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Comparison of the Predictive Accuracy of Intraocular Lens Power Calculations after Phototherapeutic Keratectomy in Granular Corneal Dystrophy Type 2. J Clin Med 2023; 12:jcm12020584. [PMID: 36675513 PMCID: PMC9861484 DOI: 10.3390/jcm12020584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 01/05/2023] [Accepted: 01/07/2023] [Indexed: 01/12/2023] Open
Abstract
Granular corneal dystrophy type 2 (GCD2) is an autosomal dominant disease affecting vision. Phototherapeutic keratectomy (PTK) is advantageous in removing vision-threatening corneal opacities and postponing keratoplasty; however, it potentially disturbs accurate intraocular lens (IOL) power calculation in cataract surgery. The myopic/hyperopic Haigis-L method with or without the central island has been reported; nevertheless, an optimal method has not yet been established. To compare the predictive accuracy of post-PTK IOL power calculations in GCD2, the retrospective data of 30 eyes from July 2017 to December 2020 were analyzed. All GCD2-affected eyes underwent post-PTK standard cataract surgery using the WaveLight EX500 platform (Alcon Laboratories, Inc., Fort Worth, TX, USA) under a single surgeon. The mean prediction error (MPE) and absolute error (MAE) with the myopic/hyperopic Haigis-L, Barrett Universal II, Barrett True-K, Haigis, and SRK/T by standard keratometry (K) and total keratometry (TK), where possible, were analyzed. Barrett Universal II and SRK/T showed significantly superior MPE, and MAE compared with the myopic/hyperopic Haigis-L method. TK was not significantly superior to K in the same formula. In conclusion, this study suggests that these biometries and formulas, especially Barrett Universal II and SRK/T, are potentially useful in IOL power calculation in GCD2 after PTK.
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Myopic outcomes after excimer laser phototherapeutic keratectomy (PTK). J Fr Ophtalmol 2020; 44:35-40. [PMID: 33158609 DOI: 10.1016/j.jfo.2020.03.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Revised: 03/24/2020] [Accepted: 03/25/2020] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate refractive outcomes following excimer laser phototherapeutic keratectomy (PTK). METHODS A retrospective non-randomized review of refractive outcomes of 146 consecutive eyes treated with excimer laser PTK at the Rothschild Foundation, Paris, France. Inclusion criteria were all patients undergoing PTK laser using a flying spot excimer laser system (Wavelight Allegretto, Alcon Surgical, Inc.) from October 2016 to June 2018. Exclusion criteria were incomplete data, irregular astigmatism and dystrophies of uncertain diagnosis. Preoperative diagnoses included recurrent corneal erosion syndrome without dystrophy and Cogan corneal dystrophies. The primary outcome measure was the change in spherical equivalent (SEQ) at M1 post PTK. The secondary outcome measure was the creation of a regression equation for predicting refractive outcomes after PTK, by analyzing the effect of ablation depth (AD) and optical zone (OZ) diameter. RESULTS Fifty-eight eyes of 54 patients were included. The mean OZ was 7.352 mm±0.622. The mean AD was 18.362μm±21.406. At M1 postoperatively, the mean SEQ was -2.485 D±2.628 and mean final SEQ was -1.052 D±1.260. Both OZ and AD were independent variables with significant effects on the final visual outcome. A regression equation for predicting refractive outcomes was established. No complications were observed. CONCLUSION The Wavelight flying spot excimer laser system produces myopic outcomes following PTK. Both OZ and AD are significant variables. A regression equation was created and may aid in prediction of refractive outcomes following PTK.
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Duration of topical steroid application after photorefractive keratectomy with mitomycin C. J Cataract Refract Surg 2020; 46:622-632. [PMID: 32271298 DOI: 10.1097/j.jcrs.0000000000000060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Contradictory results of postoperative steroid application in photorefractive keratectomy (PRK) led to a meta-analysis of the existing data to achieve a definite conclusion on the optimum dosage and duration of corticosteroid therapy after PRK. The overall pooled unstandardized mean difference (PUMD) of the corneal haze score was -0.20 (95% CI, -0.29 to -0.12). In subgroup analysis, the PUMD of the corneal haze score was statistically significant in 2 subgroups, -0.57 (-0.85 to -0.30) for 3 to 6 months postoperatively and -0.13 (-0.23 to -0.04) for ≤ 3 months postoperatively. Analysis of the PUMD of postoperative spherical equivalent in participants with low to moderate myopia (≥-6.00 D) and high myopia (<-6.00 D) showed positive effects of steroids on prevention of myopia regression. In conclusion, long-term topical steroid application after PRK seems unnecessary in low and moderate myopia. New randomized clinical trials using current technologies are recommended for postoperative treatments.
