Trending Topic

23 mins

Trending Topic

Developed by Touch
Mark CompleteCompleted
BookmarkBookmarked
Luke G Qin, Michael T Pierce, Rachel C Robbins

The uvea is a vascular stratum that includes the iris, ciliary body and choroid. Uveitis is defined as inflammation of a part of the uvea or its entirety, but it is also used to describe inflammatory processes of any part of the eye, such as the vitreous or peripheral retina. The clinical taxonomy of uveitis […]

Meta-analysis of Six Excimer Laser Platforms for Safety and Efficacy in Myopic Laser-assisted in situ Keratomileusis

Christopher L Blanton
Share
Facebook
X (formerly Twitter)
LinkedIn
Via Email
Mark CompleteCompleted
BookmarkBookmarked
Copy LinkLink Copied
Download as PDF
Published Online: Mar 20th 2015 US Ophthalmic Review, 2015;8(1):23–9 DOI: http://doi.org/10.17925/usor.2015.8.1.23
Select a Section…
1

Abstract

Overview

Purpose: To compare excimer laser platform outcomes for myopic laser-assisted in situ keratomileusis (LASIK). Methods: A peer-reviewed
literature search was conducted using the terms “myopia,” “LASIK,” and “outcomes.” Articles were selected based on inclusion/exclusion
criteria. Data regarding Snellen visual acuity, refractive error ± 0.5 and 1.0 diopter (D) and loss of best-corrected acuity were extracted. US
Food and Drug Administration (FDA) approval studies were used to fill in any data gaps. Statistical analysis was performed. Results: The
Abbott laser outperformed the other five in multiple measures of visual acuity results at 1 and 3 months. The Nidek laser outperformed
the other five lasers at the 20/16 level at 6 months. The Carl Zeiss/Meditec laser outperformed the other five at 6 months in terms of
refractive outcome ± 0.5 D. The Abbott and Alcon lasers outperformed the other four lasers in the safety category (least amount of >2 line
loss of best-corrected visual acuity [BCVA]) at the 1 month visit. There were no significant differences between the platforms, in the safety
category, at all other time intervals. Conclusion: At all times, all lasers fell within the FDA guidelines for safety regarding loss of bestcorrected
acuity.

Keywords

Myopia, LASIK, outcomes, safety, efficacy, phase IV, peer-reviewed

2

Article

Laser-assisted in situ keratomileusis (LASIK) for myopia is the most commonly performed corneal refractive procedure performed in the world today. The use of the excimer laser to reshape the cornea is accomplished utilizing an ultraviolet laser that contains sufficient energy per pulse to disrupt the organic bonds, which reside in the cornea. This allows corneal stromal tissue to be removed in very precise 0.25 micron increments enabling the surgeon to alter the shape of the cornea. Excess energy is dissipated in acoustic and photic forms. There are a number of excimer laser platforms available today for use by surgeons when performing this procedure. Although there have been sporadic articles comparing one or two laser platforms to another,1–4 and rarely an article comparing several of the most commonly used excimer lasers,5 there has not been a recent comprehensive comparison of currently available platforms looking at standard safety and efficacy data. This meta-analysis was undertaken to accomplish that goal.

