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Randleman JB, Zhang H, Dupps WJ, Scarcelli G. Reply. Ophthalmology 2024; 131:e23-e24. [PMID: 38219143 DOI: 10.1016/j.ophtha.2023.12.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 12/05/2023] [Accepted: 12/07/2023] [Indexed: 01/15/2024] Open
Affiliation(s)
- J Bradley Randleman
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio; Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio.
| | | | - William J Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio; Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
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Randleman JB, Zhang H, Asroui L, Tarib I, Dupps WJ, Scarcelli G. Subclinical Keratoconus Detection and Characterization Using Motion-Tracking Brillouin Microscopy. Ophthalmology 2024; 131:310-321. [PMID: 37839561 DOI: 10.1016/j.ophtha.2023.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 10/04/2023] [Accepted: 10/09/2023] [Indexed: 10/17/2023] Open
Abstract
PURPOSE To characterize focal biomechanical alterations in subclinical keratoconus (SKC) using motion-tracking (MT) Brillouin microscopy and evaluate the ability of MT Brillouin metrics to differentiate eyes with SKC from normal control eyes. DESIGN Prospective cross-sectional study. PARTICIPANTS Thirty eyes from 30 patients were evaluated, including 15 eyes from 15 bilaterally normal patients and 15 eyes with SKC from 15 patients. METHODS All patients underwent Scheimpflug tomography and MT Brillouin microscopy using a custom-built device. Mean and minimum MT Brillouin values within the anterior plateau region and anterior 150 μm were generated. Scheimpflug metrics evaluated included inferior-superior (IS) value, maximum keratometry (Kmax), thinnest corneal thickness, asymmetry indices, Belin/Ambrosio display total deviation, and Ambrosio relational thickness. Receiver operating characteristic (ROC) curves were generated for all Scheimpflug and MT Brillouin metrics evaluated to determine the area under the ROC curve (AUC), sensitivity, and specificity for each variable. MAIN OUTCOME MEASURES Discriminative performance based on AUC, sensitivity, and specificity. RESULTS No significant differences were found between groups for age, sex, manifest refraction spherical equivalent, corrected distance visual acuity, Kmax, or KISA% index. Among Scheimpflug metrics, significant differences were found between groups for thinnest corneal thickness (556 μm vs. 522 μm; P < 0.001), IS value (0.29 diopter [D] vs. 1.05 D; P < 0.001), index of vertical asymmetry (IVA; 0.10 vs. 0.19; P < 0.001), and keratoconus index (1.01 vs. 1.05; P < 0.001), and no significant differences were found for any other Scheimpflug metric. Among MT Brillouin metrics, clear differences were found between control eyes and eyes with SKC for mean plateau (5.71 GHz vs. 5.68 GHz; P < 0.0001), minimum plateau (5.69 GHz vs. 5.65 GHz; P < 0.0001), mean anterior 150 μm (5.72 GHz vs. 5.68 GHz; P < 0.0001), and minimum anterior 150 μm (5.70 GHz vs. 5.66 GHz; P < 0.001). All MT Brillouin plateau and anterior 150 μm mean and minimum metrics fully differentiated groups (AUC, 1.0 for each), whereas the best performing Scheimpflug metrics were keratoconus index (AUC, 0.91), IS value (AUC, 0.89), and IVA (AUC, 0.88). CONCLUSIONS Motion-tracking Brillouin microscopy metrics effectively characterize focal corneal biomechanical alterations in eyes with SKC and clearly differentiated these eyes from control eyes, including eyes that were not differentiated accurately using Scheimpflug metrics. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
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Affiliation(s)
- J Bradley Randleman
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio; Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio.
| | | | - Lara Asroui
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | - Imane Tarib
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | - William J Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio; Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland
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Dupps WJ, Randleman JB, Kohnen T, Srinivasan S, Werner L. Scientific nomenclature for keratorefractive lenticule extraction (KLEx) procedures: a joint editorial statement. J Cataract Refract Surg 2023; 49:1085. [PMID: 37867283 DOI: 10.1097/j.jcrs.0000000000001328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
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Dupps WJ, Randleman JB, Kohnen T, Srinivasan S, Werner L. Scientific Nomenclature for K eratorefractive Lenticule Extraction (KLEx) Procedures: A Joint Editorial Statement. J Refract Surg 2023; 39:726-727. [PMID: 37937757 DOI: 10.3928/1081597x-20231010-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
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Zhang H, Asroui L, Tarib I, Dupps WJ, Scarcelli G, Randleman JB. Motion-Tracking Brillouin Microscopy Evaluation of Normal, Keratoconic, and Post-Laser Vision Correction Corneas. Am J Ophthalmol 2023; 254:128-140. [PMID: 36963605 DOI: 10.1016/j.ajo.2023.03.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 03/06/2023] [Accepted: 03/11/2023] [Indexed: 03/26/2023]
Abstract
PURPOSE To characterize focal biomechanical differences between normal, keratoconic, and post-laser vision correction (LVC) corneas using motion-tracking Brillouin microscopy. DESIGN Prospective cross-sectional study. METHODS Thirty eyes from 30 patients (10 normal controls [Controls], 10 post-LVC, and 10 stage I or II keratoconus [KC]) had Scheimpflug and motion-tracking Brillouin microscopy imaging using a custom-built device. Mean, maximum (max) and minimum (min) Brillouin shift, spatial standard deviation, and max-min values were compared. Min values were correlated with local Brillouin values at multiple Scheimpflug imaging locations. RESULTS Mean (P < .0003), min (P < .00001), spatial standard deviation (P < .01), and max-min (P < .001) were significantly different between the groups. In post hoc pairwise comparisons, the best differentiators for group comparisons were mean (P = .0004) and min (P = .000002) for Controls vs KC, min (P = .0022) and max-min (P = .002) for Controls vs LVC, and mean (P = .0037) and min (P = .0043) for LVC vs KC. Min (area under the receiver operating characteristic = 1.0) and mean (area under the receiver operating characteristic = 0.96) performed well in differentiating Control and KC eyes. Min values correlated best with Brillouin shift values at the thinnest corneal point (r2 = 0.871, P = .001) and maximum keratometry value identified in the tangential curvature map (r2 = 0.840, P = .002). CONCLUSIONS Motion-tracking Brillouin microscopy effectively characterized focal corneal biomechanical alterations in LVC and KC and clearly differentiated these groups from Controls. Primary motion-tracking Brillouin metrics performed well in differentiating groups as compared with basic Scheimpflug metrics, in contrast to previous Brillouin studies, and identified focal changes after LVC where prior Brillouin studies did not.
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Affiliation(s)
- Hongyuan Zhang
- From The Cole Eye Institute, Cleveland Clinic (H.Z., L.A., I.T., W.J.D., J.B.R.)
| | - Lara Asroui
- From The Cole Eye Institute, Cleveland Clinic (H.Z., L.A., I.T., W.J.D., J.B.R.)
| | - Imane Tarib
- From The Cole Eye Institute, Cleveland Clinic (H.Z., L.A., I.T., W.J.D., J.B.R.)
| | - William J Dupps
- From The Cole Eye Institute, Cleveland Clinic (H.Z., L.A., I.T., W.J.D., J.B.R.); Cleveland Clinic Lerner College of Medicine of Case Western Reserve University (W.J.D., J.B.R.); Department of Biomedical Engineering, Case Western Reserve University (W.J.D.), Cleveland, Ohio
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland (GS), USA
| | - J Bradley Randleman
- From The Cole Eye Institute, Cleveland Clinic (H.Z., L.A., I.T., W.J.D., J.B.R.); Cleveland Clinic Lerner College of Medicine of Case Western Reserve University (W.J.D., J.B.R.).
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Dupps WJ. Artificial intelligence and academic publishing. J Cataract Refract Surg 2023; 49:655-656. [PMID: 37390321 DOI: 10.1097/j.jcrs.0000000000001223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/02/2023]
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Blackburn BJ, McPheeters MT, Jenkins MW, Dupps WJ, Rollins AM. Phase-Decorrelation Optical Coherence Tomography Measurement of Cold-Induced Nuclear Cataract. Transl Vis Sci Technol 2023; 12:25. [PMID: 36971678 PMCID: PMC10064939 DOI: 10.1167/tvst.12.3.25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
Abstract
Purpose The purpose of this work is to determine the sensitivity of phase-decorrelation optical coherence tomography (OCT) to protein aggregation associated with cataracts in the ocular lens, as compared to OCT signal intensity. Methods Six fresh porcine globes were held at 4°C until cold cataracts developed. As the globes were re-warmed to ambient temperature, reversing the cold cataract, each lens was imaged repeatedly using a conventional OCT system. Throughout each experiment, the internal temperature of the globe was recorded using a needle-mounted thermocouple. OCT scans were acquired, their temporal fluctuations were analyzed, and the rates of decorrelation were spatially mapped. Both decorrelation and intensity were evaluated as a function of recorded temperature. Results Both signal decorrelation and intensity were found to change with lens temperature, a surrogate of protein aggregation. However, the relationship between signal intensity and temperature was not consistent across different samples. In contrast, the relationship between decorrelation and temperature was found to be consistent across samples. Conclusions In this study, signal decorrelation was shown to be a more repeatable metric for quantification of crystallin protein aggregation in the ocular lens than OCT intensity-based metrics. Thus, OCT signal decorrelation measurements could enable more detailed and sensitive study of methods to prevent cataract formation. Translational Relevance This dynamic light scattering-based approach to early cataract assessment can be implemented on existing clinical OCT systems without hardware additions, so it could quickly become part of a clinical study workflow or an indication for use for a pharmaceutical cataract intervention.
