Retrospective Analysis Comparing the Preoperative and Postoperative “Q” Values for 2 Different Lasers in Refractive Surgery

Molchan, Ryan P.; Taylor, Kenneth R.; Panday, Vasudha; Caldwell, Matthew; Reilly, Charles

doi:10.1097/ico.0000000000000611

Cited by 6 publications

(5 citation statements)

References 15 publications

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“…However, Moshirfar et al [ 4 ], Khalifa et al [ 21 ], and Ghoneim et al [ 31 ] found that the level of induced HOAs was significantly higher in the WFO group than in the WFG group, which could be attributed to their use of high-resolution aberrometer measurements to define WFG ablation profiles [ 4 , 21 , 31 ]. Concerning the change in corneal asphericity, our results were similar to those of Bottos et al [ 33 ] and Molchan et al [ 34 ], where ΔQ was significantly greater in the WFG group than in the WFO group ( P = 0.034). The mean maximal laser ablation depth in our study was greater in the WFG group than in the WFO group ( P = 0.035).…”

Section: Discussionsupporting

confidence: 91%

Functional optical zone after wavefront-optimized versus wavefront-guided laser in situ keratomileusis

Elshawarby¹,

Saad²,

Helmy³

et al. 2021

Med Hypothesis Discov Innov Ophthalmol

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Background: Many studies have used functional optical zone (FOZ) as a measure to compare different refractive laser treatment modalities. However, to our knowledge, no study has compared wavefrontoptimized (WFO) and wavefront-guided (WFG) laser in situ keratomileusis (LASIK) using FOZ. We compared the FOZ after WFO versus WFG LASIK in patients with myopia and myopic astigmatism.Methods: In this prospective comparative study, we included 100 myopic eyes of 50 patients with or without astigmatism. They were divided into two groups according to the platform used: WFO or WFG femtosecond LASIK. Using Holladay’s equivalent keratometry reading (EKR) report of Pentacam HR, FOZ was defined as a zone centered on the pupil center with a standard deviation (SD) of 0.5 D, around the mean EKR. The differences in FOZ between the two platforms were analyzed at 3 months postoperatively. Visual acuity, refractive error, corneal asphericity (Q-value), and root mean square of higher-order aberrations (RMS for HOAs) were evaluated and compared.Results: The mean ± SD of patient age was 26.64 ± 5.67 years. The preoperative characteristics of the two groups were comparable (all P > 0.05). The intended optical zone (IOZ) was 6 mm in both groups. The mean laser ablation depth was significantly greater in the WFG group (18 ?m per D) than in the WFO group (16 ?m per D) (P = 0.035). At 3 months postoperatively, the mean ± SD of FOZ diameter was 4.32 ± 0.94 mm (71.99 ± 15.68% of intended optical zone) in the WFO group and 4.16 ± 1.13 mm (69.33 ± 18.78% of intended optical zone) in the WFG group, with no significant difference between the two groups (P = 0.622). The change in corneal asphericity was greater in the WFG group than in the WFO group (P = 0.034). Postoperative mean corrected and uncorrected distance visual acuity, manifest refraction, and RMS for HOAs showed no significant difference between the two groups (all P > 0.05).Conclusions: We found that WFG LASIK resulted in greater ablation depth and change in corneal asphericity than WFO LASIK at 3 months postoperatively. However, there was no significant difference in FOZ diameter, refractive error, and RMS for HOAs between the two groups. Further research is needed to confirm these findings.

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Section: Discussionsupporting

confidence: 91%

Functional optical zone after wavefront-optimized versus wavefront-guided laser in situ keratomileusis

Elshawarby¹,

Saad²,

Helmy³

et al. 2021

Med Hypothesis Discov Innov Ophthalmol

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“…7 Molchan et al demonstrated a smaller change in corneal asphericity per diopter of treatment with myopic correction using the Allegretto wavefront-optimized laser when compared to the VISX wavefront-guided laser for refractive surgery. 8 Lee and Lee demonstrated the WaveLight Refractive Suite, consisting of the femtosecond laser FS200 and WaveLight EX500 excimer laser, offers good refractive predictability in LASIK procedures. 9 At present, no studies have compared the induced aberrations postoperatively between the VISX Star S4 IR Excimer Laser System (Abbott Medical Optics, Santa Ana, California) and WaveLight EX500 Excimer Laser System (Alcon, Fort Worth, Texas).…”

Section: Introductionmentioning

confidence: 99%

Retrospective Analysis of the Post-Operative Changes in Higher-Order Aberrations: A Comparison of the WaveLight EX500 to the VISX S4 Laser in Refractive Surgery

