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Feng Y, Nitter TA, Liu X, Stojanovic A. Nominal and achieved stromal ablation depth after myopic transepithelial photorefractive keratectomy: implications for residual stromal thickness calculation. EYE AND VISION (LONDON, ENGLAND) 2024; 11:36. [PMID: 39223626 PMCID: PMC11367754 DOI: 10.1186/s40662-024-00404-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 08/09/2024] [Indexed: 09/04/2024]
Abstract
BACKGROUND The primary objective of this investigation was to compare the nominal central ablation depth with the achieved central corneal stromal ablation depth after StreamLight transepithelial photorefractive keratectomy (tPRK) for myopia with WaveLight® laser by Alcon Laboratories, TX, USA. METHODS This ambispective study encompassed a retrospective analysis of 40 eyes who underwent treatment for myopia and astigmatism, followed by a prospective examination conducted 6-9 months postoperatively. Pre- and postoperative Avanti spectral-domain optical coherence tomography (SD-OCT; Optovue Inc., CA, USA) provided stromal and epithelial thickness maps. The difference between pre- and postoperative central stromal thicknesses at the corneal vertex was used to calculate the achieved stromal thickness ablation depth. This value was then compared with the corresponding central nominal depth on the laser ablation planning map. RESULTS A total of 40 eyes (OD/OS:18/22) of 40 patients (31.4 ± 9.2 years) were available for evaluation. The mean treated spherical equivalent was - 2.98 ± 1.46 D. The mean nominal and achieved central stromal ablation depths were 51.22 µm and 59.67 μm, respectively, showing a mean stromal excessive ablation of 16.50%. The mean pre- and postoperative central epithelial thicknesses were 53.74 μm and 59.31 μm, respectively, showing a mean postoperative thickness increase of 10.46%. This increase in the epithelial thickness rendered the mean postoperative pachymetry reduction to 54.11 μm, only 2.33% greater than the mean nominal ablation depth. CONCLUSIONS The study revealed a central stromal ablation 16.50% greater than the nominal ablation depth. This excessive stromal removal was largely compensated for by the increase in epithelial thickness, resulting in a mean difference between the nominal ablation depth and the achieved central corneal pachymetry reduction of only 2.33%. This significant excessive central stromal ablation must be taken into consideration in the calculation of the residual stromal thickness.
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Affiliation(s)
- Yue Feng
- Institute of Community Medicine, Faculty of Health Sciences, University in Tromsø, Tromsø, Norway
| | | | - Xu Liu
- Institute of Community Medicine, Faculty of Health Sciences, University in Tromsø, Tromsø, Norway
| | - Aleksandar Stojanovic
- Department of Ophthalmology, University Hospital North Norway, Sykehusveien 38, 9019, Tromsø, Norway.
- Institute of Clinical Medicine, Faculty of Health Sciences, University in Tromsø, Tromsø, Norway.
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Lin K, Xu Z, Wang H, Wang Y, Wei L, Ma H, Zhao J, Lu F, Hu L. Comparison of the repeatability and reproducibility of corneal thickness mapping using optical coherence tomography according to tear film break-up time. BMC Ophthalmol 2024; 24:275. [PMID: 38970043 PMCID: PMC11227131 DOI: 10.1186/s12886-024-03536-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 06/23/2024] [Indexed: 07/07/2024] Open
Abstract
BACKGROUND To compare the repeatability and reproducibility of corneal and corneal epithelial thickness mapping using anterior segment optical coherence tomography (AS-OCT) according to tear film break-up time (TBUT). METHODS The included eyes were divided into three subgroups according to TBUT (group 1: TBUT ≤ 5 s, group 2: 5 s < TBUT ≤ 10 s, and group 3: TBUT > 10 s). All eyes were imaged separately thrice by two operators to obtain the thickness maps (TMs) of the cornea and corneal epithelium based on spatial zones encompassing a 9-mm-diameter area. Each TM consisted of 25 areas. Intraoperator (repeatability) and interoperator (reproducibility) standard deviations (Sws), coefficients of variation (CoVs), and intraclass correlation coefficients (ICCs) among the tests were calculated and compared in all the areas. RESULTS Altogether, 132 eyes of 67 subjects were included (50, 47, and 35 eyes in groups 1, 2, and 3; respectively). The ICCs of corneal epithelial thickness and corneal thickness were > 0.75 in most of the areas. Pairwise comparisons showed that AS-OCT exhibited lower repeatability in group 1 than in groups 2 and 3 (P < 0.05). However groups 2 and 3 showed similar results. Sws and CoVs of corneal epithelial thickness exhibited no significant interoperator differences. While no significant differences were observed in corneal thickness in most of the areas. CONCLUSIONS TBUT significantly influences the repeatability of corneal and corneal epithelial thickness measurements. Poor tear film stability requires careful evaluation of corneal epithelial thickness.
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Affiliation(s)
- Kan Lin
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China
- Zhejiang University School of Medicine Second Affiliated Hospital Eye Center, 88 Jiefang Road, Hangzhou, 310009, China
| | - Zhiqiang Xu
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China
| | - Hui Wang
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China
| | - Yuzhou Wang
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China
| | - Linzhi Wei
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China
| | - Hongqing Ma
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China
| | - Jian Zhao
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China
| | - Fan Lu
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China.
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan road, Wenzhou, 325000, Zhejiang, China.
| | - Liang Hu
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China.
- School of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, 270 Xueyuan road, Wenzhou, 325000, Zhejiang, China.
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Kanellopoulos AJ. Ray-Tracing Customization in Myopic and Myopic Astigmatism LASIK Treatments for Low and High Order Aberrations Treatment: 2-Year Visual Function and Psychometric Value Outcomes of a Consecutive Case Series. Clin Ophthalmol 2024; 18:565-574. [PMID: 38410630 PMCID: PMC10896098 DOI: 10.2147/opth.s444174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Accepted: 01/25/2024] [Indexed: 02/28/2024] Open
Abstract
Purpose The safety and long-term efficacy of automated ray-tracing customized myopic and myopic astigmatic femtosecond laser-assisted LASIK. Methods This consecutive case series retrospective analysis, of 20 subjects (40 eyes) treated with automated raytracing named Wavelight Plus, to include low and high order aberrations based on a three-dimensional custom virtual eye for each case-calculated from interferometry data-obtained from a single diagnostic device that also provides Hartman-Shack Wavefront and Scheimpflug tomography data. We evaluated before and after the customized LASIK procedure: visual acuity, refractive error, high order aberrations, contrast sensitivity, and psychometric post-operative visual function data. Results At 24 months, the comparison of the pre-operative to the post-operative refractive and visual function value changes in average were: subjective manifest refraction from -4.38 ± 2.54 diopters (D) (range -9.75 to -1.25 D) to +0.11 ± 0.19 D; subjective manifest refractive astigmatism from -0.76 ± 0.91 D (range -2.75 to 0 D) to -0.13 ± 0.16 D, corneal astigmatism from -1.16 ± 0.64 D (range -0.2 to -2.8) to -0.47 ± 0.11 D. 65% of the eyes studied demonstrated an increase of at least one line of vision, while from the same group 38% demonstrated 2 lines of increase. High order aberrations, contrast sensitivity as well as the subjective psychometric input based on the VFQ-25 questionnaire demonstrated actual improvement. Conclusion This longer-term follow-up, single-arm retrospective consecutive case series documents LASIK treatment customization that appears to be safe and effective in the correction of myopia and myopic astigmatism. Markedly improved objective and subjective visual function post-operatively, underlying the potential importance of simultaneously attempting to correct high order aberrations and improving the spatial alignment of total, measured human eye optics.