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Affiliation(s)
- Brecken J Blackburn
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Matthew T McPheeters
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Michael W Jenkins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH, USA
| | - William J Dupps
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- Department of Ophthalmology, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Andrew M Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
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Dupps WJ. Case for Epithelium-Off Corneal Cross-linking. Cornea 2022; 41:1205-1206. [PMID: 35439770 PMCID: PMC9481649 DOI: 10.1097/ico.0000000000003044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 03/01/2022] [Indexed: 11/26/2022]
Abstract
ABSTRACT The question of whether the epithelium should be removed in corneal cross-linking (CXL) in the treatment of keratoconus and other corneal ectatic disorders remains controversial. The motivation for epithelium-on CXL methods, which are not yet FDA approved and vary greatly in methodology, is to reduce the risk of vision-threatening complications related to debridement. However, as discussed in this counterpoint piece, most high-level evidence suggests that removal of the epithelium facilitates greater crosslinking effectiveness as measured by primary clinical outcome metrics such as topographic flattening and stabilization of disease. Furthermore, quality evidence is still lacking for a significant reduction in rates of infectious keratitis or loss of vision that can be attributed to debridement-related complications. In the absence of comparative effectiveness trials or long-term follow-up studies that show otherwise, the FDA-approved epi-off protocol is still the standard-bearer for safe and effective stabilization of corneal ectatic disease.
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Affiliation(s)
- William J Dupps
- Department of Cornea and Refractive Surgery, Cole Eye Institute, Cleveland Clinic, Cleveland, OH
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH; and
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH
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Asroui L, Dupps WJ, Randleman JB. Reply to Comment on Determining the Utility of Epithelial Thickness Mapping in Refractive Surgery Evaluations. Am J Ophthalmol 2022; 241:288-289. [PMID: 35654122 DOI: 10.1016/j.ajo.2022.05.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 05/19/2022] [Indexed: 11/26/2022]
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Asroui L, Dupps WJ, Randleman JB. Determining the Utility of Epithelial Thickness Mapping in Refractive Surgery Evaluations. Am J Ophthalmol 2022; 240:125-134. [PMID: 35247335 DOI: 10.1016/j.ajo.2022.02.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 02/18/2022] [Accepted: 02/20/2022] [Indexed: 11/29/2022]
Abstract
PURPOSE To determine the impact of corneal epithelial thickness maps on screening for refractive surgery candidacy in a single refractive surgical practice. DESIGN Comparison of screening methods. METHODS A total of 100 consecutive patients who presented for refractive surgery screening were evaluated. For each patient, screening based on Scheimpflug tomography, clinical data, and patient history was performed and a decision on eligibility for laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE)was independently made by 2 masked examiners. Examiners were then shown patients' epithelial thickness maps derived from optical coherence tomography (OCT). The percentage of screenings that changed after evaluating the epithelial thickness maps, with regard to candidacy for surgery, and ranking of surgical procedures from most to least favorable was determined. RESULTS Candidacy for corneal refractive surgery changed in 16% of patients after evaluation of the epithelial thickness maps, with 10% of patients screened in and 6% screened out. Surgery of choice changed for 16% of patients, and the ranking of surgical procedures from most to least favorable changed for 25% of patients. A total of 11% of patients gained eligibility for LASIK, whereas 8% lost eligibility for LASIK. No significant difference was found between the evaluations of the 2 examiners. CONCLUSIONS Epithelial thickness mapping derived from optical coherence tomography imaging of the cornea altered candidacy for corneal refractive surgery, as well as choice of surgery, in a substantial percentage of patients in our practice, and was thus a valuable tool for screening evaluations. Overall, the use of epithelial thickness maps resulted in screening in a slightly larger percentage of patients for corneal refractive surgery.
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Affiliation(s)
- Lara Asroui
- From the Cole Eye Institute (L.A., W.J.D., J.B.R.), Department of Biomedical Engineering, Lerner Research Institute (W.J.D.), Cleveland Clinic, Department of Biomedical Engineering, Case Western Reserve University (W.J.D.), and the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University (W.J.D, J.B.R) Cleveland, Ohio, USA
| | - William J Dupps
- From the Cole Eye Institute (L.A., W.J.D., J.B.R.), Department of Biomedical Engineering, Lerner Research Institute (W.J.D.), Cleveland Clinic, Department of Biomedical Engineering, Case Western Reserve University (W.J.D.), and the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University (W.J.D, J.B.R) Cleveland, Ohio, USA
| | - J Bradley Randleman
- From the Cole Eye Institute (L.A., W.J.D., J.B.R.), Department of Biomedical Engineering, Lerner Research Institute (W.J.D.), Cleveland Clinic, Department of Biomedical Engineering, Case Western Reserve University (W.J.D.), and the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University (W.J.D, J.B.R) Cleveland, Ohio, USA.
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Ferguson TJ, Singuri S, Jalaj S, Ford MR, De Stefano VS, Seven I, Dupps WJ. Depth-resolved Corneal Biomechanical Changes Measured Via Optical Coherence Elastography Following Corneal Crosslinking. Transl Vis Sci Technol 2021; 10:7. [PMID: 34313710 PMCID: PMC8322708 DOI: 10.1167/tvst.10.5.7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Purpose To evaluate depth-resolved changes of corneal biomechanical properties in eyes with corneal ectasia after corneal crosslinking (CXL) using optical coherence elastography. Methods In a prospective pilot series of eyes with corneal ectasia, a custom high-speed swept source optical coherence tomography system was used to image the cornea before and 3 months after CXL during a low-speed applanating deformation while monitoring applanation force. Cross-correlation was applied to track frame-by-frame two-dimensional optical coherence tomography speckle displacements, and the slope of force versus local axial displacement behavior during the deformation was used to produce a two-dimensional array of axial stiffness (k). These values were averaged for anterior (ka) and posterior (kp) stromal regions and expressed as a ratio (ka/kp) to assess depth-dependent differences in stiffness. CXL was performed according to the Dresden protocol with a system approved by the U.S. Food and Drug Administration. Results Four eyes from four patients with keratoconus (n = 3) or post-LASIK ectasia (n = 1) underwent optical coherence elastography before and 3 months after CXL. The mean ka/kp was 1.03 ± 0.07 before CXL compared with 1.34 ± 0.17 after the CXL procedure. All four eyes demonstrated at least a 20% increase in the ka/kp. Conclusions Preferential stiffening of the anterior stroma with the standard CXL protocol was demonstrated with optical coherence elastography in live human subjects. Translational Relevance Although ex vivo studies have demonstrated anterior stiffening effects after CXL using various destructive and nondestructive methods, this report presents the first evidence of such changes in serial live human measurements.
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Affiliation(s)
| | - Srinidhi Singuri
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of CWRU, Cleveland, Ohio, USA
| | - Sanjai Jalaj
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Matthew R Ford
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | | | - Ibrahim Seven
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - William J Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of CWRU, Cleveland, Ohio, USA.,Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.,Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA
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Serpe CC, Mello GR, Seven I, Dupps WJ, Santhiago MR. Results of intrastromal corneal ring segment implanted alone or combined with same-day corneal crosslinking and their correlation with preoperative corneal biomechanical strain from finite element analysis. J Cataract Refract Surg 2021; 47:916-926. [PMID: 33298778 DOI: 10.1097/j.jcrs.0000000000000533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 11/17/2020] [Indexed: 11/27/2022]
Abstract
PURPOSE To compare the results of intrastromal corneal ring segment (ICRS) alone or combined with same-day corneal crosslinking (CXL) and investigate the relationship of preoperative corneal biomechanics data on the outcomes. SETTING Department of Ophthalmology of Federal University of Parana. DESIGN Prospective nonrandomized interventional comparative study. METHODS Forty-nine eyes of 44 keratoconus patients underwent ICRS only (n = 27, Group 1) or same day ICRS+CXL (n = 22, Group 2) and were followed up for at least 24 months. Visual acuity and preoperative and postoperative tomographic variables were compared between groups. Tomographic data were obtained with a dual Scheimpflug analyzer, and eye-specific finite-element models were used to derive 3 variables related to preoperative biomechanical strain (maximum principal strain [MPS]): mean MPS (mMPS), highest local MPS (hMPS), and position of the hMPS (hMPSx and hMPSy). The relationship between preoperative strain data and the change (∆, difference between postoperative and preoperative data) in tomographic parameters was also investigated. RESULTS Steepest (K2) and maximum keratometry (Kmax), inferior-superior (I-S) index, coma, and cone location magnitude index (CLMI) significantly improved in both groups. Corrected distance visual acuity was significantly better after ICRS alone (P = .03), whereas corneal asymmetry measured through the I-S index was better after CXL+ICRS (P = .04). In Group 1, hMPSy significantly correlated with K2, tomographical cylinder, mean keratometry, and ∆spherical aberration, whereas mMPS significantly correlated with ∆eccentricity. In Group 2, hMPS significantly correlated with K2, Kmax, I-S index, and ∆coma, and hMPSy significantly correlated with I-S index and ∆coma. The mMPS significantly correlated with ∆CLMI. CONCLUSIONS ICRS alone seems to be the most suitable option to improve visual acuity, whereas combined ICRS+CXL provided better corneal regularizing results. Preoperative peak strain (hMPS) was predictive of the extent of regularization and flattening after ICRS+CXL.