et al. 2017

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Introduction: In an attempt to maximize treatment outcomes, refractive surgery techniques are being directed toward customized ablations to correct not only lower-order aberrations but also higher-order aberrations specific to the individual eye. Measurement of the entirety of ocular aberrations is the most definitive means to establish the true effect of refractive surgery on image quality and visual performance. Whether or not there is a statistically significant difference in induced higher-order corneal aberrations between the VISX Star S4 (Abbott Medical Optics, Santa Ana, California) and the WaveLight EX500 (Alcon, Fort Worth, Texas) lasers was examined. Methods: A retrospective analysis was performed to investigate the difference in root-mean-square (RMS) value of the higher-order corneal aberrations postoperatively between two currently available laser platforms, the VISX Star S4 and the WaveLight EX500 lasers. The RMS is a compilation of higher-order corneal aberrations. Data from 240 total eyes of active duty military or Department of Defense beneficiaries who completed photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) refractive surgery at the Wilford Hall Ambulatory Surgical Center Joint Warfighter Refractive Surgery Center were examined. Using SPSS statistics software (IBM Corp., Armonk, New York), the mean changes in RMS values between the two lasers and refractive surgery procedures were determined. A Student t test was performed to compare the RMS of the higher-order aberrations of the subjects' corneas from the lasers being studied. A regression analysis was performed to adjust for preoperative spherical equivalent. The study and a waiver of informed consent have been approved by the Clinical Research Division of the 59th Medical Wing Institutional Review Board (Protocol Number: 20150093H). Results: The mean change in RMS value for PRK using the VISX laser was 0.00122, with a standard deviation of 0.02583. The mean change in RMS value for PRK using the WaveLight EX500 laser was 0.004323, with a standard deviation of 0.02916. The mean change in RMS value for LASIK using the VISX laser was 0.00841, with a standard deviation of 0.03011. The mean change in RMS value for LASIK using the WaveLight EX500 laser was 0.0174, with a standard deviation of 0.02417. When comparing the two lasers for PRK and LASIK procedures, the p values were 0.431 and 0.295, respectively. Conclusion: The results of this study suggest no statistically significant difference concerning induced higher-order aberrations between the two laser platforms for either LASIK or PRK. Overall, the VISX laser did have consistently lower induced higher-order aberrations postoperatively, but this did not reach statistical significance. It is likely the statistical significance of this study was hindered by the power, given the relatively small sample size. Additional limitations of the study include its design, being a retrospective analysis, and the generalizability of the study, as the Department of Defens...

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“…Bottos et al [ 15 ] reported that the mean +Δ Q was +0.63 ± 0.44 after wavefront-guided LASIK using a femtosecond flap. Molchan et al [ 16 ] found that the mean +Δ Q was +0.39 ± 0.20 after wavefront-optimized LASIK and +0.54 ± 0.26 after wavefront-guided LASIK using PRK. El Danasoury et al [ 17 ] found that the mean Q -value was +0.07 ± 0.26 after LASIK with an optimized prolate ablation (OPA) and +0.30 ± 0.26 after LASIK with conventional ablation using a femtosecond flap.…”

Section: Discussionmentioning

confidence: 99%

“…Bottos et al [ 15 ] reported that Δ Q per diopter of treatment SE was +0.18 after wavefront-guided LASIK. Molchan et al [ 16 ] found that Δ Q per diopter of treatment SE was +0.12 after wavefront-optimized LASIK and +0.14 after wavefront-guided LASIK. Vega-Estrada et al [ 20 ] reported that, for each diopter of spherical correction, asphericity (8 mm) increased by 0.223 postoperatively in high myopic eyes after LASIK performed with an optimized ablation profile.…”

Section: Discussionmentioning

confidence: 99%

Comprehensive Evaluation of Anterior Corneal Change in Asphericity Calculated by the Tangential Radius of Curvature after LASIK

Ying

Cai

Zhu

et al. 2017

Journal of Ophthalmology

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To evaluate the change in the anterior corneal asphericity (ΔQ) comprehensively calculated using the tangential radius (rt) after LASIK. Forty-two right eyes were evaluated using the Orbscan II corneal topographer. The pre- and postoperative Q-values of the flat principal semimeridians calculated by the sagittal radius were compared to those by the tangential radius. The Q-value of each semimeridian in the horizontal region was calculated by rt. Fourier fitting was used to model the 360-semimeridional variation of Q-values and to fit the Q-values in the vertical region before and after surgery. There were significant differences in Q-values between the two methods before (P < 0.001) and after surgery (P = 0.003). A significant increase in postoperative Q-value was detected compared to preoperative Q-value (P < 0.001) calculated by rt. The 360-semimeridional variation of the Q-values was well fitted with a third- and fourth-degree Fourier function before and after surgery. The ΔQ-value distribution presented double valley variation, with the amount of ΔQ being lowest in the near-vertical regions and highest in the near-horizontal regions. Calculating the Q-value with rt combined with Fourier fitting, we evaluated 360 ΔQ-values' variation of semimeridians of the entire anterior corneal surface and then displayed true and complete anterior corneal shape after LASIK.

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Retrospective Analysis Comparing the Preoperative and Postoperative “Q” Values for 2 Different Lasers in Refractive Surgery

Cited by 6 publications

References 15 publications

Functional optical zone after wavefront-optimized versus wavefront-guided laser in situ keratomileusis

Functional optical zone after wavefront-optimized versus wavefront-guided laser in situ keratomileusis

Retrospective Analysis of the Post-Operative Changes in Higher-Order Aberrations: A Comparison of the WaveLight EX500 to the VISX S4 Laser in Refractive Surgery

Comprehensive Evaluation of Anterior Corneal Change in Asphericity Calculated by the Tangential Radius of Curvature after LASIK

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