not significantly increase higher-order aberrations and, in fact, may decrease certain higher-order aberrations.1 Recently, I upgraded one of my EC-5000s to include the Windows program, the torsional error detector, and the 200-Hz eye tracker (Figure 4). In addition to the two EC-5000 lasers that I have, I also own two Ladarvision 4000 excimer lasers with Customcornea (Alcon Laboratories, Inc., Fort Worth, TX) and a Star S4 laser with Customvue (Visx, Incorporated, Santa Clara, CA). Although the visual outcomes are no better, the advantage that the Ladarvision and Star S4 lasers have over the EC-5000 is that they are approved for hyperopic and wavefront-driven treatments.

Wavefront-driven treatments are performed on approximately half of the eyes on which I operate, a percentage that will increase as the range of approval for customized treatments expands and as wavefront technologies improve. I am particularly excited about the Navex platform (Nidek, Inc.), which utilizes data from 1,440 time-based aberrometry points as well as 6,840 points of placido-disc topography from the Nidek OPD Scan (Nidek, Inc.) (Figure 5) to perform truly customized ablations with three different software programs. These programs include the Customized Aspheric Transition Zone program, the Optical Path Difference–Customized Aspheric Transition Zone program, and the Optimized Prolate Ablation program. Each of these software programs allows for true customization of the procedure through a program known as Final Fit by giving the surgeon the ability to manipulate the optical and treatment zones, the targeted refraction, the targeted final keratometry reading, the total depth of ablation, and the amount of irregularity treated. It also has the ability to simulate the final postoperative topography (Figure 6). I am one of five US investigators for the Navex FDA study, which we expect to start in the next few months. I currently have this system in my office and receive inquiries from US surgeons on a weekly basis regarding the system's unique ability to re-treat patients who have had bad outcomes with other lasers due to irregular astigmatism.


The Nidek EC-5000 laser has the best ergonomics of any laser that I own. A wide gap between the eye and the underside of the laser head allows easy access for the keratome. The floating joystick and the optional foot pedal allow the surgeon to easily center, focus, and zoom the laser with either his hands or feet. The scanning-slit laser system performs quick treatments, even in high myopia. The three-dimensional reticule of the laser makes centration of the laser on the eye in the x, y, and z axes easier than with any laser I have ever used. It is readily apparent when the treatment will be off-center, due to parallax, thus allowing for seamless intraoperative adjustments to ensure centration. Also, patients more easily see the bright fixation light on the EC-5000 than on any of my other lasers.

The slit function of the microscope makes the view from the EC-5000 the best in the business. By utilizing high magnification and the slit beams, subflap debris and subtle wrinkling of the flap are easily seen and addressed without moving the patient out to a separate slit lamp. The 200-Hz eye tracker is accurate and easy to use. Unlike with the Ladarvision's tracker, moving instruments under the EC-5000 laser does not break tracking. Fixating the tracker on the pupil is easier and more time efficient than with either of the other lasers. The torsion error detector was the first of its kind on the market and easily detects axial rotation of the eye before and during the treatment. The upgraded Windows program is fast and easy to use. That multiple treatments may be uploaded prior to the surgery date allows for faster surgical turnover. The lens guard on the laser head prevents any spray from getting on the final laser optic during flap creation. If this lens guard is not removed prior to laser ablation, the laser automatically will not fire and will remind the surgeon to move it. Lastly, the unattached Dextra operating chair that comes with the EC-5000 allows significant versatility. Because the chair can be pulled away from the laser, I will use it for implanting IOLs and for refractive lensectomy cases in my in-office surgery suite.


There are only two minor ergonomic downsides to the EC-5000. The first is the lack of a plume evacuator. Because of the scanning-slit delivery system, the laser plume does not affect the oncoming laser pulse, and thus there is no potential for altered outcomes or central islands, despite the lack of an evacuator. The surgeon, however, must use a charcoal-filtering mask and/or hold his breath during the treatment to avoid “laser lung.” Also, patients comment about a burning smell more frequently than with other lasers. Although companies other than Nidek manufacture plume evacuators, these tend to be bulky and difficult to use.

