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Update on Corneal Confocal Microscopy Imaging. Diagnostics (Basel) 2022; 13:diagnostics13010046. [PMID: 36611338 PMCID: PMC9818591 DOI: 10.3390/diagnostics13010046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 12/18/2022] [Accepted: 12/21/2022] [Indexed: 12/28/2022] Open
Abstract
In vivo corneal confocal microscopy (IVCM) is a non-invasive ophthalmic imaging technique that provides images of the cornea at the cellular level. Despite the uses in ocular surface pathologies, in the last decades IVCM has been used to provide more knowledge in refractive surgery wound healing, in neuropathies diagnosis, etc. The observation of the corneal cells, both normal and inflammatory, and the possibility of quantification of the corneal nerve density with manual or automated tools, makes IVCM have a significant potential to improve the diagnosis and prognosis in several systemic and corneal conditions.
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Wang C, Li X, Guo Y, He R, Guo H, Chen W. Effects of Laser In Situ Keratomileusis and Small-Incision Lenticule Extraction on Corneal Biomechanical Behavior: A Finite Element Analysis. Front Bioeng Biotechnol 2022; 10:855367. [PMID: 35480973 PMCID: PMC9035518 DOI: 10.3389/fbioe.2022.855367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 02/21/2022] [Indexed: 11/13/2022] Open
Abstract
Myopia, which is the result of the uncoordinated development of the eyeball, has become a major public health focus worldwide. Laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE) have been successfully used in modern corneal refractive surgery. However, there are still controversies about postoperative results of LASIK and SMILE. In this study, a three-dimensional finite element model of the cornea was constructed based on the elevation and pachymetry data of a female volunteer. Surgical parameters, magnitudes of myopic correction, and intraocular pressure (IOP) were varied. Furthermore, an iterative algorithm was applied to retrieve the free-stress state of the intact corneal model, LASIK model, and SMILE model. To better evaluate the differences between LASIK and SMILE procedures, the displacement and Von Mises stress on the anterior and posterior corneal surface along the x- and y-axes were analyzed. Results for the zero-pressure model showed larger displacement compared to the image-based corneal model, suggesting that the initial corneal pre-stress stiffens the response of the cornea, both in the intact cornea and under refractive surgery. In addition, the displacement on the corneal surface in LASIK (both zero-pressure and image-based model) was obviously higher than that of the SMILE model. In contrast, SMILE increased Von Mises stress in the corneal cap and reduced Von Mises stress in the residual stromal bed compared with the LASIK model. However, the maximum Von Mises stress in the SMILE model was still smaller than that of the LASIK model. Moreover, the displacement and Von Mises stress on the residual stromal bed increased linearly with IOP. Overall, LASIK and SMILE refractive surgery could change biomechanical behaviors of the cornea. Compared to LASIK refractive surgery, SMILE may present a lower risk of ectasia. Creating a corneal cap rather than a corneal flap may have an advantage in improving corneal biomechanical stability.
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Affiliation(s)
- Chenyan Wang
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Xiaona Li
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
- *Correspondence: Xiaona Li, ; Weiyi Chen,
| | - Yuan Guo
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Rui He
- Department of Excimer Laser, Shanxi Eye Hospital, Taiyuan, China
| | - Hongmei Guo
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
| | - Weiyi Chen
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, China
- *Correspondence: Xiaona Li, ; Weiyi Chen,
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Leccisotti A, Fields SV. Diffuse lamellar keratitis after LASIK with low-energy femtosecond laser. J Cataract Refract Surg 2021; 47:233-237. [PMID: 32925649 DOI: 10.1097/j.jcrs.0000000000000413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Accepted: 08/16/2020] [Indexed: 11/26/2022]
Abstract
PURPOSE To evaluate the incidence, evolution, and prognosis of diffuse lamellar keratitis (DLK) in a large series of laser in situ keratomileusis (LASIK) with low-energy femtosecond laser. SETTING Private practice, Siena, Italy. DESIGN Retrospective, consecutive, noncomparative case series study. METHODS Single-use instruments, powder-free gloves, and no corneal marking were used. Flap was created by a low-energy femtosecond laser (Ziemer Z2 and Z4). RESULTS A total of 37 315 eyes of 19 602 patients were reviewed. DLK was observed in 236 eyes (0.63%) of 149 patients (0.76%). Grade 1 DLK was observed in 231 eyes of 142 patients, grade 2 in 1 eye: when treated with topical steroids, they had no visual consequences. Three patients had bilateral grade 3 to 4 DLK: one of them, with bilateral grade 3, despite flap lifting and irrigation worsened to stage 4 (central stroma thinning and flattening), partially recovered in 2 years, and underwent repeat femtosecond laser-assisted LASIK for hyperopic shift in 1 eye. In all the 5 eyes that developed grade 4 DLK, corneal thickness decreased until the first month and then partially recovered; mean final tissue loss at 1 to 2 years was 35 µm. Compensatory epithelial thickening was observed. CONCLUSIONS DLK after low-energy femtosecond laser-assisted LASIK is rare; severe DLK (stages 3 and 4) was found in only 6 eyes (0.016%). Flap lifting and irrigation might not prevent progression. Spontaneous reformation of stromal tissue and epithelial thickening improve visual acuity in the long term; residual hyperopic shift can be corrected by repeat femtosecond laser-assisted LASIK.