Methods
An Internet-based search using SCOPUS, a system designed to screen and filter journal articles, was conducted. SCOPUS is the largest abstract and citation database of peer-reviewed research literature. The words “myopia,” “LASIK,” and “outcomes” were used to filter the articles in the categories of “article title,” “abstract,” and “keywords.” The time period went from November 2013 retrospectively to January of 2007. Articles older than this were considered to be anachronistic. Inclusion criteria included the following: English-language, peer-reviewed journals for the surgical procedure of myopic LASIK. In addition, the following parameters were selected for inclusion: Snellen visual acuity at 1, 3, 6, and 12 months; efficacy regarding refractive error targeting: ± 0.5 diopters (D) at 3, 6, and 12 months; ± 1.0 D at 3, 6, and 12 months. Finally, the adverse event—loss of best-corrected visual acuity (BCVA) (>2 lines) at 1, 3, 6, and 12 months was also examined. Exclusion criteria were: any studies on eyes with 1) prior eye surgery, 2) pathology, or 3) for an intended result of “monovision.” Finally, the best data, with regards to visual acuity and loss of BCVA, were presented for each platform. At the conclusion of the database search there were 613 articles. One hundred and seventy-four articles were removed due to the fact that they did not examine the parameters in the categories of 1) visual acuity, 2) ± 0.5 D or ± 1 D of refractive accuracy, or 3) loss of >2 lines of BCVA. Seventyfour articles were excluded because they did not concern myopic LASIK for emmetropia. Seventy-one articles were excluded because they were on previously operated eyes. Ten articles were excluded because they were on pathologic eyes (amblyopia for example). Four articles were excluded since they were not in the English language. After application of the inclusion/exclusion criteria, there were 281 usable journal articles with six separate laser platforms with sufficient data for analysis.6–34 If data were lacking with regards to these parameters for a particular platform, we reverted to US Food and Drug Administration (FDA) approval studies.35–39 This was a common occurrence and even after including FDA-approval data there were still some platforms with no data points in the literature. For example, only two platforms have 20/10 visual acuity data at the 3-month post-op time frame.

The Six Platforms Compared
A comparison analysis of visual outcomes between these six common excimer platforms was performed. These lasers included the following capabilities at the time of use in the journal articles used.

Abbott-Star-S4IR
Capable of performing conventional (phoropter-based) and wavefrontguided (aberrometer-based) ablations using a Hartmann-Shack aberrometer. Speed of the laser is variable but maximized at 20 Hz. The laser uses a pattern known as variable spot scanning in which pulses of different diameters are calculated, using a Fourier algorithm, and used to remove corneal stromal tissue. Pupil tracking and iris registration are available.

Alcon Wavelight 200/400 Hz Wavefront Optimized/ Wavefront Guided
These devices are capable of performing both conventional and wavefront-guided ablations. The wavefront-guided ablations are driven by a Tscherning principle-based aberrometer. Conventional ablations are placed in an “optimized” fashion by applying a correction profile designed to maintain the natural prolate shape of the cornea. A scanning spot technology is used. The speed of the most recent version available at the time of this article was 400 Hz. Pupil tracking is available.

Carl Zeiss/Meditec Mel 80
This performs conventional, topography-, and wavefront-guided excimer laser surgery with a Hartmann-Shack type aberrometer. The speed of the laser is 250 Hz. The device uses flying spot technology to deliver excimer laser ablation. The platform can be set to correct for induced spherical aberrations. Eye tracking and iris recognition are available.

Nidek C5000
This performs conventional and wavefront-guided excimer laser ablations with scanning slit technology. Ablation profiles can be delivered attempting to create a prolate corneal profile over the mesopic pupil while targeting zero or mildly negative spherical aberration. Additionally, a conventional profile can be used with a small optical zone coupled with an aspheric transition zone that is at least 3 mm larger than the optical zone. The aberrometer is a time-based device using dynamic skiascopy. The speed of the laser is 40 Hz. Pupil tracking and torsion error detection are available.

Schwind Esiris/Amaris
This is the only laser in this analysis that is not FDA approved, but it so commonly used globally and was therefore included. The laser is capable of conventional and wavefront-guided treatments. A Hartmann-Shack aberrometer is utilized. Ablation profiles can take into account keratometry readings and can deliver aspheric profiles. The speed is 500 Hz and has pupil tracking and dynamic cyclotorsional tracking technology.

Technolas-217Z
This model is capable of performing both conventional and wavefrontguided excimer ablations with a speed of 100 Hz. The platform uses a Hartmann-Shack type of aberrometer. The ablation can be delivered using an aspheric module. Uses flying spot technology to deliver excimer ablation. Pupil tracking and dynamic iris recognition are available.

