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Reinstein DZ, Carp GI, Archer TJ, Vida RS, Yammouni R. Large Population Outcomes of Small Incision Lenticule Extraction in Young Myopic Patients. J Refract Surg 2022; 38:488-496. [PMID: 35947004 DOI: 10.3928/1081597x-20220623-01] [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 evaluate the outcomes of small incision lenticule extraction (SMILE) for myopia in a large population of young adults. METHODS In this retrospective case series, the patient population consisted of the first 4,138 consecutive SMILE treatments using the VisuMax femtosecond laser (Carl Zeiss Meditec) between 2012 and 2018 at the London Vision Clinic. Inclusion criteria were myopic spherical equivalent up to -9.00 diopters (D), cylinder up to 6.00 D, corrected distance visual acuity of 20/20 or better, age younger than 40 years, and follow-up of 12 months. Outcomes analysis was performed using the Standard Graphs for Reporting Refractive Surgery. RESULTS Data were available at 12 months in 3,722 eyes (90%), and 416 eyes (10%) were lost to follow-up. Mean attempted spherical equivalent refraction (SEQ) was -4.61 ± 1.84 D (range: -1.12 to -9.00 D). Mean cylinder was -0.78 ± 0.66 D (range: 0.00 to -6.00 D). Postoperatively, the mean SEQ relative to target was -0.13 ± 0.30 D (range: -1.35 to +1.25 D) and was within ±0.50 D in 88.1% and ±1.00 D in 99.6% of eyes. Uncorrected distance visual acuity was 20/20 or better in 95.4% of eyes and 20/25 or better in 98.7% of eyes. One line of CDVA was lost in 3.0% of eyes, and 0.08% (n = 3) lost two or more lines of CDVA, for which CDVA was restored following phototherapeutic keratectomy treatment. There was a statistically significant improvement of 0.05, 0.06, 0.07, and 0.07 log units for contrast sensitivity at 3, 6, 12, and 18 cycles per degree, respectively (P < .001). CONCLUSIONS SMILE achieved excellent outcomes for myopia up to -9.00 D with cylinder up to -5.50 D for a large population in patients without presbyopia. [J Refract Surg. 2022;38(8):488-496.].
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Changes in Corneal Morphology with Age in Asian Population: A Multicenter Study of 30,618 Cases. Adv Ther 2021; 38:5763-5776. [PMID: 34704192 PMCID: PMC8572190 DOI: 10.1007/s12325-021-01922-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 09/14/2021] [Indexed: 11/23/2022]
Abstract
Introduction To evaluate normal reference ranges for corneal morphological parameters and investigate age-related changes in these parameters in Asian subjects with healthy eyes in order to provide reference data for preoperative evaluation of corneal refractive surgery and the early differential diagnosis of subclinical and asymptomatic keratoconus. Methods This cross-sectional, multicenter, observational study was conducted in five provinces of China, from January 2014 through October 2019. It is a retrospective analysis. Examiner-blinded clinical measurements were performed after stratification of the subjects into the following age groups: < 18, 18–30, 31–40, 41–50. We evaluated 30,618 healthy eyes of Chinese subjects who exhibited a normal corneal morphology, had no history of eye surgery or trauma, stopped wearing soft contact lenses for at least 2 weeks (rigid contact lenses for at least 4 weeks), and underwent topographic studies for both eyes on the same day. Results While the anterior and posterior corneal curvatures (K1 and K2) increased with age, corneal astigmatism of the anterior and posterior surfaces (ΔK) and central, minimum, and overall corneal thicknesses decreased with age. Age-related decrease of the overall corneal thickness was more obvious toward the periphery. The anterior and posterior corneal surface heights exhibited a decrease and an increase, respectively. Both index of height asymmetry (IHA) and index of vertical asymmetry (IVA) exhibited an increase with age. Conclusions The cornea exhibits overall thinning with age and gradually changes from a flat ellipse to an elongated ellipse in Asian individuals with healthy eyes. However, the anterior and posterior surfaces become smoother with age. Owing to the very large number of cases, these small differences are statistically significant. The results obtained are consistent with the hypothesis that a normal cornea seems to withstand quite well the effect of IOP, external pressures, and the natural cross-linking.
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Moshirfar M, Tukan AN, Bundogji N, Liu HY, McCabe SE, Ronquillo YC, Hoopes PC. Ectasia After Corneal Refractive Surgery: A Systematic Review. Ophthalmol Ther 2021; 10:753-776. [PMID: 34417707 PMCID: PMC8589911 DOI: 10.1007/s40123-021-00383-w] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/02/2021] [Indexed: 01/03/2023] Open
Abstract
INTRODUCTION The incidence of ectasia following refractive surgery is unclear. This review sought to determine the worldwide rates of ectasia after photorefractive keratectomy (PRK), laser-assisted in situ keratomileusis (LASIK), and small incision lenticule extraction (SMILE) based on reports in the literature. METHODS A systematic review was conducted according to modified Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Publications were identified by a search of eight electronic databases for relevant terms between 1984 and 2021. Patient characteristics and preoperative values including manifest refractive spherical refractive equivalent (MRSE), central corneal thickness (CCT), anterior keratometry, postoperative residual stromal bed (RSB), and percent tissue altered (PTA) were summarized. In addition, annual rates of each refractive surgery were determined, and incidence of post-refractive ectasia for each type was calculated using the number of ectatic eyes identified in the literature. RESULTS In total, 57 eyes (70 eyes including those with preoperative risk factors for ectasia) were identified to have post-PRK ectasia, while 1453 eyes (1681 eyes including risk factors) had post-LASIK ectasia, and 11 eyes (19 eyes including risk factors) had post-SMILE ectasia. Cases of refractive surgery performed annually were estimated as 283,920 for PRK, 1,608,880 for LASIK, and 96,750 for SMILE. Reported post-refractive ectasia in eyes without preoperative identifiable risk factors occurred with the following incidences: 20 per 100,000 eyes in PRK, 90 per 100,000 eyes in LASIK, and 11 per 100,000 eyes in SMILE. The rate of ectasia in LASIK was found to be 4.5 times higher than that of PRK. CONCLUSION Post-refractive ectasia occurs at lower rates in eyes undergoing PRK than LASIK. Although SMILE appears to have the lowest rate of ectasia, the number of cases already reported since its recent approval suggests that post-SMILE ectasia may become a concern. Considering that keratoconus is a spectrum of disease, pre-existing keratoconus may play a larger role in postoperative ectasia than previously accounted for in the literature.
