- Email: [email protected]
Visual acuity and higher-order aberrations with wavefront-guided and wavefront-optimized laser in situ keratomileusis
ARTICLE
Visual acuity and higher-order aberrations with wavefront-guided and wavefront-optimized laser in situ keratomileusis Claudia E. Perez-Straziota, MD, J. Bradley Randleman, MD, R. Doyle Stulting, MD, PhD
PURPOSE: To compare visual acuity and higher-order aberrations (HOAs) after wavefront-guided and wavefront-optimized laser in situ keratomileusis (LASIK). METHODS: This retrospective study comprised refraction-matched myopic eyes that had wavefront-guided (Visx Star S4 laser) or wavefront-optimized (WaveLight Allegretto Wave laser) LASIK targeted for emmetropia. Preoperative and postoperative manifest refraction spherical equivalent (MRSE), uncorrected (UDVA) and corrected (CDVA) distance visual acuities, and preoperative and postoperative HOAs were compared. RESULTS: Preoperatively, there were no significant differences between the wavefront-guided and wavefront-optimized groups in age, sex, corneal thickness, MRSE, or HOAs (all P>.05). The mean MRSE was 2.88 diopters (D) G 2.6 (SD) and 2.96 G 2.6 D, respectively, preoperatively and 0.01 G 0.25 D and 0.02 G 0.33 D, respectively, postoperatively; 96% of all eyes were within G0.50 D of emmetropia postoperatively. There were no differences in UDVA, CDVA, MRSE, or HOAs between groups (all P>.05). The UDVA was 20/20 or better in 85% of eyes in the wavefront-guided group and 86% of eyes in the wavefront-optimized group. All eyes had 20/25 or better CDVA postoperatively; no eye lost 2 lines of CDVA. Fourteen eyes were converted from wavefrontguided to wavefront-optimized treatment because of poor limbal ring alignment (8 eyes), a wave scan not consistent with the manifest refraction (5 eyes), and no iris registration (1 eye). CONCLUSIONS: Wavefront-guided LASIK and wavefront-optimized LASIK produced equivalent visual outcomes and no differences in HOAs. Wavefront-guided treatment could not be performed in many eyes because of difficulties during wavefront measurement. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes. J Cataract Refract Surg 2010; 36:437–441 Q 2010 ASCRS and ESCRS
Several excimer laser platforms are available today. Although a variety of terminology has been used to label, identify, and differentiate treatment modalities, the most commonly used include conventional laser in situ keratomileusis (LASIK); wavefront-guided treatments, which customize ablation patterns based on higher- and lower-order aberration profiles unique to the eye being treated; and wavefront-optimized treatments, which take some eye variables into account but use preprogrammed ablation profiles based on population analysis. Conventional LASIK induces higher-order aberrations (HOAs).1–7 Wavefront-guided treatments are intended to reduce preoperative HOAs, and wavefront-optimized treatments are intended to minimize the induction of postoperative HOAs; both Q 2010 ASCRS and ESCRS Published by Elsevier Inc.
modalities appear to minimize postoperative HOA changes significantly compared with conventional LASIK treatments.8–11 There are some reported differences in the outcomes of wavefront-guided and wavefront-optimized platforms; however, few studies have directly compared the outcomes of these different technologies.8,12–14 The results in these studies are inconsistent, with some indicating an advantage for wavefront-guided treatments8,12 and others finding no significant differences between the 2 treatment algorithms for patients without significant preoperative HOAs.13 The purpose of this study was to compare the postoperative outcomes of wavefront-guided LASIK and wavefront-optimized LASIK for myopia. 0886-3350/10/$dsee front matter doi:10.1016/j.jcrs.2009.09.031
437
438
WAVEFRONT-GUIDED AND WAVEFRONT-OPTIMIZED LASIK OUTCOMES
PATIENTS AND MATERIALS
Table 1. Patient demographics.
