Journal of Refractive Surgery

Original Article 

Four-Year Visual, Refractive, and Contrast Sensitivity Outcomes After Wavefront-Guided Myopic LASIK Using an Advanced Excimer Laser Platform

Mohamed Shafik Shaheen, MD, PhD; Tamer Hamdy Massoud, MD, PhD; Hani Ezzeldin, MD; Mounir Ahmed Khalifa, MD, PhD

Abstract

PURPOSE:

To evaluate the 4-year visual, refractive, and contrast sensitivity outcomes of wavefront-guided LASIK for the correction of low to moderate myopia using the VISX CustomVue technology (Abbott Medical Optics, Inc., Santa Ana, CA).

METHODS:

This was a prospective study including 255 consecutive eyes of 145 patients (age range: 19 to 55 years) with low to moderate myopia (mean spherical equivalent: −3.36 ± 1.71 diopters [D]) undergoing laser refractive surgery. Wavefront-guided LASIK was performed in all eyes using the VISX STAR S4 IR excimer laser platform and the CustomVue procedure for the ablation profile design. Visual, refractive, and contrast sensitivity changes were evaluated during a 4-year follow-up period.

RESULTS:

Postoperative logMAR uncorrected distance visual acuity was 0.1 or better (20/25 Snellen) in 98.0% and 100% of eyes at 1 and 4 years, respectively. At 4 years postoperatively, mean spherical equivalent was reduced significantly to a mean value of −0.22 ± 0.28 D (P < .01), with 97.3% of eyes with a spherical equivalent within ±0.50 D. The astigmatic power vector component J0 of manifest refraction was also reduced significantly (P < .01). Postoperative logMAR corrected distance visual acuity was 0.0 or better (20/20 Snellen) in 96.1% and 98.8% of eyes at 1 and 4 years, respectively. Improvement in contrast sensitivity was observed in some spatial frequencies between 1 and 4 years postoperatively. No significant correlations were found between 4-year contrast sensitivity and corrected distance visual acuity (0.024 ⩽ r ⩽ −0.120, P ⩾ .06).

CONCLUSION:

Wavefront-guided LASIK using the VISX CustomVue technology provides an effective and predictable correction of low to moderate myopia in the long term, preserving the patient’s visual acuity and quality.

[J Refract Surg. 2013;29(12):816–822.]

From the University of Alexandria, Alexandria, Egpyt (MSS, THM); Horus Vision Correction Centre, Alexandria, Egypt (HE); and Tanta University, Tanta, Egypt (MAK).

The authors have no financial or proprietary interest in the materials presented herein.

The authors thank Investigación Personalizada al Servicio de la Salud, Alicante, Spain, for the collaboration in this study.

AUTHOR CONTRIBUTIONS

Study concept and design (MSS); data collection (MSS, HE, MAK); analysis and interpretation of data (MSS, THM); drafting of the manuscript (MSS, THM, HE); critical revision of the manuscript (MSS, THM, MAK); statistical expertise (THM); administrative, technical, or material support (THM); supervision (MSS)

Correspondence: Mohamed Shafik Shaheen, MD, PhD, University of Alexandria, P. O. Box 27, Ibrahimia, Alexandria 21321, Egypt. E-mail: m.shafik@link.net

Received: March 16, 2013
Accepted: August 05, 2013
Posted Online: October 30, 2013

Abstract

PURPOSE:

To evaluate the 4-year visual, refractive, and contrast sensitivity outcomes of wavefront-guided LASIK for the correction of low to moderate myopia using the VISX CustomVue technology (Abbott Medical Optics, Inc., Santa Ana, CA).

METHODS:

This was a prospective study including 255 consecutive eyes of 145 patients (age range: 19 to 55 years) with low to moderate myopia (mean spherical equivalent: −3.36 ± 1.71 diopters [D]) undergoing laser refractive surgery. Wavefront-guided LASIK was performed in all eyes using the VISX STAR S4 IR excimer laser platform and the CustomVue procedure for the ablation profile design. Visual, refractive, and contrast sensitivity changes were evaluated during a 4-year follow-up period.

