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Deshmukh R, Ong ZZ, Rampat R, Alió del Barrio JL, Barua A, Ang M, Mehta JS, Said DG, Dua HS, Ambrósio R, Ting DSJ. Management of keratoconus: an updated review. Front Med (Lausanne) 2023; 10:1212314. [PMID: 37409272 PMCID: PMC10318194 DOI: 10.3389/fmed.2023.1212314] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 05/30/2023] [Indexed: 07/07/2023] Open
Abstract
Keratoconus is the most common corneal ectatic disorder. It is characterized by progressive corneal thinning with resultant irregular astigmatism and myopia. Its prevalence has been estimated at 1:375 to 1:2,000 people globally, with a considerably higher rate in the younger populations. Over the past two decades, there was a paradigm shift in the management of keratoconus. The treatment has expanded significantly from conservative management (e.g., spectacles and contact lenses wear) and penetrating keratoplasty to many other therapeutic and refractive modalities, including corneal cross-linking (with various protocols/techniques), combined CXL-keratorefractive surgeries, intracorneal ring segments, anterior lamellar keratoplasty, and more recently, Bowman's layer transplantation, stromal keratophakia, and stromal regeneration. Several recent large genome-wide association studies (GWAS) have identified important genetic mutations relevant to keratoconus, facilitating the development of potential gene therapy targeting keratoconus and halting the disease progression. In addition, attempts have been made to leverage the power of artificial intelligence-assisted algorithms in enabling earlier detection and progression prediction in keratoconus. In this review, we provide a comprehensive overview of the current and emerging treatment of keratoconus and propose a treatment algorithm for systematically guiding the management of this common clinical entity.
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Affiliation(s)
- Rashmi Deshmukh
- Department of Cornea and Refractive Surgery, LV Prasad Eye Institute, Hyderabad, India
| | - Zun Zheng Ong
- Department of Ophthalmology, Queen’s Medical Centre, Nottingham, United Kingdom
| | - Radhika Rampat
- Department of Ophthalmology, Royal Free London NHS Foundation Trust, London, United Kingdom
| | - Jorge L. Alió del Barrio
- Cornea, Cataract and Refractive Surgery Unit, Vissum (Miranza Group), Alicante, Spain
- Division of Ophthalmology, School of Medicine, Universidad Miguel Hernández, Alicante, Spain
| | - Ankur Barua
- Birmingham and Midland Eye Centre, Birmingham, United Kingdom
| | - Marcus Ang
- Singapore National Eye Centre, Singapore Eye Research Institute, Singapore, Singapore
| | - Jodhbir S. Mehta
- Singapore National Eye Centre, Singapore Eye Research Institute, Singapore, Singapore
| | - Dalia G. Said
- Department of Ophthalmology, Queen’s Medical Centre, Nottingham, United Kingdom
- Academic Ophthalmology, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Harminder S. Dua
- Department of Ophthalmology, Queen’s Medical Centre, Nottingham, United Kingdom
- Academic Ophthalmology, School of Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Renato Ambrósio
- Department of Cornea and Refractive Surgery, Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
- Federal University of São Paulo (UNIFESP), São Paulo, Brazil
| | - Darren Shu Jeng Ting
- Birmingham and Midland Eye Centre, Birmingham, United Kingdom
- Academic Ophthalmology, School of Medicine, University of Nottingham, Nottingham, United Kingdom
- Academic Unit of Ophthalmology, Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
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Hamon L, Schlötzer-Schrehardt U, Flockerzi FA, Seitz B, Daas L. Morphological characterization and clinical effects of stromal alterations after intracorneal ring segment implantation in keratoconus. Graefes Arch Clin Exp Ophthalmol 2022; 260:2299-2308. [PMID: 35106630 PMCID: PMC9203383 DOI: 10.1007/s00417-022-05572-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/16/2022] [Accepted: 01/20/2022] [Indexed: 01/15/2023] Open
Abstract