A retrospective study was conducted to compare LASIK outcomes of age-matched and refraction-matched myopic eyes treated with the Visx S4 Star wavefront-guided excimer laser (Abbott Medical Optics) (wavefront-guided group) or the wavefront-optimized Allegretto Wave excimer laser (WaveLight AG) (wavefront-optimized group). Overall, both lasers have been found to be safe and effective for the treatment of myopia and hyperopia.3,15–17 The LASIK surgeries were performed at Emory Vision, Atlanta, Georgia, USA, from December 2006 to December 2007. All LASIK flaps were created with an Amadeus II microkeratome (Ziemer Ophthalmics Systems AG) with a nasally placed hinge. Emory University Institutional Review Board approval was granted for this study. All eyes included in the analysis were targeted for emmetropia. Eyes were excluded from the study if they were not targeted for emmetropia or had previous ocular surgery, insufficient preoperative data, or incomplete postoperative follow-up. Preoperative data collected included patient age and sex, refractive error, HOAs measured with a corneal analyzer (OPD-Scan ARK-10000, Nidek, Inc.), corneal thickness, and corrected distance visual acuity (CDVA). In the wavefrontguided group, wave-scan measurements were also performed and iris registration was obtained. Iris registration was used to align the topography wavefronts. If the wavefront refraction differed from the subjective refraction (obtained by 2 different technicians on 2 different days) by greater than 0.50 diopter (D), patients were taken to the examination room and shown the wavefront refraction in the phoropter to encourage them to accept the wavefront refraction with minimum modification. If agreement about the 0.50 D spherical component, 0.50 D cylindrical component, and 10-degree axis could not be obtained, patients were not treated with the wavefront-guided laser. At least 5 wave scans were attempted before it was concluded that a consistent wave scan could not be obtained. Postoperative data recorded included 3-month postoperative UDVA, CDVA, manifest refraction spherical equivalent (MRSE), and changes in HOA profiles. Statistical analysis to compare the outcomes in the 2 groups was performed using the Student t test. A P value of 0.05 was considered statistically significant. Mean values are given with the standard deviation.
Group
Demographic Age (y) Mean G SD Range Sex (% male) Mean corneal thickness (mm) G SD MRSE (D) Mean G SD Range
Wavefront Guided (n Z 66)
Wavefront Optimized (n Z 66)
38 G 10 21 to 60 51 551 G 30
39 G 9 18 to 60 48 551 G 28
3.48 G 2.0 0.25 to 9.75
3.62 G 2.0 0.88 to 10.25
P Value .1
.6 .7 .8
MRSE Z manifest refraction spherical equivalent
RESULTS The study evaluated 134 eyes, 66 eyes (33 patients) in the wavefront-guided group and 66 eyes (45 patients) in the wavefront-optimized group. There were no statistically significant differences between groups in preoperative age, sex, corneal thickness, or MRSE (Table 1) or in preoperative HOA profiles (Table 2). The mean postoperative UDVA and CDVA were 20/21 and 20/17, respectively, in the wavefrontguided group and 20/19 and 20/17, respectively, in the wavefront-optimized group. Most eyes in both groups achieved 20/20 or better UDVA, with no statistically significant differences between groups (Figure 1). All eyes achieved 20/25 or better CDVA postoperatively, and no eye lost 2 or more lines of CDVA (Figure 2). The mean postoperative MRSE was 0.01 G 0.21 D (range C0.88 to 0.75 D) in the wavefront-guided group and 0.01 G 0.34 D (range C0.63 to 1.50 D) in the wavefront-optimized group (P Z .9); 96% of eyes in both groups were within
Table 2. Preoperative HOAs.
Submitted: March 8, 2009. Final revision submitted: August 31, 2009. Accepted: September 14, 2009.
Mean (mm) G SD
From Emory Vision, Atlanta, Georgia, USA. Additional financial disclosures: Dr. Stulting is a consultant to Alcon, Inc., and Abbott Medical Optics. Supported in part by Research to Prevent Blindness, Inc. New York, New York, and the National Institutes of Health Core Grant P30 EYO6360, Bethesda, Maryland, USA. Corresponding author: J. Bradley Randleman, MD, 1365 B Clifton Road Northeast, Suite 4500, Atlanta, Georgia 30322, USA. E-mail: [email protected].