RESULTS:

Postoperative logMAR uncorrected distance visual acuity was 0.1 or better (20/25 Snellen) in 98.0% and 100% of eyes at 1 and 4 years, respectively. At 4 years postoperatively, mean spherical equivalent was reduced significantly to a mean value of −0.22 ± 0.28 D (P < .01), with 97.3% of eyes with a spherical equivalent within ±0.50 D. The astigmatic power vector component J0 of manifest refraction was also reduced significantly (P < .01). Postoperative logMAR corrected distance visual acuity was 0.0 or better (20/20 Snellen) in 96.1% and 98.8% of eyes at 1 and 4 years, respectively. Improvement in contrast sensitivity was observed in some spatial frequencies between 1 and 4 years postoperatively. No significant correlations were found between 4-year contrast sensitivity and corrected distance visual acuity (0.024 ⩽ r ⩽ −0.120, P ⩾ .06).

CONCLUSION:

Wavefront-guided LASIK using the VISX CustomVue technology provides an effective and predictable correction of low to moderate myopia in the long term, preserving the patient’s visual acuity and quality.

[J Refract Surg. 2013;29(12):816–822.]

From the University of Alexandria, Alexandria, Egpyt (MSS, THM); Horus Vision Correction Centre, Alexandria, Egypt (HE); and Tanta University, Tanta, Egypt (MAK).

The authors have no financial or proprietary interest in the materials presented herein.

The authors thank Investigación Personalizada al Servicio de la Salud, Alicante, Spain, for the collaboration in this study.

AUTHOR CONTRIBUTIONS

Study concept and design (MSS); data collection (MSS, HE, MAK); analysis and interpretation of data (MSS, THM); drafting of the manuscript (MSS, THM, HE); critical revision of the manuscript (MSS, THM, MAK); statistical expertise (THM); administrative, technical, or material support (THM); supervision (MSS)

Correspondence: Mohamed Shafik Shaheen, MD, PhD, University of Alexandria, P. O. Box 27, Ibrahimia, Alexandria 21321, Egypt. E-mail: m.shafik@link.net

Received: March 16, 2013
Accepted: August 05, 2013
Posted Online: October 30, 2013

Wavefront-guided ablations have been effective in minimizing aberrations in eyes without previous corneal refractive surgeries, providing an excellent postoperative visual acuity.1–8 Aberrometric correction can be compromised significantly if the centration of the procedure is not extremely precise. Bueeler et al.9 reported that a lateral alignment accuracy of 0.07 mm or less would be required to achieve a diffraction limited vision in 95% of normal eyes for a 7.0-mm pupillary diameter. Iris registration technology provides further optimization to wavefront-guided laser treatment by considering a static reference point for centration, the iris periphery, instead of the pupillary center that may change significantly with variable illumination conditions.10

The CustomVue laser platform (Abbott Medical Optics, Inc., Santa Ana, CA) uses iris registration and has been shown to provide excellent visual and refractive results following wavefront-guided ablation.11–13 Most of the studies reported with this laser platform showed the results obtained in a short-term period, between 3 and 12 months postoperatively. However, there are no reports on the stability or usefulness of the aberrometric optimization with this technology over a longer period. Corneal biomechanical changes14 and ocular changes associated with age15–17 may limit the potential of the correction achieved with wavefront-guided ablation profiles. The aim of this prospective, noncomparative study was to investigate the efficacy, predictability, and stability of wavefront-guided LASIK treatments for the correction of myopia or myopic astigmatism using the iris registration technology during a 4-year follow-up period.