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Affiliation(s)
- Antonio Leccisotti
- From the Siena Eye Laser (Leccisotti, Fields), Scuola di Specializzazione in Oftalmologia, Università di Siena (Leccisotti), Siena, Italy, School of Biomedical Sciences, Ulster University (Leccisotti), Coleraine, United Kingdom
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Abstract
PURPOSE To evaluate the corneal wound healing response after small incision lenticule extraction surgery. METHODS Small incision lenticule extraction was performed in both eyes of 12 New Zealand White rabbits. The refractive spherical correction was set at -6.00 D. Two animals were analyzed at each time point (1 hour, 4 hours, 1 day, 3 days, 7 days, and 28 days). The corneas were evaluated using slit-lamp and in vivo confocal microscopy. After euthanatization, the corneal tissues were subjected to light microscopy, transferase 2'-Deoxyuridine 5'-Triphosphate (dUTP) nick end labeling assay, and immunofluorescence microscopy (CD11b, fibronectin, tenascin, alpha-smooth muscle actin [α-SMA]). RESULTS The corneas did not show any opacity at any time point except at the side-cut incision. By contrast, there was obvious scar tissue at the side-cut incision. Scattered, hyperreflective spots were seen by confocal microscopy from 1 hour postoperatively. Transferase dUTP nick end labeling-positive keratocytes were abundant near the femtosecond laser incision area at 1 hour and reached a peak at 4 hours postoperatively and then decreased. Inflammatory cells migrated from the incision into the central cornea, and this process began 1 hour after surgery and peaked at 7 days. Extracellular matrix components were deposited at the beginning of day 1 postoperatively, and the distribution pattern differed between the central cornea and the incision site. α-SMA-positive myofibroblasts were only detected at the side-cut incision. CONCLUSIONS The scar tissue response in the peripheral cornea is related to the epithelium debridement. Inflammatory cells begin to be recruited by 1 hour after surgery. Therefore, it is necessary to implement antiinflammation interventions at a very early stage.
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Ong HS, Farook M, Tan BBC, Williams GP, Santhiago MR, Mehta JS. Corneal Ectasia Risk And Percentage Tissue Altered In Myopic Patients Presenting For Refractive Surgery. Clin Ophthalmol 2019; 13:2003-2015. [PMID: 31686775 PMCID: PMC6798818 DOI: 10.2147/opth.s215144] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/13/2019] [Indexed: 01/01/2023] Open
Abstract
Purpose A percentage tissue altered (PTA) score of ≥40% has been advocated as an independent indicator of post-operative ectasia risk following laser in-situ keratomileusis (LASIK). This study was performed to test the hypothesis that refractive procedures, such as laser-assisted sub-epithelial keratectomy (LASEK) or small incision lenticule extraction (SMILE), may alter the range of PTA, within which refractive corneal surgery can be safely performed. Setting Refractive department, tertiary ophthalmic hospital. Design Retrospective observational study. Methods Review of case notes was performed for patients who presented for refractive surgeries, other than LASIK. To determine the risk of corneal ectasia for each patient prior to refractive surgery, we estimated what each patient’s PTA would have been if they had undergone LASIK. The Randleman Ectasia Risk Score System (ERSS) was also calculated. Results 114 eyes (66 patients) were included. 94 eyes underwent SMILE. 20 eyes underwent LASEK. A significant proportion of eyes had PTA ≥40% – SMILE eyes: up to 31.9%, LASEK eyes: up to 60.0% (at presumed LASIK flap of 120 μm). The maximum calculated PTA was up to 47.9% in the SMILE group and up to 51.5% in the LASEK group. Using ERSS, 12.8–16% of SMILE eyes and 15.0–80.0% of LASEK eyes would have been considered to have moderate-to-high ectasia risk. No post-surgical ectasia was observed at 3 years. Conclusion SMILE and LASEK alter the range of PTA, within which corneal refractive surgery may be performed with a lower risk of developing post-operative corneal ectasia; a safe PTA threshold needs to be determined for these procedures before recommendations for clinical practice can be made.