The final results underwent a statistical analysis in the following manner: we used a one-tailed two-sample Z-test about proportions. Observed proportions were placed in descending order, then we iteratively tested each against the remaining platforms. If observed proportions were equal: the sample size was the “tie-breaker” as a potential discriminator against lower observed proportions.

Results
Visual Acuity at 1 Month
Comparison of Platforms

The following data were recovered from the eligible articles:

Abbott excimer platform—20/10—22 %,6 20/12.5—81 %,6 20/16—95 %,6 20/20—99 %6
Alcon excimer platform—20/12.5—21 %,35 20/16—64 %,12 20/20—92 %18
Carl Zeiss excimer platform—20/16—65 %,16 20/20—96 %16
Nidek excimer platform—20/20—81 %24
Schwind excimer platform—no data
Technolas excimer platform—61 %—20/16,36 20/20—86 %36 (see Figure 1)

The Abbott platform was significantly superior to all the other platforms at acuity levels 20/12.5, 20/16 and 20/20 (see Table 1).

Visual Acuity at 3 Months
Comparison of Platforms

The following data were recovered from the eligible articles:

Abbott excimer platform—20/10—23 %,6 20/12.5—80 %,6 20/16—96 %,6 20/20—98 %6
Alcon excimer platform—20/12.5—25 %,15 20/16—76 %,15 20/20—93 %15
Carl Zeiss excimer platform—20/16—50 %,16 20/20—96 %16
Nidek excimer platform—20/20—96 %23
Schwind excimer platform—20/10—23 %,30 20/16—71 %,25 20/20—97 %30
Technolas excimer platform—20/16—69 %,36 20/20—88 %34 (see Figure 2)
The Abbott platform was significantly superior to all the other platforms at acuity levels 20/12.5 and 20/16 (see Table 2).

Visual Acuity at 6 Months
Comparison of Platforms

The following data were recovered from the eligible articles:

Abbott excimer platform—20/20—88 %8
Alcon excimer platform—20/12.5—25 %,35 20/16—62 %,9 20/20—92 %9
Carl Zeiss excimer platform—20/20—93 %37
Nidek excimer platform—20/12.5—15 %,21 20/16—85 %,21 20/20—97 %21
Schwind excimer platform—20/12.5—3 %,28 20/16—65 %,26 20/20—98 %26
Technolas excimer platform—20/12.5—2 %,31 20/16—70 %,36 20/20—87 %33 (see Figure 3)

The Nidek platform was significantly superior to all the other platforms at acuity level 20/16 (see Table 3).
12 month—93 %38 Alcon excimer platform—3 month—96 %,10 6 month—92 %,9
12 month—89 %9
Carl Zeiss excimer platform—3 month—94 %,14 6 month—98 %,17 12 month—98 %19
Nidek excimer platform—3 month—91 %,22 6 month—89 %,21 12 month—85 %20
Schwind excimer platform—3 month—96 %,28 6 month—96 %,26 12 month—95 %29
Technolas excimer platform—3 month—98 %,11 6 month—94 %,31 12 month—86 %32 (see Figure 5)

The Carl Zeiss platform was superior to all the other platforms at 6 months (see Table 5)

Refractive Accuracy at ± 1.0 Diopters
Comparison of Platforms

The following data were recovered from the eligible articles:

Abbott excimer platform—3 month—95 %,7 6 month—99 %,38 12 month—100 %38
Alcon excimer platform—3 month—98 %,11 6 month—100 %,9 12 month—100 %9
Carl Zeiss excimer platform—3 month—97 %,14 6 month—no data, 12 month—100 %19
Nidek excimer platform—3 month—100 %,22 6 month—100 %,21 12 month—96 %20
Schwind excimer platform—3 month—100 %,28 6 month—90 %,27 12 month—no data
Technolas excimer platform—3 month—100 %,34 6 month—100 %,31 12 month—100 %32 (see Figure 6).