PURPOSE To analyze the histological and (ultra)structural stromal tissue changes after femtosecond (Fs) laser-assisted intracorneal ring segment (ICRS) implantation and their refractive and topographic effects in patients with keratoconus. METHODS This monocentric retrospective case series included 15 consecutive patients with clinical peri-segmental lamellar channel deposits after treatment with Fs-ICRS implantation for keratoconus. The stromal changes were investigated using in vivo confocal microscopy. Two patients underwent a penetrating keratoplasty after the Fs-ICRS implantation; the explanted corneas were processed for histopathology and transmission electron microscopy (TEM). Refractive and topographic effects were investigated comparing the uncorrected (UDVA) and corrected (CDVA) distance visual acuity, spherical equivalent (SE), flat (K1), steep (K2), and steepest (Kmax) keratometry before and after detection of lamellar channel deposits. RESULTS In vivo confocal microscopy revealed diffuse linear and focal granular hyperreflective structures. Histologically, there was mild proliferation of fibroblasts and fibrosis. TEM demonstrated focal accumulations of degenerated keratocytes with cytoplasmic lipid inclusions. There were no significant changes for UDVA (Δ = 0.0 ± 0.2 logMAR; p = 0.67), CDVA (Δ = 0.0 ± 0.1 logMAR; p = 0.32), SE (Δ 0.1 ± 0.9 D; p = 0.22), K1 (Δ = 0.3 ± 1.0 D; p = 0.28), K2 (Δ = 0.1 ± 0.9 D; p = 0.51), and Kmax (Δ = 0.3 ± 1.5 D; p = 0.17). CONCLUSIONS Two types of structural stromal changes were identified: (1) diffuse peri-segmental fibrosis and (2) lamellar channel deposits. These structural changes showed no evidence of a relevant refractive or topographic effect.
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Affiliation(s)
- Loïc Hamon
- Department of Ophthalmology, Saarland University Medical Center (UKS), Kirrberger Straße 100, Bld. 22, 66421 Homburg, Saar Germany
| | - Ursula Schlötzer-Schrehardt
- Department of Ophthalmology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Fidelis A. Flockerzi
- Department of Pathology, Saarland University Medical Center (UKS), Homburg, Saar Germany
| | - Berthold Seitz
- Department of Ophthalmology, Saarland University Medical Center (UKS), Kirrberger Straße 100, Bld. 22, 66421 Homburg, Saar Germany
| | - Loay Daas
- Department of Ophthalmology, Saarland University Medical Center (UKS), Kirrberger Straße 100, Bld. 22, 66421 Homburg, Saar Germany
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Silva FBDD, Daher ND. Influência da espessura dos segmentos de anel corneano na correção do astigmatismo ceratométrico em pacientes com ceratocone. REVISTA BRASILEIRA DE OFTALMOLOGIA 2021. [DOI: 10.37039/1982.8551.20210053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Tabatabaei SA, Soleimani M, Mirghorbani M, Tafti ZF, Rahimi F. Microbial keratitis following intracorneal ring implantation. Clin Exp Optom 2021; 102:35-42. [DOI: 10.1111/cxo.12810] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 04/12/2018] [Accepted: 06/17/2018] [Indexed: 11/26/2022] Open
Affiliation(s)
- Seyed Ali Tabatabaei
- Ocular Trauma and Emergency Unit, Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran,
| | - Mohammad Soleimani
- Ocular Trauma and Emergency Unit, Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran,
| | - Masoud Mirghorbani
- Ocular Trauma and Emergency Unit, Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran,
| | | | - Firoozeh Rahimi
- Ocular Trauma and Emergency Unit, Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran,
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Elalfy M, Maqsood S, Reinhold A, Panos GD, Khine A, Lake D, Hamada S, Gatzioufas Z. Clinical outcomes after intracorneal ring segment implantation for keratoconus management in corneas with mild apical haze. Ther Adv Ophthalmol 2021; 13:25158414211003378. [PMID: 34222792 PMCID: PMC8221670 DOI: 10.1177/25158414211003378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 02/23/2021] [Indexed: 11/29/2022] Open
Abstract
Purpose: The implantation of intracorneal ring segments represents an effective and safe therapeutic option for visual improvement in patients with keratoconus. The presence of corneal opacities is considered an exclusion criterion for this operation. Methods: This is a retrospective cohort study of six eyes of six keratoconus patients at Queen Victoria Hospital, East Grinstead, UK, between January 2012 and December 2016. Femtosecond laser-assisted intracorneal ring segment implantation was performed in six eyes with apical corneal haze. Preoperative and postoperative visual acuity, keratometry readings, as well as corneal pachymetry were compared at 6-month follow-up. Results: Uncorrected visual acuity (UCVA) [LogMAR] improved significantly from median 1.05 [95% confidence interval (CI): 0.83–0.13] preoperatively to 0.9 (95% CI: 0.63–1.00) at 6 months postoperatively (p = 0.03). Corrected visual acuity (CDVA) also improved significantly from median 0.75 (95% CI: 0.43–1.00) preoperatively to 0.4 (95% CI: 0.23–0.50) at 6 months postoperatively (p = 0.03). Keratometric readings, K-max (diopters) and K-mean (diopters), decreased significantly from 54.5 and 47.85 preoperatively to 53.45 and 46.42 postoperatively, respectively (p = 0.03). Corneal pachymetry showed no significant changes postoperatively. Conclusion: The results of this study show that the presence of apical haze should not exclude the implantation of intracorneal ring segments in patients with keratoconus.