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Affiliation(s)
- Majid Moshirfar
- Hoopes Vision Research Center, Hoopes Vision, 11820 S. State Street Suite #200, Draper, UT, 84020, USA.
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA.
- Utah Lions Eye Bank, Murray, UT, USA.
| | - Alyson N Tukan
- University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Nour Bundogji
- University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Harry Y Liu
- McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Shannon E McCabe
- Hoopes Vision Research Center, Hoopes Vision, 11820 S. State Street Suite #200, Draper, UT, 84020, USA
- Mission Hills Eye Center, Pleasant Hill, CA, USA
| | - Yasmyne C Ronquillo
- Hoopes Vision Research Center, Hoopes Vision, 11820 S. State Street Suite #200, Draper, UT, 84020, USA
| | - Phillip C Hoopes
- Hoopes Vision Research Center, Hoopes Vision, 11820 S. State Street Suite #200, Draper, UT, 84020, USA
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Corneal Tomography Multivariate Index (CTMVI) effectively distinguishes healthy corneas from those susceptible to ectasia. Biomed Signal Process Control 2021. [DOI: 10.1016/j.bspc.2021.102995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Update and Review of Diagnosis and Management of Post-Refractive Surgery Ectasia. J Cataract Refract Surg 2021; 48:487-499. [PMID: 34486581 DOI: 10.1097/j.jcrs.0000000000000808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 08/18/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT Post-Refractive Surgery Ectasia is a serious, sight-threatening, and highly - avoided complication seen after the following procedures: Laser in situ Keratomileusis, Photorefractive Keratectomy, Small Incision Lenticule Extraction, Radial and/or Arcuate Keratotomy. Specific risk factors may include age, corneal thickness, degree of refractive error, corneal topographic changes including irregular astigmatism, percent tissue ablation, and residual stromal bed. Biomarkers may be a new option to help indicate who is at greatest risk for ectasia. Visual aids including glasses or contacts lenses are often required to achieve optimal vision. Collagen crosslinking is the only treatment thought to stop progression of ectasia and prevent keratoplasty. Other surgical options may include topography-guided phototherapeutic keratectomy and intrastromal corneal ring segments. Ultimately an "ounce of prevention is a pound of cure" so careful preoperative screening and ultimately offering the safest and most effective treatments for patients is arguably the most important job of the refractive surgeon.
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Martin R, Rachidi H. Stability of posterior corneal elevation one year after myopic laser in situ keratomileusis. Clin Exp Optom 2021; 95:177-86. [DOI: 10.1111/j.1444-0938.2011.00665.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Raul Martin
- IOBA‐Eye Institute and Department of Physics TAO, University of Valladolid, Valladolid, Spain. E‐mail:
| | - Houda Rachidi
- IOBA‐Eye Institute and Department of Physics TAO, University of Valladolid, Valladolid, Spain. E‐mail:
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Mohamadpour M, Khorrami-Nejad M, Kiarudi MY, Khosravi K. Evaluating the Ectasia Risk Score System in Cancelled Laser In Situ Keratomileusis Candidates. J Ophthalmic Vis Res 2020; 15:481-485. [PMID: 33133438 PMCID: PMC7591850 DOI: 10.18502/jovr.v15i4.7788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 07/27/2020] [Indexed: 11/29/2022] Open
Abstract
Purpose To evaluate the ectasia risk score system in cancelled laser in situ keratomileusis (LASIK) candidates at an academic hospital. Methods LASIK candidates who had been cancelled by a surgeon considering the patient age, preoperative central corneal thickness, residual stromal bed thickness, or preoperative manifest refraction spherical equivalent were retrospectively reviewed, and their Randleman ectasia risk score system score was calculated. Results The mean ectasia score of 194 eyes (97 patients) was 4.5 ± 2.67; 40 (20.6%), 46 (23.7%), and 108 (55.7%) eyes were classified as low-, moderate-, and high-risk eyes, respectively. The topography was abnormal in 69% of the patients. The mean manifest refraction spherical equivalent, central corneal thickness, and estimated residual stromal bed thickness were 4 (+0.50 to –15.50) diopters, 520 (439 to 608) µm, and 312.38 (61.5 to 424.12) µm, respectively. The main cause of cancellation in low- and moderate-risk patients (86 eyes) was the presence of unstable refractive error in the past year. Conclusion Although promising, some other criteria, such as stable refraction, should be added to this scoring system to achieve greater practicality since a main cause of cancelling LASIK candidates in this study was the presence of unstable refraction.
