Download Integrating Zyoptix into the Practice

COVER STORY
Zyoptix Performs Well
Without Nomograms
A contralateral eye study, coupled with the results of the FDA clinical trial
of Zyoptix, verifies the platform’s superior capabilities.
BY STEPHEN G. SLADE, MD, FACS
T
he FDA clinical trial of the Technolas 217z
Zyoptix System (Bausch & Lomb, Rochester, NY)
and a recent contralateral eye study comparing the Zyoptix system to the CustomVue
(Visx, Inc., Santa Clara, CA) both produced satisfactory
results in terms of efficacy ratios, statistically significant improvements in vision, high refractive predictability, and a maintained or improved contrast sensitivity, as well as patient satisfaction. A noteworthy
result of the contralateral study was that patients had
fewer higher-order aberrations postoperatively than
they did preoperatively.
NOMOGR AMS AND CONTR AST SENSITIVITY
Most Visx laser users incorporate a nomogram to
address the undercorrections obtained with the laser.
To create a nomogram, my colleagues and I studied
hundreds of CustomVue cases that we had previously
performed and spoke with several experienced Visx surgeons. Our nomogram worked so well that, when we
compared the results of eyes treated with the
CustomVue system and the nomogram to eyes treated
with the Zyoptix system, but no nomogram, the
CustomVue treatments produced better results. However, the CustomVue nomogram always called for
adding treatment, which increases the eye’s corneal
aberrations. Even with a nomogram adjustment, the
CustomVue platform did not perform as well as the
Zyoptix system overall, because induced aberrations
detract from the patient’s quality of vision and contrast
sensitivity.
The Zyoptix FDA study was the only one of a customized, wavefront-driven ablation technology that
demonstrated a clinically statistically significant increase
in contrast sensitivity under both photopic and mesopic illumination conditions. In both settings, approxi-
68 I CATARACT & REFRACTIVE SURGERY TODAY I AUGUST 2004
mately 75% of eyes experienced no change from preoperative levels, and approximately 24% achieved an improvement in contrast sensitivity from their preoperative values. Although we do not yet have the contrast
sensitivity data from the contralateral eye study, I presume it will show that, the more aberrations induced,
the greater the compromising of patients’ contrast sensitivity. The Zyoptix platform also demonstrated a trend
toward fewer induced lower-order aberrations when
compared with CustomVue.
ZYOPTIX FDA CLINICAL TRIAL
The FDA clinical trial was a prospective, multicenter,
bilateral trial of 340 eyes treated at three investigational
sites. Eyes in this study were corrected for both sphere
and cylinder, with no adjustments to the nomogram. All
of the study eyes were followed through 6 months, and
there were no retreatments.
CONTRALATERAL EYE STUDY
Stephen G. Slade, MD, FACS, conducted the contralateral
eye study, which was randomized, controlled, and masked.
It compared Bausch & Lomb’s (Rochester, NY) Technolas
217z Zyoptix System, a scanning-spot technology, versus
Visx Inc.’s (Santa Clara, CA) Star S4 for CustomVue, a broadbeam technology. Each of the enrolled 40 patients was randomized to receive treatment with the CustomVue laser in
one eye and with Zyoptix in his fellow eye. Phase I patients
underwent surgery without a nomogram for either laser. In
phase II, the investigators used a nomogram only with the
CustomVue laser. The patients’ demographics, including
sphere and cylinder, were tightly matched.
COVER STORY
REFR ACTIVE PREDICTABILITY
In the FDA trial, almost 75% of the eyes were within
0.50 D of their target refraction, and 94% were within
1.00 D of their target. These results demonstrate a very
high level of refractive predictability with the Zyoptix system. In terms of manifest subjective refraction spherical
equivalent data, there was excellent stability from 1 week
onwards.
Currently, we have the 1-month results of 50 eyes of
25 patients from the contralateral eye study. Regarding
traditional metrics and UCVA, the Zyoptix wavefront
system performed better. Patients’ BCVA and manifest
spherical equivalent results were fairly close between
the two systems, slightly better with Zyoptix. As for preversus postoperative higher-order aberrations, Zyoptix
did not induce significant amounts of spherical aberration, whereas CustomVue induced more than 0.10 D of
spherical aberration, which is a significant amount.
UP AND COMING
Bausch & Lomb is developing a bilateral treatment
card to further reduce treatment times. During the next
90 days, modified Zywave software (Bausch & Lomb)
and a new version of Zylink software (Bausch & Lomb)
will be introduced to shorten patient work-up and
treatment times. Additionally, I participated in the first
contralateral eye study comparing Zyoptix with
PlanoScan (Bausch & Lomb) for customized hyperopic
treatments. In this 45-patient study, the results with
Zyoptix were better than with PlanoScan in all metrics.