No device was superior to all the other devices (see Table 6). Adverse Event—Loss of Best Spectacle-corrected Visual Acuity >2 Lines
Comparison of Platforms

The following data were recovered from the eligible articles:

Abbott excimer platform—1 month—0 %,6 3 month—0.4 %,6 6 month—0 %,38 12 month—0 %38
Alcon excimer platform—1 month—0 %,35 3 month—0 %,15 6 month—0 %,9 12 month—0 %9
Carl Zeiss excimer platform—1 month—0.8 %,37 3 month—0 %,14 6 month—0.3 %,37 12 month—0 %19
Nidek excimer platform—1 month—1.5 %,39 3 month—0 %,23 6 month—0 %,24 12 month—0.7 %39
Schwind excimer platform—1 month—no data, 3 month—0.6 %,26 6 month—0 %,26 12 month—1.8 %29
Technolas excimer platform—1 month—1.5 %,36 3 month—1.2 %,36 6 month—0.6 %,36 12 month—3 %32 (see Figure 7)

The Abbott and Alcon platforms were superior to all the other devices at the 1 month measurement. At all other time periods, no device was superior to any of the others (see Table 7). All devices remained below the 5 % FDA guidance figure.

Discussion
As with any meta-analysis, a legitimate criticism is that the different journal articles/studies reflect different study protocols with differing inclusion and exclusion criteria. Although this is a valid argument, there are several counterarguments. First of all, there are more similarities than dissimilarities when comparing these articles. Additionally, until the definitive prospective, randomized trial is conducted comparing all these available lasers, this is the best mechanism we have for comparing the currently available platforms. This article represents the current best compilation of data regarding the safety and accuracy of these six excimer platforms. Unfortunately, there are several examples where there are no data. Even after including FDA approval data, there are data gaps. This highlights the need for continuing phase IV studies with all of the platforms to fill in these data gaps. Because there is a meticulous referential database, each article can be obtained and read for its specifics allowing the reader to make a more detailed investigation and comparison.

2

References

  1. Dougherty PJ, Bains HS, A retrospective comparison of
    LASIK outcomes for myopia and myopic astigmatism with
    conventional NIDEK versus wavefront-guided VISX and Alcon
    platforms, J Refract Surg, 2008;24:891–6.

  2. Feltham MH, Wong R, Wolfe R, et al., Variables affecting
    refractive outcome following LASIK for myopia, Eye,
    2008;22:1117–23.

  3. Mearza A, Muhtaseb M, Aslanides IM, Visual and refractive
    outcomes of LASIK with SCHWIND ESIRIS and wavelight
    ALLEGRETTO WAVE eye-Q excimer lasers: A prospective
    contralateral study, J Refract Surg, 2008;24:885–90.

  4. Perez-Straziota CE, Randleman JB, Stulting RD, Visual acuity and
    higher-order aberrations with wavefront-guided and wavefrontoptimized
    laser in situ keratomileusis, J Cataract Refract Surg,
    2010;36:437–41.

  5. Bailey M, Zadnik K, Outcomes of LASIK for myopia with FDAapproved
    lasers, Cornea, 2007;26:246–54.

  6. Tanzer DJ, Brunstetter T, Zeber R, et al., Laser in situ
    keratomileusis in United States Naval Aviators, J Cataract Refract
    Surg, 2013;39:1047–58.

  7. Srivannaboon S, Sunlakaviset P, Kosrirukvongs P, et al., Refractive
    Outcomes of femtosecond LASIK for myopic correction at Siriraj
    Hospital, Thailand, J Med Assoc Thai, 2012;95 Suppl. 4:S18–23.

  8. Moshirfar M, Espandar L, Meyer JJ, et al., Prospective
    randomized trial of wavefront guided laser in situ keratomileusis
    with the CustomCornea and CustomVue laser systems,
    J Cataract Refract Surg, 2007;33:1727–33.

  9. Fares U, Otri AM, Al-Aqaba MA, et al., Wavefront-optimized
    excimer laser in situ keratomileusis for myopia and myopic
    astigmatism: Refractive outcomes and corneal densitometry,
    J Cataract Refract Surg, 2012;38:2131–8.