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Affiliation(s)
- Anastasios John Kanellopoulos
- Medical Director: The Laservision Clinical and Research Institute, Athens, Greece
- Clinical Professor, Department of Ophthalmology, NYU Grossman Medical School, Department of Ophthalmology, New York City, NY, USA
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Abtahi MA, Beheshtnejad AH, Latifi G, Akbari-Kamrani M, Ghafarian S, Masoomi A, Sonbolastan SA, Jahanbani-Ardakani H, Atighechian M, Banan L, Nouri H, Abtahi SH. Corneal Epithelial Thickness Mapping: A Major Review. J Ophthalmol 2024; 2024:6674747. [PMID: 38205099 PMCID: PMC10776199 DOI: 10.1155/2024/6674747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 06/27/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
The corneal epithelium (CE) is the outermost layer of the cornea with constant turnover, relative stability, remarkable plasticity, and compensatory properties to mask alterations in the underlying stroma. The advent of quantitative imaging modalities capable of producing epithelial thickness mapping (ETM) has made it possible to characterize better the different patterns of epithelial remodeling. In this comprehensive synthesis, we reviewed all available data on ETM with different methods, including very high-frequency ultrasound (VHF-US) and spectral-domain optical coherence tomography (SD-OCT) in normal individuals, corneal or systemic diseases, and corneal surgical scenarios. We excluded OCT studies that manually measured the corneal epithelial thickness (CET) (e.g., by digital calipers) or the CE (e.g., by confocal scanning or handheld pachymeters). A comparison of different CET measuring technologies and devices capable of producing thickness maps is provided. Normative data on CET and the possible effects of gender, aging, diurnal changes, refraction, and intraocular pressure are discussed. We also reviewed ETM data in several corneal disorders, including keratoconus, corneal dystrophies, recurrent epithelial erosion, herpes keratitis, keratoplasty, bullous keratopathy, carcinoma in situ, pterygium, and limbal stem cell deficiency. The available data on the potential role of ETM in indicating refractive surgeries, planning the procedure, and assessing postoperative changes are reviewed. Alterations in ETM in systemic and ocular conditions such as eyelid abnormalities and dry eye disease and the effects of contact lenses, topical medications, and cataract surgery on the ETM profile are discussed.
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Affiliation(s)
| | | | - Golshan Latifi
- Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Sadegh Ghafarian
- Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Ahmad Masoomi
- Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | | | | | | | - Laleh Banan
- Sunshine Coast University Hospital, Brisbane, Queensland, Australia
| | - Hosein Nouri
- Ophthalmic Research Center, Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Seyed-Hossein Abtahi
- Ophthalmic Research Center, Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Vinciguerra R, Catania F, Rosetta P, Archer TJ, Reinstein DZ, Vinciguerra P. Sequential Customized Therapeutic Keratectomy in Patients With a History of Radial Keratotomy. J Refract Surg 2023; 39:808-816. [PMID: 38063831 DOI: 10.3928/1081597x-20231018-03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
PURPOSE To evaluate the outcome of sequential customized therapeutic keratectomy (SCTK) in reducing higher order aberrations (HOAs) and improving quality of vision in highly aberrated corneas consequent to previous radial keratotomy (RK). METHODS A retrospective review of patients undergoing SCTK treatment from January 2012 to October 2020 was conducted in the Eye Center, Humanitas Clinical and Research Center (Rozzano, Italy). Indications for treatment in patients who had RK were significantly and/or progressively reduced corrected distance visual acuity (CDVA) combined with visual symptoms critically affecting quality of life. Preoperative and postoperative CDVA, corneal topography and aberrometry, Scheimpflug tomography, and anterior segment optical coherence tomography were registered. RESULTS Thirty-four patients who underwent RK a mean of 26.62 ± 7.10 years before SCTK treatment were included. SCTK induced a significant improvement of CDVA from 0.44 ± 0.82 logMAR preoperatively to 0.15 ± 0.64 logMAR postoperatively (P < .001). No patient experienced worsening of CDVA, whereas 8 patients (23,50%) gained one line and 23 patients (67.65%) gained two lines or more. A significant decrease in corneal coma, trefoil, and spherical aberrations was also noted (P = .003, .003, and .004, respectively). CONCLUSIONS SCTK proved to be a safe and effective option to treat highly aberrated eyes following RK. The authors suggest the use of SCTK as a first-line approach for the treatment of HOAs after RK and avoiding more invasive procedures such as corneal transplantation or intraocular lens implantation. [J Refract Surg. 2023;39(12):808-816.].
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Lyra AFV, Alves EM, Montenegro AA, Parente NS, Cardoso MT, Alves LM, Maia CB, Fontes BM, Nose W. Corneal Higher Order Aberrations and Epithelial Remodeling With Femtosecond Laser-Assisted LASIK Topography-guided and Customized Asphericity Ablation in the Contralateral Eye: A Randomized, Double-Blind, Prospective Study. J Refract Surg 2023; 39:751-758. [PMID: 37937761 DOI: 10.3928/1081597x-20230925-03] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
PURPOSE To evaluate refractive results, corneal higher order aberrations (HOAs), and epithelial remodeling in the preoperative and postoperative period of regular corneas that had topography-guided femtosecond laser-assisted laser in situ keratomileusis (LASIK) (Contoura WaveLight; Alcon Laboratories, Inc) and compare them with the contralateral eye that underwent ablation customized by asphericity (Custom-Q WaveLight; Alcon Laboratories, Inc) in myopic eyes with or without astigmatism. METHODS A prospective, randomized, and double-blind study was conducted. Patients underwent preoperative and postoperative epithelial mapping and corneal tomography to assess the epithelial thickness map, HOAs of the corneal anterior surface, visual acuity, and refractive evaluation. RESULTS This study enrolled 96 normal eyes of 48 patients. Uncorrected distance visual acuity of 20/20 or better was achieved in 97% of patients and gains in corrected distance visual acuity and effectiveness in correcting refractive astigmatism were similar in both techniques. Seventeen sectors of the corneal epithelium map were assessed by spectral-domain optical coherence tomography and no significant differences were found between techniques preoperatively and postoperatively (P > .05). HOA root mean square, coma Z3±1, trefoil Z3-3, and tissue consumption exhibited statistically significant between-technique differences (P < .05). CONCLUSIONS The Contoura and Custom-Q techniques were similar with respect to refractive and visual outcomes after 3 months, as well as in epithelial remodeling. The Contoura provides lower postoperative HOA root mean square, coma Z3±1, and trefoil Z3-3 values, but the techniques showed no differences in the correction of the corneal astigmatic wavefront component and in the spherical aberration after 3 months. [J Refract Surg. 2023;39(11):751-758.].
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Motwani M. A Novel Procedure for Keratoconus/Corneal Ectasia Treating Epithelial Compensation of Higher-Order Aberrations, Topographic Guided Ablation, and Corneal Cross Linking - The CREATE+CXL Protocol. Clin Ophthalmol 2023; 17:1981-1992. [PMID: 37469861 PMCID: PMC10352124 DOI: 10.2147/opth.s411472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 06/22/2023] [Indexed: 07/21/2023] Open
Abstract
Purpose To present the outcomes of a retrospective study in keratoconus/corneal ectasia patients of treating the higher order aberrations compensated for the corneal epithelium in addition to topographic guided ablation followed by corneal cross linking. Methods Twenty-seven eyes of 14 patients were treated for keratoconus/corneal ectasia utilizing trans-epithelial topographic guided ablation photorefractive keratectomy (PRK) for treatment of corneal higher order aberrations and lower order astigmatism followed immediately by 15-minute cross linking were examined retrospectively. Six-month results were analyzed via measurement of vision, refraction, residual higher-order aberrations (HOAs), residual lower-order and higher-order aberrations, as well as for loss or gains of lines of best corrected visual acuity. Results All eyes save one had reduction in K1, K2, K Max, and K Mean. All eyes had reduction in manifest astigmatism, Contoura measured astigmatism, 57% reduction of higher-order aberrations (HOA), and 53% reduction of higher-order aberrations grouped with lower-order aberrations (Grouped). Nearly all (96.3%) eyes achieved 20/40 vision or better, 20 eyes had 1-7 lines gained of vision, and no eyes had any loss of lines of vision. Conclusion Use of the CREATE+CXL protocol combined with 15-minute corneal cross linking results in a significant increase in HOA reduction, as well as a significant improvement in corrected distance visual acuity over past procedures.