The other ergonomic downside of the EC-5000 is the slow speed of the 1-mm spot used in customized ablation. Because this spot is generated from the scanning slit, spots can only be applied in one meridian at a time. The slow treatment is compensated for, in part, by the multipoint ablation, which allows a total of six 1-mm spots to be applied in the same meridian at once.


Other than these ergonomic issues, the main downside of the EC-5000 excimer laser platform is its limited range of approval in the US, specifically regarding hyperopia. Ongoing FDA studies of hyperopia with the laser have shown encouraging results.

Additionally, wavefront-driven treatments with the EC-5000 are not available in the US. Although I have demonstrated that the safety and visual outcomes of wavefront-guided lasers are no better than those of conventional Nidek treatments,2 customized ablations may have some advantages in terms of night vision symptoms and marketing. An FDA study of Customized Aspheric Transition Zone corneal-aberrometry–based treatments of both primary and retreatment eyes is planned for the near future, and the program has achieved good outcomes internationally.

Alcon Ladarvision

My staff and I have been very pleased with the Ladarvision 4000 excimer laser with the Customcornea wavefront-guided platform. When we were comparing different laser platforms, what really made the Ladarvision system stand out was the eye tracker's ability to compensate for eye movements in comparison to systems that utilize video trackers. Sampling eye movement 4,000 times per second allows true active tracking and the precise registration essential to customized treatments.


My recommendations for changes or improvements to the Ladarvision 4000 fall into two categories: (1) minor issues with ergonomics and equipment that can be easily changed and (2) new capabilities that no laser has.

One of the biggest ergonomic differences between the Ladarvision 4000 and other systems is the laser delivery post's coming up directly to the microscope. Although this design allows the system to be fairly compact, because the lasing chamber and all of the optics are in the bed under the patient, the surgeon must reach around the post to operate. I initially kept contaminating my gloves on the post, but this no longer happens and has ceased to be an issue.

Three changes I would like to see on the platform relate to peripheral items. The first is the distance between the bed and the microscope (Figure 7). With larger patients, tilting their chin closer to their chest permits proper exposure such that the edge of their cornea is not hidden by their lower lid. Placing a wedge pillow under the crown of their head tilts their chin down but requires more space. The bed on the laser does not go quite low enough to accommodate the very largest patients.

The second change is in regard to the placement of the “illumination” button right next to the “freeze” button on the monitor (Figure 7). This arrangement is not ideal, because the surgeon or staff could accidentally hit the “freeze” button and lose the centration photo.

Third, I would enjoy the Zeiss microscope (Carl Zeiss Meditec AG, Jena, Germany) even more if it were truly parfocal (Figure 8). When the magnification is adjusted, refocusing is necessary. Also, when the illumination is turned up intraoperatively, the screen brightens only momentarily. It is not always bright enough on the screen for me to discern the border between the pupil and a dark iris.


Alcon originally pointed out that pseudophakes cannot reliably be tracked with the Ladarvision 4000, because the tracker might confuse the edge of the lens implant with the edge of the pupil. Techniques have, however, been developed for successfully tracking pseudophakes. The method (developed by James Loden, MD, of Nashville, Tennessee) of initially tracking the 11-mm test circle so that the tracker subsequently tracks the pupil, has worked beautifully. Integrating this capability would be helpful.

The tracking system does not truly track cyclotorsion. I mark the conjunctiva at the 3- and 9-o'clock positions while the patient is sitting upright so that, despite torsion upon his reclining, everything is perfectly aligned for an astigmatic correction or a wavefront treatment. Occasionally, however, I notice intraoperative cyclotorsion, in which the orientation line is no longer perfectly aligned with the ink marks. Ideally, the system would be 100% accurate in tracking cyclotorsion. A customized ablation depends on exquisitely accurate placement.

First, hyperopic and hyperopic astigmatic wavefront-guided ablations reportedly are coming soon.

