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Short-term and long-term effects of small incision lenticule extraction (SMILE) on corneal endothelial cells. Cont Lens Anterior Eye 2015; 38:334-8. [PMID: 25920621 DOI: 10.1016/j.clae.2015.03.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 02/23/2015] [Accepted: 03/28/2015] [Indexed: 11/24/2022]
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Zhao MH, Wu Q, Jia LL, Hu P. Changes in central corneal thickness and refractive error after thin-flap laser in situ keratomileusis in Chinese eyes. BMC Ophthalmol 2015. [PMID: 26220189 PMCID: PMC4517627 DOI: 10.1186/s12886-015-0083-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Refractive stability is influenced by alterations in corneal curvature and corneal thickness after laser in situ keratomileusis (LASIK). The aim of this study was to analyze the changes of central corneal thickness (CCT) and refractive error following thin-flap LASIK surgery in Chinese eyes. METHODS One hundred and fifty-eight myopic patients (302 eyes) who underwent thin-flap LASIK surgery were prospectively evaluated. CCT was measured by non-contact specular microscopy before, and 1 day, 1 week, and 1, 3, and 6 months following surgery. Age, refractive error, and optic zone diameter were also recorded. RESULTS Preoperatively, the mean CCT was 531.6 ± 24.3 μm. At 1 day, 1 week, and 1, 3, and 6 months after surgery, mean CCTs were 431.4 ± 38.4 μm, 422.6 ± 3 7.8 μm, 427.2 ± 38.0 μm, 434.4 ± 38.2 μm, and 435.6 ± 38.0 μm, respectively. Significant changes were detected in CCT values at each time point after thin-flap LASIK treatment (P < 0.05). The mean preoperative spherical equivalent (SE) was -5.73 ± 2.30 diopters (D). At 1 day, 1 week, and 1, 3, and 6 months after surgery, it was 0.26 ± 0.58 D, 0.54 ± 0.52 D, 0.49 ± 0.53 D, 0.45 ± 0.49 D, and 0.37 ± 0.42 D, respectively. The spherical equivalent refraction at 6 months postsurgery was close to the predicted value (0.34 ± 0.30 D). The changes in CCT within 6 months (4.06 ± 9.99 μm) were negatively correlated with age, preoperative refractive error, and optical zone diameter, respectively (r = -0.180, P < 0.05; r = -0.187, P < 0.001; r = -0.171, P < 0.05, respectively). No significant correlation was found between CCT changes and SE changes at different time points, postoperatively. CONCLUSIONS CCTs decreased significantly at 1 day after surgery, and continued to decline at 1 week after surgery, then increased over time. From postoperative 1 week, SE over time continually shifted to the myopic side.
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Affiliation(s)
- Ming-Hui Zhao
- Department of Ophthalmology, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai,, 200233, China.
| | - Qiang Wu
- Department of Ophthalmology, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai,, 200233, China.
| | - Li-Li Jia
- Department of Ophthalmology, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai,, 200233, China.
| | - Ping Hu
- Department of Ophthalmology, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai,, 200233, China.
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Woodward MA, Edelhauser HF. Corneal endothelium after refractive surgery. J Cataract Refract Surg 2011; 37:767-77. [PMID: 21420604 DOI: 10.1016/j.jcrs.2011.01.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/28/2010] [Accepted: 10/29/2010] [Indexed: 11/25/2022]
Abstract
UNLABELLED The endothelium is vital to the health and optical clarity of the human cornea. The safety of procedures to correct refractive errors depends on preservation of an intact corneal endothelium. Disease states and genetic and environmental factors affect the corneal endothelium; an unstable corneal endothelium can impact the success of refractive surgery. Technological advances and recent laboratory findings have improved the ability to assess the endothelium. The status of the corneal endothelium after laser in situ keratomileusis, photorefractive keratectomy, phakic intraocular lenses, and adjuvants to these treatments has been the topic of numerous clinical trials. Safety guidelines for refractive surgery procedures should be followed to minimize deleterious effects on the corneal endothelium. FINANCIAL DISCLOSURE Neither author has a financial or proprietary interest in any material or method mentioned.
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Nieto-Bona A, Lorente-Velázquez A, Collar CV, Nieto-Bona P, Mesa AG. Intraocular Straylight and Corneal Morphology Six Months after LASIK. Curr Eye Res 2010; 35:212-9. [PMID: 20373879 DOI: 10.3109/02713680903470548] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Amelia Nieto-Bona
- Department of Optics II, University School of Optics, Complutense University, Madrid, Spain.