HOA RMS Total HOA Coma Trefoil Tetrafoil Spherical aberration
WavefrontGuided Group
WavefrontOptimized Group
P Value
0.13 G 0.06 0.05 G 0.03 0.10 G 0.07 0.03 G 0.03 0.03 G 0.02
0.16 G 0.17 0.05 G 0.03 0.12 G 0.17 0.04 G 0.04 0.02 G 0.02
.2 .3 .4 .1 .5
HOA RMS Z higher-order aberration root mean square value
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Figure 1. Postoperative UDVA by group (UDVA Z uncorrected distance visual acuity).
Figure 2. Postoperative CDVA by group (CDVA Z corrected distance visual acuity).
G0.50 D of emmetropia. There were no statistically significant differences in refractive outcomes between the 2 groups (Figure 3). There were no statistically significant differences in postoperative HOAs between groups (Figure 4) or in HOA changes between groups (Figure 5).
Fourteen eyes scheduled for treatment with the wavefront-guided laser could not have wavefrontguided treatment for the following reasons: poor limbal ring alignment (8 eyes), wave scan not consistent with manifest refraction (5 eyes), and no iris registration (1 eye). These eyes were all successfully treated with the wavefront-optimized laser.
DISCUSSION We found no significant differences in outcomes between wavefront-guided and wavefront-optimized excimer laser treatments. Specifically, there were no
Figure 3. Postoperative MRSE by group (MRSE Z manifest refraction spherical equivalent).
Figure 4. Postoperative HOAs by group (HOA Z higher-order aberration).
J CATARACT REFRACT SURG - VOL 36, MARCH 2010
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WAVEFRONT-GUIDED AND WAVEFRONT-OPTIMIZED LASIK OUTCOMES
Figure 5. Postoperative change in HOAs by group (HOA Z higherorder aberration).
significant differences in HOA profiles or postoperative HOA changes despite the purported superiority of wavefront-guided ablation patterns. Furthermore, the wavefront-optimized laser was easier and more versatile to use; 14 eyes scheduled for treatment with the wavefront-guided laser were converted to treatment with the wavefront-optimized laser for a variety of reasons. Other studies comparing wavefront-guided and wavefront-optimized treatments report mixed results. Moshirfar et al.18 and Awwad et al.19 compared outcomes of wavefront-guided LASIK with the CustomCornea platform (Alcon) and the wavefront-guided platform we used in this study; Moshirfar et al. reported a slight advantage for the wavefront-guided platform we used and Awwad et al. for the other platform. Padmanabhan et al.8 compared wavefrontguided and wavefront-optimized treatments and found no statistically significant differences in visual acuity or refractive outcomes; however, they did find a statistically significant difference in the induction of HOAs, with wavefront-guided technology outperforming wavefront-optimized technology. Stonecipher and Kezarian13 found similar equivalent acuity and refractive outcomes between wavefront-guided and wavefront-optimized treatments and found that only small subpopulations of eyes with high preoperative aberrations benefited from wavefront-guided treatments. Brint12 found that wavefront-guided technology induced fewer HOAs, especially coma, than wavefront-optimized treatments. In contrast, Tran and Shah14 found no significant differences between the 2 platforms. In addition to equivalent visual acuity, refractive, and HOA outcomes in this study, we found the wavefront-optimized laser was more convenient to use. First, no additional measurements are required for wavefront-guided treatments with the laser we used,