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Affiliation(s)
- Hon Shing Ong
- Department of Corneal and External Diseases, Singapore National Eye Centre, Singapore, Singapore.,Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore.,SingHealth Duke-NUS Ophthalmology and Visual Sciences Academic Clinical Programme, Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Mohamed Farook
- Department of Corneal and External Diseases, Singapore National Eye Centre, Singapore, Singapore
| | - Benjamin Boon Chuan Tan
- Department of Corneal and External Diseases, Singapore National Eye Centre, Singapore, Singapore
| | - Geraint P Williams
- Department of Corneal and External Diseases, Singapore National Eye Centre, Singapore, Singapore.,Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore
| | - Marcony R Santhiago
- Department of Ophthalmology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Department of Ophthalmology, University of Sao Paulo, Sao Paulo, Brazil
| | - Jodhbir S Mehta
- Department of Corneal and External Diseases, Singapore National Eye Centre, Singapore, Singapore.,Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore, Singapore.,SingHealth Duke-NUS Ophthalmology and Visual Sciences Academic Clinical Programme, Duke-NUS Graduate Medical School, Singapore, Singapore.,School of Material Science and Engineering, Nanyang Technological University, Singapore, Singapore
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Hammer CM, Kunert KS, Zhang Y, Lörner J, Wüllner C, Rothuber EL, Paulsen F, Seiler T. Interface morphology and gas production by a refractive 347 nm ultraviolet femtosecond laser: Comparison with established laser systems. J Cataract Refract Surg 2018; 44:1371-1377. [DOI: 10.1016/j.jcrs.2018.05.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 03/13/2018] [Accepted: 05/25/2018] [Indexed: 10/28/2022]
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Kulikova IL, Pashtaev NP, Shlenskaya OV. [Morphological changes of cornea in children with hyperopia in the immediate and remote postoperative period after laser keratomieleusis according to confocal microscopy data]. Vestn Oftalmol 2018; 134:32-41. [PMID: 29771882 DOI: 10.17116/oftalma2018134232-40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Studying morphological changes of cornea in the remote postoperative period is becoming increasingly relevant with refractive surgeries being adapted for children. PURPOSE comparative analysis of keratocyte density and hystomorphologic changes of cornea after laser in situ keratomieleusis (LASIK) and femtosecond laser-assisted LASIK (FS-LASIK) in children with hyperopia. MATERIAL AND METHODS 109 patients aged 6-17 years in 2 groups were examined with 'Confoscan-4' confocal microscope. RESULTS In comparison with initial data, keratocyte density decreased in the immediate postoperative period after FS-LASIK and LASIK in average by 17.09%, 64.31% and 12.2% in the corneal flap, directly in the laser influence zone (interface) and in the retroablation zone respectively. After 5 years, keratocyte density decreased in the corneal flap, interface zone and retroablation zone by 12.01%, 48.71% and 8.06% respectively in comparison with initial data. A circular scar at the flap edge was left after FS-LASIK; keratocyte density in the corneal flap and in the interface zone was in average 8.9% and 15.28% higher respectively, and twice more subepithelial nerves were noted compared to LASIK. CONCLUSIONS In the remote postoperative period keratocyte density in the corneal decreased in average by 43% after FS-LASIK and by 46% after LASIK in comparison with initial data. No changes were seen in the morphologic state of the cornea outside the influence zone. Both the technologies are safe, however keratocyte density and the number of subepithelial nerves are higher in the cornea flap and in the interface zone after FS-LASIK; corneal stability is assured by a circular scar formed at the flap edge.
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Affiliation(s)
- I L Kulikova
- Cheboksary branch of S. Fyodorov Eye Microsurgery Federal State Institution, 10 Traktorostroiteley Pr., Cheboksary, Chuvash Republic, Russian Federation, 428028
| | - N P Pashtaev
- Cheboksary branch of S. Fyodorov Eye Microsurgery Federal State Institution, 10 Traktorostroiteley Pr., Cheboksary, Chuvash Republic, Russian Federation, 428028; The Postgraduate Doctors' Training Institute, Health Care Ministry of the Chuvash Republic, 3 Krasnaya Sq., Cheboksary, Chuvash Republic, Russian Federation, 428003; I.N. Ulyanov Chuvash State University, 15 Moskovskiy Pr., Cheboksary, Chuvash Republic, Russian Federation, 428010
| | - O V Shlenskaya
- Cheboksary branch of S. Fyodorov Eye Microsurgery Federal State Institution, 10 Traktorostroiteley Pr., Cheboksary, Chuvash Republic, Russian Federation, 428028
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Wang X, Zhang Z, Li X, Xie L, Zhang H, Koch DD, Wang L, Zhang S. Evaluation of Femtosecond Laser Versus Manual Clear Corneal Incisions in Cataract Surgery Using Spectral-Domain Optical Coherence Tomography. J Refract Surg 2018; 34:17-22. [DOI: 10.3928/1081597x-20171109-01] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 10/25/2017] [Indexed: 11/20/2022]
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Sun Q, Deng ZZ, Zhou YH, Zhang J, Peng XY. Effect of femtosecond and microkeratome flaps creation on the cornea biomechanics during laser in situ keratomileusis: one year follow-up. Int J Ophthalmol 2016; 9:1409-1414. [PMID: 27803856 DOI: 10.18240/ijo.2016.10.07] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Accepted: 07/27/2015] [Indexed: 11/23/2022] Open