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Smith RT, Waring GO, Durrie DS, Stahl JE, Thomas P. Corneal endothelial cell density after femtosecond thin-flap LASIK and PRK for myopia: a contralateral eye study. J Refract Surg 2010; 25:1098-102. [PMID: 20000291 DOI: 10.3928/1081597x-20091117-09] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 02/03/2009] [Indexed: 11/20/2022]
Abstract
PURPOSE To compare the effect of femtosecond thinflap LASIK and photorefractive keratectomy (PRK) on postoperative endothelial cell density. METHODS In a prospective, randomized, contralateral, single-center clinical trial, 25 patients (mean age: 30+/-5 years [range: 21 to 38 years]) underwent PRK in one eye and thin-flap LASIK in the fellow eye for the correction of myopia using a wavefront-guided platform. The central corneal endothelial cell density was measured using the NIDEK Confoscan 4 preoperatively, and at 1 and 3 months postoperatively. Changes in endothelial cell density were analyzed over time between the two refractive techniques. RESULTS In PRK, the average preoperative endothelial cell density was 3011+/-329 cells/mm(2), which decreased to 2951+/-327 cells/mm(2) at 1 month (P=.5736) and 2982+/-365 cells/mm(2) at 3 months (P=.6513). In thinflap LASIK, the average preoperative endothelial cell density was 2995+/-325 cells/mm(2), which decreased to 2977+/-358 cells/mm(2) at 1 month (P=.5756) and 2931+/-369 cells/mm(2) at 3 months (P=.4106). No statistically significant difference was found between the two groups at 1 (P=.7404) or 3 (P=.3208) months postoperatively. CONCLUSIONS No statistically significant change was noted in endothelial cell density following either PRK or thin-flap LASIK for the treatment of myopia. Furthermore, no statistically significant difference was found between the two groups out to 3 months postoperatively, indicating that thin-flap LASIK is as safe as PRK with regards to endothelial health.
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Patel SV, Bourne WM. Corneal endothelial cell loss 9 years after excimer laser keratorefractive surgery. ACTA ACUST UNITED AC 2009; 127:1423-7. [PMID: 19901206 DOI: 10.1001/archophthalmol.2009.192] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To determine the long-term changes in the corneal endothelium after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). METHODS Twenty-nine eyes (16 patients) received myopic LASIK or PRK, with intended correction to emmetropia. Central endothelial photographs were taken before and 9 years after surgery and were analyzed by the same masked investigator after appropriate calibration for magnification. Comparisons were made by using generalized estimating equation models to account for any correlation between fellow eyes of the same patient. The annual exponential rate of cell loss was compared with cell loss during a 10-year period in 42 normal (unoperated) corneas of 42 subjects. RESULTS Endothelial cell density 9 years after LASIK and PRK had decreased by 5.3% from preoperative density (P < .001), whereas coefficient of variation of cell area (P = .24) and percentage of hexagonal cells (P = .19) did not change. The mean annual rate of cell loss after refractive surgery (0.6% [standard deviation, 0.8%]) was not different from that in normal corneas (0.6% [0.5%], P = .88; minimum detectable difference = 0.5%; alpha = .05; beta = .20). CONCLUSIONS Laser in situ keratomileusis and PRK had no long-term effect on the corneal endothelium. Corneas that have undergone LASIK or PRK can be considered for use as donors for posterior lamellar keratoplasty procedures.
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Affiliation(s)
- Sanjay V Patel
- Department of Ophthalmology, Mayo Clinic, Rochester, MN 55905, USA.
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Tsiklis NS, Kymionis GD, Pallikaris AI, Diakonis VF, Ginis HS, Kounis GA, Panagopoulou SI, Pallikaris IG. Endothelial cell density after photorefractive keratectomy for moderate myopia using a 213 nm solid-state laser system. J Cataract Refract Surg 2007; 33:1866-70. [DOI: 10.1016/j.jcrs.2007.06.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Accepted: 06/11/2007] [Indexed: 10/22/2022]
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Barraquer C C, Rodriguez-Barraquer T. Five-Year Results of Laser In-Situ Keratomileusis (LASIK) After Penetrating Keratoplasty. Cornea 2004; 23:243-8. [PMID: 15084856 DOI: 10.1097/00003226-200404000-00005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To study the long-term refractive results of LASIK after penetrating keratoplasty. PLACE Clinica Barraquer de América. METHODS Retrospective review of 46 eyes of 38 patients that underwent LASIK for the correction of refractive errors after penetrating keratoplasty. RESULTS The mean interval between keratoplasty and LASIK was 7 years. The preoperative defocus equivalent refraction (DEQ) was 2.0 to 7.0 D in 56% (26/46) of eyes and 8.0 to 24.0 D in the remaining 20 eyes. Five years after LASIK, DEQ was 1.0 to 7.0 D in all eyes. Seventy-five percent of eyes had a refractive error within 2.00 D of emmetropia. Thirty-two percent had uncorrected visual acuity of 20/40 or better, and 59% of eyes gained more than 1 line of best spectacle-corrected visual acuity at 5 years. Vector analysis showed a success index of 60% at 5 years. The refraction in eyes with keratoconus remained stable. CONCLUSION LASIK is safe and effective for the correction of refractive errors in eyes that have previously undergone corneal transplantation.