  10. George MR, Shah RA, Hood C, et al., Transitioning to optimized
    correction with the Wavelight Allegretto Wave: Case distribution,
    visual outcomes, and wavefront aberrations, J Refract Surg,
    2010;26:S806–13.

  11. Han DCY, Chen J, Htoon HM, et al., Comparison of outcomes of
    conventional Wavelight Allegretto Wave and Technolas excimer
    lasers in myopic laser in situ keratomileusis, Clin Ophthalmol,
    2012;6:1159–68.

  12. Moshirfar M, Betts BS, Churgin DS, et al., A prospective,
    randomized, fellow eye comparison of Wavelight Allegretto
    Wave Eye-Q versus VISX CustomVue Star S4IR in laser in situ
    keratomileusis (LASIK): analysis of visual outcomes and higher
    order aberrations, Clin Ophthalmol, 2011;5:1339–47.

  13. Reinstein DZ, Carp GI, Archer TJ, et al., Transitioning from
    mechanical microkeratome to femtosecond laser flap creation:
    Visual outcomes of an experienced and a novice LASIK surgeon,
    J Cataract Refract Surg, 2012;38:1788–95.

  14. Blum M, Kunert K, Gille A, et al., LASIK for myopia using the Zeiss
    visuMax femtosecond laser and MEL 80 excimer laser, J Refract
    Surg, 2009;25:350–6.

  15. Stonecipher KG, Kezirian GM, Wavefront-optimized versus
    wavefront-guided LASIK for myopic astigmatism with the
    allegretto wave: three-month results of a prospective FDA trial,
    J Refract Surg, 2008;24:S424–S430.

  16. Wu F, Yang Y, Dougherty PJ, Contralateral comparison of
    wavefront-guided LASIK surgery with iris recognition versus
    without iris recognition using the MEL80 Excimer laser system,
    Clin Exp Optom, 2009;92:320–7.

  17. Reinstein DZ, Morral M, Gobbe M, et al., Accuracy of refractive
    outcomes in myopic and hyperopic laser in situ keratomileusis:
    Manifest versus aberrometric refraction, J Cataract Refract Surg,
    2012;38:1989–95.

  18. Padmanabhan P, Mrochen M, Basuthkar S, et al., Wavefrontguided
    versus wavefront-optimized laser in situ keratomileusis:
    Contralateral comparative study, J Cataract Refract Surg,
    200;34:389–97.

  19. Issa A, Al Hassany U, Femtosecond laser flap parameters and
    visual outcomes in laser in situ keratomileusis, J Cataract
    Refract Surg, 2010;37:665–74.

  20. Abdallat W, The outcome of the first 1000 cases of LASIK
    performed at the King Hussein Medical Center, Jordan Medical
    Journal, 2010;45:262–7.

  21. Chayet A, Bains HS, Prospective, randomized, double-blind,
    contralateral eye comparison of myopic LASIK with
    optimized aspheric or prolate ablations, J Refract Surg,
    2012;28:112–19.

  22. Hori-Komai Y, Toda I, Yamamoto T, et al., Comparison of LASIK
    with the OPDCAT or OATz algorithm using the NIDEK EC-
    5000CXII excimer laser, J Refract Surg, 2010;26:411–22.

  23. Chen S, Wang Y, Wang Q, Outcomes of NIDEK optical path
    difference custom ablation treatments (OPDCAT) for Myopia
    with or without astigmatism, J Refract Surg, 2009;25(Suppl.
    1):S142–7.

  24. Dougherty PJ, Waring III G, Chayet A, et al., Topographically
    guided laser in situ keratomileusis for myopia using a
    customized aspherical treatment zone, J Cataract Refract Surg,
    2008;34:1862–71.

  25. Arbelaez MC, Vidal C, Al Jabri B, et al., LASIK for myopia with
    aspheric “aberration neutral” ablations using the ESIRIS laser
    system, J Refract Surg, 2009;25:991–9.