Second, integrating wavefront data with directly measured elevation data would allow for even more precise treatments and be helpful in identifying an aberration as corneal or not in origin, something surgeons currently have no accurate way to do. Attempts to calculate elevation from placido-derived curvature measurements are inherently flawed. Curvature (the rate of change of slope) is the second derivative of height. Taking a derivative involves the loss of a constant and therefore a loss of location information. This is why doubly integrating curvature information in order to retrieve elevation information does not specify whether a steep area is elevated or depressed. Assumptions that apply to healthy, unoperated corneas are not likely to be valid in the corneas that would benefit from such a customized treatment. The capability of using directly measured elevation data in combination with wavefront data would allow surgeons to avoid correcting noncorneal aberrations at the corneal plane (which is suboptimal optically, even if these aberrations are stable, and worse if they are evolving lenticular changes).

I use a PAR elevation topography system (PAR Technology, New Hartford, NY), which utilizes raster photogrammetry (projecting a grid of known geometry onto the cornea from one angle, then photographing it from another to provide directly measured elevation data over the entire cornea). PAR is not currently manufacturing these, but a group at Ohio State University is further improving the technology. I rely on this system and look forward to its newest version.

Third, the conventional Ladarvision 4000 ablation offers a treatment zone as large as 8mm (with a blend out to 10.5mm), which has allowed me to treat even patients with relatively large scotopic pupils, depending upon corneal thickness and the amount of correction needed. In patients whose pupils are large, it might be advantageous to perform wide-diameter Customcornea treatments. This is a theoretical consideration only; the customized treatment diameter of 6.5mm, with a blend out to 8.5mm, has been fine for my patients.

Fourth, I would like Customcornea to offer an available target offset larger than the current ±0.75D. Highly aberrated corneas, the customized treatment of which requires relatively large amounts of tissue to be removed, are susceptible to the induction of hyperopia.

Fifth, I often like to provide a patient with some degree of monovision, particularly if he is presbyopic or about to become so. One option would be a conventional algorithm that takes off more peripheral tissue (to avoid inducing spherical aberration by compensating for the cosine effect). Another would simply be a larger offset available for the customized treatments, perhaps +2.00D instead of ±0.75D In conclusion, I have been very pleased with my results with the Ladarvision 4000. I look forward to future advances as we strive to provide even better care for our patients.

Visx S4 Laser System

I have seen multiple iterations in the development of laser vision correction. I own the Star S4 Excimer Laser System, featuring the Customvue wavefront-guided platform, and have been operating with this laser for the past 5 years.

I have visited the manufacturing facilities of several laser companies to see how these expensive machines are assembled. Visx, Incorporated, has strong engineering and development. It evaluates and studies many different technologies in order to create its products. The company has successfully progressed from broad-beam to variable-spot technology.

The Star S4 laser is built well and rarely breaks (Figure 9). Refractive surgery is my livelihood. I cannot rely on a piece of equipment that is constantly in need of repairs, and the Star S4 platform has the best guts. The way the shutters and mirrors work and the actual mechanics of the machine are superior to those of the other available platforms.

Secondary Tracking System

I would like to be assured, from an industry standard, that Visx, Incorporated, has the most efficient tracking laser. Optimally, the eye-tracking system should be wedded to the fastest saccades of the eye and the speed of the treating laser; the match is excellent with the Visx platform. If the patient's eye begins to roll down and rotate, the beam is still tracking the pupil, but the eye has turned several degrees. As a result, the laser is hitting the surface of the eye obliquely. That can be a significant treatment issue, because the laser is traveling different distances, and energy is lost every millimeter the laser travels. There is a loss of power at the periphery, and the laser removes less tissue when it is deflected than it does when it hits straight on. We need a secondary system to track the position of the limbus to ensure that the entire limbus or cornea is perpendicular to the tracking beam. Ideally, the laser would move with the eye.

Global Stabilization

Stabilizing the globe so that surgeons know that it is perpendicular to the laser is perhaps more critical than we understand at this point. Keeping the eye perpendicular to the laser is necessary in order to prevent oblique treatments. Presently, this is still completely dependent on the surgeon. The tracking on the Star S4 platform is based on video and called pattern recognition technology. It takes the first picture of the eye perfectly aligned. Iris Registration (Visx, Incorporated) is based on this concept and addresses cyclotorsion. The next step will be a globe-stabilization tracker.