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Affiliation(s)
- Manoj Motwani
- Cornea Revolution/Motwani LASIK Institute, San Diego, CA, 92121, USA
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Zhou W, Reinstein DZ, Archer TJ, Nitter T, Feng Y, Mule G, Stojanovic A. The Impact of Epithelial Remodeling on Surgical Techniques Used in Topography-guided Surface Ablation in Irregular Corneas. J Refract Surg 2022; 38:529-537. [PMID: 35947001 DOI: 10.3928/1081597x-20220711-02] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To analyze the optical consequences of epithelial remodeling in irregular corneas and their impact on the choice of different surface ablation techniques. METHODS Anterior corneal and stromal surface topographies and epithelial thickness maps were analyzed in 24 eyes with irregular corneal optics. On two of the eyes, four different surface ablation techniques were simulated: (1) conventional anterior topography-guided photorefractive keratectomy (PRK), (2) transepithelial phototherapeutic keratectomy (PTK), (3) transepithelial anterior topography-guided PRK, and (4) stromal topography-guided PRK. RESULTS Stromal surface topographies showed higher keratometric values, astigmatism, asphericity, and corneal higher order aberrations compared to topographies of anterior corneas covered by epithelium. Transepithelial anterior topography-guided PRK and stromal topography-guided PRK both resulted in regularized stromal surface, transepithelial PTK achieved partial regularization corresponding to the smoothing effect of the epithelial remodeling, and conventional anterior topography-guided PRK delivered after epithelial removal resulted in residual stromal surface irregularities. CONCLUSIONS The difference in optical landscapes between the stromal and anterior surfaces in irregular corneas will represent a source of error when anterior topography-guided treatments are delivered on the deepithelialized stroma, as in conventional PRK. In contrast, anterior topography-guided ablations performed as transepithelial PRK and stromal topography-guided PRK delivered after epithelial removal address the full stromal irregularity, whereas transepithelial PTK alone may be used when topography-guided treatments are not possible. The authors conclude topography-guided PRK of irregular corneas should lead to significantly improved regularization only if it includes the effect of epithelial remodeling. [J Refract Surg. 2022;38(8):529-537.].
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Reinstein DZ, Archer TJ, Vida RS. Epithelial thickness mapping for corneal refractive surgery. Curr Opin Ophthalmol 2022; 33:258-268. [PMID: 35779050 DOI: 10.1097/icu.0000000000000867] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW As more devices become available that offer corneal epithelial thickness mapping, this is becoming more widely used for numerous applications in corneal refractive surgery. RECENT FINDINGS The epithelial thickness profile is nonuniform in the normal eye, being thinner superiorly than inferiorly and thinner temporally than nasally. Changes in the epithelial thickness profile are highly predictable, responding to compensate for changes in the stromal curvature gradient, using the eyelid as an outer template. This leads to characteristic changes that can be used for early screening in keratoconus, postoperative monitoring for early signs of corneal ectasia, and for determining whether further steepening can be performed without the risk of apical syndrome following primary hyperopic treatment. Compensatory epithelial thickness changes are also a critical part of diagnosis in irregular astigmatism as these partially mask the stromal surface irregularities. The epithelial thickness map can then be used to plan a trans-epithelial PRK treatment for cases of irregularly irregular astigmatism. Other factors can also affect the epithelial thickness profile, including dry eye, anterior basement membrane dystrophy and eyelid ptosis. SUMMARY Epithelial thickness mapping is becoming a crucial tool for refractive surgery, in particular for keratoconus screening, ectasia monitoring, hyperopic treatment planning, and therapeutic diagnosis and treatment.
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Affiliation(s)
- Dan Z Reinstein
- Reinstein Vision
- London Vision Clinic, London, UK
- Department of Ophthalmology, Columbia University Medical Center, New York, USA
- Sorbonne Université, Paris, France
- School of Biomedical Sciences, University of Ulster, Coleraine, UK
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Díaz-Bernal J, García-Basterra I, Mora-Castilla J, Nguyen A, Fernandez-Barrientos Y, Guerrero AM. Evolution of corneal epithelial remodeling after myopic laser in situ keratomileusis surgery measured by anterior segment optical coherence tomography combined with Placido disk. Indian J Ophthalmol 2021; 69:3451-3456. [PMID: 34826973 PMCID: PMC8837314 DOI: 10.4103/ijo.ijo_3820_20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Purpose: To investigate patterns of short- and long-term variations in corneal epithelial thickness (CET) after myopic laser in situ keratomileusis (LASIK) using anterior segment optical coherence tomography (AS-OCT) combined with Placido disk-based topography. Methods: In this retrospective study, 36 subjects (72 eyes) who underwent LASIK myopic surgery and 53 healthy subjects (106 eyes) who served as controls were enrolled. AS-OCT (MS-39) was performed in all patients before, 1 day, 1 month, and 6 months after surgery. Statistical analysis was performed to analyze CET changes over time after LASIK and to detect patterns of definitive CET remodeling compared to healthy subjects. Multivariate analysis was performed to look for possible predictors of final CET. Results: There was no statistically significant difference between groups in terms of demographic and anterior segment parameters (all P > 0.05). After LASIK, all sectors and rings got thicker over time (1.62–8.32 μm; P < 0.01). Except for the central sector, all areas achieved the thickest CET value one day after surgery with a progressive epithelial thinning between 1 and 6 months of follow-up. Changes on CET occurred independently of the grade of myopia before LASIK or final refraction (P > 0.05). None of the clinical variables studied, including diopters corrected, were found to be correlated with final CET (P > 0.05). Conclusion: Independent of anterior segment parameters and diopters corrected, CET becomes thicker after LASIK surgery. Central and inner ring sectors thicken more than those more peripheral. CET remodeling after myopic LASIK should be taken into consideration when planning refractive surgery.
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Affiliation(s)
- José Díaz-Bernal
- Department of Ophthalmology, University Hospital Virgen de la Victoria Málaga; Department of Radiology and Physical Medicine, Ophthalmology and Otorhinolaryngology, University of Málaga, Spain
| | - Ignacio García-Basterra
- Department of Ophthalmology, University Hospital Virgen de la Victoria Málaga; Universidad Internacional de La Rioja, Spain
| | | | - Annie Nguyen
- Department of Ophthalmology, USC Roski Eye Institute, Keck School of Medicine, Los Angeles, California, USA
| | | | - Antonio M Guerrero
- Department of Radiology and Physical Medicine, Ophthalmology and Otorhinolaryngology, University of Málaga; Antonio Moreno Eye Clinic, Málaga, Spain
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Zhou W, Reinstein DZ, Archer TJ, Chen X, Utheim TP, Feng Y, Stojanovic A. Intraoperative Swept-Source OCT-Based Corneal Topography for Measurement and Analysis of Stromal Surface After Epithelial Removal. J Refract Surg 2021; 37:484-492. [PMID: 34236903 DOI: 10.3928/1081597x-20210405-01] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess intraoperative stromal topography measurements using swept-source optical coherence tomography (OCT)-based topography/tomography after epithelial removal and to analyze the epithelial contribution to the corneal topography and optics. METHODS This was a prospective series of 22 eyes of 19 patients referred to receive phototherapeutic keratotomy (PTK) for treatment of recurrent corneal erosion and a control group of 22 virgin eyes. Swept-source OCT corneal topography/tomography was obtained immediately before and immediately after mechanical deepithelialization before PTK. Epithelial thickness maps were obtained before the surgery using spectral-domain OCT in the control group and as a reference in the group with anterior basement membrane dystrophy. Topographic and optical characteristics, including the curvature, astigmatism, asphericity, and higher order aberrations of the cornea before and after deepithelialization were compared, and their differences correlated with the measurements derived from the epithelial thickness maps. RESULTS Stromal topography measurements after deepithelialization were easily obtained and showed excellent repeatability. Assessment of corneal edema induced by deepithelialization revealed that it did not significantly affect the measured parameters. The stromal surface was steeper by 1.28 diopters, had higher with-the-rule astigmatism by 0.41 diopters, was more prolate, and had more higher order aberrations compared to the intact epithelialized corneal surface. These differences correlated well with the parameters derived from epithelial thickness maps. CONCLUSIONS Measurement of stromal topography using swept-source OCT immediately after mechanical deepithelialization may be a viable method in therapeutic refractive surgery, where stromal topography-guided ablation is needed. A significant epithelial contribution to anterior corneal topography and optics was confirmed. [J Refract Surg. 2021;37(7):484-492.].