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Affiliation(s)
- Crislaine C Serpe
- From the Department of Ophthalmology (Serpe, Santhiago), University of Sao Paulo, Brazil ; Department of Ophthalmology (Serpe, Mello), Federal University of Paraná, Curitiba, Brazil; Cole Eye Institute (Serpe, Dupps), Cleveland Clinic, Ohio; Department of Ophthalmology (Seven, Dupps), Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Ohio; Department of Biomedical Engineering (Dupps), Lerner Research Institute, Ohio; Department of Biomedical Engineering (Dupps), Case Western Reserve University, Ohio; Department of Ophthalmology (Santhiago), University of Southern California, California
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Abstract
Crosslinking involves the formation of bonds between polymer chains, such as proteins. In biological tissues, these bonds tend to stiffen the tissue, making it more resistant to mechanical degradation and deformation. In ophthalmology, the crosslinking phenomenon is being increasingly harnessed and explored as a treatment strategy for treating corneal ectasias, keratitis, degenerative myopia, and glaucoma. This review surveys the multitude of exogenous crosslinking strategies reported in the literature, both "light" (involving light energy) and "dark" (involving non-photic chemical processes), and explores their mechanisms, cytotoxicity, and stage of translational development. The spectrum of ophthalmic applications described in the literature is then discussed, with particular attention to proposed therapeutic mechanisms in the cornea and sclera. The mechanical effects of crosslinking are then discussed in the context of their proposed site and scale of action. Biomechanical characterization of the crosslinking effect is needed to more thoroughly address knowledge gaps in this area, and a review of reported methods for biomechanical characterization is presented with an attempt to assess the sensitivity of each method to crosslinking-mediated changes using data from the experimental and clinical literature. Biomechanical measurement methods differ in spatial resolution, mechanical sensitivity, suitability for detecting crosslinking subtypes, and translational readiness and are central to the effort to understand the mechanistic link between crosslinking methods and clinical outcomes of candidate therapies. Data on differences in the biomechanical effect of different crosslinking protocols and their correspondence to clinical outcomes are reviewed, and strategies for leveraging measurement advances predicting clinical outcomes of crosslinking procedures are discussed. Advancing the understanding of ophthalmic crosslinking, its biomechanical underpinnings, and its applications supports the development of next-generation crosslinking procedures that optimize therapeutic effect while reducing complications.
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Affiliation(s)
- Brecken J. Blackburn
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - Andrew M. Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
| | - William J. Dupps
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, USA
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
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Dupps WJ. Structural relationships in post-refractive surgery ectasia: What have we learned? J Cataract Refract Surg 2021; Publish Ahead of Print:02158034-900000000-99547. [PMID: 33770428 DOI: 10.1097/j.jcrs.0000000000000636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Chong J, Dupps WJ. Corneal biomechanics: Measurement and structural correlations. Exp Eye Res 2021; 205:108508. [PMID: 33609511 DOI: 10.1016/j.exer.2021.108508] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/09/2021] [Accepted: 02/12/2021] [Indexed: 02/02/2023]
Abstract
The characterization of corneal biomechanical properties has important implications for the management of ocular disease and prediction of surgical responses. Corneal refractive surgery outcomes, progression or stabilization of ectatic disease, and intraocular pressure determination are just examples of the many key clinical problems that depend highly upon corneal biomechanical characteristics. However, to date there is no gold standard measurement technique. Since the advent of a 1-dimensional (1D) air-puff based technique for measuring the corneal surface response in 2005, advances in clinical imaging technology have yielded increasingly sophisticated approaches to characterizing the biomechanical properties of the cornea. Novel analyses of 1D responses are expanding the clinical utility of commercially-available air-puff-based instruments, and other imaging modalities-including optical coherence elastography (OCE), Brillouin microscopy and phase-decorrelation ocular coherence tomography (PhD-OCT)-offer new opportunities for probing local biomechanical behavior in 3-dimensional space and drawing new inferences about the relationships between corneal structure, mechanical behavior, and corneal refractive function. These advances are likely to drive greater clinical adoption of in vivo biomechanical analysis and to support more personalized medical and surgical decision-making.
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Affiliation(s)
- Jillian Chong
- Cleveland Clinic Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - William J Dupps
- Cleveland Clinic Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA; Dept. of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve Univ, Cleveland, OH, USA; Dept. of Biomedical Engineering, Lerner Research Institute and Case Western Reserve Univ, Cleveland, OH, USA.
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McPheeters MT, Blackburn BJ, Dupps WJ, Rollins AM, Jenkins MW. Genetically Encoded Calcium Indicators for In Situ Functional Studies of Corneal Nerves. Invest Ophthalmol Vis Sci 2020; 61:10. [PMID: 33151279 PMCID: PMC7645214 DOI: 10.1167/iovs.61.13.10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/28/2020] [Indexed: 11/27/2022] Open
Abstract
Purpose Millions of people suffer from diseases that involve corneal nerve dysfunction, caused by various conditions, including dry eye syndrome, neurotrophic keratopathy, diabetes, herpes simplex, glaucoma, and Alzheimer's disease. The morphology of corneal nerves has been studied extensively. However, corneal nerve function has only been studied in a limited fashion owing to a lack of tools. Here, we present a new system for studying corneal nerve function. Methods Optical imaging was performed on the cornea of excised murine globes taken from a model animal expressing a genetically encoded calcium indicator, GCaMP6f, to record calcium transients. A custom perfusion and imaging chamber for ex vivo murine globes was designed to maintain and stabilize the cornea, while allowing the introduction of chemical stimulation during imaging. Results Imaging of calcium signals in the ex vivo murine cornea was demonstrated. Strong calcium signals with minimal photobleaching were observed in experiments lasting up to 10 minutes. Concentrated potassium and lidocaine solutions both modulated corneal nerve activity. Similar responses were observed in the same neurons across multiple chemical stimulations, suggesting the feasibility of using chemical stimulations to test the response of the corneal nerves. Conclusions Our studies suggest that this tool will be of great use for studying functional changes to corneal nerves in response to disease and ocular procedures. This process will enable preclinical testing of new ocular procedures to minimize damage to corneal innervation and therapies for diminished neural function.
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Affiliation(s)
- Matthew T McPheeters
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States
| | - Brecken J Blackburn
- Department of Biomedical Engineering, 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 Foundation, 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
| | - 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
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De Stefano VS, Ford MR, Seven I, Dupps WJ. Depth-Dependent Corneal Biomechanical Properties in Normal and Keratoconic Subjects by Optical Coherence Elastography. Transl Vis Sci Technol 2020; 9:4. [PMID: 32832211 PMCID: PMC7414661 DOI: 10.1167/tvst.9.7.4] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 04/07/2020] [Indexed: 12/15/2022] Open
Abstract
Purpose Compare depth-resolved biomechanical properties in normal and keratoconic corneas in live human subjects using optical coherence elastography (OCE). Methods In a prospective series of normal and keratoconus (KC) eyes, a corneal perturbation was applied by a custom swept-source OCE system using a transparent flat lens coupled to force transducers. Cross-correlation was applied to track frame-by-frame OCT speckle displacement. Regional displacements for the anterior and posterior stroma were plotted in force versus displacement (k) graphs. A spatial biomechanical property ratio (ka/kp ) was defined by dividing the maximum total displacement by the maximum force for the anterior (ka ) and posterior cornea (kp) and was compared between normal and KC groups with the Mann-Whitney U test. Area under the receiver operating characteristics curve (AUROC) for differentiating normal and KC eyes was calculated for ka/kp , kmax, and thinnest point of corneal thickness (TPCT). Results Thirty-six eyes were analyzed (21 eyes of 12 normal subjects and 15 KC eyes of 12 subjects). The ka/kp for the normal group was 1.135 ± 0.07 (mean ± standard deviation) and 1.02 ± 0.08 for the KC group (P < 0.001), indicating a relative deficit in anterior stromal stiffness in KC eyes. AUROC was 0.91 for ka /kp , 0.95 for kmax, and 1 for TPCT. Conclusions Significant differences in depth-dependent corneal biomechanical properties were observed between normal and KC subjects. Translational Relevance OCE was applied for the first time to human KC subjects and revealed alterations in the normal anterior-to-posterior stromal stiffness gradient, a novel and clinically accessible disease biomarker.