IN SUMMARY
Because FDA studies are difficult to compare to one
another, my colleagues and I opted to perform the contralateral eye study, which is a statistically powerful
method.
Our cohort was small, and we have only 1-month fol-
REFRACTIVE SCENARIOS ADDRESSED WITH THE ZYOPTIX SYSTEM
1. A 23-year-old male aeronautical engineering graduate
student seeking refractive surgery has manifest refractions of
-5.00 -2.00 X 170 for 20/15 OD and -5.50 -2.25 X 175 for 20/15
OS. Pachymetry readings are 510 mm OD and 505 mm
OS, and his pupils measure 8.5 mm OU. How would you
proceed?
This complex patient would require more study. What is
his current quality of vision? Does he have glare or halos? In
the Zyoptix (Bausch & Lomb, Rochester, NY) trial, we
found, in balance, patients did not gain night vision symptoms, but if they had them before surgery they still might
have them after surgery. So, it is important to document
and fully counsel the patient. The warning sign of an “engineering student” could mean a potentially difficult-to-treat
patient.
If surgery is planned, a 7-mm zone with a 2-mm blend is the
largest currently available to the surgeon. This would mean the
outer edges of the pupil would be served by the blend zone
optics in some lighting conditions.
Corneal depth may also be a problem as the larger zones on
any laser system do take more tissue. The surgeon might want
to consider a thinner flap such as a 110-µm head of even surface ablation, which only starts 50 or 60 µm (depth of the
epithelium) into the cornea.
The surgeon should fully discuss other options, including,
but not limited to, contact lenses or glasses.
2. A 54-year-old female transcriptionist with +1.50 D of
sphere for 20/20 OD and +1.75 D of sphere for 20/20 OS
seeks refractive surgery. Her right eye is dominant. The
patient has successfully worn monovision soft contact lenses
but demonstrates increasing contact lens intolerance.
Pachymetry measures 560 µm OD and 550 µm OS. Her
pupils measure 5.5 mm OU. How would you proceed?
I could only treat this patient in the clinical trial as she is
hyperopic. Right now, there are no FDA-approved hyperopic
customized ablation systems in the US. However, the Zyoptix
hyperopic trials have already shown better vision is possible
with Zyoptix than with standard hyperopic treatment.
3. A 30-year-old male sales representative seeks refractive surgery. He is contact lens intolerant. Rigid gas permeable lenses were suggested, but he could not become comfortable with the fit, despite achieving excellent clarity of
vision with the lenses. He is -3.50 -1.00 X 180 for 20/15 OD
and -3.25 -1.50 X 175 for 20/15 OS. His pachymetry measures 530 mm OD and 535 mm OS. His pupils measure
6 mm OU. Topography shows asymmetric bowties OU.
There is a superior/inferior discrepancy of 1.80 D OD and
2.00 D OS. Retinscopy is regular without scissors. How
would you proceed?
Although all the numbers are acceptable, the question is one
of corneal stability or dystrophy such as keratoconus or pellucid
marginal degeneration. A diagnosis of either should be made
not just on one topography reading but on clinical examination, the refraction history, family history, and older topographies. Orbscan (Bausch &Lomb) data, such as posterior float
and thickness correlating to the steeper areas, are also valuable.
Finally, in some such suspect patients who have no other alternative, PRK may be an option for them.
AUGUST 2004 I CATARACT & REFRACTIVE SURGERY TODAY I 69
COVER STORY
low-up data to date. We did find statistically a significant difference between the two systems, however. Results were better with the Zyoptix platform when we
compared the two lasers without nomograms. After a
nomogram adjustment was made to the Visx system,
results for that laser improved in terms of traditional
metrics but worsened as regards induced aberrations.
Thus, in quality-of-vision measures, such as contrast
sensitivity, the Zyoptix system performed
extremely well. ■
Stephen G. Slade, MD, FACS, is in private practice in Houston. He is a consultant for Bausch &
Lomb but holds no financial interest in the technologies or
products discussed herein. Dr. Slade may be reached at (713)
626-5544; [email protected].
INTEGR ATING THE ZYOPTIX SYSTEM INTO PR ACTICE
Surgeons discuss the ease of adapting to Bausch & Lomb’s refractive surgery system.