  26. Arbelaez MC, Aslanides IM, Barraquer C, et al., LASIK for myopia
    and astigmatism using the SCHWIND AMARIS excimer laser: An
    International multicenter trial, J Refract Surg, 2010;26:88–98.

  27. Arbelaez MC, Vidal C, Arba Mosquera S, Clinical outcomes of
    LASIK for myopia using the SCHWIND platform with ocular
    wavefront customized ablation, J Refract Surg, 2009;25:1083–90.

  28. Ortueta DD, Mosquera SA, Baatz H., Comparison of standard and
    aberration-neutral profiles for myopic LASIK with the SCHWIND
    ESIRIS platform, J Refract Surg, 2010;25:339–9.

  29. Zhou C, Jin M, Wang X, et al., Corneal wavefront guided ablation
    with the SCHWIND ESIRIS laser for myopia, J Refract Surg,
    2007;23:573–80.

  30. Tomita M, Waring IV GO, Magnago T, et al., Clinical results of
    using a high-repetition-rate excimer laser with an optimized
    ablation profile for myopic correction in 10,235 eyes, J Cataract
    Refract Surg, 2013;39:1543–9.

  31. Prakash G, Agarwal A, Ashok Kumar D, et al., Comparison of
    laser in situ keratomileusis for myopic astigmatism without
    iris registration, with iris registration, and with iris registrationassisted
    dynamic rotational eye tracking, J Cataract Refract
    Surg, 2011;37:574–81.

  32. Ryan A, O’Keefe M, Wavefront-guided and aspheric ablation for
    myopia- one-year results of the Zyoptix personalized treatment
    advanced algorithm, Am J Ophthal, 2012;153:1169–77.

  33. Taneri S, Oehler S, MacRae SM, Aspheric wavefront-guided
    versus wavefront-guided LASIK for myopic astigmatism with
    the Technolas 217z100 excimer laser, Graefes Arch Clin Exp
    Ophthalmol, 2013;251:609–16.

  34. D’Arcy F, Kirwan C, Qasem Q, et al., Prospective contralateral
    eye study to compare conventional and wavefront- guided laser
    in situ keratomileusis, Acta Ophthalmol, 2012;90:76–80.

  35. Wavelight allegretto wave excimer laser system—FDA approval
    study, P020050/S4, July 26, 2006.

  36. Technolas 217Z Zyoptix system for personalized vision
    correction—FDA approval study; P990027/S6, October 10, 2003.

  37. MEL 80 excimer laser system–FDA approval study; P060004,
    August 11, 2006.

  38. VISX Star S4 Activetrak excimer laser system—FDA approval
    study; P930016/S16, May 23, 2003.

  39. Nidek EC-5000 excimer laser system—FDA approval study;
    P970053/S9, October 11, 2006.
3

Article Information

Disclosure

Christopher L Blanton, MD, is a consultant, and has received speaker fees and grant support from Abbott Medical Optics. He is a consultant for Allergan and has received speaker fees.

Correspondence

Christopher L Blanton, MD, 9481 Haven Ave, Suite 200, Rancho Cucamonga, CA 91730, US. E: Blanton007@aol.com

Support

This study was sponsored by a grant from Abbott Medical Optics. Abbott Medical Optics had no role in study design, collection, analysis, or interpretation of the data, or
manuscript preparation. There were no publication charges associated with this manuscript.

Access

This article is published under the Creative Commons Attribution Noncommercial License, which permits any noncommercial use, distribution, adaptation, and reproduction provided the original author(s) and source are given appropriate credit.

Received

2015-01-15T00:00:00

4

Further Resources

Share
Facebook
X (formerly Twitter)
LinkedIn
Via Email
Mark CompleteCompleted
BookmarkBookmarked
Copy LinkLink Copied
Download as PDF

This Functionality is for
Members Only

Explore the latest in medical education and stay current in your field. Create a free account to track your learning.

Close Popup