and the measurements and treatment require an adequately dilated pupil. In our study, 14 eyes scheduled for treatment with the wavefront-guided laser were converted to treatment with the wavefront-optimized laser for reasons including poor limbal ring alignment, mismatch of wave-scan and manifest refractions, and pupils that were too small to obtain accurate wavescan measurements. Furthermore, although not included in this study, eyes intended for monovision treatments cannot, at present, have wavefront-guided treatment with the laser we used. In conclusion, our results suggest that there are no significant differences in clinical outcomes or HOAs between LASIK using wavefront-guided technology and LASIK using wavefront-optimized technology. However, wavefront-guided treatment could not be performed in many eyes due to difficulties during wavefront measurement. REFERENCES 1. Buzzonetti L, Iarossi G, Valente P, Volpi M, Petrocelli G, Scullica L. Comparison of wavefront aberration changes in the anterior corneal surface after laser-assisted subepithelial keratectomy and laser in situ keratomileusis: preliminary study. J Cataract Refract Surg 2004; 30:1929–1933 2. Chalita MR, Chavala S, Xu M, Krueger RR. Wavefront analysis in post-LASIK eyes and its correlation with visual symptoms, refraction, and topography. Ophthalmology 2004; 111:447–453 3. Chalita MR, Xu M, Krueger RR. Correlation of aberrations with visual symptoms using wavefront analysis in eyes after laser in situ keratomileusis. J Refract Surg 2003; 19:S682–S686 4. Melamud A, Chalita MR, Krueger RR, Lee MS. Comatic aberration as a cause of monocular diplopia. J Cataract Refract Surg 2006; 32:529–532 5. Sharma M, Wachler BS, Chan CCK. Higher order aberrations and relative risk of symptoms after LASIK. J Refract Surg 2007; 23:252–256 6. Moreno-Barriuso E, Merayo Lloves J, Marcos S, Navarro R, Llorente L, Barbero S. Ocular aberrations before and after myopic corneal refractive surgery: LASIK-induced changes measured with laser ray tracing. Invest Ophthalmol Vis Sci 2001; 42:1396–1403. Available at: http://www.iovs.org/cgi/reprint/42/ 6/1396.pdf. Accessed November 10, 2009 7. Yamane N, Miyata K, Samejima T, Hiraoka T, Kiuchi T, Okamoto F, Hirohara Y, Mihashi T, Oshika T. Ocular higherorder aberrations and contrast sensitivity after conventional laser in situ keratomileusis. Invest Ophthalmol Vis Sci 2004; 45:3986–3990. Available at: http://www.iovs.org/cgi/reprint/45/ 11/3986. Accessed November 10, 2009 8. Padmanabhan P, Mrochen M, Basuthkar S, Viswanathan D, Joseph R. Wavefront-guided versus wavefront-optimized laser in situ keratomileusis: contralateral comparative study. J Cataract Refract Surg 2008; 34:389–397 9. Racine L, Wang L, Koch DD. Size of corneal topographic effective optical zone: comparison of standard and customized myopic laser in situ keratomileusis. Am J Ophthalmol 2006; 142:227–232 10. Zhou C, Chai X, Yuan L, He Y, Jin M, Ren Q. Corneal higherorder aberrations after customized aspheric ablation and conventional ablation for myopic correction. Curr Eye Res 2007; 32:431–438
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11. Randleman JB, Perez-Straziota CE, Hu MH, White AJ, Loft ES, Stulting RD. Higher-order aberrations after wavefront-optimized photorefractive keratectomy and laser in situ keratomileusis. J Cataract Refract Surg 2009; 35:260–264 12. Brint SF. Higher order aberrations after LASIK for myopia with Alcon and WaveLight lasers: a prospective randomized trial. J Refract Surg 2005; 21:S799–S803 13. 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 14. Tran DB, Shah V. Higher order aberrations comparison in fellow eyes following IntraLase LASIK with WaveLight Allegretto and CustomCornea LADARvision4000 systems. J Refract Surg 2006; 22:S961–S964 15. Kanellopoulos AJ, Conway J, Pe LH. LASIK for hyperopia with the WaveLight excimer laser. J Refract Surg 2006; 22:43–47 16. Kezirian GM, Moore CR, Stonecipher KG. Four-year postoperative results of the US ALLEGRETTO WAVE clinical trial for the treatment of hyperopia; SurgiVisionÒ Consultants Inc WaveLight Investigator Group. J Refract Surg 2008; 24:S431–S438