TIM PETERS, MD, FACS
WORK-UP PROCESS
My colleagues and I expected the work-up method using
the Technolas 217z Zyoptix system (Bausch & Lomb,
Rochester, NY) to be a time-consuming process of moving
patients between different rooms for various stages of testing that would ultimately leave our clinic appearing disorganized and unprofessional. My colleagues and I were concerned that our technicians would be unable to rapidly
obtain quality Zywave (Bausch & Lomb) calculations with
good centration, raw data, and a correlation with the manifest refraction. We worried that patients would be frightened by the multiple attempts to gather these data and
that they would lose confidence in our treatment abilities.
One main consideration with the Zyoptix work-up is
the need to reorganize patient flow and gather the necessary preoperative data before helping the patient decide
about the benefits of Zyoptix. However, the platform does
allow the surgeon to plan the surgical cases at his leisure at
a separate computer.
My staff and I increased our allotted work-up time by
15 minutes per patient until we mastered the work-up flow
with Zyoptix. Currently, we conduct a patient work-up
every 40 minutes, as we did before Zyoptix when we were
using the Technolas 217 for PlanoScan (Bausch & Lomb).
We reorganized our flow as follows: (1) we enter a patient’s spectacle data into the Orbscan (Bausch & Lomb);
(2) we perform the Orbscan and an undilated Zywave
measurements; (3) we use the information from the
Orbscan and Zywave to perform the first part of our
work-up, which includes the patient’s ocular history, manifest refraction, pupil size, and anterior segment examination; (4) the patient receives one drop of a mixture of 2.5%
phenylephrine and 0.5% Mydriacyl (Alcon Laboratories,
Inc., Fort Worth, TX); (5) the patient watches a consent
video until his pupils dilate; (6) we perform the dilated
70 I CATARACT & REFRACTIVE SURGERY TODAY I AUGUST 2004
Zywave calculation (making sure the Zywave data correlate with the manifest refraction and that we receive no
exclamation-point signs on the screen indicating not to
proceed with the treatment); (7) we perform the cycloplegic refraction and the retinal examination; and (8) we
discuss whether to perform a Zyoptix procedure or traditional LASIK on the patient.
We have been using this method for 6 months and now
execute this technique on all nonhyperopic patients. We
are not a “hard sales” practice, but 80% to 90% of our
myopes receive treatment with the Zyoptix system.
SURGICAL FLOW
We expected the surgical need for extra fluence tests
would require additional time in the surgery schedule. We
were concerned that patients would have to be moved off
the bed or that the extra fluence would frighten the
patients. Of course, we were also concerned about the
patients’ outcomes because this is a new system and a new
nomogram would need to be established.
Instead, we have kept the same surgical pace we always
have had (eg, one patient every half-hour) and experienced no difficulties with keeping on track. We perform a
fluence test between every eye by swinging the bed out
from underneath the laser and asking the patient to sit
upright. Afterward, we swing the bed back underneath the
laser for the fluence test. This approach has worked quite
well and consumes little additional time.
Our outcomes with the Zyoptix system have been outstanding. We have a 1% to 2% enhancement rate, which is
identical to our PlanoScan enhancement rate. We have a
large percentage of patients (25%) who have gained lines of
BCVA, and none has lost lines of BCVA. Interestingly, from
the few patients who do not achieve a plano or near-plano
postoperatively, we have observed an unprecedented level
result of satisfaction. We have found that patients with the
COVER STORY
same postoperative prescription and vision after Zyoptix
treatment are significantly happier than with the identical
prescriptions and visions (our postoperative PlanoScan
patients).
I plan every treatment myself after verifying the raw data.
With multiple variables to consider in the planning stage, I
feel surgeon involvement in this step is critical. We have not
performed dilated Zywaves postoperatively to quantify the
change in higher-order aberrations due to time constraints
and patients’ aversions to additional dilated examinations.
ROBERT W. LINGUA, MD, PC
WORK-UP FLOW
Before acquiring the Zyoptix system, I previously used
another wavefront platform and was looking for a more
streamlined diagnostic and therapeutic instrument that
would obviate the need for dilation on surgery days. Because the Zyoptix system does not require dilation for
the treatment phase, I expected that platform to facilitate a more efficient process on surgery days.
Creating a nomogram is an issue with the work-up
flow process using Zyoptix. This system’s nomogram
development, not unlike that required of any other new
instrumentation, mandates time-intensive analysis, because nomograms were not readily available for purchase with the Zyoptix system.
My present nomogram has been very successful and is a
simple one-step process of choosing the percent according
to the higher-order aberrations at 6 mm (Table 1).
The nomogram is based upon the concept that the
higher the degree of the higher-order aberration to be
treated, the higher the amount of myopia that is treated centrally. To avoid overcorrection, the percentage of
treatment is reduced proportionately to the increased
higher-order aberration treatment to be delivered.