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Li Y, Yokogawa H, Tang M, Chamberlain W, Zhang X, Huang D. Guiding flying-spot laser transepithelial phototherapeutic keratectomy with optical coherence tomography. J Cataract Refract Surg 2019; 43:525-536. [PMID: 28532939 DOI: 10.1016/j.jcrs.2017.03.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 01/06/2017] [Accepted: 01/08/2017] [Indexed: 11/16/2022]
Abstract
PURPOSE To analyze transepithelial phototherapeutic keratectomy (PTK) results using optical coherence tomography (OCT) and develop a model to guide the laser dioptric and depth settings. SETTING Casey Eye Institute, Portland, Oregon, USA. DESIGN Prospective nonrandomized case series. METHODS Patients with superficial corneal opacities and irregularities had transepithelial PTK with a flying-spot excimer laser by combining wide-zone myopic and hyperopic astigmatic ablations. Optical coherence tomography was used to calculate corneal epithelial lenticular masking effects, guide refractive laser settings, and measure opacity removal. The laser ablation efficiency and the refractive outcome were investigated using multivariate linear regression models. RESULTS Twenty-six eyes of 20 patients received PTK to remove opacities and irregular astigmatism due to scar, dystrophy, radial keratotomy, or previous corneal surgeries. The uncorrected distance visual acuity and corrected distance visual acuity were significantly improved (P < .01) by 3.7 Snellen lines and 2.0 Snellen lines, respectively, to a mean of 20/41.2 and 20/22.0, respectively. Achieved laser ablation depths were 31.3% (myopic ablation) and 63.0% (hyperopic ablation) deeper than the manufacturer's nomogram. The spherical equivalent of the corneal epithelial lenticular masking effect was 0.73 diopter ± 0.61 (SD). The refractive outcome highly correlated to the laser settings and epithelial lenticular masking effect (Pearson R = 0.96, P < .01). The ablation rate of granular dystrophy opacities appeared to be slower. Smoothing ablation under masking fluid was needed to prevent focal steep islands in these cases. CONCLUSIONS The OCT-measured ablation depth efficiency could guide opacity removal. The corneal epithelial lenticular masking effect could refine the spherical refractive nomogram to achieve a better refractive outcome after transepithelial ablation.
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Affiliation(s)
- Yan Li
- From the Center for Ophthalmic Optics and Lasers (Li, Yokogawa, Tang, Chamberlain, Zhang, Huang), Casey Eye Institute and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, USA; and the Department of Ophthalmology (Yokogawa), Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Hideaki Yokogawa
- From the Center for Ophthalmic Optics and Lasers (Li, Yokogawa, Tang, Chamberlain, Zhang, Huang), Casey Eye Institute and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, USA; and the Department of Ophthalmology (Yokogawa), Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Maolong Tang
- From the Center for Ophthalmic Optics and Lasers (Li, Yokogawa, Tang, Chamberlain, Zhang, Huang), Casey Eye Institute and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, USA; and the Department of Ophthalmology (Yokogawa), Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Winston Chamberlain
- From the Center for Ophthalmic Optics and Lasers (Li, Yokogawa, Tang, Chamberlain, Zhang, Huang), Casey Eye Institute and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, USA; and the Department of Ophthalmology (Yokogawa), Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Xinbo Zhang
- From the Center for Ophthalmic Optics and Lasers (Li, Yokogawa, Tang, Chamberlain, Zhang, Huang), Casey Eye Institute and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, USA; and the Department of Ophthalmology (Yokogawa), Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - David Huang
- From the Center for Ophthalmic Optics and Lasers (Li, Yokogawa, Tang, Chamberlain, Zhang, Huang), Casey Eye Institute and Department of Ophthalmology, Oregon Health and Science University, Portland, Oregon, USA; and the Department of Ophthalmology (Yokogawa), Kanazawa University Graduate School of Medical Science, Kanazawa, Japan.