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Yu N, Ye Y, Chen P, Yang Y, Zhuang J, Yu K. Corneal Epithelial Thickness Changes Following SMILE for Myopia With High Astigmatism. J Refract Surg 2021; 37:224-230. [PMID: 34038662 DOI: 10.3928/1081597x-20210126-01] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the corneal epithelial thickness (CET) profile changes after small incision lenticule extraction (SMILE) surgery for myopic astigmatism correction of greater than 2.00 diopters (D). METHODS This prospective observational study included 40 eyes (23 patients) treated with SMILE for myopia with cylinders of -2.25 to -4.50 D. Along with standard ophthalmic examinations, CET maps with a diameter of 9 mm were measured by high-resolution spectral-domain optical coherence tomography preoperatively and postoperatively. Correlations between the degree of residual astigmatism and the difference in CET values between preoperative flat and steep meridians were analyzed. RESULTS The CET showed significant changes in the central (2 mm), paracentral (2 to 5 mm), midperipheral (5 to 7 mm), and peripheral (7 to 9 mm) zones 6 months after SMILE (P < .001). Among the regions, the CET in the paracentral zones displayed the largest increase (9.75%) with the highest average thickness (57.29 µm). Moreover, symmetrical regional epithelial thickening at the preoperative astigmatism axis was observed in the midperipheral zones. The difference in CET between preoperative flat and steep meridians in the mid-peripheral zones continuously increased from postoperative 1 day to 6 months. This difference was positively correlated with the residual cylinder errors at 6 months postoperatively (r = -0.334, P = .035). CONCLUSIONS The 9-mm diameter CET in eyes with high astigmatism significantly increased 6 months after SMILE. Additionally, the difference in CET between preoperative flat and steep meridians in midperipheral zones may be related to astigmatic undercorrection in SMILE. [J Refract Surg. 2021;37(4):224-230.].
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Excimer laser tissue interactions in the cornea. Exp Eye Res 2021; 206:108537. [PMID: 33716013 DOI: 10.1016/j.exer.2021.108537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 03/04/2021] [Accepted: 03/06/2021] [Indexed: 11/22/2022]
Abstract
Excimer lasers induces significant changes to corneal structure and corneal biomechanics. The aim of this paper is to describe all laser-tissue interactions which are relevant for clinical practice, particularly, we will focus on laser ablations profiles, causes of regression and haze and prevention of those. At last the manuscript will describe the impact on corneal biomechanics of different Laser Vision Corrections techniques.
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Kanellopoulos AJ. Initial Outcomes with Customized Myopic LASIK, Guided by Automated Ray Tracing Optimization: A Novel Technique. Clin Ophthalmol 2020; 14:3955-3963. [PMID: 33239861 PMCID: PMC7680798 DOI: 10.2147/opth.s280560] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/03/2020] [Indexed: 11/23/2022] Open
Abstract
Purpose Safety and efficacy of a novel automated ray tracing optimization in customization of excimer ablation in myopic LASIK. Methods In a consecutive case series, 25 patients (50 eyes) undergoing femtosecond-laser-assisted myopic LASIK were evaluated. The novel, artificial-intelligence platform initially calculates the ablation profile based on a model eye for each case, based on interferometry axial length data. Low- and high-order aberration calculation is performed by raytracing based on wavefront and Scheimpflug tomography measurements, all from a single diagnostic device. Visual acuity, refractive error, keratometry, topography, high-order aberrations and contrast sensitivity were evaluated, over six months follow-up. Results Change from pre- to 6 months post-operative: mean refractive error improved from −5.06 ± 2.54 diopters (D) (range −8.0 to −0.50 D) to −0.11 ± 0.09 D (range −0.25 to + 0.25); refractive astigmatism from −1.07 ± 0.91 D (range −4.25 to 0 D) to −0.15 ± 0.04 D (range −0.25 to 0); and topographic astigmatism from −1.65 ± 0.85 D to −0.26 ± 0.11 D (range −0.60 to 0). About 65% of eyes gained one line of vision and 38% 2 lines. Pre- to post-operative high-order aberration average: RMSh changed from 0.25 um to 0.35 um. Contrast sensitivity improved post-operatively. Conclusion We report safe and effective preliminary outcomes with a novel excimer laser customization by ray tracing optimization, for myopic LASIK treatments, employing several independent up-till-now diagnostics and a customized eye model reference for each case. It bears the potential advantage through total eye aberration data and ray tracing refraction calculation to offer improved and more predictable visual outcomes. ![]()
Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use: https://youtu.be/D9pRQDAcjLg
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Affiliation(s)
- Anastasios John Kanellopoulos
- Laservision.gr Clinical and Research Institute, Athens, Greece.,NYU Medical School, Department of Ophthalmology, New York City, NY, USA
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Díaz-Bernal J, García-Basterra I, Mora-Castilla J, Moreno Guerrero A. Corneal epithelial thickness one year after myopic LASIK surgery, measured by anterior segment optical coherence tomography combined with Placido disk. ARCHIVOS DE LA SOCIEDAD ESPANOLA DE OFTALMOLOGIA 2020; 95:544-549. [PMID: 32349906 DOI: 10.1016/j.oftal.2020.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 03/23/2020] [Accepted: 03/24/2020] [Indexed: 06/11/2023]
Abstract
OBJECTIVE To compare corneal epithelial thickness (CET) between patients who underwent LASIK surgery for the correction of myopia at least one year ago and healthy subjects. METHODS A retrospective observational study was conducted that included 93 healthy subjects (186eyes) and 26 subjects (52eyes) that underwent myopic LASIK surgery. OCT-SA, combined with Placido disk, was performed on all subjects, and CET maps were measured. Statistical analysis was performed to analyse differences between groups. Multivariate analysis was also performed to look for possible predictors of final CET. RESULTS There was no statistically significant differences between the groups in the demographic (age, sex) or anterior segment parameters (spherical equivalent, pachymetry) (all P>.05). Statistically significant differences (P<.05) were obtained between both groups when comparing CET, including central, internal, and external rings (higher in patients that underwent LASIK surgery ≥1year). With the exception of the time elapsed since surgery (P=.00), no correlation was found between the CET and age, sex, ablated dioptres, or other variables studied (P<.05). CONCLUSIONS CET values measured by the OCT-SA were higher in patients that underwent LASIK surgery ≥1year. The only variable that correlated with the CET after LASIK was the time elapsed since surgery. CET changes should be taken into consideration when planning refractive surgery due to its implications on the final outcome.
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Affiliation(s)
- J Díaz-Bernal
- Departamento de Oftalmología, Hospital Universitario Virgen de la Victoria, Málaga, España.
| | - I García-Basterra
- Departamento de Oftalmología, Hospital Universitario Virgen de la Victoria, Málaga, España
| | | | - A Moreno Guerrero
- Clínica Oftalmológica Antonio Moreno, Málaga, España; Departamento de Oftalmología, Universidad de Málaga, Málaga, España
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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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Zhou W, Reinstein DZ, Chen X, Chen S, Xu Y, Utheim TP, Stojanovic A. Transepithelial Topography-Guided Ablation Assisted by Epithelial Thickness Mapping for Treatment of Regression After Myopic Refractive Surgery. J Refract Surg 2019; 35:525-533. [DOI: 10.3928/1081597x-20190730-01] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 07/30/2019] [Indexed: 11/20/2022]
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Reinstein DZ, Archer TJ, Vida RS, Carp GI. Suction Stability Management in SMILE: Development of a Decision Tree for Managing Eye Movements and Suction Loss. J Refract Surg 2019; 34:809-816. [PMID: 30540363 DOI: 10.3928/1081597x-20181023-01] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 10/22/2018] [Indexed: 11/20/2022]
Abstract
PURPOSE To develop a comprehensive protocol for suction stability management during small incision lenticule extraction (SMILE). METHODS This was a retrospective video review of all SMILE cases where suction loss occurred or eye movement was noted in the medical record. The different types of eye movement were collated. A suction stability grading scale was derived to represent the magnitude of eye movements. A decision tree protocol was developed to define the management in each scenario depending on the suction stability grading and the femtosecond laser cutting progress. RESULTS Eight types of eye movement were identified: fixation light tracking, Bell's reflex, saccades, oscillations, anxiety/uncooperative patient, nociceptive reflex movement, false suction, and nystagmus. Type I eye movements were defined as small movements that shift the corneal position by a clinically negligible amount. The surgeon may want to pause the femtosecond laser cutting, regain control of the patient, then continue. Type II eye movements were defined as large movements that shift the corneal position by a clinically relevant amount, in which case the surgeon may choose to release suction (ie, a surgeon-initiated suction loss). Type III eye movements were defined as those with sufficient force to break suction (ie, a patient-generated suction loss). A comprehensive decision tree was developed to cover all possible eye movement and suction loss scenarios. Example scenarios outside the preprogrammed machine restart treatment module include converting to laser in situ keratomileusis (LASIK) if there was tracking of the interface and restarting SMILE with a thinner cap if the original cap thickness was 135 μm or greater. CONCLUSIONS With appropriate management, it is possible for the SMILE procedure to be completed on the same day by either continuing with SMILE or converting to LASIK depending on the progress of the femtosecond laser cutting. [J Refract Surg. 2018;34(12):809-816.].