Patients and Methods

Patients

This prospective, noncomparative study included a total of 255 consecutive eyes of 145 patients undergoing wavefront-guided LASIK using the VISX STAR S4 IR excimer laser platform (Abbott Medical Optics, Inc.) at Horus Vision Correction Center, Alexandria, Egypt. Inclusion criteria consisted of a preoperative myopic spherical equivalent (range: −0.5 to −9.0 diopters [D]) with astigmatism up to 5.0 D at the spectacle plane, an age of 18 years or older, and a stable refraction. Patients diagnosed as having postoperative residual error or regression requiring re-intervention (n = 3) were excluded from the analysis, reducing the total eyes to 252. Patients who wore contact lenses were asked to discontinue their use for at least 1 week for soft contact lenses and 3 weeks for rigid gas permeable contact lenses before preoperative examination. This study was reviewed and approved by the Institutional Review Board at Horus Vision Correction Center in Alexandria, Egypt. Written informed consent was obtained from all patients before participation in the study.

Preoperative and Postoperative Examination

Preoperative evaluation included manifest and cycloplegic refraction, uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) testing, pupil diameter measurement under both photopic and mesopic conditions using the Colvard pupillometer (Oasis, Glendora, CA), corneal topography, and anterior segment imaging using the Pentacam-HR system (Oculus, Inc., Berlin, Germany), slit-lamp examination, and applanation tonometry. The WaveScan aberrometer (Hartmann-Shack wavefront sensor; Abbott Medical Optics, Inc.) was used for the preoperative measurement of wavefront aberrations (6-mm pupil). Data obtained with this instrument were used for the planning of the most optimum ablation profile for each case (wavefront-guided ablation). Target postoperative refraction was emmetropia in all eyes. The ablation profile was designed and calculated using the commercially available software CustomVue. For this purpose, aberrometric data, manifest refraction, central corneal pachymetric measurements, and the intended flap thickness were introduced in the software.

Postoperatively, patients were examined on day 1, 1 week, and 1, 3, 6, 12, 24, and 48 months after surgery. UDVA, manifest refraction, and CDVA testing, as well as biomicroscopic examination, were performed. Mesopic contrast sensitivity testing using the CVS-1000HGT chart (Vector-Vision Inc., Greenville, OH) with and without a glare source was done at the 12- and 48-month follow-up visits to check for the stability of the visual quality experienced by the patients. To simplify the analysis of postoperative data, we only report in the current study the postoperative outcomes at 12 and 48 months.

Surgery

All surgical procedures were performed by the same surgeon (MS) at Horus Vision Correction Centre. The treatment designed with the CustomVue software, according to the preoperative refraction and aberrometric profile, were loaded into the excimer laser computer and reviewed by the surgeon to confirm the data. The VISX STAR S4 IR excimer laser platform was used to perform all ablation procedures. After ablation profile confirmation by the surgeon, a corneal flap was created by means of the mechanical microkeratome Moria M2 (Moria, Antony, France) and lifted to expose the stromal bed. The programmed treatment was then applied on the corneal stroma. All surgeries were performed under topical anesthesia. Postoperative treatment consisted of topical antibiotics, topical steroids, and topical preservative free artificial tears drops.

Refraction Notation

The spherocylindrical refractions obtained before and after surgery were converted to vectorial notation using the power vector method described by Thibos and Horner.18 Using this procedure, any spherocylindrical refractive error could be expressed by three dioptric powers: M, J0, and J45, where M is a spherical lens equal to the spherical equivalent of the given refractive error and J0 and J45 are two Jackson crossed cylinders equivalent to the conventional cylinder. These numbers represent the coordinates of a point in a three-dimensional dioptric space (M, J0, and J45). The length of this vector is a measure of the overall blurring strength of a spherocylindrical refractive error.

Statistical Analysis

Data analysis was performed using SPSS software version 19.0 (SPSS, Inc., Chicago, IL) for Windows (Microsoft Corporation, Redmond, WA). Normality of data samples were evaluated by means of the Kolmogorov–Smirnov test. When parametric analysis was possible, the paired t test was used for comparisons between the preoperative and postoperative data and the Student’s t test for comparison between postoperative data from consecutive visits, whereas the Wilcoxon rank sum test (for comparisons between the preoperative and postoperative data) and Mann–Whitney U test (for comparison between postoperative data from consecutive visits) were applied to assess the significance of such differences when parametric analysis was not possible. Differences were considered to be statistically significant when the associated P value was less than .05. Correlation coefficients (Pearson or Spearman depending if normality condition could be assumed) were used to assess the correlation between different variables. The standard graphs for reporting the outcomes in refractive surgery according to the Waring protocol19 were used for displaying and summarizing the main outcomes of this study.