Interface Illumination
A pristine interface is critical. Visx, Incorporated, just received approval for its Customvue Slit Illuminator, the CV SL-1, which addresses this concern.
Splash Guard

In order to achieve optimal results, the fluence of the beam is an important consideration. The most common reason for a loss of homogeneity is the accumulation of salt spray or debris on the mirrors. I have discovered “hot spots” where this tends to occur. To combat this problem, my staff and I use a splash-guard device (Figure 10) that I developed with Gulden Ophthalmics (Elkins Park, PA). It is a piece of plexiglass and not FDA approved. I have asked Visx, Incorporated, to add an interlock so they have an official, moveable splash guard.


One of my biggest complaints with the Star S4 is with the physician's chair that comes with the system. It is not well engineered or well designed for its intended use. I never use it. Instead, I purchased an OR chair from Stryker (Kalamazoo, MI) that is much more high-tech and comfortable. Visx automated the patient's chair to move from left to right, and the interlock coordinates the chair and corresponding eye positioning. The chair has to be locked before the laser will fire, which is another great precaution. However, the quality of the patient's chair could be improved. It is time the company considered ergonomically designed, patient- and doctor-friendly elements.


Perhaps the company should develop a completely new platform that features a smaller, more compact machine. I strive to provide high-end service at my practice. I rely on the Star S4 laser and want it to look good. Patients do not know how well the machine is assembled or the quality of the parts, but visual presentation is important to establish their confidence, especially for elective procedures.

The Star S4 laser system is a reliable work horse that gives me consistent quality and minimal down time. The Visx technical staff is competent and almost immediately available. Although the service contract is quite expensive, the quick, efficient service makes it worthwhile.

Avery D. Alexander, MD, is Medical Director of the Alexander Eye Institute in Appleton, Wisconsin. He states that he holds no financial interest in any products or companies mentioned herein. Dr. Alexander may be reached at (920) 830-2020.
Timothy B. Cavanaugh, MD, was an Associate Professor at the University of Kansas, Kansas City, and is President and Medical Director of both Cavanaugh Eye Center and The Laser Vision Center of Kansas City in Overland Park, Kansas. He states that he holds no financial interest in any of the products or companies mentioned herein. Dr. Cavanaugh may be reached at (913) 897-9200; tbc@cavanaugheye.com.
Paul J. Dougherty, MD, is Clinical Instructor of Ophthalmology at Jules Stein Eye Institute, University of California at Los Angeles, and Medical Director of Dougherty Laser Vision Institute in Camarillo, California. He is an investigator for Nidek, Inc. Dr. Dougherty may be reached at (805) 987-5300; info@doughertylaservision.com.
Anita Nevyas-Wallace, MD, is Director of Refractive Surgery at Nevyas Eye Associates and the Delaware Valley Laser Surgery Institute in Bala Cynwyd, Pennsylvania. She states that she holds no financial interest in any of the products or companies mentioned herein. Dr. Nevyas-Wallace may be reached at (610) 668- 2777; anevyaswallace@comcast.net.
Steven B. Siepser, MD, FACS, is Medical Director of Siepser Laser Eyecare in King of Prussia, Pennsylvania. He has a working relationship with Gulden Ophthalmics. Dr. Siepser may be reached at (610) 296-3333; siepser@clear-sight.com.
1. Dougherty PJ. Effect of conventional LASIK on OPD-Measured higher-order aberrations. Paper presented at: The ASCRS/ASOA Symposium on Cataract, IOL and Refractive Surgery; May 1, 2004; San Diego, CA.
2. Dougherty PJ. Comparison of outcomes between the Nidek EC-5000, Alcon Customcornea and Visx Customvue laser systems. Paper presented at: The ASCRS/ASOA Symposium on Cataract, IOL and Refractive Surgery; April 18, 2005; Washington, DC.
For a downloadable pdf of this article, including Tables and Figures, click here.
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