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Affiliation(s)
- Carmen Barraquer C
- Department of Refractive Surgery, Instituto Barraquer de América, Bogotá, Colombia
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Perez-Gomez I, Efron N. Change to Corneal Morphology after Refractive Surgery (Myopic Laser In Situ Keratomileusis) as Viewed with a Confocal Microscope. Optom Vis Sci 2003; 80:690-7. [PMID: 14560119 DOI: 10.1097/00006324-200310000-00010] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE This study aimed to look at morphological changes induced by myopic laser in situ keratomileusis (LASIK) in the human cornea using the confocal microscope and to investigate the link between these changes and alterations to corneal sensitivity. METHODS An in vivo slit-scanning real-time confocal microscope (Tomey ConfoScan P4, Erlangen, Germany) fitted with an Achroplan 40x/0.75 NA immersion objective and a Cochet-Bonnet esthesiometer were used to examine the morphology and sensitivity of the central corneas of six subjects (12 eyes) at an initial visit (before surgery), and at 1 week, 1 month, 3 months, and 6 months after LASIK for myopia. RESULTS Keratocyte density anterior to the flap interface showed differences between visits (p < 0.0001) and was found to be lower than at the initial visit at 1 week, 1 month, 3 months, and 6 months. Microfolds were noted at the level of the anterior limiting membrane in 11 of 12 eyes after surgery at all visits. Highly reflective flap interface particles were seen in all eyes at all visits after surgery. The subepithelial nerve fiber layer was clearly visible before surgery but could not be imaged in any of the eyes after surgery. Short, unconnected nerve fibers were observed 3 months after surgery; these appeared to form anastomosing interconnections after 6 months. Postsurgical corneal sensitivity was reduced during the first 3 months and recovered to presurgical levels after 6 months. CONCLUSION LASIK showed a decrease in anterior keratocyte density and microfolds in the anterior limiting membrane, and reflective particles were observed at the flap interface. Corneal sensitivity was depressed during the first 6 months after LASIK surgery; this time course paralleled the appearance of nerve regeneration during this period. Confocal microscopy is capable of providing interesting new insights into the effects of refractive surgery on corneal morphology.
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Affiliation(s)
- Inma Perez-Gomez
- Department of Optometry and Neuroscience, UMIST, Manchester, United Kingdom.
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Nawa Y, Ueda T, Masuda K, Ishibashi H, Hara Y, Uozato H. Evaluation of the corneal endothelium after hyperopic laser in situ keratomileusis. J Cataract Refract Surg 2003; 29:1543-5. [PMID: 12954302 DOI: 10.1016/s0886-3350(03)00460-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE To evaluate corneal endothelial changes after hyperopic laser in situ keratomileusis (LASIK) considering overestimation and underestimation of the cell count measurement. SETTING Department of Ophthalmology, Nara Medical University, Nara, Japan. METHODS The data were from the clinical trial of the Nidek EC-5000 excimer laser for hyperopic LASIK. The mean correction was 3.59 diopters (D) +/- 1.54 (SD) (range 2.0 to 6.0 D). Using noncontact specular microscopy, the corneal endothelial changes in 25 eyes of 15 patients who had hyperopic LASIK were measured. Follow-up ranged from 6 months (n = 25) to 1 year (n = 21). The overestimation and underestimation of the corneal endothelial cell count that would occur after +5.0 D hyperopic LASIK was hypothetically calculated. RESULTS The measured endothelial cell count per 1.0 mm(2) did not significantly decrease up to 1 year after hyperopic LASIK (preoperatively, 2508 +/- 395; at 1 year, 2814 +/- 349). The hypothetical calculation revealed that a +5.0 D hyperopic correction corresponded to a 0.1% underestimation of the corneal endothelial cell count. CONCLUSIONS Underestimation of the corneal endothelial cell count after hyperopic LASIK was negligible. Hyperopic LASIK with the Nidek EC-5000 excimer laser did not significantly decrease corneal endothelial cells up to 1 year after surgery.
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Affiliation(s)
- Yoshiaki Nawa
- Department of Ophthalmology, Nara Medical University, Nara, Japan.