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Szekrényesi C, Kiss H, Filkorn T, Nagy ZZ. Shielding effect of the smoke plume by the ablation of excimer lasers. BMC Ophthalmol 2018; 18:273. [PMID: 30352572 PMCID: PMC6199794 DOI: 10.1186/s12886-018-0942-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/15/2018] [Indexed: 12/04/2022] Open
Abstract
Background Shielding and scattering effect of the smoke plume column ejected from the laser ablated material is a well-known phenomenon. Debris evacuation system of the excimer laser equipment removes these particles, but insufficient air flow can result in undesired refractive outcomes of the treatment. The aim of this study was to reveal the effect of the air flow speed on the actual ablation depth. Methods SCWIND AMARIS 500E flying spot excimer laser was tested in this study. A 150 μm phototherapeutic keratectomy (PTK) profile with 8 mm diameter was applied to the surface of polymethyl methacrylate (PMMA) plates. The velocity of the air flow was changed with adjustable air aspiration system. Ablation depth was measured with highly-precise contact micrometer. Results The prediction model was statistically significant, F(1,8) = 552.85, p < 0.001, and accounted for approximately 98.7% of variance of ablation (R2 = 0.987, R2adj = 0.986). Lower air flow speed resulted in a weaker ablation capability of the excimer laser. Conclusion Air flow generated by the aspiration equipment is a key factor for the predictable outcomes of refractive treatment. Therefore, manufacturer inbuilt debris removal system should be regularly checked and maintained to ensure proper clinical and predictable refractive results.
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Affiliation(s)
- Csaba Szekrényesi
- Faculty of Health Sciences, Semmelweis University, Vas u. 17, Budapest, 1088, Hungary.
| | - Huba Kiss
- Department of Ophthalmology, Semmelweis University, Budapest, Hungary
| | - Tamás Filkorn
- Department of Ophthalmology, Semmelweis University, Budapest, Hungary
| | - Zoltán Zsolt Nagy
- Faculty of Health Sciences, Semmelweis University, Vas u. 17, Budapest, 1088, Hungary.,Department of Ophthalmology, Semmelweis University, Budapest, Hungary
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El Bahrawy M, Alió JL. Excimer laser 6(th) generation: state of the art and refractive surgical outcomes. EYE AND VISION (LONDON, ENGLAND) 2015; 2:6. [PMID: 26605362 PMCID: PMC4655460 DOI: 10.1186/s40662-015-0015-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 02/11/2015] [Indexed: 12/03/2022]
Abstract
After nearly three decades of innovation in excimer laser, today we are presented with a state of the art generation targeting minimally invasive refractive surgery with high speed laser, faster trackers, pupil monitoring systems and better customization profiles. These systems are capable of delivering better treatments with less induced postoperative high order aberrations. The results reported by many authors had confirmed the superiority in efficiency and safety profiles of this generation compared to previous generations. Still, current technology is facing major challenges in the correction of high hyperopic errors and in presbyopic treatments, with upgrades in ablation centration and thermal control needed, which will ensure better biomechanical results, as a step closer to perfection in refractive surgery.
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Affiliation(s)
- Mohamed El Bahrawy
- />Clinical research fellow in Vissum Corporación Alicante, Universidad Miguel Hernández, Alicante, Spain
| | - Jorge L Alió
- />Vissum Corporación Alicante, Alicante, Spain
- />Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain
- />Avda de Denia s/n, Edificio Vissum, 03016 Alicante, Spain
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Han J, Sparkes M, O'Neill W. Controlling the optical fiber output beam profile by focused ion beam machining of a phase hologram on fiber tip. APPLIED OPTICS 2015; 54:890-894. [PMID: 25967801 DOI: 10.1364/ao.54.000890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 12/23/2014] [Indexed: 06/04/2023]
Abstract
A phase hologram was machined on an optical fiber tip using a focused ion beam (FIB) system so that a ring-shaped beam emerges from the fiber tip. The fiber used for this work was a commercial single-mode optical fiber patch cable for a design wavelength of 633 nm with a germanosilicate core. The ring-shaped beam was chosen to ensure a simple geometry in the required phase hologram, though the Gerchberg-Saxton algorithm can be used to calculate a hologram for an arbitrary beam shape. The FIB machining took approximately 45 min at 30 kV and 200 pA. The radius of the resulting ring beam was 0.083 m at 1 m standoff, as compared to 0.1 m as was initially desired. Results suggest that this imaging technique may provide a basis for a beam-shaping method with several advantages over the current commercial solutions, having permanent alignment, compactness, and mechanical robustness. However, it would appear that minimizing the speckle pattern will remain a critical challenge for this technique to become widely implemented.