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Motwani M, Pei R. The use of WaveLight Contoura to create a uniform cornea: 6-month results with subjective patient surveys. Clin Ophthalmol 2018; 12:1559-1566. [PMID: 30214139 PMCID: PMC6118238 DOI: 10.2147/opth.s175661] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose The aim of this study was to report on the 6-month visual results of Contoura with Layer Yolked Reduction of Astigmatism (LYRA) protocol, as well as the subjective patient-reported outcomes (PRO) by standardized survey. Patients and methods A retrospective analysis was conducted in 50 consecutive eyes with 6-month results that had bilateral Contoura laser-assisted in situ keratomileusis (LASIK) correction of measured astigmatism and axis using the LYRA protocol. PRO were measured via the Refractive Status and Vision Profile (RSVP) standardized survey. Objective visual results, subjective patient results, and rates of regression were reported. Results Most (78%) of the eyes achieved an uncorrected visual acuity (UCVA) of 20/15 and 98% of the eyes achieved an UCVA of 20/20 vision after primary correction. After enhancements, the percentage of uncorrected eyes achieving 20/15 vision was 90 and 20/20 vision was 100. RSVP patient-related outcomes showed that all patients (100%) were either satisfied or very satisfied with their vision. Most patients (21/25, 84%) were very satisfied. On a numerical ordinal scale of 1–10 (where 10 is the best vision), as reported by patients post-operative (post-op), 15 (60%) patients reported a vision score of 10, nine (36%) patients reported a score of 9, and one (4%) patient reported a score of 8. Initial correction was accurate on all patients, but nine eyes had refractive error changes due to epithelial masking of higher order aberrations (HOAs) over the follow-up period, a number that was also likely artificially high due to study bias. Conclusion Contoura measured axis and astigmatism-eliminated HOA, resulting in a more uniform cornea with an accurate removal of astigmatism, excellent 20/15 and 20/20 visual outcomes, and favorable patient-reported subjective outcomes.
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Affiliation(s)
| | - Ronald Pei
- Precision Outcome Consultants, Fresno, CA, USA
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Guglielmetti S, Kirton A, Reinstein DZ, Carp GI, Archer TJ. Repair of Irregularly Irregular Astigmatism by Transepithelial Phototherapeutic Keratectomy. J Refract Surg 2017; 33:714-719. [DOI: 10.3928/1081597x-20170721-04] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 07/20/2017] [Indexed: 11/20/2022]
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Chen X, Stojanovic A, Wang X, Liang J, Hu D, Utheim TP. Epithelial Thickness Profile Change After Combined Topography-Guided Transepithelial Photorefractive Keratectomy and Corneal Cross-linking in Treatment of Keratoconus. J Refract Surg 2017; 32:626-34. [PMID: 27598733 DOI: 10.3928/1081597x-20160531-02] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Accepted: 05/03/2016] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate corneal epithelial remodeling after topography-guided transepithelial photorefractive keratectomy (PRK) combined with corneal collagen cross-linking (CXL) in the treatment of keratoconus. METHODS Retrospective analysis of the epithelial thickness distribution changes in 53 keratoconic eyes of 44 patients. Manifest refraction, maximum (Kmax) and minimum (Kmin) keratometry obtained by Placido topography, corneal irregularity index (IRI) measured by Scheimpflug topography, and the epithelial thickness profile over the central 5-mm zone obtained by anterior-segment spectral domain optical coherence tomography (SD-OCT) were evaluated preoperatively and at 1 to 3, 3 to 6, and more than 6 months postoperatively. RESULTS Preoperatively, the epithelial thickness at the thinnest area (MinArea) was 48.8 ± 4.4 µm, correlating negatively with Kmax (r = -0.310, P < .05) and IRI (r = -0.362, P < .05). At more than 6 months postoperatively, epithelial thickening of 5.5 ± 5.1 µm occurred at the thinnest area (MinArea). There was no significant change in the epithelial thickness in other areas, resulting in a decrease of difference in epithelial thickness between MinArea and the rest of the paracentral areas of 5.5 ± 4.3 µm. Corrected distance visual acuity, refractive astigmatism, Kmax, Kmin, and IRI all improved after the treatment (P < .05). CONCLUSIONS A significant epithelial thickness profile change occurred after the treatment due to an increase in thickness at the preoperatively thinnest area. Because the thickness in other areas remained largely unchanged, the treatment resulted in a more even epithelial thickness distribution. This may be attributed to regularized postoperative corneal stromal shape. [J Refract Surg. 2016;32(9):626-634.].
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Dynamic Roles of the Corneal Epithelium in Refractive Surgery. CURRENT OPHTHALMOLOGY REPORTS 2017. [DOI: 10.1007/s40135-017-0149-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Reinstein DZ, Gobbe M, Archer TJ, Carp GI. Mechanism for a Rare, Idiosyncratic Complication Following Hyperopic LASIK: Diurnal Shift in Refractive Error Due to Epithelial Thickness Profile Changes. J Refract Surg 2016; 32:364-71. [DOI: 10.3928/1081597x-20160428-05] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 02/04/2016] [Indexed: 11/20/2022]
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Aristeidou A, Taniguchi EV, Tsatsos M, Muller R, McAlinden C, Pineda R, Paschalis EI. The evolution of corneal and refractive surgery with the femtosecond laser. EYE AND VISION 2015; 2:12. [PMID: 26605365 PMCID: PMC4655461 DOI: 10.1186/s40662-015-0022-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/20/2015] [Indexed: 01/12/2023]
Abstract
The use of femtosecond lasers has created an evolution in modern corneal and refractive surgery. With accuracy, safety, and repeatability, eye surgeons can utilize the femtosecond laser in almost all anterior refractive procedures; laser in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), penetrating keratoplasty (PKP), insertion of intracorneal ring segments, anterior and posterior lamellar keratoplasty (Deep anterior lamellar keratoplasty (DALK) and Descemet's stripping endothelial keratoplasty (DSEK)), insertion of corneal inlays and cataract surgery. As the technology matures, it will push surgical limits and open new avenues for ophthalmic intervention in areas not yet explored. As we witness the transition from femto-LASIK to femto-cataract surgery it becomes obvious that this innovation is here to stay. This article presents some of the most relevant advances of femtosecond lasers to modern corneal and refractive surgery.