Abstract
AIM To compare the corneal biomechanical outcomes at one year after laser in situ keratomileusis (LASIK) with the flaps created by Ziemer and Moria M2 microkeratome with 110 head and -20 blade. METHODS Totally 100 eyes of 50 consecutive patients were enrolled in this prospective study and divided into two groups for corneal flaps created by ZiemerFemto LDV and Moria M2 microkeratome with 110 head and -20 blade. Corneal biomechanical properties including cornea resistance factor (CRF) and cornea hysteresis (CH) were measured before and 1, 3, 6, 12mo after surgery by ocular response analyzer. Central cornea thickness and corneal flap thickness were measured by optical coherence tomography. RESULTS The ablation depth (P=0.693), residual corneal thickness (P=0.453), and postoperative corneal curvature (P=0.264) were not significant different between Ziemer group and Moria 110-20 group after surgery. The residual stromal bed thickness, corneal flap thickness, CH and CRF at 12mo after surgery were significant different between Ziemer group and Moria 110-20 group (P<0.01);Ziemer group gained better corneal biomechanical results. The CRF and CH increased gradually from 1 to 12mo after surgery in Ziemer group, increased from 1 to 6mo but decreased from 6 to 12mo in Moria 110-20 group. Both CRF and CH at one year after surgery increased with the increasing of residual cornea thickness; pre-LASIK CRF, CRF also increased with residual stromal bed thickness, while CH decreased with the increasing of pre-LASIK intraocular pressure and cornea flap thickness (P<0.01). CONCLUSION In one year follow-up, femtosecond laser can provide better cornea flaps with stable cornea biomechanics than mechanical microkeratome.
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Affiliation(s)
- Qian Sun
- Ophthalmic Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing100730, China
| | | | - Yue-Hua Zhou
- Ophthalmic Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing100730, China
| | - Jing Zhang
- Ophthalmic Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing100730, China
| | - Xiao-Yan Peng
- Ophthalmic Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing100730, China
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Savini G, Huang J, Lombardo M, Serrao S, Schiano-Lomoriello D, Venanzio S, Ducoli P. Objective Monitoring of Corneal Backward Light Scattering After Femtosecond Laser-assisted LASIK. J Refract Surg 2016; 32:20-5. [PMID: 26812710 DOI: 10.3928/1081597x-20151207-08] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 10/21/2015] [Indexed: 12/13/2022]
Abstract
PURPOSE To investigate the changes in corneal backward light scattering, as measured by a rotating Scheimpflug camera with automated corneal densitometry software, in eyes treated with femtosecond laser-assisted LASIK (FS-LASIK). METHODS The cornea was examined preoperatively and postoperatively at 1 day, 1 week, and 1, 3, and 6 months in 23 patients who underwent myopic FS-LASIK. Local analysis of corneal backscatter was performed on four concentric radial zones across a 12-mm diameter (0 to 2, 2 to 6, 6 to 10, and 10 to 12 mm) and at a different corneal depth (anterior 120 µm, central and posterior 60 µm). RESULTS A statistically significant increase in corneal backward light scattering (P < .0001) was detected within the central 10 mm of the anterior cornea. The increase in corneal densitometry was gradually reversed over 6 months. The difference compared to preoperative values was no longer statistically significant at 3 and 6 months after surgery in the central cornea, whereas it remained significant in the mid-peripheral annulus (ranging from 6 to 10 mm), where the flap edge was located. CONCLUSIONS FS-LASIK is followed by an increase in corneal backward light scattering during the early postoperative period that returns to baseline by 3 months. Whereas the increase in corneal densitometry at the flap edge location can be related to a scarring reaction, the explanation for such an increase in the central anterior cornea remains speculative.
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Sáles CS, Manche EE. Comparison of self-reported quality of vision outcomes after myopic LASIK with two femtosecond lasers: a prospective, eye-to-eye study. Clin Ophthalmol 2016; 10:1691-9. [PMID: 27621589 PMCID: PMC5012845 DOI: 10.2147/opth.s111328] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Purpose To compare self-reported quality of vision (QoV) outcomes after myopic LASIK (laser-assisted in situ keratomileusis) with two femtosecond lasers. Design Prospective, randomized, eye-to-eye study. Methods Consecutive myopic patients were treated with wavefront-guided LASIK bilaterally. Eyes were randomized according to ocular dominance. The flap of one eye was made with the IntraLase FS 60 kHz femtosecond laser with a conventional 70° side-cut, and the flap of the fellow eye was made with the IntraLase iFS 150 kHz femtosecond laser with an inverted 130° side-cut. Patients completed the validated, Rasch-tested, linear-scaled 30-item QoV questionnaire preoperatively and at Months 1, 3, 6, and 12. Results The study enrolled 120 fellow eyes in 60 patients. None of the measured QoV parameters exhibited statistically significant differences between the groups preoperatively or at any postoperative time point. Conclusion Creating LASIK flaps with an inverted side-cut using a 150 kHz femtosecond laser and with a conventional 70° side-cut using a 60 kHz femtosecond laser resulted in no significant differences in self-reported QoV assessed by the QoV questionnaire.