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Simaroj P, Kosalprapai K, Chuckpaiwong V. Effect of Laser in situ Keratomileusis on the Corneal Endothelium. J Refract Surg 2003; 19:S237-40. [PMID: 12699180 DOI: 10.3928/1081-597x-20030302-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess the effects of laser in situ keratomileusis (LASIK) on the corneal endothelium. METHODS In a prospective study, preoperative and 12-month postoperative specular microscopy of the central corneal endothelium and corneal thickness assessment was done in 180 eyes of 105 patients (mean age 31.96 +/- 8.88 years; range 16 to 55 yr) who had LASIK to correct myopia. The central endothelium was analyzed for several parameters including cell density, coefficient of variation, and corneal thickness. Preoperative and postoperative data were compared. RESULTS The mean preoperative endothelial cell density was 2,547.37 +/- 282.00 cells/mm2, mean coefficient of variation of cell size was 58.33 +/- 11.50%, and mean central corneal thickness was 558.90 +/- 28.42 microm. There was not a statistically significant change in mean endothelial cell density (2,508.24 +/- 289.57 cells/mm2) or mean coefficient of variation (58.61 +/- 9.89%) at 1 year after surgery (P >.05 ). Average endothelial cell loss was 1.54% at 1 year after surgery. Mean central corneal thickness at 12 months postoperatively was 493.24 +/- 52.55 microm (P<.01). CONCLUSION LASIK did not appear to alter corneal endothelial cell density at 12 months postoperatively.
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Affiliation(s)
- Pornchai Simaroj
- Department of Ophthalmology, Ramathibodi Hospital, Faculty of Medicine, Mahidol University. Bangkok, Thailand.
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Abstract
PURPOSE To report central and peripheral corneal endothelial cell studies performed as part of the VISX hyperopic photorefractive keratectomy (PRK) clinical trial. METHODS During this prospective, multicenter clinical trial, which was part of an FDA investigation, endothelial cell specular microscopy was done at five centers. Non-contact central and peripheral cell density, percent hexagonality, and coefficient of variability of cell size were obtained using the Konan Noncon Robo SP-8000FA with BAMBI analysis software. Data were gathered at baseline and at 1, 6, and 12 months after hyperopic PRK. RESULTS Analysis of results of 171 eyes demonstrated no statistically significant detrimental changes in the corneal endothelium at any postoperative time point. The statistically significant changes noted were interpreted as an improvement in cell morphology and were attributed to the cessation of contact lens wear following treatment. CONCLUSION Hyperopic PRK with the VISX STAR S2 Excimer Laser System produced no statistically significant adverse effect on the corneal endothelium.
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Affiliation(s)
- Nada S Jabbur
- The Refractive Surgery Center, The Wilmer Eye Institute, The Johns Hopkins Hospital, Baltimore, MD, USA.
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Vroman DT, Solomon KD, Holzer MP, Peng Q, Apple DJ, Bowie EM. Endothelial decompensation after laser in situ keratomileusis. J Cataract Refract Surg 2002; 28:2045-9. [PMID: 12457684 DOI: 10.1016/s0886-3350(01)01352-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report the results of laser in situ keratomileusis (LASIK) in a 58-year-old woman with a history of corneal guttata in the right eye and mild Fuchs' dystrophy in the left eye. Preoperative pachymetry was 586 microm and 656 microm, respectively. The surgical treatment was +1.50 diopters (D) in the right eye and +3.25 D in the left eye. Surgery was performed using a VISX S2 Star laser and a Hansatome microkeratome with a 9.5 mm ring. Postoperatively, edema in the right eye resolved and pachymetry returned to 585 microm, but the left cornea decompensated despite maximum medical therapy and had a final pachymetry of 779 microm. The patient was referred to our cornea service for penetrating keratoplasty, which was performed 14 months after the LASIK treatment.
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Affiliation(s)
- David T Vroman
- Magill Research Center for Vision Correction, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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Chan JWW, Edwards MH, Woo GC, Woo VCP. Contrast sensitivity after laser in situ keratomileusis. one-year follow-up. J Cataract Refract Surg 2002; 28:1774-9. [PMID: 12388027 DOI: 10.1016/s0886-3350(02)01499-2] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
PURPOSE To determine whether contrast sensitivity measurement, a more sensitive test of visual function than visual acuity, better characterizes visual outcomes after laser in situ keratomileusis (LASIK). SETTING Hong Kong Laser Eye Centre, Hong Kong, China. METHODS Contrast sensitivity was monitored in 41 LASIK patients for 1 year. Seven spatial frequencies (0.3, 0.8, 1.5, 3.4, 6.9, 10.3, and 20.5 cpd) were tested with 15 sequences per spatial frequency, and a staircase technique was used for target presentation. RESULTS There was a general depression in the contrast sensitivity function after LASIK; 1.5 cpd and 3.4 cpd were the most affected frequencies. Recovery took at least 6 months. The reduction in contrast sensitivity was greater for higher amounts of myopia. CONCLUSION The post-LASIK nonpermanent depression in contrast sensitivity was probably due to optical factors.