Patients who consult for laser vision correction and
desire a wavefront-guided procedure are scheduled for
a Zyoptix evaluation on a separate day and processed
by the technical staff. On the day of evaluation, my staff
performs the triple-capture Orbscan and “dry” Zywave
assessment. A technician then dilates the patient’s pupil
with Paremyd (Akorn Inc., Buffalo Grove, IL) (gentle on
the epithelium, and efficient with one drop) and, after
20 minutes, executes the final “wet” Zywave capture.
On the evening prior to the patient’s surgery, I return to
the workstation and access the Zylink program (Bausch
& Lomb), retrieve the Orbscan and Zywave files, and
select the percentage of treatment and optical zone size
for the patient, as described earlier. Next, I download
the information onto a disc and attach the disc to the
patient’s chart. This dilation and Zywave evaluation,
performed on a separate day, are the only steps that the
Zyoptix system adds to my previous preoperative LASIK
routine.
SURGICAL FLOW
I expected the surgical flow with the Zyoptix system to
be uninterrupted and accommodate our laser vision correction center well. The Zyoptix system is superior to others that require dilation on the day of surgery. On surgery
days, the Zyoptix patients’ surgical flow is identical to that
of traditional LASIK patients, because the Zyoptix patients’
information is prepared the night before and the procedural time is extended only for the several minutes required to
check laser fluence, prior to performing surgery on the second eye. Because we have seen variations in power density
between the separate ablations of eyes of wavefront
patients, my staff and I continue to perform this additional
step and recommend it to all surgeons.
To expedite laser recalibration between eyes, I swing the
head of the bed of my Technolas 217z outward to the
locked position, ask the patient to sit up, and replace his
headrest with the calibration platform. We then swing the
bed back under the scope for the few minutes it takes to
perform the calibration. When complete, I swing the bed
out again, replace the headrest, instruct the patient to lie
down, and swing the head of the bed back underneath the
laser to treat the patient’s second eye. The total time for
this step is less than 5 minutes.
TABLE 1. DR. LINGUA’S NOMOGRAM FOR CALCULATING THE PERCENTAGE OF TREATMENT
USING THE ZYLINK PROGRAM
If the higher-order
aberration at 6 mm is:
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
Select:
97%
95%
94%
92%
91%
90%
88.5%
87%
85%
83%
81%
79%
78%
77%
76%
AUGUST 2004 I CATARACT & REFRACTIVE SURGERY TODAY I 71
COVER STORY
Therefore, the only two new steps added to a LASIK procedure using the Zyoptix system are the patient’s Zywave
evaluation day and the few minutes for recalibration between eyes. The surgeon’s time at the workstation preoperatively, to calculate the discs of information to be used during a procedure, is less than 5 minutes per patient.
The outcomes of our first 100 eyes treated with Zyoptix
are favorable at 1 month, and future results will likely
improve as my technicians and I refine our nomogram.
Patient flow however, has fit well into the technicians’ skill
sets, and the office has run smoothly with their cooperation. Surveying the staff and involving them in problem
solving expedited the integration of the Zyoptix system
into our practice. It is a very technician-friendly system.
Our patients experience nothing unexpected in their
care compared with what patients of other practices may
have told them about the wavefront-guided procedure.
Based on a casual patient survey we conduct, our patients
have a high rate of satisfaction with their outcomes. Most
patients have reported that their Zyoptix treatment seemed to flow smoothly and without interruption.
MARK JOHNSTON, MD, FRCSC
WORK-UP FLOW
Our expectation was that the workflow with the Zyoptix
system would be similar to that of the Visx CustomVue
wavefront-guided excimer laser system (Visx, Inc., Santa
Clara, CA). While we initially found the Zyoptix system to
be more complicated and time-consuming, with experience we have found it to only a minimally increase our
workload. We have been pleased with the results with the
Zyoptix system. At 3 months, our average postoperative
spherical equivalent is -0.10 D, with 84.9% of patients
achieving 20/20 or better.
The Zyoptix system requires dilation. Currently, we use
0.5% topicamide for routine preoperative evaluations. If dilation is performed on the day of surgery, we use 0.125% topicamide. This solution enables us to achieve sufficient dilation
of a patient’s pupils with minimal cycloplegia. We prepare
this dilute solution by introducing a sterile syringe and needle into the dropper opening of the commercial preparation
and diluting it in a commercial tear supplement.
We track our results with outcome analysis software.
Based on these results we presently use a 100% treatment
factor, meaning that the treatment is completely determined by the wavefront scan. We have not had to add an
age factor because our results show minimal undercorrection with increasing age.