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Affiliation(s)
| | - Elise V Taniguchi
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA USA ; Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Boston Keratoprosthesis Laboratory, Harvard Medical School, Boston, 02114 MA USA
| | | | - Rodrigo Muller
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA USA
| | - Colm McAlinden
- Flinders University, Adelaide, South Australia Australia ; Wenzhou Medical University, Wenzhou, Zhejiang China
| | - Roberto Pineda
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA USA
| | - Eleftherios I Paschalis
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA USA ; Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Boston Keratoprosthesis Laboratory, Harvard Medical School, Boston, 02114 MA USA
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Shaheen MS, El-Kateb M, Hafez TA, Piñero DP, Khalifa MA. Wavefront-Guided Laser Treatment Using a High-Resolution Aberrometer to Measure Irregular Corneas: A Pilot Study. J Refract Surg 2015; 31:411-8. [DOI: 10.3928/1081597x-20150521-08] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 04/09/2015] [Indexed: 11/20/2022]
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Reinstein DZ, Gobbe M, Archer TJ, Youssefi G, Sutton HFS. Stromal surface topography-guided custom ablation as a repair tool for corneal irregular astigmatism. J Refract Surg 2015; 31:54-9. [PMID: 25599543 DOI: 10.3928/1081597x-20141218-06] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 09/26/2014] [Indexed: 11/20/2022]
Abstract
PURPOSE To illustrate the concept of using a stromal surface topography-guided procedure for therapeutic repair after a complication following primary laser refractive surgery. METHODS One case example of therapeutic retreatment for short nasal flap after primary LASIK performed in September 2000 is presented. The Artemis very high-frequency digital ultrasound arc-scanner (Arc-Scan, Inc., Morrison, CO) was used to obtain layered corneal thickness including epithelial thickness profile. Corneal front surface elevation was measured with the Orbscan II (Bausch & Lomb, Salt Lake City, UT). Stromal surface height was then calculated by subtracting epithelial thickness data from corneal front surface elevation data and used to calculate the ablation profile applied to the eye. The treatment was performed using the Ultralink system (ArcScan, Inc.), linking the ultrasound corneal thickness data with the Technolas 217c laser (Bausch & Lomb). Postoperative data were available at 30 days and 13 years. RESULTS One month after treatment, the epithelial thickness map demonstrated that the difference in thickness between the thinnest and thickest points located 2.5-mm nasally was reduced by 26 µm (from 56 to 30 µm). The axial difference map demonstrated an increase in corneal curvature of approximately 4 diopters where the cornea was the flattest nasally, thereby reducing the corneal asymmetry. The anterior elevation map also showed a reduced depression nasally. The patient reported significant improvement of her night vision. CONCLUSIONS This case example of stromal surface topography-guided treatment demonstrated a significant reduction in the irregularity of the stromal surface and an improvement in the topography, and the visual quality. Stromal surface topography-guided ablation might become the tool of the future for therapeutic repairs because it offers advantages over the current alternative of transepithelial phototherapeutic keratectomy.
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Reinstein DZ, Archer TJ, Gobbe M. Rate of Change of Curvature of the Corneal Stromal Surface Drives Epithelial Compensatory Changes and Remodeling. J Refract Surg 2014; 30:799-802. [DOI: 10.3928/1081597x-20141113-02] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Rocha KM, Krueger RR. Spectral-domain optical coherence tomography epithelial and flap thickness mapping in femtosecond laser-assisted in situ keratomileusis. Am J Ophthalmol 2014; 158:293-301.e1. [PMID: 24792107 DOI: 10.1016/j.ajo.2014.04.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 04/14/2014] [Accepted: 04/15/2014] [Indexed: 11/15/2022]
Abstract
PURPOSE To evaluate the change of epithelial and flap thickness after femtosecond laser-assisted in situ keratomileusis (LASIK) using spectral-domain optical coherence tomography (SD OCT) in correlation with the spherical equivalent refraction treated and clinical outcomes. DESIGN Prospective, randomized, contralateral-eye study. METHODS Forty myopic eyes underwent LASIK using an excimer laser with refraction ranging from -1.00 to -7.25 diopters (mean -3.25±1.9). Flap creation was randomized between eyes, using the IntraLASE FS60 laser (IL) in 1 eye and WaveLight FS200 laser (FS) in the contralateral eye. SD OCT was used to evaluate the epithelial and flap thickness profiles and corneal power preoperatively and at 1 week and 1, 3, and 9 months postoperatively. Manifest and wavefront refractions were performed at each postoperative visit. RESULTS Statistically significant epithelial thickening was observed in both IL and FS groups as early as 1 month postoperatively (P=.033 and P=.042), but this stabilized between 3 (P=.042 and P=.035) and 9 months (P=.043 and P=.041). Femtosecond-LASIK flaps were thicker in the IL group in comparison to the FS group at 3 and 9 months postoperatively (P=.003 and P=.005, respectively). There was a statistically significant correlation between the magnitude of preoperative myopic refraction and the central epithelial thickness at 1, 3, and 9 months (Pearson correlation coefficients 0.485, 0.587 and 0.576) (P=.0021, P=.0010, and P=.0011), respectively. SD OCT corneal power maps showed steepening at 3 and 9 months along with mild myopic shift. CONCLUSION Progressive epithelial and flap thickening with increased corneal power were observed after femtosecond laser-assisted in situ keratomileusis for myopia with consequent stabilization between 3 to 9 months postoperatively. The magnitude of epithelial and flap thickness remodeling correlated to the preoperative myopic refractive error.
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Affiliation(s)
| | - Ronald R Krueger
- Cleveland Clinic Foundation - Cole Eye Institute, Cleveland, Ohio
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Reinstein DZ, Archer TJ, Dickeson ZI, Gobbe M. Transepithelial phototherapeutic keratectomy protocol for treating irregular astigmatism based on population epithelial thickness measurements by artemis very high-frequency digital ultrasound. J Refract Surg 2014; 30:380-7. [PMID: 24972404 DOI: 10.3928/1081597x-20140508-01] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 02/17/2014] [Indexed: 11/20/2022]
Abstract
PURPOSE To report the outcomes of transepithelial phototherapeutic keratectomy (TE-PTK) in the treatment of irregular astigmatism and define a standard treatment protocol based on population epithelial thickness measurements. METHODS Retrospective analysis of 41 TE-PTK procedures in cases of irregular astigmatism after refractive surgery or with corneal irregularities. The TE-PTK ablations were performed according to preoperative epithelial thickness maps obtained using an Artemis very high-frequency digital ultrasound arc-scanner (ArcScan, Inc., Morrison, CO). Visual and refractive outcomes were analyzed 12 months after the procedure. The efficacy of the stromal surface regularization was evaluated as the change in epithelial thickness range (ie, the difference between minimum and maximum epithelial thickness). A further refractive ablation was performed immediately after TE-PTK in 12 eyes. RESULTS Corrected distance visual acuity was improved by one or more lines in 58% of eyes, whereas 1 eye lost one line and no eyes lost two lines. Significant stromal surface regularization was achieved with epithelial thickness range reduced on average from 41 to 29 μm. There was an unpredictable refractive shift in the TE-PTK only group with a change of more than 0.50 diopter (D) in 59% of eyes. Refractive accuracy in the TE-PTK with refractive ablation group was reasonably good, although there were two outliers (18%) outside ±1.00 D. A therapeutic window was identified between the highest thinnest epithelium of 51 μm and lowest thickest epithelium of 60 μm. CONCLUSIONS TE-PTK can be a safe and effective method of reducing stromal surface irregularities by taking advantage of the natural masking effect of the epithelium. There can be a significant refractive shift due to lenticular epithelial masking. A standard protocol of targeting an initial TE-PTK ablation for 55 μm will likely achieve breakthrough of the thinnest epithelium without total epithelial removal, allowing the treatment to be continued in a stepwise fashion.
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Liu B, Chen W, Shao DW, Wang H, Ru HX, Zhang M, Wang Y, Yang CY. Using LaserSight Astrapro Planner 2.2 Z software in corneal topography-guided laser in situ keratomileusis for myopia with asymmetric corneal shape. Int J Ophthalmol 2014; 7:452-6. [PMID: 24967190 DOI: 10.3980/j.issn.2222-3959.2014.03.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Accepted: 12/04/2013] [Indexed: 11/02/2022] Open
Abstract
AIM To determine the clinical outcomes of laser in situ keratomileusis (LASIK) treatments using LaserSight AstraPro Planner 2.2 Z software for myopia with asymmetric corneal shape. METHODS Four hundred and eighty-five eyes [243 patients; spherical equivalent (SE), -5.93±1.88 diopters (D)] were treated with asymmetric ablations using LaserSight SLX laser (version 5.3, 300Hz) were retrospectively analyzed and LaserSight AstraPro Planner 2.2 Z software. Preoperative and postoperative uncorrected visual acuities (UCVA), spherical equivalent (SE) refraction, pachymetry, and corneal asphericity (Q value) and decentration were evaluated. RESULTS At 12mo postoperatively, the decimal UCVA was 1.0 or better in 449 (92.6%) eyes. Two eyes (0.4%) lost 1 line of the decimal best spectacle-corrected visual acuity (BCVA), 316 (65.2%) did not change, 149 (30.7%) gained 1 line, and 18 (3.7%) gained 2 lines or more after surgery. Three hundred and thirty-two eyes (68.5%) were within 0.5 D in SE. The mean tissue saving ablation depth was 4.28±2.86 (0-16) µm (median, 4 µm). The mean attempted remaining central corneal thickness was 435.79±29.56 µm, the mean postoperative pachymetry was 444.94±28.93 µm. The mean preoperative Q value was -0.19±0.18, the postoperative was 0.30±0.48 (P=0.000). The mean postoperative decentration was 0.39±0.19 mm. CONCLUSION Topography-guided LASIK with AstraPro Planner 2.2 Z custom ablation planning software in an asymmetric ablation mode was an effective, safe, predictable, and stable refractive procedure for the myopia with asymmetric corneal topography.