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Affiliation(s)
- Vinicius S De Stefano
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA.,Department of Ophthalmology and Visual Sciences, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Matthew R Ford
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Ibrahim Seven
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - William J Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA.,Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, USA
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Dupps WJ. Gratitude. J Cataract Refract Surg 2019; 45:1695. [DOI: 10.1016/j.jcrs.2019.11.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Dupps WJ, Kohnen T, Mamalis N, Rosen ES, Srinivasan S, Koch DD, Obstbaum SA. The Journal of Cataract & Refractive Surgery: 2018 in Review. J Cataract Refract Surg 2019; 44:1411-1412. [PMID: 30473079 DOI: 10.1016/j.jcrs.2018.11.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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De Stefano VS, Seven I, Randleman JB, Dupps WJ. Custom air puff-derived biomechanical variables in a refractive surgery screening setting: Study from 2 centers. J Cataract Refract Surg 2019; 44:589-595. [PMID: 29773456 DOI: 10.1016/j.jcrs.2018.03.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 03/13/2018] [Accepted: 03/16/2018] [Indexed: 11/18/2022]
Abstract
PURPOSE To assess the ability of air puff-derived biomechanical variables to predict surgeon-perceived candidacy for laser in situ keratomileusis (LASIK). SETTING Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, and Emory Eye Institute, Emory University, Atlanta, Georgia, USA. DESIGN Retrospective case series. METHODS Data were collected from refractive surgery screening examinations by 2 surgeons at 2 centers. Disqualified cases (19 eyes and 28 eyes from each surgeon) were judged not to be candidates based on available data including standard variables from the Ocular Response Analyzer. Controls consisted of LASIK candidates (n = 26 and 23). Three custom biomechanical variables not available during screening were calculated and compared by group and surgeon. RESULTS The hysteresis loop area was significantly different between disqualified cases and controls for both surgeons (Surgeon 1: controls, 121.50 ± 25.38 [SD], disqualified, 107.62 ± 18.50, P = .04; Surgeon 2: controls, 135.89 ± 22.47, disqualified, 106.11 ± 16.40, P < .001). The area under the curves of the receiver operating characteristics and the cutoff values were statistically significant for the concavity minimum and hysteresis loop area for Surgeon 1 and for all variables except concavity minimum for Surgeon 2. The hysteresis loop area had the highest odds ratio (Surgeon 1, 4.48, Surgeon 2, 20.00). Adjusted R2 in best-subsets regressions were 40.2% for Surgeon 1 and 62.9% for Surgeon 2. CONCLUSIONS The hysteresis loop area was predictive of which patients were disqualified for LASIK at different sites. Certain measures of the corneal dynamic response to an air puff might serve as correlates to clinically perceived ectasia risk.
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Affiliation(s)
- Vinicius S De Stefano
- From the Cole Eye Institute (De Stefano, Seven, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, and the Keck School of Medicine (Randleman) and the Roski Eye Institute (Randleman), University of Southern California Los Angeles, Los Angeles, California, USA; Ophthalmology (De Stefano), Federal University of São Paulo, São Paulo, Brazil
| | - Ibrahim Seven
- From the Cole Eye Institute (De Stefano, Seven, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, and the Keck School of Medicine (Randleman) and the Roski Eye Institute (Randleman), University of Southern California Los Angeles, Los Angeles, California, USA; Ophthalmology (De Stefano), Federal University of São Paulo, São Paulo, Brazil
| | - J Bradley Randleman
- From the Cole Eye Institute (De Stefano, Seven, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, and the Keck School of Medicine (Randleman) and the Roski Eye Institute (Randleman), University of Southern California Los Angeles, Los Angeles, California, USA; Ophthalmology (De Stefano), Federal University of São Paulo, São Paulo, Brazil
| | - William J Dupps
- From the Cole Eye Institute (De Stefano, Seven, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, and the Keck School of Medicine (Randleman) and the Roski Eye Institute (Randleman), University of Southern California Los Angeles, Los Angeles, California, USA; Ophthalmology (De Stefano), Federal University of São Paulo, São Paulo, Brazil.
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Dupps WJ. You don't know what you don't know. J Cataract Refract Surg 2019; 45:1057-1058. [PMID: 31371004 DOI: 10.1016/j.jcrs.2019.06.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Rocha KM, Mercer RN, Dupps WJ, Krueger RR. The Incidence and Natural History of Subjectively and Objectively Determined Metrics of Light Scattering in Femtosecond Laser-Assisted In Situ Keratomileusis. EC Ophthalmol 2019; 10:586-591. [PMID: 35463040 PMCID: PMC9022719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
PURPOSE To assess the incidence and long-term persistence of both subjective (rainbow glare phenomenon) and objective metrics of light scattering (stray light measurement) in femtosecond laser-assisted in situ keratomileusis (FS-LASIK). SETTINGS Cleveland Clinic Foundation, Cole Eye Institute. DESIGN Prospective, contralateral eye study in which 54 myopic eyes of 27 patients underwent LASIK using the ALLEGRETTO® Eye-Q excimer laser. Flap creation was created by IntraLASE FS60 (IL) in one eye and Wave Light FS200 (FS) in the contralateral eye. Rainbow glare and stray light measurements (C-Quant, Oculus Inc, Lynnwood, WA) were obtained preoperatively, and at 1 week, 1, 3, and 9 months postoperatively. Manifest and wavefront refractions were performed at each postoperative visit. RESULTS Stray light measurements in both IL and FS groups peaked at 1 week postoperatively (log 1.28 ± 0.16, p = 0.02 and log 1.26 ± 0.12, p = 0.039, respectively) with statistically significant improvement at 3 months (log 1.12 ± 0.35, p = 0.007 and log 1.20 ± 0.15, p = 0.04) and 9 months (log 1.11 ± 0.17, p = 0.008 and log 1.15 ± 0.14, p = 0.011). No statistically significant differences were found between IL and FS eyes at all time points. 11 patients reported postoperative rainbow glare at 1 week (42%), which decreased to 6 patients at 9 months (33%) in the IL treated eye. 14 patients reported postoperative rainbow glare at 1 week (54%), which decreased to 7 patients at 9 months (39%) in the FS treated eye. CONCLUSION Both rainbow glare and objective light scatter were greatest at 1 week and were significantly reduced by 1 to 3 months postoperatively. Rainbow glare is a mild optical side effect of femtosecond laser LASIK that improves with time.
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Affiliation(s)
- Karolinne M Rocha
- Medical University of South Carolina (MUSC), Storm Eye Institute, Charleston, South Carolina, USA
- Cleveland Clinic Foundation, Cole Eye Institute, Cleveland, Ohio, USA
| | - Ryan N Mercer
- University of Missouri, Columbia, Mason Eye Institute, Columbia, Missouri, USA
| | - William J Dupps
- Cleveland Clinic Foundation, Cole Eye Institute, Cleveland, Ohio, USA
| | - Ronald R Krueger
- Cleveland Clinic Foundation, Cole Eye Institute, Cleveland, Ohio, USA
- Stanley H Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska, USA
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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: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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Blackburn BJ, Jenkins MW, Rollins AM, Dupps WJ. A Review of Structural and Biomechanical Changes in the Cornea in Aging, Disease, and Photochemical Crosslinking. Front Bioeng Biotechnol 2019; 7:66. [PMID: 31019909 PMCID: PMC6459081 DOI: 10.3389/fbioe.2019.00066] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/07/2019] [Indexed: 12/27/2022] Open
Abstract
The study of corneal biomechanics is motivated by the tight relationship between biomechanical properties and visual function within the ocular system. For instance, variation in collagen fibril alignment and non-enzymatic crosslinks rank high among structural factors which give rise to the cornea's particular shape and ability to properly focus light. Gradation in these and other factors engender biomechanical changes which can be quantified by a wide variety of techniques. This review summarizes what is known about both the changes in corneal structure and associated changes in corneal biomechanical properties in aging, keratoconic, and photochemically crosslinked corneas. In addition, methods for measuring corneal biomechanics are discussed and the topics are related to both clinical studies and biomechanical modeling simulations.
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Affiliation(s)
- Brecken J. Blackburn
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of CWRU, Cleveland, OH, United States
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - Michael W. Jenkins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH, United States
| | - Andrew M. Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - William J. Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
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De Stefano VS, Ford MR, Seven I, Dupps WJ. Live human assessment of depth-dependent corneal displacements with swept-source optical coherence elastography. PLoS One 2018; 13:e0209480. [PMID: 30592752 PMCID: PMC6310362 DOI: 10.1371/journal.pone.0209480] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 12/06/2018] [Indexed: 01/01/2023] Open
Abstract
Purpose To assess depth-dependent corneal displacements in live normal subjects using optical coherence elastography (OCE). Methods A corneal elastography method based on swept-source optical coherence tomography (OCT) was implemented in a clinical prototype. Low amplitude corneal deformation was produced during OCT imaging with a linear actuator-driven lens coupled to force transducers. A cross-correlation algorithm was applied to track frame-by-frame speckle displacement across horizontal meridian scans. Intra-measurement force and displacement data series were plotted against each other to produce local axial stiffness approximations, k, defined by the slope of a linear fit to the force/displacement data (ignoring non-axial contributions from corneal bending). Elastographic maps displaying local k values across the cornea were generated, and the ratio of mean axial stiffness approximations for adjacent anterior and posterior stromal regions, ka/kp, was calculated. Intraclass correlation coefficients (ICC) were used to estimate repeatability. Results Seventeen eyes (ten subjects) were included in this prospective first-in-humans translational study. The ICC was 0.84. Graphs of force vs. displacement demonstrated that, for simultaneously acquired measurements involving the same applied force, anterior stromal displacements were lower (suggesting stiffer behavior) than posterior stromal displacements. Mean ka was 0.016±0.004 g/mm and mean kp was 0.014±0.004 g/mm, giving a mean ka/kp ratio of 1.123±0.062. Conclusion OCE is a clinically feasible, non-invasive corneal biomechanical characterization method capable of resolving depth-dependent differences in corneal deformation behavior. The anterior stroma demonstrated responses consistent with stiffer properties in compression than the posterior stroma, but to a degree that varied across normal eyes. The clinical capability to measure these differences has implications for assessing the biomechanical impact of corneal refractive surgeries and for ectasia risk screening applications.