Although our staff initially had difficulty using the Zyoptix
workstation, they are now very comfortable with its operation. Preoperatively, wavefront measurements are captured
with the pupil dilated. We prefer to have the pupil dilated at
72 I CATARACT & REFRACTIVE SURGERY TODAY I AUGUST 2004
the time of surgery. The quality of the preoperative wavefront is critical to achieving good postoperative results. The
wavefront measurement replaces manifest refraction because it is the single most important measurement before
surgery. Given their importance, only the physician or a welltrained technician under direct physician supervision performs these scans. The scan should be centered on the dilated pupil. Only wavefront measurements that are taken during optimal patient fixation and that vary less than 0.25 D
with repeat scans are used for surgery.
Initially, the work and surgery process with the Zyoptix
system was slower than with our standard Visx or Visx
CustomVue treatments. With an additional technician to
assist us in the clinic on high-volume days and by paying
close attention to the surgical process, we can continue
our long-standing routine of booking three patients for
bilateral surgery each hour.
SURGICAL FLOW
The laser technician time and laser ablation time with
Zyoptix is longer than we were used to with the Visx laser.
With the latter, before every second patient, a test correction is made on a plastic blank and confirmed with a lensometer. With the Zyoptix system, the laser is calibrated by
determining how many pulses are needed to break through
a standard thickness film. This test, as well as a centration
test, must be performed before treating each eye. To avoid
delays between treating the first and second eye of a patient, we shorten this process by performing the centration
test on a sponge placed on the patient’s forehead, and we
use the same calibration factor we found on testing before
the case was started. The laser technician begins programming the next patient’s data as soon as the laser ablation is
completed on the second eye.
One advantage of both the CustomVue and the Zyoptix
systems is that the ablation is preprogrammed in the clinic
and stored on a floppy disc. This disc is used to program
the laser with the patient’s name and desired correction.
Because the corrections are entered in one-hundredths of a
diopter, each treatment is unique, and confirmation of the
desired ablation is facilitated.
With Zyoptix, the surgeon determines centration. Because much of the treatment is delivered in a midperipheral
circular direction, a dilated or partially dilated pupil enables
the surgeon to continually assess laser centration. Centration must be confirmed and adjusted not only at the
beginning of each case, but also before the surgeon performs each segment of the treatment. If the patient pushes
his head back into the head support, then the x axis will no
longer become decentered. This decentration is easily visualized and corrected by adjusting the focus to reset the aiming beam at the center of the patient’s pupil. Fixation of the
COVER STORY
y axis is very dependent on the infrared lighting. If the patient moves sideways, either the patient’s head or the infrared lights must be adjusted. Both infrared lights are used
during each ablation. Our preference is that the surgeon
adjust the infrared illumination before and during the laser
ablation as necessary. Laser controls and infrared light supports are therefore cleaned with alcohol between patients.
Each laser ablation is divided into multiple segments,
between eight and 16 for a typical case. Between laser segments, the surgeon must release the foot pedal, verify fixation, and make any required adjustments. Treatment times
of 1 to 2 minutes, not including pauses, are common. With
the introduction of the Zylink version 2.33 software, the
number of laser segments and length of treatment time will
be reduced. Using the Zyoptix system requires humidity control within the OR, especially during dry seasons. Excessive
drying of the flap can be minimized by placing it over the
top of a small wedge made from the end of a moist microsponge. Because thin flaps are less stable and will dry out
more rapidly, we target a minimum flap thickness of 130 µm.
Because laser treatment times are longer, we prefer not
to use the Zyoptix system for high corrections. Bausch &
Lomb has developed a faster laser head and will be simpli-
fying the laser ablation segments to increase the laser’s
speed. Given our results to date, we expect to expand our
use of the Zyoptix system as these changes in delivery
speed become available to us. ■
Tim Peters, MD, FACS, is Medical Director at
Clear Advantage Laser Vision Center in Portsmouth, New Hampshire. He holds no financial
interest in any products, technologies, or companies mentioned herein. Dr. Peters may be reached at
(603) 501-5000; [email protected].
Robert W. Lingua, MD, PC, is the director of Lingua
Vision Surgical Group. He holds no financial interest
in the products, technologies, or companies mentioned herein. Dr. Lingua may be reached at (714)
870 2010, or via email at [email protected], or by
clicking the contact tab at www.lingualasik.com.
Mark Johnston, MD, FRCSC, is in private practice
with Nebraska Laser Eye Associates in Omaha. He
holds no financial interest in the products, technologies, or companies mentioned herein. Dr. Johnston
may be reached at (402) 397-2010;
[email protected].