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Affiliation(s)
| | - Edward E Manche
- Byers eye Institute, stanford University school of Medicine, Palo alto, CA, USA
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Mastropasqua L, Calienno R, Lanzini M, Salgari N, De Vecchi S, Mastropasqua R, Nubile M. Opaque bubble layer incidence in Femtosecond laser-assisted LASIK: comparison among different flap design parameters. Int Ophthalmol 2016; 37:635-641. [DOI: 10.1007/s10792-016-0323-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 08/08/2016] [Indexed: 10/21/2022]
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Santos AMD, Torricelli AAM, Marino GK, Garcia R, Netto MV, Bechara SJ, Wilson SE. Femtosecond Laser-Assisted LASIK Flap Complications. J Refract Surg 2016; 32:52-9. [DOI: 10.3928/1081597x-20151119-01] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 11/01/2015] [Indexed: 01/13/2023]
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Aristeidou A, Taniguchi EV, Tsatsos M, Muller R, McAlinden C, Pineda R, Paschalis EI. The evolution of corneal and refractive surgery with the femtosecond laser. EYE AND VISION 2015; 2:12. [PMID: 26605365 PMCID: PMC4655461 DOI: 10.1186/s40662-015-0022-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 06/20/2015] [Indexed: 01/12/2023]
Abstract
The use of femtosecond lasers has created an evolution in modern corneal and refractive surgery. With accuracy, safety, and repeatability, eye surgeons can utilize the femtosecond laser in almost all anterior refractive procedures; laser in situ keratomileusis (LASIK), small incision lenticule extraction (SMILE), penetrating keratoplasty (PKP), insertion of intracorneal ring segments, anterior and posterior lamellar keratoplasty (Deep anterior lamellar keratoplasty (DALK) and Descemet's stripping endothelial keratoplasty (DSEK)), insertion of corneal inlays and cataract surgery. As the technology matures, it will push surgical limits and open new avenues for ophthalmic intervention in areas not yet explored. As we witness the transition from femto-LASIK to femto-cataract surgery it becomes obvious that this innovation is here to stay. This article presents some of the most relevant advances of femtosecond lasers to modern corneal and refractive surgery.
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Affiliation(s)
| | - Elise V Taniguchi
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA USA ; Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Boston Keratoprosthesis Laboratory, Harvard Medical School, Boston, 02114 MA USA
| | | | - Rodrigo Muller
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA USA
| | - Colm McAlinden
- Flinders University, Adelaide, South Australia Australia ; Wenzhou Medical University, Wenzhou, Zhejiang China
| | - Roberto Pineda
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA USA
| | - Eleftherios I Paschalis
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA USA ; Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Boston Keratoprosthesis Laboratory, Harvard Medical School, Boston, 02114 MA USA
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McLaren JW, Bourne WM, Maguire LJ, Patel SV. Changes in Keratocyte Density and Visual Function Five Years After Laser In Situ Keratomileusis: Femtosecond Laser Versus Mechanical Microkeratome. Am J Ophthalmol 2015; 160:163-70. [PMID: 25868758 DOI: 10.1016/j.ajo.2015.04.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Revised: 04/02/2015] [Accepted: 04/06/2015] [Indexed: 11/19/2022]
Abstract
PURPOSE To determine the effects of keratocyte loss on optical properties and vision after laser in situ keratomileusis (LASIK) with the flap created with a femtosecond laser or a mechanical microkeratome. DESIGN Randomized clinical paired-eye study. METHODS Both eyes of 21 patients received LASIK for myopia or myopic astigmatism. One eye of each patient was randomized by ocular dominance to flap creation with a femtosecond laser and the other eye to flap creation with a mechanical microkeratome. Before LASIK and at 1, 3, and 6 months and 1, 3, and 5 years after LASIK, keratocyte density was measured using confocal microscopy, and high-contrast visual acuity and anterior corneal wavefront aberrations were measured by standard methods. At each visit, all variables were compared between methods of creating the flap and to the same variable before treatment using paired tests with Bonferroni correction for multiple comparisons. RESULTS Keratocyte density in the flap decreased by 20% during the first year after LASIK and remained low through 5 years (P < .001). High-order wavefront aberrations increased and uncorrected visual acuity improved immediately after surgery, but these variables did not change further to 5 years. There were no differences in any variables between treatments. CONCLUSIONS A sustained reduction in keratocyte density does not affect vision or optical properties of the cornea through 5 years after LASIK. The method of creating a LASIK flap does not influence the changes in keratocyte density in the flap.
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Affiliation(s)
- Jay W McLaren
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota
| | | | - Leo J Maguire
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota
| | - Sanjay V Patel
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota.