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Affiliation(s)
- Bing Liu
- Department of Ophthalmology, Air Force General Hospital of PLA, Beijing 100142, China
| | - Wei Chen
- Department of Ophthalmology, Air Force General Hospital of PLA, Beijing 100142, China
| | - De-Wang Shao
- Department of Ophthalmology, Air Force General Hospital of PLA, Beijing 100142, China
| | - Hua Wang
- Department of Ophthalmology, Air Force General Hospital of PLA, Beijing 100142, China
| | - Hai-Xia Ru
- Department of Ophthalmology, Air Force General Hospital of PLA, Beijing 100142, China
| | - Min Zhang
- Department of Ophthalmology, Air Force General Hospital of PLA, Beijing 100142, China
| | - Ying Wang
- Department of Ophthalmology, Air Force General Hospital of PLA, Beijing 100142, China
| | - Chun-Yan Yang
- Department of Ophthalmology, Air Force General Hospital of PLA, Beijing 100142, China
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Reinstein DZ, Archer TJ, Gobbe M, Rothman RC. Epithelial thickness changes following realignment of a malpositioned free cap. J Cataract Refract Surg 2014; 40:1237-9. [PMID: 24957444 DOI: 10.1016/j.jcrs.2014.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Indexed: 11/19/2022]
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Abstract
BACKGROUND Within less than 30 years refractive laser surgery has been developed from an experimental technique to one of the most frequently applied procedures in ophthalmology worldwide. RESULTS Regarding the success rate of refractive results, myopia correction has reached a level (95% within ± 0.5 D) that is comparable to manifest refraction so that there is not much room for improvement. The most recently developed technique is femtosecond laser lenticule extraction which was introduced in 2007 in Germany. Early clinical results were very promising but the awaited bilateral comparative studies are still lacking. Although new laser types that will be able to provide improved profiles are on the horizon, the problem of reoperations has not yet been solved. Topography-guided ablation is notoriously plagued by undercorrection so that topography-guided treatment is planned as a two step-procedure. The reason for the undercorrection is the leveling effect of the epithelium. PERSPECTIVES The evolution of refractive surgery has slowed down during the last years, however, some important innovations are at the advent.
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Affiliation(s)
- T Seiler
- Institut für Refraktive und Ophthalmo-Chirurgie (IROC), Stockerstr. 37, 8002, Zürich, Schweiz,
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Vinciguerra P, Roberts CJ, Albé E, Romano MR, Mahmoud A, Trazza S, Vinciguerra R. Corneal curvature gradient map: a new corneal topography map to predict the corneal healing process. J Refract Surg 2014; 30:202-7. [PMID: 24763726 DOI: 10.3928/1081597x-20140218-02] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 11/20/2013] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate a new curvature gradient topography map to predict postoperative corneal remodeling. METHODS In this retrospective study, 32 eyes of 16 patients with myopia underwent excimer ablation surgery with a postoperative high curvature gradient. The new curvature gradient map (acquired immediately postoperatively) shows the difference between the curvatures of two points over the distance between them; it was compared to the tangential curvature difference map between 1 and 12 months postoperatively to determine their relationship. Corneas were divided into 12 regions for analysis: four 90°-wide sectors centered on 0°, 90°, 180°, and 270°. There were three subdivisions in each sector: central (radius: 0 to 2.75 mm), paracentral (radius: 2.75 to 3.25 mm), and peripheral (radius: 3.25 to 4.5 mm). Linear regression analysis was performed by region. RESULTS The following regions had significant relationships between the initial curvature gradient and curvature difference between 1 and 12 months postoperatively: the paracentral zone of the 90° sector (P = .0145; R(2) = 0.1832) and both the central (P = .0034; R(2) = 0.2522) and paracentral (P = .0452; R(2) = 0.1271) zones of the 270° sector. The greatest average initial tangential curvature was in the 270° sector. CONCLUSIONS The initial curvature gradient after surgery predicted change in tangential curvature over the subsequent 12 months in areas where initial tangential curvature was greatest. When the curvature gradient was high, the surface curvature modification remained in progress months after surgery.
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Ivarsen A, Hjortdal JØ. Topography-guided Photorefractive Keratectomy for Irregular Astigmatism After Small Incision Lenticule Extraction. J Refract Surg 2014; 30:429-32. [DOI: 10.3928/1081597x-20140508-02] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 03/17/2014] [Indexed: 11/20/2022]
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Navas A. June consultation #6. J Cataract Refract Surg 2014; 40:1052-3; discussion 1054. [PMID: 24857449 DOI: 10.1016/j.jcrs.2014.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Cleary C, Li Y, Tang M, Gendy NSE, Huang D. Predicting transepithelial phototherapeutic keratectomy outcomes using Fourier domain optical coherence tomography. Cornea 2014; 33:280-7. [PMID: 24452208 PMCID: PMC3946298 DOI: 10.1097/ico.0000000000000050] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE The aim of this study was to use Fourier domain optical coherence tomography to predict transepithelial phototherapeutic keratectomy outcomes. METHODS This is a prospective case series. Subjects with anterior stromal corneal opacities underwent an excimer laser phototherapeutic keratectomy (PTK) combined with a photorefractive keratectomy using the VISX S4 excimer laser (AMO, Inc, Santa Ana, CA). Preoperative and postoperative Fourier domain optical coherence tomography images were used to develop a simulation algorithm to predict treatment outcomes. Main outcome measures included preoperative and postoperative uncorrected distance visual acuities and corrected distance visual acuity. RESULTS Nine eyes of 8 patients were treated. The nominal ablation depth was 75 to 177 μm centrally and 62 to 185 μm peripherally. Measured PTK ablation depths were 20% higher centrally and 26% higher peripherally, compared with those for laser settings. Postoperatively, the mean uncorrected distance visual acuity was 20/41 (range, 20/25-20/80) compared with 20/103 (range, 20/60-20/400) preoperatively. The mean corrected distance visual acuity was 20/29 (range, 20/15-20/60) compared with 20/45 (range, 20/30-20/80) preoperatively. The MRSE was +1.38 ± 2.37 diopters (D) compared with -2.59 ± 2.83 D (mean ± SD). The mean astigmatism magnitude was 1.14 ± 0.83 D compared with 1.40 ± 1.18 D preoperatively. Postoperative MRSE correlated strongly with ablation settings, central and peripheral epithelial thickness (r = 0.99, P < 0.00001). Central islands remained difficult to predict and limited visual outcomes in some cases. CONCLUSIONS Optical coherence tomography measurements of opacity depth and 3-dimensional ablation simulation provide valuable guidance in PTK planning. Post-PTK refraction may be predicted with a regression formula that uses epithelial thickness measurements obtained by optical coherence tomography. The laser ablation rates described in this study apply only to the VISX laser.