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Affiliation(s)
- Mehrdad Mohamadpour
- Translational Ophthalmology Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Masoud Khorrami-Nejad
- Translational Ophthalmology Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.,School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Yaser Kiarudi
- Translational Ophthalmology Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Keivan Khosravi
- Translational Ophthalmology Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
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Saad A, Binder PS, Gatinel D. Evaluation of the percentage tissue altered as a risk factor for developing post-laser in situ keratomileusis ectasia. J Cataract Refract Surg 2019; 43:946-951. [PMID: 28823442 DOI: 10.1016/j.jcrs.2017.04.040] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 04/12/2017] [Accepted: 04/28/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE To assess the currently recommended percentage tissue altered (PTA) metric for its ability to screen for ectasia after laser in situ keratomileusis (LASIK). SETTING Gavin Herbert Eye Institute, University of California, Irvine, California, USA, and Rothschild Foundation, Paris, France. DESIGN Retrospective case series. METHODS The study used a LASIK database created by 1 surgeon for LASIK cases with normal preoperative topography that had a minimum follow-up of 24 months with complete preoperative and intraoperative data to permit the calculation of PTA values to detect eyes at risk for developing ectasia. RESULTS Of the eyes, 593 eyes had complete data and met the inclusion criteria. Based on measured flap thickness, 126 eyes (21%) had a PTA value of 40% or more (mean 44) and a percentage of that flap thickness accounted for the PTA (mean 66.7%; range 34% to 92%). The mean attempted laser ablation was 79.8 μm ± 29.2 (SD), and the mean residual bed thickness was 304.4 ± 29.2 μm (range 212 to 369 μm). No eye developed ectasia over a mean follow-up of 30 months. CONCLUSIONS The current PTA calculation when applied to a LASIK population with normal preoperative topography and flap thickness measured with ultrasound did not predict the risk for ectasia. Differences between study populations and assumptions might have accounted for the different outcomes obtained in the initially published PTA study.
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Affiliation(s)
- Alain Saad
- From the Rothschild Foundation (Saad, Gatinel) and the Center of Expertise and Research in Optics for Clinicians (Saad, Gatinel), Paris, France; American University of Beirut (Saad), Beirut, Lebanon; Gavin Herbert Eye Institute (Binder), Department of Ophthalmology, University of California Irvine, Irvine, California, USA.
| | - Perry S Binder
- From the Rothschild Foundation (Saad, Gatinel) and the Center of Expertise and Research in Optics for Clinicians (Saad, Gatinel), Paris, France; American University of Beirut (Saad), Beirut, Lebanon; Gavin Herbert Eye Institute (Binder), Department of Ophthalmology, University of California Irvine, Irvine, California, USA
| | - Damien Gatinel
- From the Rothschild Foundation (Saad, Gatinel) and the Center of Expertise and Research in Optics for Clinicians (Saad, Gatinel), Paris, France; American University of Beirut (Saad), Beirut, Lebanon; Gavin Herbert Eye Institute (Binder), Department of Ophthalmology, University of California Irvine, Irvine, California, USA
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Chan C, Saad A, Randleman JB, Harissi-Dagher M, Chua D, Qazi M, Saragoussi JJ, Shetty R, Ancel JM, Ang R, Reinstein DZ, Gatinel D. Analysis of cases and accuracy of 3 risk scoring systems in predicting ectasia after laser in situ keratomileusis. J Cataract Refract Surg 2019; 44:979-992. [PMID: 30115298 DOI: 10.1016/j.jcrs.2018.05.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 03/27/2018] [Accepted: 05/15/2018] [Indexed: 11/17/2022]
Abstract
PURPOSE To identify risk factors for ectasia after laser in situ keratomileusis (LASIK) by comparing the accuracy of the Ectasia Risk Score System (ERSS), Screening Corneal Objective Risk of Ectasia (SCORE) Analyzer, and percentage of tissue altered (PTA) in predicting the occurrence of ectasia. SETTING Multiple centers in 8 countries. DESIGN Retrospective case series. METHODS Previously unpublished post-LASIK ectasia cases were analyzed. Consecutive patients who had LASIK performed at least 5 years previously with no resultant ectasia were used as controls. Axial maps from preoperative Orbscan IIz topographies were analyzed in a masked fashion, and examination files tested with the SCORE Analyzer. The PTA values and ERSS scores were generated using available preoperative and perioperative data. Only eyes with subjectively identified normal preoperative topography were tested with the PTA. Threshold values for the SCORE, ERSS, and PTA were more than or equal to 0, 4, and 40, respectively. RESULTS Ectasia occurred in 31 eyes (22 patients); 79 eyes (44 patients) were used as controls. In all eyes, the sensitivity and specificity for predicting ectasia, respectively, were 67.7% and 79.7% for the ERSS and 64.5% and 100% for the SCORE. In eyes with normal topography (ectasia group, 12 eyes; controls, 64 eyes), the PTA yielded sensitivity of 33.3% and specificity of 85.9%. The area under the receiver operating characteristic curve was highest for SCORE (0.911) followed by the ERSS (0.844) and PTA (0.557). CONCLUSIONS The SCORE was most predictive of ectasia, achieving the best specificity; the ERSS had the best sensitivity. Further studies are required to validate the PTA as a screening metric for ectasia.
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Affiliation(s)
- Cordelia Chan
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - Alain Saad
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - J Bradley Randleman
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - Mona Harissi-Dagher
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - Daniel Chua
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - Mujtaba Qazi
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - Jean-Jacques Saragoussi
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - Rohit Shetty
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - Jean-Marc Ancel
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - Robert Ang
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - Dan Z Reinstein
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom
| | - Damien Gatinel
- From Singapore National Eye Center (Chan, Chua) and Eye Surgeons @ Novena (Chan), Singapore, Singapore; the Rothschild Foundation (Saad, Gatinel), Clinique Lamartine (Ancel), and the Centre D'Ophtalmologie (Saragoussi), Paris, France; the American University of Beirut (Saad), Beirut, Lebanon; Roski Eye Institute (Randleman), University of Southern California, Los Angeles, California, and Pepose Vision Institute (Qazi), Chesterfield, Missouri, USA; the Departement d'Ophtalmologie (Harissi-Dagher), Université de Montréal, Montreal, Quebec, Canada; Narayana Nethralaya Hospital (Shetty), Bangalore, India; Asian Eye Institute (Ang), Manila, Philippines; London Vision Clinic (Reinstein), London, United Kingdom.