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Abstract
Corneal photorefractive surgery is currently performed by ablation of corneal stroma under the stromal flap. A stromal flap is created using a femtosecond (FS) laser or mechanical microkeratome, although the FS laser procedure is considered safer and more accurate. This review assesses and compares the use of FS laser versus mechanical microkeratome ablation for corneal stromal characteristics mainly examined by histology and cellular biological responses. Supporting data from our studies, using corneas of enucleated porcine eye globes, are included in this review. Histological analysis and experimental studies of cellular/tissue responses to FS laser irradiation should be further investigated, and the equipment used to perform these techniques should be improved.
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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: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [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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Torricelli AAM, Wilson SE. Cellular and extracellular matrix modulation of corneal stromal opacity. Exp Eye Res 2014; 129:151-60. [PMID: 25281830 DOI: 10.1016/j.exer.2014.09.013] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 08/08/2014] [Accepted: 09/30/2014] [Indexed: 01/23/2023]
Abstract
Stromal transparency is a critical factor contributing to normal function of the visual system. Corneal injury, surgery, disease and infection elicit complex wound healing responses that serve to protect against insults and maintain the integrity of the cornea, and subsequently to restore corneal structure and transparency. However, in some cases these processes result in prolonged loss of corneal transparency and resulting diminished vision. Corneal opacity is mediated by the complex actions of many cytokines, growth factors, and chemokines produced by the epithelial cells, stromal cells, bone marrow-derived cells, lacrimal tissues, and nerves. Myofibroblasts, and the disorganized extracellular matrix produced by these cells, are critical determinants of the level and persistence of stromal opacity after corneal injury. Decreases in corneal crystallins in myofibroblasts and corneal fibroblasts contribute to cellular opacity in the stroma. Regeneration of a fully functional epithelial basement membrane (BM) appears to have a critical role in the maintenance of corneal stromal transparency after mild injuries and recovery of transparency when opacity is generated after severe injuries. The epithelial BM likely has a regulatory function whereby it modulates epithelium-derived growth factors such as transforming growth factor (TGF) β and platelet-derived growth factor (PDGF) that drive the development and persistence of myofibroblasts from precursor cells. The purpose of this article is to review the factors involved in the maintenance of corneal transparency and to highlight the mechanisms involved in the appearance, persistency and regression of corneal opacity after stromal injury.
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Abstract
PURPOSE OF REVIEW To update the knowledge on differences between mechanical microkeratome and femtosecond flaps for laser in-situ keratomileusis (LASIK) in terms of accuracy and complications. RECENT FINDINGS Corneal flaps created with the femtosecond laser present a more planar architecture and provide greater precision in flap diameter and thickness; a more uniform flap thickness across the flap diameter and it allows the surgeon to programme the angulation of the flap periphery. Femtosecond LASIK flaps are classically related to complications derived from a more intense inflammatory response, such as diffuse lamellar keratitis and transient light-sensitivity syndrome. Newer femtosecond models allow for much lower energy delivery to cut the flap, to the point the overall inflammatory response is not significantly different from the microkeratome. The incidence of complications such as epithelial defect and flap dislocations is higher with microkeratome flaps. SUMMARY This review examines the accuracy and complications of flaps created with femtosecond and microkeratome. Both femtosecond and microkeratome are able to create accurate LASIK flaps. Femtosecond LASIK flaps represent significant improvement in morphology and predictability with implications for safety.
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Santhiago MR, Wilson SE, Hallahan KM, Smadja D, Lin M, Ambrosio R, Singh V, Sinha Roy A, Dupps WJ. Changes in custom biomechanical variables after femtosecond laser in situ keratomileusis and photorefractive keratectomy for myopia. J Cataract Refract Surg 2014; 40:918-28. [PMID: 24726160 DOI: 10.1016/j.jcrs.2013.11.030] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Revised: 11/12/2013] [Accepted: 11/21/2013] [Indexed: 10/25/2022]
Abstract
PURPOSE To analyze changes in new biomechanical descriptors with myopic femtosecond laser-assisted laser in situ keratomileusis (LASIK), compare them with the biomechanical response after photorefractive keratectomy (PRK) with similar levels of myopic ablation, and evaluate correlations between changes in custom variables and biomechanically relevant variables. SETTING Cleveland Clinic, Cleveland, Ohio, USA. DESIGN Cohort study. METHODS Custom biomechanical variables from the Optical Response Analyzer were assessed preoperatively and 1 and 3 months postoperatively. Differences between preoperative values and postoperative values were determined. Intraindividual change (preoperative value minus postoperative value) was calculated and compared with changes after PRK. The correlation of the change in each custom biomechanical variable with the preoperative central corneal thickness, residual stromal bed tissue ablated, and percentage of tissue depth altered was also studied. RESULTS The study enrolled 156 eyes of 156 consecutive patients. Fifteen variables changed significantly after femtosecond myopic LASIK and were stable postoperatively because no significant difference was shown between 1-month values and 3-month values. Comparison of the changes in biomechanical variables between LASIK and PRK eyes showed no significant differences. Surgical changes in several custom biomechanical variables correlated with the percentage of tissue depth altered. CONCLUSIONS The results provide the first reference values for a more comprehensive panel of indicators of the biomechanical response to myopic LASIK and PRK. Changes in custom variables reflected a consistent decrease in corneal biomechanical resistance to deformation after myopic femtosecond LASIK and PRK. For comparable attempted corrections, biomechanical changes were comparable between femtosecond laser-assisted LASIK and PRK. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosures are listed after the references.