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Affiliation(s)
- Jay W W Chan
- Centre for Myopia Research, Department of Optometry and Radiography, The Hong Kong Polytechnic University , Hong Kong, China
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Baldwin HC, Marshall J. Growth factors in corneal wound healing following refractive surgery: A review. ACTA OPHTHALMOLOGICA SCANDINAVICA 2002; 80:238-47. [PMID: 12059860 DOI: 10.1034/j.1600-0420.2002.800303.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The first part of this review article aims to provide important basic definitions of growth factor terminology, and to put forward a model for understanding the role of growth factors in a wound healing context. In the second part of the paper, we review the literature on growth factors in the cornea, including that on changes associated with wound healing following refractive surgery in the epithelial, stromal, and endothelial layers. The role of growth factors in stromal removal, corneal neovascularization, corneal innervation and wound healing is considered. The importance of the epithelial-stromal interaction is discussed, including the role of growth factors in keratocyte apoptosis. In the final section, we review the current literature on endogenous and exogenous modulation of growth factors in corneal wound healing. This includes important in vitro work but aims to emphasize clinically relevant results. Photorefractive keratectomy (PRK) may have short-term complications such as pain and haze, whereas laser in situ keratomilieusis (LASIK) may have longer-term adverse effects on corneal biomechanics. The emerging technique of laser epithelial keratomilieusis (LASEK) provides an interesting alternative wound which may be less susceptible to the inherent complications of PRK and LASIK. At present, the phenomenon of iatrogenic keratectasia following LASIK is not fully understood, but these features of wound healing following PRK may be amenable to growth factor modulation.
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Chuck RS, Behrens A, Wellik SR, Liaw LH, Sweet PM, Osann KE, McDonnell PJ, Berns MW. Simple organ cornea culture model for re-epithelialization after in vitro excimer laser ablation. Lasers Surg Med 2002; 29:288-92. [PMID: 11573233 DOI: 10.1002/lsm.1121] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND AND OBJECTIVE Most of the in vitro work to characterize the effects of clinical laser surgery on corneal tissues has concentrated on the effects on stromal keratocytes and endothelium with little attention being paid to corneal epithelium. Our purpose is to describe the epithelial healing rates observed in freshly cultured rabbit corneas treated with phototherapeutic keratectomy (PTK). STUDY DESIGN/MATERIALS AND METHODS Corneas were placed in a simple organ culture system, with media change every 2 days. A clinical excimer laser was used to perform a 6 mm diameter, 100 microm depth transepithelial PTK on 24 cultured rabbit corneas, 1 day after culture initiation. For each post-treatment day, one experimental and one control cornea were removed from culture and stained with fluorescein, photographed, and fixed for histology. Epithelial defect area was measured with digital imaging software and analyzed statistically to assess the re-epithelialization rate. RESULTS Control corneas, maintained in culture for 1-4 days, had no epithelial defects. Those corneas treated with PTK exhibited an immediate epithelial defect that slowly healed over 3 days. This was confirmed on histopathological analysis. A significant linear trend in re-epithelialization across the time points studied was found (F = 80.48, P = 0.0029). The slope of the linear regression model showed an estimate rate of re-epithelialization of -6.70 over the 3 days. CONCLUSION We have described the development of a simple, whole organ, rabbit cornea culture model for re-epithelialization after PTK. Our rates of epithelial healing resemble those found in the literature in live rabbit models. Therefore, this model may possibly be used to monitor epithelial wound healing in different corneal diseases or injuries.
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Affiliation(s)
- R S Chuck
- Department of Ophthalmology, University of California Irvine, Irvine, California 92697, USA.
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Michaeli-Cohen A, Lambert AC, Coloma F, Rootman DS. Two cases of a penetrating keratoplasty with tissue from a donor who had undergone LASIK surgery. Cornea 2002; 21:111-3. [PMID: 11805519 DOI: 10.1097/00003226-200201000-00023] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To report two cases of penetrating keratoplasty using tissue from a donor who had undergone laser-assisted in situ keratomileusis (LASIK) surgery before its transplantation. PARTICIPANTS Two patients who had penetrating keratoplasties and received donor corneas from eyes that had previous LASIK. INTERVENTION The two patients underwent corneal transplantation by two different surgeons who were unaware that the donor eyes had previous LASIK treatment. RESULTS Penetrating keratoplasty was completed without complication in both cases, although a separation of the corneal lamellae was noted during surgery in one of the cases. The two patients are doing well at 5.5 months postsurgery. CONCLUSION With the increasing popularity of laser refractive surgery, eye banks should increase their awareness and refine screening techniques to rule out refractive surgery in the donor corneas. The long-term follow-up of those patients will reveal if surgical success was compromised by prior refractive surgery.