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Blackburn BJ, Gu S, Ford MR, de Stefano V, Jenkins MW, Dupps WJ, Rollins AM. Noninvasive Assessment of Corneal Crosslinking With Phase-Decorrelation Optical Coherence Tomography. Invest Ophthalmol Vis Sci 2019; 60:41-51. [PMID: 30601930 PMCID: PMC6322634 DOI: 10.1167/iovs.18-25535] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Purpose There is strong evidence that abnormalities in corneal biomechanical play a causal role in corneal ectasias, such as keratoconus. Additionally, corneal crosslinking (CXL) treatment, which halts progression of keratoconus, directly appeals to corneal biomechanics. However, existing methods of corneal biomechanical assessment have various drawbacks: dependence on IOP, long acquisition times, or limited resolution. Here, we present a method that may avoid these limitations by using optical coherence tomography (OCT) to detect the endogenous random motion within the cornea, which can be associated with stromal crosslinking. Methods Phase-decorrelation OCT (PhD-OCT), based in the theory of dynamic light scattering, is a method to spatially resolve endogenous random motion by calculating the decorrelation rate, Γ, of the temporally evolving complex-valued OCT signal. PhD-OCT images of ex vivo porcine globes were recorded during CXL and control protocols. In addition, human patients were imaged with PhD-OCT using a clinical OCT system. Results In both the porcine cornea and the human cornea, crosslinking results in a reduction of Γ (P < 0.0001), indicating more crosslinks. This effect was repeatable in ex vivo porcine corneas (change in average Γ = −41.55 ± 9.64%, n = 5) and not seen after sham treatments (change in average Γ = 2.83 ± 12.56%, n = 5). No dependence of PhD-OCT on IOP was found, and correctable effects were caused by variations in signal-to-noise ratio, hydration, and motion. Conclusions PhD-OCT may be a useful and readily translatable tool for investigating biomechanical properties of the cornea and for enhancing the diagnosis and treatment of patients.
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Affiliation(s)
- Brecken J Blackburn
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States
| | - Shi Gu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States
| | - Matthew R Ford
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | | | - Michael W Jenkins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States.,Department of Pediatrics, Case Western Reserve University, Cleveland, Ohio, United States
| | - William J Dupps
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States.,Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States.,Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Andrew M Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States
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Bohac M, Koncarevic M, Pasalic A, Biscevic A, Merlak M, Gabric N, Patel S. Incidence and Clinical Characteristics of Post LASIK Ectasia: A Review of over 30,000 LASIK Cases. Semin Ophthalmol 2018; 33:869-877. [PMID: 30359155 DOI: 10.1080/08820538.2018.1539183] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
PURPOSE To report the incidence of postoperative ectasia after laser in situ keratomileusis (LASIK). METHODS A retrospective case review of 30,167 eyes (16,732 patients) was conducted following LASIK between August 2007 and August 2015. The follow-up was between 2 and 8 years. Tomography was performed after 2 years postop. After identifying cases of ectasia, the charts of these patients were examined to identify any common factors that may have predisposed them to develop ectasia. RESULTS Ten eyes of seven patients developed post-LASIK ectasia. Eight eyes had been treated for myopia and myopic astigmatism, two eyes for mixed astigmatism. There were no cases of ectasia after LASIK for hyperopia. All 10 cases of ectasia had a flap that was created using the Moria M2 mechanical microkeratome (average flap thickness 118.15 ± 12.88 µm) and refractive error corrected using the Wavelight Allegretto excimer laser. Retrospectively, most prevalent risk factors were thin cornea (≤ 500 µm, 50% of cases), anterior topographic map irregularities (e.g., asymmetric bow tie, 40% of cases), Ectasia Risk Score > 3 (40% of cases), percent tissue thickness alteration ≥ 40% (20% of cases) and low residual stromal bed (≤ 300 µm, 30% of cases). One eye had no identifiable risk factors. In the retrospective chart review 14.97% (4,506) of all the eyes had similar risk factors to the cases that went on to develop ectasia. CONCLUSION The incidence of ectasia was 0.033% over 8 years. The incidence could be higher as some cases may destabilize beyond this period and some patients were lost to follow-up asymptomatic of any clinical signs. Other intrinsic factors may trigger the development of post LASIK ectasia. The current widely accepted risk factors are not sufficiently rigorous for screening out potential ectasia from developing after LASIK. There is a need to augment accuracy with higher sensitivity and specificity.