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Affiliation(s)
- Marcony R Santhiago
- From Cole Eye Institute (Santhiago, Wilson, Hallahan, Smadja, Lin, Singh, Roy, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; the Departments of Ophthalmology, University São Paulo (Santhiago), Sao Paulo, Federal University of São Paulo (Ambrosio), São Paulo, and the Federal University of Rio de Janeiro (Santhiago), Rio de Janeiro, Brazil.
| | - Steven E Wilson
- From Cole Eye Institute (Santhiago, Wilson, Hallahan, Smadja, Lin, Singh, Roy, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; the Departments of Ophthalmology, University São Paulo (Santhiago), Sao Paulo, Federal University of São Paulo (Ambrosio), São Paulo, and the Federal University of Rio de Janeiro (Santhiago), Rio de Janeiro, Brazil
| | - Katie M Hallahan
- From Cole Eye Institute (Santhiago, Wilson, Hallahan, Smadja, Lin, Singh, Roy, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; the Departments of Ophthalmology, University São Paulo (Santhiago), Sao Paulo, Federal University of São Paulo (Ambrosio), São Paulo, and the Federal University of Rio de Janeiro (Santhiago), Rio de Janeiro, Brazil
| | - David Smadja
- From Cole Eye Institute (Santhiago, Wilson, Hallahan, Smadja, Lin, Singh, Roy, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; the Departments of Ophthalmology, University São Paulo (Santhiago), Sao Paulo, Federal University of São Paulo (Ambrosio), São Paulo, and the Federal University of Rio de Janeiro (Santhiago), Rio de Janeiro, Brazil
| | - Michelle Lin
- From Cole Eye Institute (Santhiago, Wilson, Hallahan, Smadja, Lin, Singh, Roy, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; the Departments of Ophthalmology, University São Paulo (Santhiago), Sao Paulo, Federal University of São Paulo (Ambrosio), São Paulo, and the Federal University of Rio de Janeiro (Santhiago), Rio de Janeiro, Brazil
| | - Renato Ambrosio
- From Cole Eye Institute (Santhiago, Wilson, Hallahan, Smadja, Lin, Singh, Roy, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; the Departments of Ophthalmology, University São Paulo (Santhiago), Sao Paulo, Federal University of São Paulo (Ambrosio), São Paulo, and the Federal University of Rio de Janeiro (Santhiago), Rio de Janeiro, Brazil
| | - Vivek Singh
- From Cole Eye Institute (Santhiago, Wilson, Hallahan, Smadja, Lin, Singh, Roy, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; the Departments of Ophthalmology, University São Paulo (Santhiago), Sao Paulo, Federal University of São Paulo (Ambrosio), São Paulo, and the Federal University of Rio de Janeiro (Santhiago), Rio de Janeiro, Brazil
| | - Abhjit Sinha Roy
- From Cole Eye Institute (Santhiago, Wilson, Hallahan, Smadja, Lin, Singh, Roy, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; the Departments of Ophthalmology, University São Paulo (Santhiago), Sao Paulo, Federal University of São Paulo (Ambrosio), São Paulo, and the Federal University of Rio de Janeiro (Santhiago), Rio de Janeiro, Brazil
| | - William J Dupps
- From Cole Eye Institute (Santhiago, Wilson, Hallahan, Smadja, Lin, Singh, Roy, Dupps) and the Department of Biomedical Engineering (Dupps), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA; the Departments of Ophthalmology, University São Paulo (Santhiago), Sao Paulo, Federal University of São Paulo (Ambrosio), São Paulo, and the Federal University of Rio de Janeiro (Santhiago), Rio de Janeiro, Brazil
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Dong Z, Zhou X, Wu J, Zhang Z, Li T, Zhou Z, Zhang S, Li G. Small incision lenticule extraction (SMILE) and femtosecond laser LASIK: comparison of corneal wound healing and inflammation. Br J Ophthalmol 2013; 98:263-9. [PMID: 24227802 PMCID: PMC3913294 DOI: 10.1136/bjophthalmol-2013-303415] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Aim To evaluate and compare early corneal wound healing and inflammatory responses after small incision lenticule extraction (SMILE) versus femtosecond laser laser in situ keratomileusis (LASIK). Methods Thirty-six eyes of 36 rabbits underwent SMILE, while another 36 eyes of 36 rabbits were treated with femtosecond laser LASIK. All the eyes were subjected to the same refractive correction of −6.00 DS/−1.00 DC. Twelve eyes that had no surgery were included for control. After euthanisation, corneal tissue sections were evaluated with terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labelling (TUNEL) assay to detect apoptosis at postoperative 4 and 24 h, immunocytochemistry for Ki67 to detect keratocyte proliferation at postoperative day 3, week 1 and month 1, and immunocytochemistry for CD11b to detect inflammation at postoperative day 1, day 3 and week 1, respectively. Results No adverse effects were noted after SMILE or LASIK. Corneal healing postoperatively was uneventful in all cases. There were significantly fewer TUNEL-positive corneal stromal cells after the SMILE procedure at 4 and 24 h postoperatively (p<0.01) compared with the LASIK procedure. In addition, immunocytochemistry showed significantly fewer Ki67-positive cells in the SMILE group than those in the femtosecond laser LASIK group at day 3 and week 1 postoperatively (p<0.05), but there was little expression of Ki67 at month 1 postoperatively in both groups. The CD11b-positive cells were significantly fewer in the SMILE group at day 1, day 3 and week 1 postoperatively (p<0.01). Conclusions SMILE induces less keratocyte apoptosis, proliferation and inflammation compared with femtosecond laser LASIK.