Results

Mean patient age of the analyzed sample was 31.4 years (standard deviation: 3.1; range: 19 to 55 years). Sixty-five patients (44.8%) were males and 80 were females (55.2%). Table 1 summarizes the preoperative and postoperative visual and refractive outcomes.

Visual and Refractive Outcomes During the Follow-Up Period

Table 1:

Visual and Refractive Outcomes During the Follow-Up Period

Visual Outcomes

A logMAR UDVA of 0.0 (20/20 Snellen) or better was achieved in 68.2% of eyes (n = 172) at 1 year postoperatively and 75.3% of eyes (n = 190) at 4 years follow-up (Figure 1).

Comparative distribution of the preoperative corrected distance visual acuity (CDVA) and the uncorrected distance visual acuity (UDVA) during the follow-up period.

Figure 1:

Comparative distribution of the preoperative corrected distance visual acuity (CDVA) and the uncorrected distance visual acuity (UDVA) during the follow-up period.

A logMAR CDVA of 0.0 (approximately 20/20 Snellen) or better was achieved in 96.1% of eyes (n = 242) at the 1 year and 98.8% of eyes (n = 249) at 4 years postoperatively.

A minimal but statistically significant worsening in postoperative logMAR CDVA was found 1 year after surgery (Wilcoxon test, P < .01), with a small but statistically significant improvement 4 years after surgery (Wilcoxon test, P < .01).

No statistically significant difference was detected on comparing the 1- and 4-year UDVA results (Wilcoxon test, P = .147), whereas a minimal but statistically significant difference was found on comparing the 1- and 4-year CDVA results, with the 4-year results being slightly better (Wilcoxon test, P < .01) (Table 1).

A loss of two or more lines of CDVA was not observed in any case, whereas losses of one line of CDVA were observed in 1.58% (4 eyes) and 0.39% (1 eye) of eyes at 1 and 4 years postoperatively, respectively (Figure 2). On the other hand, gains of lines of CDVA were detected in a total of 13 eyes (5.2%) and 62 eyes (24.6%) at 1 and 4 years postoperatively, respectively (Figure 2).

Distribution of changes in postoperative corrected distance visual acuity (CDVA) during the follow-up period.

Figure 2:

Distribution of changes in postoperative corrected distance visual acuity (CDVA) during the follow-up period.

Refractive Outcomes

Statistically significant reductions in blurring strength and M values were found at 1 year postoperatively (Wilcoxon test, P < .01), with a small but statistically significant regression of the refractive effect achieved 4 years after surgery (Wilcoxon test, P < .01) (Figure 3). Regarding predictability, 251 eyes (99.6%) and all eyes (100%) had a postoperative value of M (spherical equivalent) within ±1.00 D of emmetropia at 1 and 4 years after surgery, respectively (Figure 4). Likewise, 236 eyes (93.7%) and 245 eyes (97.3%) had a postoperative M value within ±0.50 D of emmetropia at 1 and 4 years after surgery, respectively (Figure 4). Figure 5 shows the achieved spherical equivalent correction at the end of the follow-up period plotted against the intended. A strong and statistically significant correlation was found among the achieved and the intended correction (r = 0.99, P < .01). Regarding astigmatic outcomes (Table 1), a statistically significant reduction was detected in the power vector component J0 at 1 year postoperatively and between 1 and 4 years after surgery (Wilcoxon test, P < .01). The power vector component J45 did not show a significant change during the first postoperative year (Wilcoxon test, P = .60), but it decreased significantly at the end of the follow-up (Wilcoxon test, P = .02).