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Affiliation(s)
- Maja Bohac
- a School of Medicine, University of Rijeka , Specialty Eye Hospital "Svjetlost" , Zagreb , Croatia
| | - Mateja Koncarevic
- a School of Medicine, University of Rijeka , Specialty Eye Hospital "Svjetlost" , Zagreb , Croatia
| | - Adi Pasalic
- a School of Medicine, University of Rijeka , Specialty Eye Hospital "Svjetlost" , Zagreb , Croatia
| | - Alma Biscevic
- a School of Medicine, University of Rijeka , Specialty Eye Hospital "Svjetlost" , Zagreb , Croatia
| | - Maja Merlak
- b Department of Ophthalmology , School of Medicine, University of Rijeka , Rijeka , Croatia
| | - Nikica Gabric
- a School of Medicine, University of Rijeka , Specialty Eye Hospital "Svjetlost" , Zagreb , Croatia
| | - Sudi Patel
- a School of Medicine, University of Rijeka , Specialty Eye Hospital "Svjetlost" , Zagreb , Croatia.,c NHS National Services Scotland , Edinburgh , UK
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Vinciguerra R, Ambrósio R, Roberts CJ, Azzolini C, Vinciguerra P. Biomechanical Characterization of Subclinical Keratoconus Without Topographic or Tomographic Abnormalities. J Refract Surg 2018; 33:399-407. [PMID: 28586501 DOI: 10.3928/1081597x-20170213-01] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 02/03/2017] [Indexed: 12/20/2022]
Abstract
PURPOSE To present a case series of patients with subclinical keratoconus with normal topometric (anterior curvature) and tomographic findings in one eye who showed abnormalities detected by Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) in vivo biomechanical assessment. METHODS All patients had a complete ophthalmic examination, including the Corvis ST biomechanical measurements, optical tomography, and pachymetry with Pentacam (Oculus Optikgeräte GmbH), and Placido-based topography with either the Nidek (OPD III Nidek, Gamagori, Japan) or CSO platform (Costruzione Strumenti Oftalmici, Florence, Italy). Inclusion criteria were a clinical diagnosis of ectasia in one eye and normal topometric and tomographic findings in the fellow eye (subclinical keratoconus), including a Belin/Ambrósio Enhanced Ectasia total deviation index from the Pentacam with less than 1.6 standard deviations from normative values and a Corvis Biomechanical Index score of greater than 0.5 in both eyes. RESULTS Tomographic and topographic analysis was normal in one eye and abnormal in the fellow eye in 12 patients. The biomechanical results with the Corvis Biomechanical Index were shown to be abnormal in both eyes of all patients and aided the diagnosis. CONCLUSIONS Biomechanical analysis showed abnormalities, whereas tomography and topography were normal. Basing on these findings, the authors suggest the use of biomechanics as an additional diagnostic tool. [J Refract Surg. 2017;33(6):399-407.].
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Salomão M, Lopes B, Ambrósio R, Faria-Correia F, Silva-Lopes Í, Azevedo-Wagner A, Tanos FW. Paradigms, Paradoxes, and Controversies on Keratoconus and Corneal Ectatic Diseases. ACTA ACUST UNITED AC 2018. [DOI: 10.5005/jp-journals-10025-1158] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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La prédictibilité du SMILE sur quatre ans chez les myopes forts. J Fr Ophtalmol 2017; 40:561-570. [DOI: 10.1016/j.jfo.2017.01.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 01/09/2017] [Accepted: 01/17/2017] [Indexed: 11/22/2022]
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15
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Ambrósio R, Lopes BT, Faria-Correia F, Salomão MQ, Bühren J, Roberts CJ, Elsheikh A, Vinciguerra R, Vinciguerra P. Integration of Scheimpflug-Based Corneal Tomography and Biomechanical Assessments for Enhancing Ectasia Detection. J Refract Surg 2017; 33:434-443. [DOI: 10.3928/1081597x-20170426-02] [Citation(s) in RCA: 207] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 04/11/2017] [Indexed: 12/20/2022]
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Burazovitch J, Naguzeswski D, Beuste T, Guillard M. Predictability of SMILE over four years in high myopes. J Fr Ophtalmol 2017; 40:e201-e209. [DOI: 10.1016/j.jfo.2017.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 04/25/2017] [Accepted: 05/02/2017] [Indexed: 10/19/2022]
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Zhang L, Danesh J, Tannan A, Phan V, Yu F, Hamilton DR. Second-generation corneal deformation signal waveform analysis in normal, forme fruste keratoconic, and manifest keratoconic corneas after statistical correction for potentially confounding factors. J Cataract Refract Surg 2016; 41:2196-204. [PMID: 26703296 DOI: 10.1016/j.jcrs.2015.11.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Revised: 03/19/2015] [Accepted: 03/21/2015] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the difference in corneal biomechanical waveform parameters between manifest keratoconus, forme fruste keratoconus, and healthy eyes with a second-generation biomechanical waveform analyzer (Ocular Response Analyzer 2). SETTING Jules Stein Eye Institute, University of California, Los Angeles, California, USA. DESIGN Retrospective chart review. METHODS The biomechanical waveform analyzer was used to obtain corneal hysteresis (CH), corneal resistance factor (CRF), and 37 biomechanical waveform parameters in manifest keratoconus eyes, forme fruste keratoconus eyes, and healthy eyes. Useful distinguishing parameters were found using t tests and a multivariable logistic regression model with stepwise variable selection. Potential confounders were controlled for. RESULTS The study included 68 manifest keratoconus eyes, 64 forme fruste keratoconus eyes, and 249 healthy eyes. There was a statistical difference in the mean CRF between the normal group (10.2 mm Hg ± 1.7 [SD]) and keratoconus group (6.3 ± 1.9 mm Hg) (P = .003), and between the normal group and the forme fruste keratoconus group (7.8 ± 1.4 mm Hg) (P < .0001). There was no statistical difference in the mean CH between the normal group and the keratoconus group or the forme fruste keratoconus group. The CRF, height of peak 1 (P1) (P = .001), downslope of P1 (dslope1) (P = .027), upslope of peak 2 (P2) (P = .004), and downslope of P2 (P = .006) distinguished the normal group from the keratoconus groups. The CRF, downslope of P2 derived from upper 50% of applanation peak (P = .035), dslope1 (P = .014), and upslope of P1 (P = .008) distinguished the normal group from the forme fruste keratoconus group. CONCLUSION Differences in multiple biomechanical waveform parameters can differentiate between healthy and diseased conditions and might improve early diagnosis of keratoconus and forme fruste keratoconus. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned.