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Affiliation(s)
- Vinicius S. De Stefano
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
- Dept. of Ophthalmology and Visual Sciences, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Matthew R. Ford
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
| | - Ibrahim Seven
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
| | - William J. Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
- Dept. of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States of America
- Dept. of Ophthalmology, Cleveland Clinic Lerner College of Medicine of CWRU, Cleveland, OH, United States of America
- * E-mail:
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Ehlers JP, Modi YS, Pecen PE, Goshe J, Dupps WJ, Rachitskaya A, Sharma S, Yuan A, Singh R, Kaiser PK, Reese JL, Calabrise C, Watts A, Srivastava SK. The DISCOVER Study 3-Year Results: Feasibility and Usefulness of Microscope-Integrated Intraoperative OCT during Ophthalmic Surgery. Ophthalmology 2018; 125:1014-1027. [PMID: 29409662 PMCID: PMC6015779 DOI: 10.1016/j.ophtha.2017.12.037] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 11/26/2017] [Accepted: 12/28/2017] [Indexed: 10/17/2022] Open
Abstract
PURPOSE To report the 3-year assessment of feasibility and usefulness of microscope-integrated intraoperative OCT (iOCT) during ophthalmic surgery. DESIGN Prospective, consecutive case series. PARTICIPANTS Adult participants undergoing incisional ophthalmic surgery with iOCT imaging who consented to be enrolled in the Determination of Feasibility of Intraoperative Spectral-Domain Microscope Combined/Integrated OCT Visualization during En Face Retinal and Ophthalmic Surgery (DISCOVER) study. METHODS The DISCOVER study is a single-site, multisurgeon, institutional review board-approved investigational device prospective study. Participants included patients undergoing anterior or posterior segment surgery who underwent iOCT imaging with 1 of 3 prototype microscope-integrated iOCT systems (i.e., Zeiss Rescan 700, Leica EnFocus, or Cole Eye iOCT systems). Clinical characteristics were documented, iOCT was directed by the operating surgeon at predetermined surgical time points, and each surgeon completed a questionnaire after surgery to evaluate the usefulness of iOCT during surgery. MAIN OUTCOME MEASURES Feasibility of iOCT based ability to obtain an OCT image during surgery and usefulness of iOCT based on surgeon reporting during surgery. RESULTS Eight hundred thirty-seven eyes (244 anterior segment cases and 593 posterior segment cases) were enrolled in the DISCOVER study. Intraoperative OCT demonstrated feasibility with successful image acquisition in 820 eyes (98.0%; 95% confidence interval [CI], 96.8%-98.8%). In 106 anterior segment cases (43.4%; 95% CI, 37.1%-49.9%), the surgeons indicated that the iOCT information impacted their surgical decision making and altered the procedure. In posterior segment procedures, surgeons reported that iOCT enabled altered surgical decision making during the procedure in 173 cases (29.2%; 95% CI, 25.5%-33.0%). CONCLUSIONS The DISCOVER iOCT study demonstrated both generalized feasibility and usefulness based on the surgeon-reported impact on surgical decision making. This large-scale study confirmed similar findings from other studies on the potential value and impact of iOCT on ophthalmic surgery.
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Affiliation(s)
| | - Yasha S Modi
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | - Paula E Pecen
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | - Jeff Goshe
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | | | | | - Sumit Sharma
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | - Alex Yuan
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | - Rishi Singh
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | | | - Jamie L Reese
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
| | | | - Allison Watts
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio
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Seven I, Vahdati A, Pedersen IB, Vestergaard A, Hjortdal J, Roberts CJ, Dupps WJ. Contralateral Eye Comparison of SMILE and Flap-Based Corneal Refractive Surgery: Computational Analysis of Biomechanical Impact. J Refract Surg 2018; 33:444-453. [PMID: 28681903 DOI: 10.3928/1081597x-20170504-01] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 03/23/2017] [Indexed: 11/20/2022]
Abstract
PURPOSE Computational analyses were performed to quantify and directly compare the biomechanical impact of flapless and flap-based procedures in a series of patients undergoing small incision lenticule extraction (SMILE) in one eye and flap-based femtosecond lenticule extraction in the other. METHODS Tomographic data from 10 eyes of 5 patients undergoing femtosecond laser refractive lenticule extraction for myopic astigmatism with or without a stromal flap (femtosecond lenticule extraction in one eye, SMILE in the contralateral eye) were used to generate computational models. Inverse finite element analyses were performed at physiologic intraocular pressure followed by forward analyses at elevated intraocular pressure to assess corneal displacement and stress under differential loading. Case-specific treatment settings were incorporated. Preoperative material constants were obtained through inverse finite element analyses, and the surgically induced change in fiber stiffness within each flap was determined by minimization of the error between the simulated and actual 6-month topographic outcomes. RESULTS Flap-based procedures produced a 49% (range: 2% to 87%) greater mean reduction in effective stromal collagen fiber stiffness within the flap region than contralateral SMILE cases. Lower stresses and deformations were observed within the residual stromal bed in SMILE cases than in flap-based cases. Stromal bed displacements and stresses were more affected by a loading increase in flap-based eyes than flapless eyes. CONCLUSIONS Intrastromal flapless procedures had less impact on anterior stromal collagen mechanics and resulted in lower stromal bed displacements and stresses than flap-based procedures in contralateral eyes. However, biomechanical impact varied widely between individuals and this reinforces the need for individualized assessment of ectasia risk. [J Refract Surg. 2017;33(7):444-453].
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Reinstein DZ, Archer TJ, Srinivasan S, Mamalis N, Kohnen T, Dupps WJ, Randleman JB. Standard for Reporting Refractive Outcomes of Intraocular Lens-Based Refractive Surgery. J Refract Surg 2017; 33:218-222. [PMID: 28407160 DOI: 10.3928/1081597x-20170302-01] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Luz A, Lopes B, Hallahan KM, Valbon B, Ramos I, Faria-Correia F, Schor P, Dupps WJ, Ambrósio R. Enhanced Combined Tomography and Biomechanics Data for Distinguishing Forme Fruste Keratoconus. J Refract Surg 2017; 32:479-94. [PMID: 27400080 DOI: 10.3928/1081597x-20160502-02] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 03/17/2016] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the performance of the Ocular Response Analyzer (ORA) (Reichert Ophthalmic Instruments, Depew, NY) variables and Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) tomographic parameters in differentiating forme fruste keratoconus (FFKC) from normal corneas, and to assess a combined biomechanical and tomographic parameter to improve outcomes. METHODS Seventy-six eyes of 76 normal patients and 21 eyes of 21 patients with FFKC were included in the study. Fifteen variables were derived from exported ORA signals to characterize putative indicators of biomechanical behavior and 37 ORA waveform parameters were tested. Sixteen tomographic parameters from Pentacam HR were tested. Logistic regression was used to produce a combined biomechanical and tomography linear model. Differences between groups were assessed by the Mann-Whitney U test. The area under the receiver operating characteristics curve (AUROC) was used to compare diagnostic performance. RESULTS No statistically significant differences were found in age, thinnest point, central corneal thickness, and maximum keratometry between groups. Twenty-one parameters showed significant differences between the FFKC and control groups. Among the ORA waveform measurements, the best parameters were those related to the area under the first peak, p1area1 (AUROC, 0.717 ± 0.065). Among the investigator ORA variables, a measure incorporating the pressure-deformation relationship of the entire response cycle was the best predictor (hysteresis loop area, AUROC, 0.688 ± 0.068). Among tomographic parameters, Belin/Ambrósio display showed the highest predictive value (AUROC, 0.91 ± 0.057). A combination of parameters showed the best result (AUROC, 0.953 ± 0.024) outperforming individual parameters. CONCLUSIONS Tomographic and biomechanical parameters demonstrated the ability to differentiate FFKC from normal eyes. A combination of both types of information further improved predictive value. [J Refract Surg. 2016;32(7):479-485.].
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Seven I, Vahdati A, De Stefano VS, Krueger RR, Dupps WJ. Comparison of Patient-Specific Computational Modeling Predictions and Clinical Outcomes of LASIK for Myopia. Invest Ophthalmol Vis Sci 2017; 57:6287-6297. [PMID: 27893094 PMCID: PMC5119490 DOI: 10.1167/iovs.16-19948] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To assess the predictive accuracy of simulation-based LASIK outcomes. Methods Preoperative and 3-month post-LASIK tomographic data from 20 eyes of 12 patients who underwent wavefront-optimized LASIK for myopia were obtained retrospectively. Patient-specific finite element models were created and case-specific treatment settings were simulated. Simulated keratometry (SimK) values and the mean tangential curvature of the central 3 mm (Kmean) were obtained from the anterior surfaces of the clinical tomographies, and computational models were compared. Correlations between Kmean prediction error and patient age, preoperative corneal hysteresis (CH), and corneal resistance factor (CRF) were assessed. Results The mean difference for Kmean between simulated and actual post-LASIK cases was not statistically significant (−0.13 ± 0.36 diopters [D], P = 0.1). The mean difference between the surgically induced clinical change in Kmean and the model-predicted change was −0.11 ± 0.34 D (P = 0.2). Kmean prediction error was correlated to CH, CRF, and patient age (r = 0.63, 0.53, and 0.5, respectively, P < 0.02), and incorporation of CH values into predictions as a linear offset increased their accuracy. Simulated changes in Kmean accounted for 97% of the variance in actual spherical equivalent refractive change. Conclusions Clinically feasible computational simulations predicted corneal curvature and manifest refraction outcomes with a level of accuracy in myopic LASIK cases that approached the limits of measurement error. Readily available preoperative biomechanical measures enhanced simulation accuracy. Patient-specific simulation may be a useful tool for clinical guidance in de novo LASIK cases.