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Affiliation(s)
- Mohamed Elalfy
- Corneo-Plastic Unit, Queen Victoria Hospital NHS Trust, Holtye Road, East Grinstead RH19 3DZ, West Sussex, UK
| | - Sundas Maqsood
- Corneo-Plastic Unit, Queen Victoria Hospital NHS, East Grinstead, UK
| | - Aja Reinhold
- Department of Ophthalmology, University Hospital Basel, Basel, Switzerland
| | - Georgios D Panos
- Eye Treatment Center, Whipps Cross University Hospital, Barts Health NHS Trust, London, UK
| | - Aye Khine
- Corneo-Plastic Unit, Queen Victoria Hospital NHS, East Grinstead, UK
| | - Damian Lake
- Corneo-Plastic Unit, Queen Victoria Hospital NHS, East Grinstead, UK
| | - Samer Hamada
- Corneo-Plastic Unit, Queen Victoria Hospital NHS, East Grinstead, UK
| | - Zisis Gatzioufas
- Corneo-Plastic Unit, Queen Victoria Hospital NHS, East Grinstead, UK
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Peris-Martínez C, Dualde-Beltrán C, Fernández-López E, Roig-Revert MJ, Hernández-Díaz M, Piñero DP. Effect of the variability in implantation depth of intracorneal ring segments using the femtosecond laser technology in corneal ectasia. Eur J Ophthalmol 2019; 30:668-675. [DOI: 10.1177/1120672119852026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Purpose: To analyze the impact of the depth of implantation of intracorneal ring segments on morphological, biomechanical, and clinical outcomes in ectatic corneas. Methods: This prospective longitudinal study enrolled 40 eyes of 29 patients (age 20–51 years) with corneal ectasia that underwent intracorneal ring segments implantation (KeraRing, Mediphacos). Changes in visual acuity, refraction, corneal tomography, and corneal biomechanics (Ocular Response Analyzer, Reichert) were evaluated during a 6 month follow-up. Likewise, changes in ring segment implantation depth measured by optical coherence tomography (Visante OCT, Carl Zeiss Meditec) were also evaluated. Results: Mean relative depth of implantation was 71.6 ± 5.8%, 71.5 ± 6.5%, and 71.9 ± 6.3% at 1, 3, and 6 months after surgery, respectively (p = 0.827). The difference between the real relative depth of implantation and the theoretical attempted value of 70% was not statistically significant (p = 0.072). Differences in spherical equivalent during the follow-up changed significantly depending on the level of relative depth of implantation (p = 0.036), with an increase of 0.114 D per each 1% increase in relative depth of implantation. Likewise, a decrease of –0.194 D in the steepest keratometric reading was found per each decrease of 1% in relative depth of implantation (p = 0.026). Changes in corneal thickness (p = 0.092) and biomechanics (p = 0.080) were not related to relative depth of implantation. Conclusion: The effect on visual acuity and refraction of intracorneal ring segments when implanted in corneal ectasia is less clinically relevant when the implantation is done at a very deep plane. The variability of the depth of intracorneal ring segments implantation when using femtosecond laser technology is minimal and with no clinically significant effect on clinical outcomes.