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Abstract
Laser in situ keratomileusis (LASIK) is a rapidly evolving ophthalmic surgical procedure. Several anatomic and refractive complications have been identified. Anatomic complications include corneal flap abnormalities, epithelial ingrowth, and corneal ectasia. Refractive complications include unexpected refractive outcomes, irregular astigmatism, decentration, visual aberrations, and loss of vision. Infectious keratitis, dry eyes, and diffuse lamellar keratitis may also occur following LASIK. By examining the etiology, management, and prevention of these complications, the refractive surgeon may be able to improve visual outcomes and prevent vision-threatening problems. Reporting outcomes and mishaps of LASIK surgery will help refine our approach to the management of emerging complications.
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Affiliation(s)
- S A Melki
- Cornea and Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Boston, MA 02114, USA
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Azar RG, Holdbrook MJ, Lemp M, Edelhauser HF. Two-year Corneal Endothelial Cell Assessment Following INTACS Implantation. J Refract Surg 2001; 17:542-8. [PMID: 11583224 DOI: 10.3928/1081-597x-20010901-07] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the 2-year effects of intrastromal corneal ring segments (INTACS) on the corneal endothelium. METHODS Non-contact specular microscopy was performed as a subgroup test in a Phase III clinical trial. Endothelial cell images were collected before surgery and at 6, 12, and 24 months after surgery at the central and peripheral (6 and 10 o'clock) regions. Images were recorded and analyzed later by a central reading center. Cell density, coefficient of variation, and percent hexagonal cells were determined. RESULTS There were no clinically significant changes in the endothelial cell structure at 6, 12, and 24 months (102 eyes). There was a gain of 5 cells/mm2 (6 months) and 3 cells/mm2 (12 months) at the central region of the cornea and a loss of 28 cells/mm2 at 24 months. At the 6 o'clock region of the cornea, there was a loss of 0, 24, and 92 cells/mm2 at 6, 12, and 24 months. At the 10 o'clock region of the cornea, there was a loss of 14, 30, and 94 cells/mm2 at 6, 12, and 24 months. INTACS did not statistically affect the central cell density at 6 and 12 months, however, there was a slight loss centrally at 24 months. At 24 months, all corneal regions had a slight decrease in cell density. In all eyes, mean central and peripheral endothelial cell counts remained above 2495 cells/mm2. Coefficient of variation improved and percent hexagonal cells remained unchanged. CONCLUSION Endothelial cell density changes at 2 years after INTACS implantation were not clinically significant and endothelial cell remodeling was present.
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Affiliation(s)
- R G Azar
- Emory Eye Center Emory University, Atlanta, GA 30322, USA
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22
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Frueh BE, Eggli P, Böhnke M. Morphology of the Stromal Surface and Endothelium Using Two Different Microkeratomes. J Refract Surg 2001; 17:428-32. [PMID: 11472000 DOI: 10.3928/1081-597x-20010701-04] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To compare stromal surface and endothelial morphology after keratectomies and after laser in situ keratomileusis (LASIK), using two different microkeratomes. METHODS Keratectomies (160-microm and 400-microm) were performed on 82 enucleated porcine eyes using the Chiron Automated Corneal Shaper (52 eyes) and the Microtech Turbokeratome (30 eyes). LASIK procedures of -9.00 D, -27.00 D, and -36.00 D were performed with a Schwind excimer laser. The corneas were immediately fixed in glutaraldehyde or stained with alizarin red and trypan. Scanning electron microscopy was then performed. RESULTS All keratectomies performed with the Chiron microkeratome displayed a relatively smooth surface. The quality of the keratectomies with the manually advanced Microtech microkeratome was variable, with a high incidence (4 of 9) of incomplete cuts and irregular surfaces. In the eyes in which the stromal laser ablation was performed, a thin layer of condensed stroma (pseudomembrane formation) was seen. Vital staining did not indicate endothelial damage. CONCLUSIONS The surface morphology was unacceptable for one of the microkeratomes tested. Keratectomies of 160 to 400 microm and LASIK up to -36.00 D did not acutely alter endothelial morphology in porcine eyes.