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17. Kulkamthorn T, Silao JNI, Torres LF, Lim JN, Purcell TL, Tantayakom T, Schanzlin DJ. Wavefront-guided laser in situ keratomileusis in the treatment of high myopia by using the CustomVue wavefront platform. Cornea 2008; 27:787–790 18. Moshirfar M, Espandar L, Meyer JJ, Tanner JR, Holz HA. Prospective randomized trial of wavefront-guided laser in situ keratomileusis with the CustomCornea and CustomVue laser systems. J Cataract Refract Surg 2007; 33:1727–1733 19. Awwad ST, Bowman RW, Cavanagh HD, McCulley JP. Wavefront-guided LASIK for myopia using the LADAR CustomCornea and the VISX CustomVue. J Refract Surg 2007; 23:26–38
J CATARACT REFRACT SURG - VOL 36, MARCH 2010
First author: Claudia E. Perez-Straziota, MD Emory Vision, Atlanta, Georgia, USA
Visual acuity and higher-order aberrations with wavefront-guided and wavefront-optimized laser in situ keratomileusis Claudia E. Perez-Straziota, MD, J. Bradley Randleman, MD, R. Doyle Stulting, MD, PhD
PURPOSE: To compare visual acuity and higher-order aberrations (HOAs) after wavefront-guided and wavefront-optimized laser in situ keratomileusis (LASIK). METHODS: This retrospective study comprised refraction-matched myopic eyes that had wavefront-guided (Visx Star S4 laser) or wavefront-optimized (WaveLight Allegretto Wave laser) LASIK targeted for emmetropia. Preoperative and postoperative manifest refraction spherical equivalent (MRSE), uncorrected (UDVA) and corrected (CDVA) distance visual acuities, and preoperative and postoperative HOAs were compared. RESULTS: Preoperatively, there were no significant differences between the wavefront-guided and wavefront-optimized groups in age, sex, corneal thickness, MRSE, or HOAs (all P>.05). The mean MRSE was 2.88 diopters (D) G 2.6 (SD) and 2.96 G 2.6 D, respectively, preoperatively and 0.01 G 0.25 D and 0.02 G 0.33 D, respectively, postoperatively; 96% of all eyes were within G0.50 D of emmetropia postoperatively. There were no differences in UDVA, CDVA, MRSE, or HOAs between groups (all P>.05). The UDVA was 20/20 or better in 85% of eyes in the wavefront-guided group and 86% of eyes in the wavefront-optimized group. All eyes had 20/25 or better CDVA postoperatively; no eye lost 2 lines of CDVA. Fourteen eyes were converted from wavefrontguided to wavefront-optimized treatment because of poor limbal ring alignment (8 eyes), a wave scan not consistent with the manifest refraction (5 eyes), and no iris registration (1 eye). CONCLUSIONS: Wavefront-guided LASIK and wavefront-optimized LASIK produced equivalent visual outcomes and no differences in HOAs. Wavefront-guided treatment could not be performed in many eyes because of difficulties during wavefront measurement. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes. J Cataract Refract Surg 2010; 36:437–441 Q 2010 ASCRS and ESCRS
Several excimer laser platforms are available today. Although a variety of terminology has been used to label, identify, and differentiate treatment modalities, the most commonly used include conventional laser in situ keratomileusis (LASIK); wavefront-guided treatments, which customize ablation patterns based on higher- and lower-order aberration profiles unique to the eye being treated; and wavefront-optimized treatments, which take some eye variables into account but use preprogrammed ablation profiles based on population analysis. Conventional LASIK induces higher-order aberrations (HOAs).1–7 Wavefront-guided treatments are intended to reduce preoperative HOAs, and wavefront-optimized treatments are intended to minimize the induction of postoperative HOAs; both Q 2010 ASCRS and ESCRS Published by Elsevier Inc.