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Affiliation(s)
- Ibrahim Seven
- Ocular Biomechanics and Imaging Lab, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - Ali Vahdati
- Ocular Biomechanics and Imaging Lab, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | | | - Ronald R Krueger
- Refractive Surgery Service, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States
| | - William J Dupps
- Ocular Biomechanics and Imaging Lab, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States 2Refractive Surgery Service, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, United States 3Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States
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Reinstein DZ, Archer TJ, Srinivasan S, Mamalis N, Kohnen T, Dupps WJ, Randleman BJ. Standard for reporting refractive outcomes of intraocular lens–based refractive surgery. J Cataract Refract Surg 2017; 43:435-439. [DOI: 10.1016/j.jcrs.2017.04.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Hallahan KM, Cost B, Goshe JM, Dupps WJ, Srivastava SK, Ehlers JP. Intraoperative Interface Fluid Dynamics and Clinical Outcomes for Intraoperative Optical Coherence Tomography-Assisted Descemet Stripping Automated Endothelial Keratoplasty From the PIONEER Study. Am J Ophthalmol 2017; 173:16-22. [PMID: 27702622 DOI: 10.1016/j.ajo.2016.09.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 09/25/2016] [Accepted: 09/25/2016] [Indexed: 10/20/2022]
Abstract
PURPOSE To correlate intraoperative interface fluid dynamics during Descemet stripping automated endothelial keratoplasty (DSAEK) using intraoperative optical coherence tomography (iOCT) in the Prospective Intraoperative and Perioperative Ophthalmic Imaging with Optical Coherence Tomography (PIONEER) study with postoperative outcomes. DESIGN Prospective consecutive, interventional, comparative case series. PARTICIPANTS One hundred seventy-eight eyes of 173 patients undergoing DSAEK from the Cole Eye Institute, Cleveland, Ohio. METHODS Eyes that underwent DSAEK between October 2011 and March 2014 from the PIONEER intraoperative and perioperative OCT study were included. An automated interface fluid segmentation algorithm evaluated intraoperative dynamics of interface fluid before and after surgical manipulations. iOCT images were also captured at multiple intraoperative time points for 2 different DSAEK techniques, 1 that used an active air infusion system and 1 that did not. MAIN OUTCOME MEASURES Interface fluid metrics, graft nonadherence. RESULTS iOCT measurements of interface fluid after final surgical manipulations and immediately before leaving the operating room identified that total fluid volume (P = .002), largest fluid volume pocket (P = .002), max fluid area (P = .006), mean fluid thickness (P = .03), and max fluid thickness (P = .01) significantly correlated with graft nonadherence rates within the first postoperative week. After placement and optimization of intraoperative lenticle adherence, iOCT revealed a significant difference between the area, volume, and thickness of maximum fluid pockets between the 2 surgical techniques, but both techniques resulted in significant reduction of interface fluid during the procedure. CONCLUSIONS Larger residual interface fluid volume, area, and thickness at the end of surgery detected with iOCT are associated with early graft nonadherence and can be quantified with an automated algorithm. iOCT imaging can successfully capture technique-dependent differences in fluid dynamics during DSAEK.
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Dupps WJ, Kohnen T, Mamalis N, Srinivasan S, Rosen ES, Koch DD, Obstbaum SA. The Journal of Cataract & Refractive Surgery in 2016: A Momentous Year. J Cataract Refract Surg 2016; 42:1701. [PMID: 28007098 DOI: 10.1016/j.jcrs.2016.11.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Vahdati A, Seven I, Mysore N, Randleman JB, Dupps WJ. Computational Biomechanical Analysis of Asymmetric Ectasia Risk in Unilateral Post-LASIK Ectasia. J Refract Surg 2016; 32:811-820. [PMID: 27930791 DOI: 10.3928/1081597x-20160929-01] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 08/29/2016] [Indexed: 11/20/2022]
Abstract
PURPOSE To develop a computational approach to corneal biomechanical risk analysis in refractive surgery and to investigate its utility in an enigmatic case of unilateral ectasia after bilateral LASIK. METHODS Preoperative corneal elevation datasets from both eyes of a patient who developed unilateral post-LASIK ectasia were used to construct geometrically patient-specific, microstructurally motivated finite element models. Models were assessed before and after implementation of case-specific treatment parameters for interocular differences in corneal geometry and strain behavior under physiological loading conditions. RESULTS Standard clinical predictors of post-LASIK ectasia risk were similar for the affected and contralateral eyes, and no risk factor asymmetry was identified in tomographic screening that included posterior corneal elevation analysis. However, differences in the magnitude and distribution of strain and stress were observed that are consistent with greater predisposition to biomechanical instability in the affected eye. Load testing with simulated intraocular pressure increases provoked opposite trends in curvature change in the preoperative models representing affected and unaffected eyes, with steepening in the ectatic eye and flattening in the clinically stable eye. CONCLUSIONS Patient-specific computational analyses revealed differences in intrinsic biomechanical behaviors that may predispose a cornea to instability after refractive surgery. Strain and stress analyses elucidated differential risk not ascertained with current refractive surgery screening paradigms. This pilot study illustrates a risk analysis approach that implicitly considers the entire corneal three-dimensional geometry and can be performed a priori in a screening setting. [J Refract Surg. 2016;32(12):811-820.].
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Kohnen T, Mamalis N, Dupps WJ, Srinivasan S, Koch DD, Obstbaum SA, Rosen E. Journal of Cataract & Refractive Surgery: 20 years on. J Cataract Refract Surg 2016; 42:807-8. [PMID: 27373383 DOI: 10.1016/j.jcrs.2016.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Dupps WJ. Preoperative screening for occult disease in cataract surgery candidates. J Cataract Refract Surg 2016; 42:513-4. [PMID: 27113870 DOI: 10.1016/j.jcrs.2016.03.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Sinha Roy A, Rocha KM, Randleman JB, Stulting RD, Dupps WJ. Corrigendum to "Inverse computational analysis of in vivo corneal elastic modulus change after collagen crosslinking for keratoconus" [Exp. Eye Res. 113C (2013) 92-104]. Exp Eye Res 2016; 145:472. [PMID: 27107347 DOI: 10.1016/j.exer.2015.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
| | - Karol M Rocha
- Cleveland Clinic, Cole Eye Institute, Cleveland, OH 44120, USA
| | | | - R Doyle Stulting
- Department of Ophthalmology, Emory University, Atlanta, GA, USA; Woolfson Eye Clinic, Atlanta, GA, USA
| | - William J Dupps
- Cleveland Clinic, Cole Eye Institute, Cleveland, OH 44120, USA; Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, OH, USA; Transplant Center, Surgery Institute, Cleveland Clinic, OH, USA; Department of Biomedical Engineering, Case Western Reserve University, OH, USA.
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Luz A, Lopes B, Hallahan KM, Valbon B, Fontes B, Schor P, Dupps WJ, Ambrósio R. Discriminant Value of Custom Ocular Response Analyzer Waveform Derivatives in Forme Fruste Keratoconus. Am J Ophthalmol 2016; 164:14-21. [PMID: 26743618 DOI: 10.1016/j.ajo.2015.12.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 12/18/2015] [Accepted: 12/18/2015] [Indexed: 11/28/2022]
Abstract
PURPOSE To evaluate the performance of corneal hysteresis (CH), corneal resistance factor (CRF), 37 Ocular Response Analyzer (ORA) waveform parameters, and 15 investigator-derived ORA variables in differentiating forme fruste keratoconus (KC) from normal corneas. DESIGN Case-control study. METHODS Seventy-eight eyes of 78 unaffected patients and 21 topographically normal eyes of 21 forme fruste KC patients with topographically manifest KC in the contralateral eye were matched for age, the thinnest point of the cornea, central corneal thickness, and maximum keratometry. Fifteen candidate variables were derived from exported ORA signals to characterize putative indicators of biomechanical behavior, and 37 waveform parameters were tested. Differences between groups were assessed by the Mann-Whitney test. The area under the receiver operating characteristic curve (AUROC) was used to compare the diagnostic performance. RESULTS Ten of 54 parameters reached significant differences between the groups (Mann-Whitney test, P < .05). Neither CRF nor CH differed significantly between the groups. Among the ORA waveform measurements, the best parameters were those related to the area under the first peak, p1area, and p1area1 (AUROC, 0.714 ± 0.064 and 0.721 ± 0.065, respectively). Among the investigator ORA variables, a measure incorporating the pressure-deformation relationship of the entire response cycle performed best (hysteresis loop area, AUROC, 0.694 ± 0.067). CONCLUSION Waveform-derived ORA parameters, including a custom measure incorporating the pressure-deformation relationship of the entire response cycle, performed better than traditional CH and CRF parameters in differentiating forme fruste KC from normal corneas.