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Affiliation(s)
- Zixian Dong
- Institute of Ophthalmology, Eye and ENT Hospital, Fudan University, , Shanghai, PR China
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Mayer WJ, Grueterich M, Wolf AH, Lackerbauer CA, Eibl K, Kampik A, Kook D. Corneal cell response after flap creation using a mechanical microkeratome or a 200 kHz femtosecond laser. J Cataract Refract Surg 2013; 39:1088-92. [DOI: 10.1016/j.jcrs.2013.01.047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 11/13/2012] [Accepted: 01/04/2013] [Indexed: 10/26/2022]
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Cañadas P, de Benito-Llopis L, Hernández-Verdejo JL, Teus MA. Comparison of keratocyte density after femtosecond laser vs mechanical microkeratome from 3 months up to 5 years after LASIK. Graefes Arch Clin Exp Ophthalmol 2013; 251:2171-9. [DOI: 10.1007/s00417-013-2357-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 03/22/2013] [Accepted: 04/18/2013] [Indexed: 10/26/2022] Open
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Peripheral keratitis following low-pulse energy femtosecond laser in situ keratomileusis. J Cataract Refract Surg 2012; 38:1881-2. [PMID: 22999630 DOI: 10.1016/j.jcrs.2012.08.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Indexed: 11/23/2022]
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Santhiago MR, Smadja D, Zaleski K, Espana EM, Armstrong BK, Wilson SE. Flap Relift for Retreatment After Femtosecond Laser–assisted LASIK. J Refract Surg 2012; 28:482-7. [DOI: 10.3928/1081597x-20120615-02] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 05/31/2012] [Indexed: 11/20/2022]
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Mayer WJ, Mackert MJ, Kranebitter N, Messmer EM, Grüterich M, Kampik A, Kook D. Distribution of antigen presenting cells in the human cornea: correlation of in vivo confocal microscopy and immunohistochemistry in different pathologic entities. Curr Eye Res 2012; 37:1012-8. [PMID: 22667765 DOI: 10.3109/02713683.2012.696172] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE The purpose of this study was to determine the quantity and distribution of antigen presenting cells (APC) in various inflammatory and non-inflammatory corneal diseases, comparing in vivo confocal microscopy (IVCM) and immunohistochemistry. MATERIAL AND METHODS Corneae of 41 eyes, composed of group 1 (status post herpes-keratitis), group 2 (keratoconus) and group 3 (graft rejection after keratoplasty) were investigated. IVCM was used preoperatively to assess the distribution and density of dendritic cells in the corneal center versus the paracentral area. Afterwards, all patients underwent penetrating keratoplasty. The host corneas were analyzed by immunohistochemistry for antigen presenting cell distribution, density and characterization by using specific markers for CD207/Langerin, CD209/DC-SIGN and HLA-DR. The IVCM findings were compared with immunohistochemistry results in the corneal epithelium. RESULTS Cells with branching dendritic morphology were visualized by IVCM mainly in the basal epithelial layer and subepithelial nerve plexus of the central and paracentral cornea. The density of APC in IVCM decreased in all groups towards the central part of the cornea. The highest gradient was observed in group 2, followed by groups 1 and 3. The corneal paracenter showed similiar distribution of APC in group 1 and 2 (76.7 cells/mm(2) and 74.4 cells/mm(2)). The highest density of central APC was observed in group 1 (53.76 cells/mm(2)), followed by group 3 (27.0 cells/mm(2)) and group 2 (24.2 cells/mm(2)). In immunohistochemistry positive stained, APC were distributed similarly to IVCM but with a higher density (p < 0.05). CONCLUSION Distribution, density and stage of maturation of corneal epithelial APCs can be evaluated on morphological basis by IVCM. However, the corneal APCs density was about three-fold lower compared to immunohistochemistry findings.
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Affiliation(s)
- Wolfgang J Mayer
- Department of Ophthalmology, Ludwig-Maximilians-University Munich, Germany.
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