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Affiliation(s)
- B E Frueh
- Department of Ophthalmology, University of Bern, Switzerland
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23
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Affiliation(s)
- N Preschel
- Unidad Oftalmologica de Caracas, Centro Profesional Santa Paula, Caracas, Venezuela
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24
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Collins MJ, Carr JD, Stulting RD, Azar RG, Waring GO, Smith RE, Thompson KP, Edelhauser HF. Effects of laser in situ keratomileusis (LASIK) on the corneal endothelium 3 years postoperatively. Am J Ophthalmol 2001; 131:1-6. [PMID: 11162971 DOI: 10.1016/s0002-9394(00)00664-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To investigate the effects of laser in situ keratomileusis (LASIK) on the corneal endothelium 3 years postoperatively. METHODS Patients who were subjects of a previous prospective study (Am J Ophthalmol 125:465-471, (April) 1998) were contacted for a follow-up analysis of the central corneal endothelium. Noncontact specular microscopy was performed 35 to 37 months after LASIK on 52 eyes of 27 patients of the original cohort of 98 eyes of 65 patients and six eyes of three patients who were previously lost to follow-up after their initial post-LASIK evaluation. Patient age ranged from 29 to 66 years at the time of the original LASIK procedure. Attempted corrections ranged from 2.25 to 14.5 diopters of myopia, giving theoretical ablation depths of 182 to 332 microm below the corneal surface. Forty-eight eyes (83%) had a history of preoperative contact lens use (3 to 33 years). Central endothelial cell density, coefficient of variation of cell size, and percent of hexagonal cells were analyzed using 72 to 152 cells from each image. Multivariate analysis was used to search for factors that might predict changes in cell density, coefficient of variation, and percent of hexagonal cells. RESULTS The mean +/- SD preoperative cell density was 2,498 +/- 354 cells per mm(2), the mean coefficient of variation was 0.36 +/- 0.07, and the percent of hexagonal cells was 58 +/- 6. Three years after surgery there was no statistically significant change in the mean endothelial cell density (2,489 +/- 335 cells per mm(2); P = 0.88, paired t test) or the percent of hexagonal cells (60 +/- 7; P = 0.14, paired t test). The mean coefficient of variation was significantly lower postoperatively (0.32 +/- 0.04; P = 0.0006, paired t test); a repeated measures analysis showed that this significant improvement could not be explained by cessation of contact lens wear after LASIK (P = 0.34). Multivariate analysis did not identify any factors that were predictive of change in cell density, coefficient of variation, and percent of hexagonal cells. CONCLUSIONS Laser in situ keratomileusis for the correction of 2.25 to 14.5 diopters of myopia had no significant effect on central corneal endothelial cell density or the percent of hexagonal cells 3 years after surgery. The coefficient of variation of cell size improved significantly 3 years after surgery.
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Affiliation(s)
- M J Collins
- Department of Ophthalmology, Emory University, Atlanta, Georgia, USA
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25
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Abstract
PURPOSE To review the major advances in the field of refractive surgery occurring over the past 25 years. METHODS Literature review. RESULTS The major developments in refractive surgery over the past 25 years are reviewed. CONCLUSIONS The past 25 years have witnessed great changes in refractive surgery. As a result of advancements in technology, instrumentation, and technique, we have seen improvements in the treatment of all types of ametropias. In this article, we review some of the successes and failures of the past quarter-century.
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Affiliation(s)
- R D Stulting
- Cornea Service, Emory University School of Medicine, Department of Ophthalmology, Atlanta, Georgia, USA
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26
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Abstract
PURPOSE To evaluate the visual and refractive results of laser in situ keratomileusis (LASIK) retreatment on eyes with residual myopia with or without astigmatism. METHODS LASIK retreatment was performed on 35 eyes of 23 patients for correction of residual myopia, with or without astigmatism, with a mean manifest spherical equivalent refraction of -2.17+/-0.82 D (range, -1.00 to -3.87 D) and mean refractive astigmatism of -0.55+/-0.61 D (range, 0 to -1.75 D). Retreatment was performed 3 to 18 months after primary LASIK (mean, 5.1+/-2.6 mo). The corneal flap of the previous LASIK was lifted and laser ablation was performed using the Chiron-Technolas Keracor 116 excimer laser. Follow-up was 12 months for all eyes. RESULTS At 1 year after retreatment, manifest spherical equivalent refraction was reduced to a mean -0.23+/-0.28 D (range, 0 to -0.87 D), and refractive astigmatism was reduced to a mean -0.16+/-0.25 D (range, 0 to -0.75 D). Thirty-two eyes (91.5%) had a manifest spherical equivalent refraction within +/-0.50 D of emmetropia, and 33 eyes (94.3%) had 0 to 0.50 D of refractive astigmatism. Uncorrected visual acuity was 20/20 or better in 11 eyes (31.4%). Spectacle-corrected visual acuity was not reduced in any eye after retreatment. There were no significant complications. CONCLUSION LASIK retreatment was effective for correction of residual myopia or astigmatism after primary LASIK. Refractive results were predictable with good stability after 3 months. Lifting the flap during LASIK retreatment was relatively easy to perform and did not result in visual morbidity in eyes treated from 3 up to 18 months after primary LASIK.