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Affiliation(s)
- Lijun Zhang
- From the Refractive Center (Zhang), the 3rd Hospital of Dalian, Dalian Medical University, China; the UCLA Laser Refractive Center (Hamilton), Jules Stein Eye Institute (Tannan, Phan), David Geffen School of Medicine at the University of California (Danesh), and the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, Los Angeles, California, USA
| | - Jennifer Danesh
- From the Refractive Center (Zhang), the 3rd Hospital of Dalian, Dalian Medical University, China; the UCLA Laser Refractive Center (Hamilton), Jules Stein Eye Institute (Tannan, Phan), David Geffen School of Medicine at the University of California (Danesh), and the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, Los Angeles, California, USA
| | - Anjali Tannan
- From the Refractive Center (Zhang), the 3rd Hospital of Dalian, Dalian Medical University, China; the UCLA Laser Refractive Center (Hamilton), Jules Stein Eye Institute (Tannan, Phan), David Geffen School of Medicine at the University of California (Danesh), and the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, Los Angeles, California, USA
| | - Vivian Phan
- From the Refractive Center (Zhang), the 3rd Hospital of Dalian, Dalian Medical University, China; the UCLA Laser Refractive Center (Hamilton), Jules Stein Eye Institute (Tannan, Phan), David Geffen School of Medicine at the University of California (Danesh), and the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, Los Angeles, California, USA
| | - Fei Yu
- From the Refractive Center (Zhang), the 3rd Hospital of Dalian, Dalian Medical University, China; the UCLA Laser Refractive Center (Hamilton), Jules Stein Eye Institute (Tannan, Phan), David Geffen School of Medicine at the University of California (Danesh), and the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, Los Angeles, California, USA
| | - D Rex Hamilton
- From the Refractive Center (Zhang), the 3rd Hospital of Dalian, Dalian Medical University, China; the UCLA Laser Refractive Center (Hamilton), Jules Stein Eye Institute (Tannan, Phan), David Geffen School of Medicine at the University of California (Danesh), and the Department of Biostatistics (Yu), UCLA Fielding School of Public Health, Los Angeles, California, USA.
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Abstract
PURPOSE To improve keratoconus (KC) screening with new in vivo biomechanical Scheimpflug analyses. METHODS After adjusting for intraocular pressure and corneal thickness, predefined static and new dynamic Scheimpflug curve analyses [Pentacam HR and Corvis ST (CST); Oculus] of 87 normal eyes, 27 subclinical KC eyes, 42 suspected KC, and 65 manifest KC eyes were reviewed retrospectively. A t test (for a normal distribution), Wilcoxon matched-pairs test (if not normally distributed), and receiver operating characteristics were used to test for statistically significant differences between these groups. In addition, new dynamic curve analyses were performed to analyze corneal dynamics throughout the entire response to the CST air puff impulse. RESULTS Comparing normal and KC-suspect eyes, the parameters A1 length, A2 length, radius of the inward-bended cornea, and deflection length at the highest concavity revealed statistically significant differences. In addition, the newly calculated "applanation length level" and "deflection length level" demonstrated consistently increasing differences with increasing statistical significance between normal eyes and those with advancing KC stages. However, when comparing normal and subclinical KC eyes, none of the analyzed parameters demonstrated statistically significant differences. CONCLUSIONS In vivo biomechanical analyses (CST) at their current state only marginally improve KC screening protocols. Newly generated parameters such as the applanation length level and deflection length level might further improve early KC screening.
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[Corneal morphometric predictive models from ametropia to excimer laser treatment]. ACTA ACUST UNITED AC 2015; 90:312-23. [PMID: 25865651 DOI: 10.1016/j.oftal.2014.09.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/09/2014] [Accepted: 09/30/2014] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To develop corneal morphometric models with refractive error in excimer laser surgery. METHOD A prospective-longitudinal study was conducted on 78 patients (151 eyes) using the LASIK surgical technique, and 56 patients (111 eyes) with myopic astigmatism using ESIRIS (Schwind-Germany) equipment with pendulous microkeratome. The results were analyzed using descriptive statistics. A NIDEK Confoscan microscope was used to obtain and study the images. RESULTS After LASIK treatment 84.3% of the variations in epithelium thickness variations were due to the magnitude of refractive error and the epithelium thickness before LASIK treatment. More than two-thirds (68.8%) of the variations in keratocyte density variations in posterior flap and 48.2% of the variations in the anterior retroablation zone were due to the magnitude of the refractive error. Variations of 90% were found in the corneal thickness after LASEK, which were due to the magnitude of the refractive error before LASEK. CONCLUSIONS Predictive models reveal that morphometrical variations depend of the magnitude of the refractive error. These models are very important in the selection of patient for refractive surgery, and also for the specific technique to use.
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Miraftab M, Fotouhi A, Hashemi H, Jafari F, Shahnazi A, Asgari S. A modified risk assessment scoring system for post laser in situ keratomileusis ectasia in topographically normal patients. J Ophthalmic Vis Res 2015; 9:434-8. [PMID: 25709767 PMCID: PMC4329702 DOI: 10.4103/2008-322x.150806] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 12/30/2013] [Indexed: 12/01/2022] Open
Abstract
Purpose: To evaluate and modify the Randleman Ectasia Risk Score System for predicting post-laser in situ keratomileusis (LASIK) ectasia in patients with normal preoperative corneal topography. Methods: In this retrospective study we reviewed data from 136 eyes which had undergone LASIK including 34 ectatic and 102 normal eyes between 1999 and 2009. After determining the sensitivity and specificity of the Randleman system, a modified model was designed to predict the risk of post-LASIK corneal ectasia more accurately. Next, the sensitivity and specificity of this modified scoring system was determined and compared to that of the original scoring system. Results: In our sample, the sensitivity and specificity of the Randleman system was 70.1% and 50.5%, respectively. Our modified model included the following parameters: preoperative central corneal thickness, manifest refraction spherical equivalent, and maximum keratometry, as well as the number of months elapsed from surgery. Sensitivity and specificity rates of the modified system were 74.2% and 76.2%, respectively. The difference in receiver operating characteristic curves between the Randleman and modified scoring systems was statistically significant (P<0.001). The best sensitivity and specificity for our model occurred with a cumulative cutoff score of 4.00; a low risk was considered if the score was ≤4.00, and high risk was defined with a score > 4.00. Conclusion: Our modified ectasia risk scoring system for patients with normal corneal topography can predict post LASIK ectasia risk with acceptable sensitivity and specificity. However, there are still unidentified risk factors for which further studies are required.