Stability of the postoperative spherical equivalent during the follow-up period.

Figure 3:

Stability of the postoperative spherical equivalent during the follow-up period.

Distribution of the postoperative spherical equivalent during the follow-up period. D= diopters

Figure 4:

Distribution of the postoperative spherical equivalent during the follow-up period. D= diopters

Scattergram showing the relationship between the achieved and intended postoperative spherical equivalent (SE) correction.

Figure 5:

Scattergram showing the relationship between the achieved and intended postoperative spherical equivalent (SE) correction.

Mesopic Contrast Sensitivity Outcomes

Table 2 summarizes the monocular contrast sensitivity outcomes with and without a glare source obtained in the analyzed sample under mesopic conditions postoperatively. Both tests showed slightly better but no statistically significant results for 3 cycles per degree (cpd) at 1 year compared to 4 years postoperatively. However, for the three remaining spatial frequencies (6, 12, and 18 cpd), the 4-year contrast sensitivity testing results showed higher values than those recorded at the 1-year follow-up, but only that of the 6 cpd was statistically significant (contrast without glare P = .000, contrast with glare P = .007) (Figure A, available in the online version of this article).

Comparison of Contrast Sensitivity Testing Results With and Without a Glare Source at 1 and 4 Years Postoperatively

Table 2:

Comparison of Contrast Sensitivity Testing Results With and Without a Glare Source at 1 and 4 Years Postoperatively

A weak negative but statistically significant correlation was found between some values of contrast sensitivity and CDVA 1 year after surgery: no glare 3 cpd (r = −0.168, P = .01), glare 6 cpd (r = −0.156, P = 0.01), and glare 18 cpd (r = −0.134, P = .03). However, no significant correlations were found between CDVA at 4 years postoperatively and contrast sensitivity for any of the spatial frequencies evaluated (0.024 ⩽ r ⩽ −0.120, P ⩾ .06).

Discussion

To date, all clinical studies on wavefront-guided LASIK focused on the short-term outcomes, with follow-up periods of 12 months at the most. Kashani et al.20 reported the results of wavefront-guided retreatments after primary wavefront-guided LASIK in myopes and hyperopes with longer follow-up periods (mean: 17.75 months). Therefore, there exists no scientific evidence of the stability of wavefront-guided LASIK over medium- and long-term periods.

In the current study, excellent UDVA was achieved postoperatively in almost all cases, with a logMAR value of 0.1 (approximately 20/25 Snellen) or better in almost all eyes (> 98%) during the entire follow-up. This is consistent with the outcomes reported with wavefront-guided LASIK in previous studies using the same laser platform1,2,4,11–13 and other platforms (Table 3).3–5,7,8 As expected, this excellent visual outcome was associated with a significant reduction of the spherocylindrical error, which was statistically significant 1 year after surgery. However, a slight but statistically significant regression of the corrective effect achieved was observed at the end of the follow-up period. This same trend has been reported with standard LASIK in the long-term, especially in cases of high myopia.21–23 Several factors may have accounted for this phenomenon, such as the growth of the axial length in the younger myopic population,24 corneal biomechanical changes,14 late stromal and epithelial healing changes,25 and even changes in the corneal refractive index.26 The percentage of eyes in our study at the end of the follow-up period was 100% within ±1.00 D of emmetropia and 97.3% within ±0.50 D of emmetropia, with only three re-treatments required during the follow-up. These values are equivalent and even better than those obtained with other excimer laser platforms also providing wavefront-guided treatments (Table 3).3–5,7,8 In addition, it should be mentioned that eyes from our series with the least predictable outcomes were those with the highest values of preoperative myopia, as shown in Figure 4. This is logical because corneal remodeling plays a special role in such types of eyes in which a significant ablation depth is required and, consequently, a more significant corneal alteration is induced. Indeed, it has been demonstrated that the epithelial hyperplasia is a key factor in the regression of refractive effect after LASIK to correct high myopia.27 Regarding astigmatic correction, it was found to be effective in the initial postoperative period with a late change in J0 and J45, confirming a slight change in the astigmatic axis with time. This phenomenon is possibly associated with those factors leading to some degree of myopic regression with time, especially in high myopic eyes.