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Arba-Mosquera S, Verma S. Analytical optimization of the ablation efficiency at normal and non-normal incidence for generic super Gaussian beam profiles. BIOMEDICAL OPTICS EXPRESS 2013; 4:1422-1433. [PMID: 24010004 PMCID: PMC3756584 DOI: 10.1364/boe.4.001422] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 07/11/2013] [Accepted: 07/11/2013] [Indexed: 06/02/2023]
Abstract
We suggest a general method to determine the optimum laser parameters for maximizing the ablation efficiency for different materials (in particular human cornea) at different incidence angles. The model is comprehensive and incorporates laser beam characteristics and ablative spot properties. The model further provides a method to convert energy fluctuations during ablation to equivalent ablation deviations in the cornea. The proposed model can be used for calibration, verification and validation purposes of laser systems used for ablation processes at relatively low cost and would directly improve the quality of results.
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Wang TJ, Lin YH, Chang DCK, Chou HC, Wang IJ. Comparison of the effects of cylindrical correction with and without iris recognition technology in wavefront laser-assisted in situ keratomileusis. Clin Exp Ophthalmol 2011; 40:239-46. [DOI: 10.1111/j.1442-9071.2011.02614.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Wavefront-guided LASIK for Myopia: Effect on Visual Acuity, Contrast Sensitivity, and Higher Order Aberrations. J Refract Surg 2009; 25:524-33. [DOI: 10.3928/1081597x-20090512-06] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Kwon Y, Choi M, Bott S. Impact of ablation efficiency reduction on post-surgery corneal asphericity: simulation of the laser refractive surgery with a flying spot laser beam. OPTICS EXPRESS 2008; 16:11808-11821. [PMID: 18679453 DOI: 10.1364/oe.16.011808] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We developed a rigorous simulation model to evaluate ablation algorithms and surgery outcomes in laser refractive surgery. The model (CASIM: Corneal Ablation SIMulator) simulates an entire surgical process, which includes calculating an ablation profile from measured wavefront errors, generating a shot pattern for a flying spot laser beam, simulation of the shot-by-shot ablation process based on a measured or modeled beam profile, and healing of the cornea after surgery. Using simulated post-surgery corneal shapes for various ablation parameters and beam fluences, we calculated angular dependence of ablation efficiency and the amount of increase in corneal asphericity. Without considering the effect of corneal healing, our result shows the following; 1) ablation efficiency reduction in the periphery depends on the peak fluence of the laser beam, 2) corneal asphericity increases even in the surgery using an ablation profile based on the exact Munnerlyn formula, contrary to previous reports, and 3) post-surgery corneal asphericity increases by a smaller amount in high fluence small Gaussian beam surgery than in low fluence truncated Gaussian beam. Our model can provide improved ablation profiles that compensate for the change of corneal asphericity and induction of spherical aberration in a flying spot laser system, resulting in better surgery outcomes in laser refractive surgeries.
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Affiliation(s)
- Young Kwon
- Alcon Labs, 2501 Discovery Dr. Orlando, FL 32826, USA.
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Hafezi F, Jankov M, Mrochen M, Wüllner C, Seiler T. Customized ablation algorithm for the treatment of steep central islands after refractive laser surgery. J Cataract Refract Surg 2006; 32:717-21. [PMID: 16765785 DOI: 10.1016/j.jcrs.2006.02.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Accepted: 11/04/2005] [Indexed: 11/23/2022]
Abstract
Steep central island (SCI) formation after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) represents a major drawback in the visual rehabilitation of patients after refractive laser surgery. Because of the small size of SCIs, current ablation algorithms are unable to properly calculate an ablation pattern for customized retreatment. We present the use of a new ablation algorithm for the treatment of SCIs that occurred after PRK or LASIK surgery. This algorithm uses a smaller zone of approximation and takes into account the spherical shift induced by removal of the SCI. In all 3 eyes treated, best spectacle-corrected visual acuity increased to 20/16 and remained stable at the 1- and 3-month follow-up, with disappearance of the SCI in corneal topography. This new treatment algorithm may be of benefit to patients experiencing visual side effects due to SCI formation after PRK or LASIK surgery.
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Affiliation(s)
- Farhad Hafezi
- Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland.
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Abstract
PURPOSE To present a case of central island after myopic laser in situ keratomileusis and the treatment technique using Technolas 217 laser based on topography findings. METHODS Serial corneal topographies with Orbscan were taken and an ablation profile was generated with subsequent treatment using the phototherapeutic keratectomy mode and surface ablation technique. RESULTS Marked reduction was noted in the height of central island and the best spectacle-corrected visual acuity improved from 20/40 to 20/25. CONCLUSIONS Ablation profile based on corneal topography can provide a possible treatment option for patients with central island.
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Affiliation(s)
- Arthur C K Cheng
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, University Eye Center, Hong Kong Eye Hospital, Hong Kong, China.
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