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Affiliation(s)
| | - Akbar Fotouhi
- Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Hassan Hashemi
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
| | - Fatemeh Jafari
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
| | - Ashkan Shahnazi
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
| | - Soheila Asgari
- Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, International Campus, Tehran, Iran
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Ramos IC, Correa R, Guerra FP, Trattler W, Belin MW, Klyce SD, Fontes BM, Schor P, Smolek MK, Dawson DG, Chalita MR, Cazal JO, Ruiz M, Randleman JB, Ambrósio R. Variability of Subjective Classifications of Corneal Topography Maps From LASIK Candidates. J Refract Surg 2013; 29:770-5. [DOI: 10.3928/1081597x-20130823-01] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 06/12/2013] [Indexed: 11/20/2022]
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Bühren J, Schäffeler T, Kohnen T. Preoperative topographic characteristics of eyes that developed postoperative LASIK keratectasia. J Refract Surg 2013; 29:540-9. [PMID: 23909781 DOI: 10.3928/1081597x-20130719-04] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 03/26/2013] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess the suitability of corneal anterior and posterior surface aberrations and pachymetry profile data to discriminate between eyes that later developed postoperative LASIK iatrogenic keratectasia and eyes that remained stable. METHODS Ten eyes of five patients that later developed iatrogenic keratectasia and 245 control eyes of 245 patients with a stable postoperative LASIK follow-up of 12 months or more were included. Zernike coefficients from anterior and posterior cornea, data from corneal pachymetry profiles, and output values of discriminant functions (input from Zernike coefficients, pachymetry data, and age) were assessed for their usefulness to discriminate between preoperative eyes with iatrogenic keratectasia eyes and controls using receiver operator characteristic (ROC) curve analysis. Furthermore, Randleman Ectasia Risk Scores were calculated for each eye. RESULTS Anterior horizontal coma (C3(1)) was the coefficient with highest discriminative ability (area under the ROC curve [AZROC] = 0.819). For posterior coefficients and pachymetry data, AZROC values were lower. Constructing discriminant functions increased AZROC values. The function containing anterior and posterior Zernike coefficients, pachymetry data, and age reached an AZROC of 0.991. The other functions ranged from 0.858 (pachymetry) to 0.981 (anterior and posterior Zernike coefficients and age). With the Randleman Ectasia Risk Scores, 80.4% were classified correctly if eyes with 4 points or more were excluded from treatment (87.1% for 3 points or more). CONCLUSIONS Preoperative corneal topographic characteristics of eyes that developed iatrogenic keratectasia were different than those of eyes that remained stable. However, topography patterns were not identical with those found in eyes with subclinical keratoconus in previous studies. Discriminant functions from Zernike coefficients and pachymetry data were useful to discriminate between normal eyes and eyes with preoperative iatrogenic keratectasia.
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Affiliation(s)
- Jens Bühren
- Department of Ophthalmology, Goethe University, Frankfurt am Main, Germany.
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Sutton G, Lawless M, Hodge C. Laser in situ keratomileusis in 2012: a review. Clin Exp Optom 2013; 97:18-29. [PMID: 23786377 DOI: 10.1111/cxo.12075] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Revised: 11/08/2012] [Accepted: 12/14/2012] [Indexed: 11/25/2022] Open
Abstract
Laser in situ keratomileusis (LASIK) is a safe and effective treatment for refractive error. A combination of technological advances and increasing surgeon experience has served to further refine refractive outcomes and reduce complication rates. In this article, we review LASIK as it stands in late 2012: the procedure, indications, technology, complications and refractive outcomes.
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Affiliation(s)
- Gerard Sutton
- Vision Eye Institute, Chatswood, New South Wales, Australia; Save Sight Institute, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
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Moshirfar M, Edmonds JN, Behunin NL, Christiansen SM. Corneal biomechanics in iatrogenic ectasia and keratoconus: A review of the literature. Oman J Ophthalmol 2013; 6:12-7. [PMID: 23772119 PMCID: PMC3678190 DOI: 10.4103/0974-620x.111895] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Ocular Response Analyzer (ORA) (Reichert Ophthalmic Instruments, Buffalo, NY) allows direct measurement of corneal biomechanical properties. Since its introduction, many studies have sought to elucidate the clinical applications of corneal hysteresis (CH) and corneal resistance factor (CRF). More recently, detailed corneal deformation signal waveform analysis (WA) has potentially expanded the diagnostic capabilities of the ORA. In this review, the role of CH, CRF, and WA are examined in keratoconus (KC) and iatrogenic ectasia (IE). The PubMed database was searched electronically for peer-reviewed literature in July 2012 and August 2012 without date restrictions. The search strategy included medical subject heading (MeSH) and natural language terms to retrieve references on corneal biomechanics, CH, CRF, corneal deformation signal WA, IE, and KC. The evidence suggests that while CH and CRF are poor screening tools when used alone, increased sensitivity and specificity of KC and IE screening result when these parameters are combined with tomography and topography. Recent advances in WA are promising, but little is currently understood about its biomechanical and clinical relevance. Future studies should seek to refine the screening protocols for KC and IE as well as define the clinical applicability of WA parameters.