Comparative Table of the Visual and Refractive Outcomes Obtained With Wavefront-Guided LASIK in Previous Studies Using Different Excimer Laser Platforms

Table 3:

Comparative Table of the Visual and Refractive Outcomes Obtained With Wavefront-Guided LASIK in Previous Studies Using Different Excimer Laser Platforms

A minimal but statistically significant worsening in logMAR CDVA was found at 1 year postoperatively. In most previous studies on wavefront-guided LASIK, maintenance or even an improvement in CDVA was observed.1–8,11–13

At the end of the follow-up period, only 1 eye (0.39%) lost one line of CDVA, a similar percentage found in a previous study using the same laser platform and evaluating the outcomes during a 6-month follow-up period.6 In other studies evaluating the outcomes after wavefront-guided LASIK in the short term, the percentages of eyes losing lines of CDVA were somewhat higher than those presented in our study. Future studies should also evaluate whether the aberrometric optimization achieved with wavefront-guided LASIK treatments minimizes or slows down the impact of aberrometric modifications associated with age.15–17 This would also help explain the trend to CDVA improvement in the medium term of this study.

Regarding mesopic contrast sensitivity (with and without glare), only the 6 cpd spatial frequency showed significant improvement at 4 years compared to 1 year postoperatively. Artal et al. reported that the decrease in the contrast sensitivity at low spatial frequencies is attributable to neural processing of the retinal image, which is known to decline with age, whereas the higher spatial frequencies are affected mainly by the quality of the ocular optics.28 This suggests that the improvement in visual quality at higher spatial frequencies at 4 years can be attributed to improved optics by the wavefront-guided correction and the neural adaptation to the new refractive status.29 Furthermore, weak negative but statistically significant correlations were found between 1-year contrast sensitivity for the different spatial frequencies analyzed and the CDVA. All of them were inverse and, therefore, the better the CDVA, the higher the contrast sensitivity. However, all of these trends disappeared at the end of the follow-up, with the absence of correlation between contrast sensitivity and CDVA.

Ocular wavefront-guided LASIK using the VISX STAR S4 IR excimer laser platform is an effective and predictable procedure for the correction of low to moderate myopia and/or myopic astigmatism maintaining an excellent and stable level of visual quality in the medium term. Future studies with longer follow-ups are necessary to confirm the stability of the outcomes reported here. Future studies should try to elucidate whether the aberrometric optimization achieved with this type of wavefront-guided LASIK treatments provides an advantage for achieving a better tolerance to the impact of aberrometric modifications associated with age.

References

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Mean monocular contrast sensitivity (CS) function measured under mesopic conditions with and without glare at 1 and 4 years postoperatively. c/d = cycle per degree

Figure A. Mean monocular contrast sensitivity (CS) function measured under mesopic conditions with and without glare at 1 and 4 years postoperatively. c/d = cycle per degree