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Affiliation(s)
- Allan Luz
- Department for Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil; Hospital de Olhos de Sergipe, Aracaju, Brazil; Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.
| | - Bernardo Lopes
- Department for Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil; Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil; Instituto de Olhos Renato Ambrósio and Visare Personal Laser, Rio de Janeiro, Brazil
| | - Katie M Hallahan
- Cole Eye Institute, Cleveland Clinic; and Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio
| | - Bruno Valbon
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil; Instituto de Olhos Renato Ambrósio and Visare Personal Laser, Rio de Janeiro, Brazil
| | - Bruno Fontes
- Instituto de Olhos Renato Ambrósio and Visare Personal Laser, Rio de Janeiro, Brazil
| | - Paulo Schor
- Department for Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil
| | - William J Dupps
- Cole Eye Institute, Cleveland Clinic; and Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio
| | - Renato Ambrósio
- Department for Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil; Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil; Instituto de Olhos Renato Ambrósio and Visare Personal Laser, Rio de Janeiro, Brazil
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Dupps WJ, Kohnen T, Mamalis N, Srinivasan S, Rosen ES, Koch DD, Obstbaum SA. JCRS 2015: Gratitude and progress. J Cataract Refract Surg 2016; 41:2597. [PMID: 26796438 DOI: 10.1016/j.jcrs.2015.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Ehlers JP, Goshe J, Dupps WJ, Kaiser PK, Singh RP, Gans R, Eisengart J, Srivastava SK. Determination of feasibility and utility of microscope-integrated optical coherence tomography during ophthalmic surgery: the DISCOVER Study RESCAN Results. JAMA Ophthalmol 2016; 133:1124-32. [PMID: 26226623 DOI: 10.1001/jamaophthalmol.2015.2376] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Optical coherence tomography (OCT) has transformed the clinical management of a myriad of ophthalmic conditions. Applying OCT to ophthalmic surgery may have implications for surgical decision making and patient outcomes. OBJECTIVE To assess the feasibility and effect on surgical decision making of a microscope-integrated intraoperative OCT (iOCT) system. DESIGN, SETTING, AND PARTICIPANTS Report highlighting the 1-year results (March 2014-February 2015) of the RESCAN 700 portion of the DISCOVER (Determination of Feasibility of Intraoperative Spectral Domain Microscope Combined/Integrated OCT Visualization During En Face Retinal and Ophthalmic Surgery) study, a single-site, multisurgeon, prospective consecutive case series regarding this investigational device. Participants included patients undergoing ophthalmic surgery. Data on clinical characteristics were collected, and iOCT was performed during surgical milestones, as directed by the operating surgeon. A surgeon questionnaire was issued to each surgeon and was completed after each case to evaluate the role of iOCT during surgery and its particular role in select surgical procedures. MAIN OUTCOMES AND MEASURES Percentage of cases with successful acquisition of iOCT (ie, feasibility). Percentage of cases in which iOCT altered surgical decision making (ie, utility). RESULTS During year 1 of the DISCOVER study, a total of 227 eyes (91 anterior segment cases and 136 posterior segment cases) underwent imaging with the RESCAN 700 system. Successful imaging (eg, the ability to acquire an OCT image of the tissue of interest) was obtained for 224 of 227 eyes (99% [95% CI, 98%-100%]). During lamellar keratoplasty, the iOCT data provided information that altered the surgeon's decision making in 38% of the cases (eg, complete graft apposition when the surgeon believed there was interface fluid). In membrane peeling procedures, iOCT information was discordant with the surgeon's impression of membrane peel completeness in 19% of cases (eg, lack of residual membrane or presence of occult membrane), thus affecting additional surgical maneuvers. CONCLUSIONS AND RELEVANCE The DISCOVER study demonstrates the feasibility of real-time iOCT with a microscope-integrated iOCT system for ophthalmic surgery. The information gained from iOCT appears to allow surgeons to assess subtle details in a unique perspective from standard en face visualization, which can affect surgical decision making some of the time, although the effect of these changes in decision making on outcomes remains unknown. A prospective randomized masked trial is needed to confirm these results.
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Affiliation(s)
| | - Jeff Goshe
- Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | | | | | | | - Richard Gans
- Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio
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Beene LC, Traboulsi EI, Seven I, Ford MR, Sinha Roy A, Butler RS, Dupps WJ. Corneal Deformation Response and Ocular Geometry: A Noninvasive Diagnostic Strategy in Marfan Syndrome. Am J Ophthalmol 2016; 161:56-64.e1. [PMID: 26432567 DOI: 10.1016/j.ajo.2015.09.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 09/21/2015] [Accepted: 09/22/2015] [Indexed: 11/29/2022]
Abstract
PURPOSE To evaluate corneal air-puff deformation responses and ocular geometry as predictors of Marfan syndrome. DESIGN Prospective observational clinical study. METHODS Sixteen investigator-derived, 4 standard Ocular Response Analyzer (ORA), and geometric variables from corneal tomography and optical biometry using Oculus Pentacam and IOL Master were assessed for discriminative value in Marfan syndrome, measuring right eyes of 24 control and 13 Marfan syndrome subjects. Area under the receiver operating characteristic (AUROC) curve was assessed in univariate and multivariate analyses. RESULTS Six investigator-derived ORA variables successfully discriminated Marfan syndrome. The best lone disease predictor was Concavity Min (Marfan syndrome 47.5 ± 20, control 69 ± 14, P = .003; AUROC = 0.80). Corneal hysteresis (CH) and corneal resistance factor (CRF) were decreased (Marfan syndrome CH 9.45 ± 1.62, control CH 11.24 ± 1.21, P = .01; Marfan syndrome CRF 9.77 ± 1.65, control CRF 11.03 ± 1.72, P = .01) and corneas were flatter in Marfan syndrome (Marfan syndrome Kmean 41.25 ± 2.09 diopter, control Kmean 42.70 ± 1.81 diopter, P = .046). No significant differences were observed in central corneal thickness, axial eye length, or intraocular pressure. A multivariate regression model incorporating corneal curvature and hysteresis loop area (HLA) provided the best predictive value for Marfan syndrome (AUROC = 0.85). CONCLUSIONS This study describes novel biodynamic features of corneal deformation responses in Marfan syndrome, including increased deformation, decreased bending resistance, and decreased energy dissipation capacity. A predictive model incorporating HLA and corneal curvature shows greatest potential for noninvasive clinical diagnosis of Marfan syndrome.
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Affiliation(s)
- Lauren C Beene
- Case Western Reserve University School of Medicine, Cleveland, Ohio; Center for Genetic Eye Diseases, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Elias I Traboulsi
- Center for Genetic Eye Diseases, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Ibrahim Seven
- Ocular Biomechanics & Imaging Laboratory, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Matthew R Ford
- Ocular Biomechanics & Imaging Laboratory, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio
| | - Abhijit Sinha Roy
- Ocular Biomechanics & Imaging Laboratory, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Robert S Butler
- Quantitative Health Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio
| | - William J Dupps
- Ocular Biomechanics & Imaging Laboratory, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio; Department of Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio.
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Dupps WJ. Surgical diversity and evolution in cataract and refractive surgery. J Cataract Refract Surg 2015; 41:1557-8. [PMID: 26432109 DOI: 10.1016/j.jcrs.2015.08.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Girard MJA, Dupps WJ, Baskaran M, Scarcelli G, Yun SH, Quigley HA, Sigal IA, Strouthidis NG. Translating ocular biomechanics into clinical practice: current state and future prospects. Curr Eye Res 2015; 40:1-18. [PMID: 24832392 PMCID: PMC4233020 DOI: 10.3109/02713683.2014.914543] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Biomechanics is the study of the relationship between forces and function in living organisms and is thought to play a critical role in a significant number of ophthalmic disorders. This is not surprising, as the eye is a pressure vessel that requires a delicate balance of forces to maintain its homeostasis. Over the past few decades, basic science research in ophthalmology mostly confirmed that ocular biomechanics could explain in part the mechanisms involved in almost all major ophthalmic disorders such as optic nerve head neuropathies, angle closure, ametropia, presbyopia, cataract, corneal pathologies, retinal detachment and macular degeneration. Translational biomechanics in ophthalmology, however, is still in its infancy. It is believed that its use could make significant advances in diagnosis and treatment. Several translational biomechanics strategies are already emerging, such as corneal stiffening for the treatment of keratoconus, and more are likely to follow. This review aims to cultivate the idea that biomechanics plays a major role in ophthalmology and that the clinical translation, lead by collaborative teams of clinicians and biomedical engineers, will benefit our patients. Specifically, recent advances and future prospects in corneal, iris, trabecular meshwork, crystalline lens, scleral and lamina cribrosa biomechanics are discussed.
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Affiliation(s)
- Michaël J A Girard
- In Vivo Biomechanics Laboratory, Department of Biomedical Engineering, National University of Singapore , Singapore
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Randleman JB, Akhtar J, Lynn MJ, Ambrósio R, Dupps WJ, Krueger RR, Klyce SD. Comparison of objective and subjective refractive surgery screening parameters between regular and high-resolution Scheimpflug imaging devices. J Cataract Refract Surg 2014; 41:286-94. [PMID: 25537685 DOI: 10.1016/j.jcrs.2014.06.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 06/24/2014] [Accepted: 06/26/2014] [Indexed: 11/29/2022]
Abstract
PURPOSE To compare objective and subjective metrics from regular and high-resolution Scheimpflug devices (Pentacam) to determine their equivalence and interchangeability for refractive surgery screening. SETTING Emory Vision at Emory University, Atlanta, Georgia, USA. DESIGN Retrospective comparative case series. METHODS Eyes of consecutive screened refractive surgery patients were evaluated with high-resolution and regular Scheimpflug devices. Objective parameters evaluated included keratometry (K) values, central corneal thickness (CCT), and device-generated keratoconus screening indices. Masked expert reviewers subjectively graded images as normal, suspicious, or abnormal. RESULTS One hundred eyes of 50 patients were evaluated. The mean K values were not significantly different (anterior K: high resolution 1.21 diopters [D] ± 1.13 (SD) versus regular 1.15 ± 1.16 D, P = 0.73; posterior K: 0.34 ± 0.23 D versus regular 0.35 ± 0.23 D, P = .67). The mean CCT was significantly thinner in the high-resolution group (514.7 ± 26.6 μm versus 527.6 ± 27.6 μm (P < .0001) with limits of agreement of -12.9 to +17.5 μm. Most keratoconus screening indices were more suspicious with the high-resolution device than with the regular device except the indices of height asymmetry and height deviation. Subjectively, 60% of cases received the same score, high resolution was more suspicious in 28% of cases, and regular was more suspicious in 12% of cases; there was only slight subjective agreement between technologies (κ = 0.26 to 0.31). CONCLUSIONS Regular and high-resolution Scheimpflug imaging devices generated different objective values and significantly different subjective interpretations with poor inter-reviewer agreement. The high-resolution device provided a more conservative overall output. For refractive surgical screening, the 2 devices are not interchangeable. FINANCIAL DISCLOSURE Proprietary or commercial disclosures are listed after the references.