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Affiliation(s)
- Majid Moshirfar
- Department of Ophthalmology, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, USA
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Ambrósio R, Randleman JB. Screening for Ectasia Risk: What Are We Screening For and How Should We Screen For It? J Refract Surg 2013; 29:230-2. [DOI: 10.3928/1081597x-20130318-01] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Enhanced Screening for Ectasia Susceptibility Among Refractive Candidates: The Role of Corneal Tomography and Biomechanics. CURRENT OPHTHALMOLOGY REPORTS 2013. [DOI: 10.1007/s40135-012-0003-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Moisseiev E, Sela T, Minkev L, Varssano D. Increased preference of surface ablation over laser in situ keratomileusis between 2008-2011 is correlated to risk of ecatasia. Clin Ophthalmol 2013; 7:93-8. [PMID: 23345963 PMCID: PMC3548437 DOI: 10.2147/opth.s38959] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To evaluate the trends in corneal refractive procedure selection for the correction of myopia, focusing on the relative proportions of laser in situ keratomileusis (LASIK) and surface ablation procedures. METHODS Only eyes that underwent LASIK or surface ablation for the correction of myopia between 2008-2011 were included in this retrospective study. Additional recorded parameters included patient age, preoperative manifest refraction, corneal thickness, and calculated residual corneal bed thickness. A risk score was given to each eye, based on these parameters, according to the Ectasia Risk Factor Score System (ERFSS), without the preoperative corneal topography. RESULTS This study included 16,163 eyes, of which 38.4% underwent LASIK and 61.6% underwent surface ablation. The risk score correlated with procedure selection, with LASIK being preferred in eyes with a score of 0 and surface ablation in eyes with a score of 2 or higher. When controlling for age, preoperative manifest refraction, corneal thickness, and all parameters, the relative proportion of surface ablation compared with LASIK was found to have grown significantly during the study period. CONCLUSIONS Our results indicate that with time, surface ablation tended to be performed more often than LASIK for the correction of myopia in our cohort. Increased awareness of risk factors and preoperative risk assessment tools, such as the ERFSS, have shifted the current practice of refractive surgery from LASIK towards surface ablation despite the former's advantages, especially in cases in which the risk for ectasia is more than minimal (risk score 2 and higher).
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Affiliation(s)
- Elad Moisseiev
- Department of Ophthalmology, Tel-Aviv Medical Center, Tel-Aviv, Israel ; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Spadea L, Cantera E, Cortes M, Conocchia NE, Stewart CW. Corneal ectasia after myopic laser in situ keratomileusis: a long-term study. Clin Ophthalmol 2012; 6:1801-13. [PMID: 23152659 PMCID: PMC3497457 DOI: 10.2147/opth.s37249] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background The purpose of this study was to evaluate the long-term postoperative incidence of and key factors in the genesis of corneal ectasia after myopic laser-assisted in situ keratomileusis (LASIK) in a large number of cases. Methods A retrospective review of one surgeon’s myopic LASIK database was performed. Patients were stratified into two groups based on date of surgery, ie, group 1 (1313 eyes) from 1999 to 2001 and group 2 (2714 eyes) from 2001 to 2003. Visual acuity, refraction, pachymetry, and corneal topography data were available for each patient from examinations performed both before and after the refractive procedures. Results Of the 4027 surgically treated eyes, 23 (0.57%) developed keratectasia during the follow-up period, which was a minimum seven years; nine eyes (0.69%) were from group 1 and 14 eyes (0.51%) were from group 2. The onset of corneal ectasia was at 2.57 ± 1.04 (range 1–4) years and 2.64 ± 1.29 (range 0.5–5) years, respectively, for groups 1 and 2. The most important preoperative risk factors using the Randleman Ectasia Risk Score System were manifest refractive spherical error in group 1 and a thin residual stromal bed in group 2. Each of the cases that developed corneal ectasia had risk factors that were identified. Conclusion Ectasia was an uncommon outcome after an otherwise uncomplicated laser in situ keratomileusis procedure. The variables present in eyes developing postoperative LASIK ectasia can be better understood using the Randleman Ectasia Risk Score System.
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Affiliation(s)
- Leopoldo Spadea
- University of L'Aquila, Department of Biotechnological and Applied Clinical Sciences, Eye Clinic, L'Aquila
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Hodge C, Lawless M, Sutton G. Keratectasia following LASIK in a patient with uncomplicated PRK in the fellow eye. J Cataract Refract Surg 2011; 37:603-7. [PMID: 21333883 DOI: 10.1016/j.jcrs.2010.12.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2010] [Revised: 11/14/2010] [Accepted: 11/16/2010] [Indexed: 10/18/2022]
Abstract
We present a case of unilateral keratectasia in a laser refractive surgery patient. Laser in situ keratomileusis (LASIK) was performed in the first eye, but because of difficulty lifting the femtosecond-created cap in the second eye, photorefractive keratectomy was performed in that eye. Neither eye had risk factors for keratectasia; both had identical low scores on the Randleman risk factor score. Although femtosecond laser caps were created in both eyes, ectasia developed in only the LASIK eye, in which the cap was lifted. We believe this is the first case of this complication reported in the literature. It highlights our incomplete knowledge of the risk factors for keratectasia following LASIK and suggests that unlifted flaps do not undergo the same biomechanical weakening as flaps that are lifted.
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Affiliation(s)
- Chris Hodge
- Vision Eye Institute Chatswood, Level 3 270 Victoria Avenue, Chatswood, NSW, Australia.
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