Visual and Refractive Outcomes During the Follow-Up Period

VariablePreoperative1 Year Postoperative4 Year PostoperativeP (Preoperative to 4 Years)P (1 to 4 Years)
logMAR UDVA
  Mean ± SD0.03 ± 0.080.01 ± 0.07.147
  Median (range)0.04 (−0.60 to 0.60)0.02 (−0.10 to 0.10)
Manifest sphere (D)
  Mean ± SD−2.37 ± 1.67−0.08 ± 0.22−0.14 ± 0.25< .01.016
  Median (range)−2.00 (−7.00 to 0.00)0.00 (−1.25 to 0.75)0.00 (−0.75 to +1.00)
Manifest cylinder (D)
  Mean ± SD−1.98 ± 1.21−0.14 ± 0.22−0.16 ± 0.23< .01.255
  Median (range)−1.75 (−6.00 to 0.00)0.00 (−0.75 to 0.00)0.00 (−0.75 to 0.00)
J0 (D)
  Mean ± SD0.69 ± 0.750.05 ± 0.100.01 ± 0.10< .01
  Median (range)0.67 (−1.62 to 2.73)0.00 (−0.37 to 0.35)0.00 (−0.33 to 0.37)
J45 (D)
  Mean ± SD0.01 ± 0.560.003 ± 0.067−0.01 ± 0.10.56
  Median (range)0.00 (−1.62 to 2.60)0.00 (−0.24 to 0.30)0.00 (−0.35 to 0.25)
B (D)
  Mean ± SD3.57 ± 1.690.20 ± 0.240.27 ± 0.28< .01
  Median (range)3.26 (1.03 to 8.86)0.18 (0.00 to 1.52)0.25 (0.00 to 0.95)
M (D)
  Mean ± SD−3.36 ± 1.71−0.15 ± 0.24−0.22 ± 0.28< .01.000
  Median (range)−3.00 (−8.50 to −0.88)0.00 (−1.50 to 0.50)−0.13 (−0.88 to 0.88)
logMAR CDVA
  Mean ± SD−0.02 ± 0.05−0.01 ± 0.07−0.05 ± 0.04< .01.0000
  Median (range)−0.02 (−0.10 to 0.12)0.00 (−0.60 to 0.60)−0.04 (−0.20 to 0.10)

Comparison of Contrast Sensitivity Testing Results With and Without a Glare Source at 1 and 4 Years Postoperatively

VariableContrast Sensitivity Without GlareContrast Sensitivity With Glare


1 Year4 YearsTest of Significance Student’s t TestP1 Year4 YearsTest of Significance Student’s t TestP
3 cpd5.96435.82541.87.0624.69054.63100.852.395
6 cpd5.58735.8929−3.586.0004.41274.6508−2.721.007
12 cpd5.19055.2421−0.565.5723.90084.0159−1.364.173
18 cpd4.98815.0516−0.753.4523.55563.7778−2.406.017

Comparative Table of the Visual and Refractive Outcomes Obtained With Wavefront-Guided LASIK in Previous Studies Using Different Excimer Laser Platforms

Study (y)No. of EyesPreoperative SE Mean (SD) (Range)Laser Platform Technology and MicrokeratomeSE ±0.50, ±1.00 DlogMAR UDVA 0.1 or BetterLoss of Lines of CDVAFollow-up (Months)
Current study (2012)255−3.36 (1.71)VISX STAR S4 IR97.3%, 100%100%0.39%48
−8.50 to −0.88M2
Perez-Straziota et al.1 (2010)66−3.48 (2.00)VISX STAR S4 IR96%, ±0.50No losses3
−9.75 to −0.25Amadeus II⩾ 2 lines
Moshirfar et al.2 (2010)102−4.27 (2.21)VISX STAR S4 IR89%, ±0.5019%6
−9.11 to −0.36IntraLase 60 kHz
Keir et al.3 (2009)162−3.25 (1.30)LADAR-Vision400080.9%, ±0.504.9%6
−1.00 to −7.13Hansatome
Awwad et al.4 (2007)50−3.26 (1.56)VISX STAR S4 IR96%, ±0.5098%10%3
50−3.70 (1.64)LADAR-Vision4000 Hansatome96%, ±0.5098%12%3
Alió and Montés-Micó5 (2006)20−2.01 (1.36)Technolas 217z Hansatome94.4%, ±0.50100%0%6
Jabbur et al.6 (2005)277−3.20 (1.30)VISX STAR S490.3%, 99.3%0%6
−0.60 to −6.00Hansatome or Amadeus II
Kanjani et al.7 (2004)150−5.25 (1.68)Technolas 217z79.92%, 87.91%7.93%6
−0.87 to −15.00Hansatome
Kohnen et al.8 (2004)97−5.22 (2.07)Technolas 217z77%, 95%No losses12
−0.25 to −9.00Hansatome⩾ 2 lines

10.3928/1081597X-20131023-04

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