modalities appear to minimize postoperative HOA changes significantly compared with conventional LASIK treatments.8–11 There are some reported differences in the outcomes of wavefront-guided and wavefront-optimized platforms; however, few studies have directly compared the outcomes of these different technologies.8,12–14 The results in these studies are inconsistent, with some indicating an advantage for wavefront-guided treatments8,12 and others finding no significant differences between the 2 treatment algorithms for patients without significant preoperative HOAs.13 The purpose of this study was to compare the postoperative outcomes of wavefront-guided LASIK and wavefront-optimized LASIK for myopia. 0886-3350/10/$dsee front matter doi:10.1016/j.jcrs.2009.09.031
437
438
WAVEFRONT-GUIDED AND WAVEFRONT-OPTIMIZED LASIK OUTCOMES
PATIENTS AND MATERIALS
Table 1. Patient demographics.
A retrospective study was conducted to compare LASIK outcomes of age-matched and refraction-matched myopic eyes treated with the Visx S4 Star wavefront-guided excimer laser (Abbott Medical Optics) (wavefront-guided group) or the wavefront-optimized Allegretto Wave excimer laser (WaveLight AG) (wavefront-optimized group). Overall, both lasers have been found to be safe and effective for the treatment of myopia and hyperopia.3,15–17 The LASIK surgeries were performed at Emory Vision, Atlanta, Georgia, USA, from December 2006 to December 2007. All LASIK flaps were created with an Amadeus II microkeratome (Ziemer Ophthalmics Systems AG) with a nasally placed hinge. Emory University Institutional Review Board approval was granted for this study. All eyes included in the analysis were targeted for emmetropia. Eyes were excluded from the study if they were not targeted for emmetropia or had previous ocular surgery, insufficient preoperative data, or incomplete postoperative follow-up. Preoperative data collected included patient age and sex, refractive error, HOAs measured with a corneal analyzer (OPD-Scan ARK-10000, Nidek, Inc.), corneal thickness, and corrected distance visual acuity (CDVA). In the wavefrontguided group, wave-scan measurements were also performed and iris registration was obtained. Iris registration was used to align the topography wavefronts. If the wavefront refraction differed from the subjective refraction (obtained by 2 different technicians on 2 different days) by greater than 0.50 diopter (D), patients were taken to the examination room and shown the wavefront refraction in the phoropter to encourage them to accept the wavefront refraction with minimum modification. If agreement about the 0.50 D spherical component, 0.50 D cylindrical component, and 10-degree axis could not be obtained, patients were not treated with the wavefront-guided laser. At least 5 wave scans were attempted before it was concluded that a consistent wave scan could not be obtained. Postoperative data recorded included 3-month postoperative UDVA, CDVA, manifest refraction spherical equivalent (MRSE), and changes in HOA profiles. Statistical analysis to compare the outcomes in the 2 groups was performed using the Student t test. A P value of 0.05 was considered statistically significant. Mean values are given with the standard deviation.
Group
Demographic Age (y) Mean G SD Range Sex (% male) Mean corneal thickness (mm) G SD MRSE (D) Mean G SD Range
Wavefront Guided (n Z 66)
Wavefront Optimized (n Z 66)
38 G 10 21 to 60 51 551 G 30
39 G 9 18 to 60 48 551 G 28
3.48 G 2.0 0.25 to 9.75
3.62 G 2.0 0.88 to 10.25
P Value .1
.6 .7 .8
MRSE Z manifest refraction spherical equivalent
RESULTS The study evaluated 134 eyes, 66 eyes (33 patients) in the wavefront-guided group and 66 eyes (45 patients) in the wavefront-optimized group. There were no statistically significant differences between groups in preoperative age, sex, corneal thickness, or MRSE (Table 1) or in preoperative HOA profiles (Table 2). The mean postoperative UDVA and CDVA were 20/21 and 20/17, respectively, in the wavefrontguided group and 20/19 and 20/17, respectively, in the wavefront-optimized group. Most eyes in both groups achieved 20/20 or better UDVA, with no statistically significant differences between groups (Figure 1). All eyes achieved 20/25 or better CDVA postoperatively, and no eye lost 2 or more lines of CDVA (Figure 2). The mean postoperative MRSE was 0.01 G 0.21 D (range C0.88 to 0.75 D) in the wavefront-guided group and 0.01 G 0.34 D (range C0.63 to 1.50 D) in the wavefront-optimized group (P Z .9); 96% of eyes in both groups were within
Table 2. Preoperative HOAs.