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Affiliation(s)
- K M Rashad
- Ophthalmology Department, Alexandria University, Egypt
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27
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Forseto AS, Francesconi CM, Nosé RA, Nosé W. Laser in situ keratomileusis to correct refractive errors after keratoplasty. J Cataract Refract Surg 1999; 25:479-85. [PMID: 10198851 DOI: 10.1016/s0886-3350(99)80043-1] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE To assess the safety and effectiveness of excimer laser in situ keratomileusis (LASIK) to correct refractive myopia, astigmatism, or both after keratoplasty. SETTING Eye Clinic Day Hospital, São Paulo, Brazil. METHODS Twenty-two eyes that had previously had corneal transplantation were studied. Laser in situ keratomileusis was performed using the Chiron automated microkeratome and the VISX Twenty-Twenty B excimer laser. RESULTS Mean follow-up after LASIK was 10.09 months +/- 3.87 (SD). The spherical equivalent refraction dropped from -4.55 +/- 3.66 D before LASIK to -0.67 +/- 1.24 D after surgery. At the last examination, 72.7% of patients had a refractive error within +/- 1.00 D of emmetropia and 54.5% had uncorrected visual acuity of 20/40 or better. Vector analysis of astigmatic correction showed an index of success of 54.0%. Best spectacle-corrected visual acuity was unchanged in 8 cases, improved in 9, and decreased in 5. Significant endothelial cell loss, keratoplasty wound dehiscence, and other serious complications did not develop in any eye. CONCLUSION The correction of refractive error with LASIK in postkeratoplasty patients proved to be safe, effective, and predictable. Further studies with longer follow-up are needed to determine the method's clinical value.
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Steinert RF, Bafna S. Surgical correction of moderate myopia: which method should you choose? II. PRK and LASIK are the treatments of choice. Surv Ophthalmol 1998; 43:157-79. [PMID: 9841455 DOI: 10.1016/s0039-6257(98)00027-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- R F Steinert
- Center for Eye Research and Education, Ophthalmic Consultants of Boston, MA., USA
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Farah SG, Azar DT, Gurdal C, Wong J. Laser in situ keratomileusis: literature review of a developing technique. J Cataract Refract Surg 1998; 24:989-1006. [PMID: 9682123 DOI: 10.1016/s0886-3350(98)80056-4] [Citation(s) in RCA: 219] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We reviewed papers published in peer-reviewed journals describing techniques and results of laser in situ keratomileusis (LASIK) and summarized the instruments used, nomograms, preoperative and postoperative refractions, predictability, outcome, safety, and complications. We performed a similar review of abstracts published in the abstract books of the 1996 meeting of the International Society of Refractive Surgery, the 1997 meeting of the Association for Research in Vision and Ophthalmology, and the 1997 meeting of the American Society of Cataract and Refractive Surgery. The number of LASIK and photorefractive keratectomy (PRK) patients described in the abstracts were sorted by city. Mean weighted latitudes were calculated and compared for each procedure. The mean preoperative refraction in the papers was -12.59 diopters (D), which was statistically higher than that in the abstracts, -8.71 D (P < .001), and the mean postoperative refraction, -1.10 and + 0.93 D, respectively. The mean percentage of cases within +/- 1.00 D was 67.0% in the papers and 82.5% in the abstracts. Uncorrected visual acuity (UCVA) of 20/40 or better was achieved in 49.2% of eyes in the papers and 83.2% of those in the abstracts; a UCVA of 20/20 or better was achieved in 22.0 and 56.6%, respectively. The portion of eyes that lost two or more lines of best corrected visual was 8.0% in the papers and 0.9% in the abstracts. Complications in the papers included irregular flap (4.0%), incomplete cut (2.5%), free cap (4.9%), perforated lenticule (2.6%), short flap (3.0%), sliding flap (1.4%), interface debris (6.8%), central island (5.3%), decentration (4.7%), epithelial ingrowth (4.3%), induced astigmatism (5.1%), wrinkles (5.9%), haze (8.7%), night vision problems (14.0%), and reoperation (8.2%), Mean latitude for LASIK cases (27.00 degrees +/- 13.73 [SD] was significantly lower than that for PRK cases (42.85 +/- 11.7 degrees). Visual outcomes of LASIK surgery show significant improvements when recent abstracts are compared with published papers. This may reflect continued improvement in the surgical techniques, surgeons' skills, and visual outcomes.
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Affiliation(s)
- S G Farah
- Corneal and Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts 02114, USA
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