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Affiliation(s)
- J Bradley Randleman
- From the Department of Ophthalmology (Randleman, Akhtar) and the Department of Biostatistics and Bioinformatics (Lynn), Rollins School of Public Health, Emory University, and Emory Vision (Randleman, Akhtar), Emory Eye Center, Atlanta, Georgia, the Cleveland Clinic Cole Eye Institute (Dupps, Krueger), the Department of Biomedical Engineering (Dupps), the Lerner Research Institute and the Transplant Center (Dupps), Surgery Institute, Cleveland Clinic, the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, Ohio, the Department of Ophthalmology (Klyce), Mount Sinai School of Medicine, New York, New York, USA; Instituto de Olhos Renato Ambrósio (Ambrósio), Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, the Department for Ophthalmology of the Federal University of São Paulo (Ambrósio), São Paulo, Brazil.
| | - Jihan Akhtar
- From the Department of Ophthalmology (Randleman, Akhtar) and the Department of Biostatistics and Bioinformatics (Lynn), Rollins School of Public Health, Emory University, and Emory Vision (Randleman, Akhtar), Emory Eye Center, Atlanta, Georgia, the Cleveland Clinic Cole Eye Institute (Dupps, Krueger), the Department of Biomedical Engineering (Dupps), the Lerner Research Institute and the Transplant Center (Dupps), Surgery Institute, Cleveland Clinic, the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, Ohio, the Department of Ophthalmology (Klyce), Mount Sinai School of Medicine, New York, New York, USA; Instituto de Olhos Renato Ambrósio (Ambrósio), Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, the Department for Ophthalmology of the Federal University of São Paulo (Ambrósio), São Paulo, Brazil
| | - Michael J Lynn
- From the Department of Ophthalmology (Randleman, Akhtar) and the Department of Biostatistics and Bioinformatics (Lynn), Rollins School of Public Health, Emory University, and Emory Vision (Randleman, Akhtar), Emory Eye Center, Atlanta, Georgia, the Cleveland Clinic Cole Eye Institute (Dupps, Krueger), the Department of Biomedical Engineering (Dupps), the Lerner Research Institute and the Transplant Center (Dupps), Surgery Institute, Cleveland Clinic, the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, Ohio, the Department of Ophthalmology (Klyce), Mount Sinai School of Medicine, New York, New York, USA; Instituto de Olhos Renato Ambrósio (Ambrósio), Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, the Department for Ophthalmology of the Federal University of São Paulo (Ambrósio), São Paulo, Brazil
| | - Renato Ambrósio
- From the Department of Ophthalmology (Randleman, Akhtar) and the Department of Biostatistics and Bioinformatics (Lynn), Rollins School of Public Health, Emory University, and Emory Vision (Randleman, Akhtar), Emory Eye Center, Atlanta, Georgia, the Cleveland Clinic Cole Eye Institute (Dupps, Krueger), the Department of Biomedical Engineering (Dupps), the Lerner Research Institute and the Transplant Center (Dupps), Surgery Institute, Cleveland Clinic, the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, Ohio, the Department of Ophthalmology (Klyce), Mount Sinai School of Medicine, New York, New York, USA; Instituto de Olhos Renato Ambrósio (Ambrósio), Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, the Department for Ophthalmology of the Federal University of São Paulo (Ambrósio), São Paulo, Brazil
| | - William J Dupps
- From the Department of Ophthalmology (Randleman, Akhtar) and the Department of Biostatistics and Bioinformatics (Lynn), Rollins School of Public Health, Emory University, and Emory Vision (Randleman, Akhtar), Emory Eye Center, Atlanta, Georgia, the Cleveland Clinic Cole Eye Institute (Dupps, Krueger), the Department of Biomedical Engineering (Dupps), the Lerner Research Institute and the Transplant Center (Dupps), Surgery Institute, Cleveland Clinic, the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, Ohio, the Department of Ophthalmology (Klyce), Mount Sinai School of Medicine, New York, New York, USA; Instituto de Olhos Renato Ambrósio (Ambrósio), Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, the Department for Ophthalmology of the Federal University of São Paulo (Ambrósio), São Paulo, Brazil
| | - Ronald R Krueger
- From the Department of Ophthalmology (Randleman, Akhtar) and the Department of Biostatistics and Bioinformatics (Lynn), Rollins School of Public Health, Emory University, and Emory Vision (Randleman, Akhtar), Emory Eye Center, Atlanta, Georgia, the Cleveland Clinic Cole Eye Institute (Dupps, Krueger), the Department of Biomedical Engineering (Dupps), the Lerner Research Institute and the Transplant Center (Dupps), Surgery Institute, Cleveland Clinic, the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, Ohio, the Department of Ophthalmology (Klyce), Mount Sinai School of Medicine, New York, New York, USA; Instituto de Olhos Renato Ambrósio (Ambrósio), Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, the Department for Ophthalmology of the Federal University of São Paulo (Ambrósio), São Paulo, Brazil
| | - Stephen D Klyce
- From the Department of Ophthalmology (Randleman, Akhtar) and the Department of Biostatistics and Bioinformatics (Lynn), Rollins School of Public Health, Emory University, and Emory Vision (Randleman, Akhtar), Emory Eye Center, Atlanta, Georgia, the Cleveland Clinic Cole Eye Institute (Dupps, Krueger), the Department of Biomedical Engineering (Dupps), the Lerner Research Institute and the Transplant Center (Dupps), Surgery Institute, Cleveland Clinic, the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, Ohio, the Department of Ophthalmology (Klyce), Mount Sinai School of Medicine, New York, New York, USA; Instituto de Olhos Renato Ambrósio (Ambrósio), Rio de Janeiro Corneal Tomography and Biomechanics Study Group (Ambrósio), Rio de Janeiro, the Department for Ophthalmology of the Federal University of São Paulo (Ambrósio), São Paulo, Brazil
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Sinha Roy A, Dupps WJ, Roberts CJ. Comparison of biomechanical effects of small-incision lenticule extraction and laser in situ keratomileusis: finite-element analysis. J Cataract Refract Surg 2014; 40:971-80. [PMID: 24857440 DOI: 10.1016/j.jcrs.2013.08.065] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 07/12/2013] [Accepted: 08/14/2013] [Indexed: 11/18/2022]
Abstract
PURPOSE To theoretically compare the corneal stress distribution of laser in situ keratomileusis (LASIK) with the stress distribution of small-incision lenticule extraction. SETTING Cleveland Clinic Cole Institute, Cleveland, and The Ohio State University, Columbus, Ohio, USA. DESIGN Computational modeling study. METHODS A finite-element anisotropic collagen fiber-dependent model of myopic surgery using patient-specific corneal geometry was constructed for LASIK, small-incision lenticule extraction, and a geometry analog model with unaltered material properties from preoperative but with postoperative geometry including thickness. Surgical parameters, magnitude of myopic correction, LASIK flap thickness, and lenticule depth in small-incision lenticule extraction were varied. Two sets of models, 1 with uniform and 1 with depth-dependent material properties, were constructed. RESULTS Stress distribution between small-incision lenticule extraction simulations and the geometry analog model were similar. In contrast, LASIK consistently reduced stress in the flap and increased stress in the residual stromal bed (RSB) compared with the geometry analog model. An increase in flap thickness or lenticule depth resulted in a greater increase in RSB stress in the LASIK model than in the small-incision lenticule extraction model. CONCLUSIONS Small-incision lenticule extraction may present less biomechanical risk to the residual bed of susceptible corneas than comparable corrections involving LASIK flaps. Deeper corrections in the stroma may be possible in small-incision lenticule extraction without added risk for ectasia. FINANCIAL DISCLOSURES Proprietary or commercial disclosures are listed after the references.
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Affiliation(s)
- Abhijit Sinha Roy
- From the Cole Eye Institute (Sinha Roy, Dupps), Cleveland Clinic Foundation, the Department of Biomedical Engineering (Dupps), Lerner Research Institute, and the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, and the Departments of Ophthalmology and Biomedical Engineering (Roberts), The Ohio State University, Columbus, Ohio, USA
| | - William J Dupps
- From the Cole Eye Institute (Sinha Roy, Dupps), Cleveland Clinic Foundation, the Department of Biomedical Engineering (Dupps), Lerner Research Institute, and the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, and the Departments of Ophthalmology and Biomedical Engineering (Roberts), The Ohio State University, Columbus, Ohio, USA
| | - Cynthia J Roberts
- From the Cole Eye Institute (Sinha Roy, Dupps), Cleveland Clinic Foundation, the Department of Biomedical Engineering (Dupps), Lerner Research Institute, and the Department of Biomedical Engineering (Dupps), Case Western Reserve University, Cleveland, and the Departments of Ophthalmology and Biomedical Engineering (Roberts), The Ohio State University, Columbus, Ohio, USA.
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