Submitted: March 8, 2009. Final revision submitted: August 31, 2009. Accepted: September 14, 2009.
Mean (mm) G SD
From Emory Vision, Atlanta, Georgia, USA. Additional financial disclosures: Dr. Stulting is a consultant to Alcon, Inc., and Abbott Medical Optics. Supported in part by Research to Prevent Blindness, Inc. New York, New York, and the National Institutes of Health Core Grant P30 EYO6360, Bethesda, Maryland, USA. Corresponding author: J. Bradley Randleman, MD, 1365 B Clifton Road Northeast, Suite 4500, Atlanta, Georgia 30322, USA. E-mail: [email protected].
HOA RMS Total HOA Coma Trefoil Tetrafoil Spherical aberration
WavefrontGuided Group
WavefrontOptimized Group
P Value
0.13 G 0.06 0.05 G 0.03 0.10 G 0.07 0.03 G 0.03 0.03 G 0.02
0.16 G 0.17 0.05 G 0.03 0.12 G 0.17 0.04 G 0.04 0.02 G 0.02
.2 .3 .4 .1 .5
HOA RMS Z higher-order aberration root mean square value
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Figure 1. Postoperative UDVA by group (UDVA Z uncorrected distance visual acuity).
Figure 2. Postoperative CDVA by group (CDVA Z corrected distance visual acuity).
G0.50 D of emmetropia. There were no statistically significant differences in refractive outcomes between the 2 groups (Figure 3). There were no statistically significant differences in postoperative HOAs between groups (Figure 4) or in HOA changes between groups (Figure 5).
Fourteen eyes scheduled for treatment with the wavefront-guided laser could not have wavefrontguided treatment for the following reasons: poor limbal ring alignment (8 eyes), wave scan not consistent with manifest refraction (5 eyes), and no iris registration (1 eye). These eyes were all successfully treated with the wavefront-optimized laser.
DISCUSSION We found no significant differences in outcomes between wavefront-guided and wavefront-optimized excimer laser treatments. Specifically, there were no
Figure 3. Postoperative MRSE by group (MRSE Z manifest refraction spherical equivalent).
Figure 4. Postoperative HOAs by group (HOA Z higher-order aberration).
J CATARACT REFRACT SURG - VOL 36, MARCH 2010
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WAVEFRONT-GUIDED AND WAVEFRONT-OPTIMIZED LASIK OUTCOMES
Figure 5. Postoperative change in HOAs by group (HOA Z higherorder aberration).