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Affiliation(s)
- Catherine Cleary
- Center for Ophthalmic Optics and Lasers (www.COOLLab.net ), Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Yan Li
- Center for Ophthalmic Optics and Lasers (www.COOLLab.net ), Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Maolong Tang
- Center for Ophthalmic Optics and Lasers (www.COOLLab.net ), Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Nehal Samy El Gendy
- Center for Ophthalmic Optics and Lasers (www.COOLLab.net ), Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
- Department of Ophthalmology, Kaser Al Aini School of medicine, Cairo University, Cairo, Egypt
| | - David Huang
- Center for Ophthalmic Optics and Lasers (www.COOLLab.net ), Doheny Eye Institute and Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
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Agreement of Corneal Epithelial Profiles Produced by Automated Segmentation of SD-OCT Images Having Different Optical Resolutions. Eye Contact Lens 2014; 40:99-105. [DOI: 10.1097/icl.0000000000000017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Kalkan Akcay E, Uysal BS, Sarac O, Ugurlu N, Yulek F, Cagil N, Aslan N. The Effect of Corneal Epithelium on Corneal Curvature in Patients with Keratoconus. Semin Ophthalmol 2014; 30:364-71. [DOI: 10.3109/08820538.2013.874490] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Zhou W, Stojanovic A. Comparison of corneal epithelial and stromal thickness distributions between eyes with keratoconus and healthy eyes with corneal astigmatism ≥ 2.0 D. PLoS One 2014; 9:e85994. [PMID: 24489687 PMCID: PMC3904857 DOI: 10.1371/journal.pone.0085994] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 11/25/2013] [Indexed: 11/18/2022] Open
Abstract
PURPOSE To identify corneal epithelial- and stromal-thickness distribution patterns in keratoconus using spectral-domain optical coherence tomography (SD-OCT). PATIENTS AND METHODS We analyzed SD-OCT findings in 20 confirmed cases of keratoconus (group 1) and in 20 healthy subjects with corneal astigmatism ≥ 2 D (group 2). Epithelial and stromal thicknesses were measured at 11 strategic locations along the steepest and flattest meridians, previously located by corneal topography. Vertical mirrored symmetry superimposition was used in the statistical analysis. RESULTS The mean maximum keratometry measurements in groups 1 and 2 were 47.9 ± 2.9 D (range, 41.8-52.8) and 45.6 ± 1.1 D (range, 42.3-47.5), respectively, with mean corneal cylinders of 3.3 ± 2.2 D (range, 0.5-9.5) and 3.6 ± 1.2 D (range, 2.0-6.4), respectively. The mean epithelial thickness along the steepest meridian in group 1 was the lowest (37.4 ± 4.4 µm) at 1.2 mm inferotemporally and the highest (59.3 ± 4.4 µm) at 1.4 mm supranasally from the corneal vertex. There was only a small deviation in thickness along the steepest meridian in group 2, as well as along the flattest meridians in both groups. The stromal thickness distribution in the two groups was similar to the epithelial, while the stromal thickness was generally lower in group 1 than in group 2. CONCLUSIONS SD-OCT provides details about the distribution of corneal epithelial and stromal thicknesses. The epithelium and stroma in keratoconic eyes were thinner inferotemporally and thicker supranasally compared with control eyes. The distribution pattern was more distinct in epithelium than in stroma. This finding may help improve the early diagnosis of keratoconus. TRIAL REGISTRATION ClinicalTrials.gov NCT02023619.
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Affiliation(s)
- Wen Zhou
- SynsLaser Kirurgi AS, Tromsø, Troms, Norway
| | - Aleksandar Stojanovic
- SynsLaser Kirurgi AS, Tromsø, Troms, Norway
- Eye Department, University Hospital North Norway, Tromsø, Troms, Norway
- * E-mail:
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Reinstein DZ, Gobbe M, Archer TJ. Coaxially sighted corneal light reflex versus entrance pupil center centration of moderate to high hyperopic corneal ablations in eyes with small and large angle kappa. J Refract Surg 2013; 29:518-25. [PMID: 23909778 DOI: 10.3928/1081597x-20130719-08] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 04/01/2013] [Indexed: 11/20/2022]
Abstract
PURPOSE To determine whether centering ablations on the coaxially sighted corneal light reflex (CSCLR) in eyes with large angle kappa leads to poor visual outcomes when compared to patients with eyes with negligible angle kappa that by default would be centered on the entrance pupil. In eyes with no angle kappa, the CSCLR coincides with the entrance pupil center, whereas eyes with large angle kappa possess an offset between the CSCLR and the entrance pupil center. METHODS This study was a retrospective case series of consecutive patients treated by hyperopic LASIK using the MEL80 excimer laser (Carl Zeiss Meditec, Jena, Germany). All ablations were centered on the CSCLR using the standard non-wavefront-guided ablation profile. Angle kappa was classified according to pupil offset defined as the distance in the corneal plane between the entrance pupil center and the corneal vertex. Eyes were divided into two discrete groups according to the pupil offset: small angle kappa for pupil offset of 0.25 mm or less (n = 30) and large angle kappa for pupil offset of 0.55 mm or greater (n = 30). Safety, accuracy, cylinder vector analysis, contrast sensitivity, vertex centered corneal aberrations, entrance pupil centered whole eye aberrometry, and night vision disturbances were compared between the two groups. RESULTS There were no statistically significant differences in safety, accuracy, induced astigmatism, contrast sensitivity, or night vision disturbances between the two groups. There was also no statistically significant difference between groups for vertex centered corneal aberrations; however, as expected, coma was higher in the large angle kappa group for entrance pupil centered aberrometry because the treatment had been centered on the CSCLR rather than the entrance pupil center. CONCLUSION Refractive outcomes of high hyperopic LASIK were not found to be worse for eyes where ablation was centered more than 0.55 mm from the entrance pupil as determined by CSCLR in eyes with large angle kappa. The absence of poor quality visual outcomes in cases, which by entrance pupil centration are considered significantly "decentered," supports the notion that centration relative to the CSCLR may be preferable. This provides evidence that refractive corneal ablation should not be systematically aligned with the entrance pupil center.
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Abstract
PURPOSE OF REVIEW Topography-guided laser refractive surgery regularizes the front corneal surface irregularities to achieve the desired refractive outcome. This is particularly applicable in highly aberrated corneas, where wavefront aberrometry is often not possible. This article aims to review the recently published results of topography-guided ablations in normal regular corneas, highly aberrated corneas, and its application in conjunction with collagen cross-linking (CXL) in cases of keratectasia. RECENT FINDINGS Topography-guided laser ablation is increasingly used with good efficacy and safety outcomes in highly aberrated corneas with irregular astigmatism. These include eyes with refractive surgery complications including postlaser in-situ keratomileusis ectasia, decentered ablation, small optical zones, asymmetrical astigmatism, and postradial keratectomy astigmatism. Further indications are for postkeratoplasty astigmatism and keratoconus. Simultaneous topography-guided ablations with CXL in keratectasia have been promising, both in addressing the surface irregularities and progressive nature of the conditions. SUMMARY Topography-guided laser refractive surgery is proving to be effective and well tolerated in the visual rehabilitation of highly aberrated eyes, with increasing predictability based on the recent research.
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Abstract
PURPOSE OF REVIEW To review the principles and clinical applications of Scheimpflug corneal and anterior segment imaging with special relevance for laser refractive surgery. RECENT FINDINGS Computerized Scheimpflug imaging has been used for corneal and anterior segment tomography (CASTm) in different commercially available instruments. Such approach computes the three-dimensional image of the cornea and anterior segment, enabling the characterization of elevation and curvature of the front and back surfaces of the cornea, pachymetric mapping, calculation of the total corneal refractive power and anterior segment biometry. CASTm represents a major evolution for corneal and anterior segment analysis, beyond front surface corneal topography and single point central corneal thickness measurements. This approach enhances the diagnostic abilities for screening ectasia risk as well as for planning, evaluating the results, managing complications of refractive procedures, and selecting intraocular lens power, type, and design. In addition, dynamic Scheimpflug imaging has been recently introduced for in-vivo corneal biomechanical measurements and has also been used for anterior segment imaging of femtocataract surgery. SUMMARY Scheimpflug imaging has an important role for laser refractive surgery with different applications, which continuously improve due to advances in technology.
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Reinstein DZ, Archer TJ, Gobbe M. Improved Effectiveness of Transepithelial PTK Versus Topography-Guided Ablation for Stromal Irregularities Masked by Epithelial Compensation. J Refract Surg 2013; 29:526-33. [DOI: 10.3928/1081597x-20130719-02] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 03/18/2013] [Indexed: 11/20/2022]
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