significant differences in HOA profiles or postoperative HOA changes despite the purported superiority of wavefront-guided ablation patterns. Furthermore, the wavefront-optimized laser was easier and more versatile to use; 14 eyes scheduled for treatment with the wavefront-guided laser were converted to treatment with the wavefront-optimized laser for a variety of reasons. Other studies comparing wavefront-guided and wavefront-optimized treatments report mixed results. Moshirfar et al.18 and Awwad et al.19 compared outcomes of wavefront-guided LASIK with the CustomCornea platform (Alcon) and the wavefront-guided platform we used in this study; Moshirfar et al. reported a slight advantage for the wavefront-guided platform we used and Awwad et al. for the other platform. Padmanabhan et al.8 compared wavefrontguided and wavefront-optimized treatments and found no statistically significant differences in visual acuity or refractive outcomes; however, they did find a statistically significant difference in the induction of HOAs, with wavefront-guided technology outperforming wavefront-optimized technology. Stonecipher and Kezarian13 found similar equivalent acuity and refractive outcomes between wavefront-guided and wavefront-optimized treatments and found that only small subpopulations of eyes with high preoperative aberrations benefited from wavefront-guided treatments. Brint12 found that wavefront-guided technology induced fewer HOAs, especially coma, than wavefront-optimized treatments. In contrast, Tran and Shah14 found no significant differences between the 2 platforms. In addition to equivalent visual acuity, refractive, and HOA outcomes in this study, we found the wavefront-optimized laser was more convenient to use. First, no additional measurements are required for wavefront-guided treatments with the laser we used,
and the measurements and treatment require an adequately dilated pupil. In our study, 14 eyes scheduled for treatment with the wavefront-guided laser were converted to treatment with the wavefront-optimized laser for reasons including poor limbal ring alignment, mismatch of wave-scan and manifest refractions, and pupils that were too small to obtain accurate wavescan measurements. Furthermore, although not included in this study, eyes intended for monovision treatments cannot, at present, have wavefront-guided treatment with the laser we used. In conclusion, our results suggest that there are no significant differences in clinical outcomes or HOAs between LASIK using wavefront-guided technology and LASIK using wavefront-optimized technology. However, wavefront-guided treatment could not be performed in many eyes due to difficulties during wavefront measurement. REFERENCES 1. Buzzonetti L, Iarossi G, Valente P, Volpi M, Petrocelli G, Scullica L. Comparison of wavefront aberration changes in the anterior corneal surface after laser-assisted subepithelial keratectomy and laser in situ keratomileusis: preliminary study. J Cataract Refract Surg 2004; 30:1929–1933 2. Chalita MR, Chavala S, Xu M, Krueger RR. Wavefront analysis in post-LASIK eyes and its correlation with visual symptoms, refraction, and topography. Ophthalmology 2004; 111:447–453 3. Chalita MR, Xu M, Krueger RR. Correlation of aberrations with visual symptoms using wavefront analysis in eyes after laser in situ keratomileusis. J Refract Surg 2003; 19:S682–S686 4. Melamud A, Chalita MR, Krueger RR, Lee MS. Comatic aberration as a cause of monocular diplopia. J Cataract Refract Surg 2006; 32:529–532 5. Sharma M, Wachler BS, Chan CCK. Higher order aberrations and relative risk of symptoms after LASIK. J Refract Surg 2007; 23:252–256 6. Moreno-Barriuso E, Merayo Lloves J, Marcos S, Navarro R, Llorente L, Barbero S. Ocular aberrations before and after myopic corneal refractive surgery: LASIK-induced changes measured with laser ray tracing. Invest Ophthalmol Vis Sci 2001; 42:1396–1403. Available at: http://www.iovs.org/cgi/reprint/42/ 6/1396.pdf. Accessed November 10, 2009 7. Yamane N, Miyata K, Samejima T, Hiraoka T, Kiuchi T, Okamoto F, Hirohara Y, Mihashi T, Oshika T. Ocular higherorder aberrations and contrast sensitivity after conventional laser in situ keratomileusis. Invest Ophthalmol Vis Sci 2004; 45:3986–3990. Available at: http://www.iovs.org/cgi/reprint/45/ 11/3986. Accessed November 10, 2009 8. Padmanabhan P, Mrochen M, Basuthkar S, Viswanathan D, Joseph R. Wavefront-guided versus wavefront-optimized laser in situ keratomileusis: contralateral comparative study. J Cataract Refract Surg 2008; 34:389–397 9. Racine L, Wang L, Koch DD. Size of corneal topographic effective optical zone: comparison of standard and customized myopic laser in situ keratomileusis. Am J Ophthalmol 2006; 142:227–232 10. Zhou C, Chai X, Yuan L, He Y, Jin M, Ren Q. Corneal higherorder aberrations after customized aspheric ablation and conventional ablation for myopic correction. Curr Eye Res 2007; 32:431–438
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First author: Claudia E. Perez-Straziota, MD Emory Vision, Atlanta, Georgia, USA