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Affiliation(s)
- Cristina Peris-Martínez
- Cornea and External Diseases Unit, FISABIO-Oftalmología Médica (FOM), Valencia, Spain
- Clínica Oftalmológica Aviñó&Peris, Valencia, Spain
| | | | - Ester Fernández-López
- Cornea and External Diseases Unit, FISABIO-Oftalmología Médica (FOM), Valencia, Spain
| | | | - Mikhail Hernández-Díaz
- Cornea and External Diseases Unit, FISABIO-Oftalmología Médica (FOM), Valencia, Spain
- Clínica Oftalmológica Aviñó&Peris, Valencia, Spain
| | - David P Piñero
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
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Rocha GADN, Ferrara de Almeida Cunha P, Torquetti Costa L, Barbosa de Sousa L. Outcomes of a 320-degree intrastromal corneal ring segment implantation for keratoconus: Results of a 6-month follow-up. Eur J Ophthalmol 2018; 30:139-146. [DOI: 10.1177/1120672118818018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Importance: This study shows that a newer long-arc length intrastromal corneal ring segment is efficient and safe for keratoconus treatment. Background: To evaluate visual, tomographic results and complications of a 320-degree intrastromal corneal ring segment implantation with the femtosecond laser for keratoconus treatment. Design: A prospective, nonrandomized, and interventional study. Participants: A total of 34 eyes of 31 patients diagnosed with keratoconus were enrolled. Methods: Patients were divided into two groups based on the strategy used for 320-degree intrastromal corneal ring segment thickness selection. In one group, this selection was based on spherical equivalent (SE group) and in the other on the mean asphericity (Q group). The uncorrected and corrected distance visual acuities, spherical equivalent, K1, K2, Km, Kmax, and mean asphericity ( Q) on corneal tomography were evaluated preoperatively and at 3 and 6 months postoperatively. For astigmatism improvement, we analyzed the corneal tomographic vectorial astigmatism change preoperatively and at 6 months postoperatively. The mean follow-up period was 6.63 ± 0.96 months. Results: The mean uncorrected distance visual acuity and corrected distance visual acuity improved with a significant spherical equivalent improvement ( p < 0.05), with no differences between the 320-degree intrastromal corneal ring segment groups. All corneal tomographic parameters improved significantly ( p < 0.05) between the preoperative and postoperative intervals, with a significant better performance when we used spherical equivalent for the 320-degree intrastromal corneal ring segment thickness selection. Finally, the mean vectorial corneal tomographic astigmatism significantly improved after 6 months, again with no differences between groups. Conclusion: This study suggests that implanting a 320-degree intrastromal corneal ring segment is a safe and effective procedure for treating patients with keratoconus. It also suggests that for thickness selection spherical equivalent is the better strategy.
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Tognon T, Campos M, Wengrzynovski JP, Barella KA, Pasqualotti A, de Brito Martins LA, dos Santos Forseto A, de Sousa LB. Indications and visual outcomes of intrastromal corneal ring segment implantation in a large patient series. Clinics (Sao Paulo) 2017; 72:370-377. [PMID: 28658437 PMCID: PMC5463252 DOI: 10.6061/clinics/2017(06)07] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 04/17/2017] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVES: To describe the indications for and visual outcomes of intrastromal corneal ring segment implantation. METHODS: A large retrospective case-series chart-review study was conducted using Sorocaba Ophthalmological Hospital medical records. This study included 1222 eyes (1196 patients) that were surgically treated between November 2009 and December 2012. The following preoperative data were collected: age, gender, type of medical care and funding source, surgical technique, best-corrected visual acuity, manifest sphere and cylinder refractive error, maximum and minimum central keratometry, and pachymetry measurements of the cornea at the thinnest point and at the ring channel. The postoperative best-corrected visual acuity and patient satisfaction were also determined. The cases were classified into six groups: four keratoconus groups (severe, advanced, moderate and mild), a pellucid marginal degeneration group and a post-graft irregular astigmatism group. This study was approved by the Brazilian Registry of Clinical Trials (UTN number 1111-1182-6181, TRIAL RBR-6S72RF). RESULTS: The age (mean±standard deviation) of the patients was 31.0±10.0 years. The most prevalent pathology was keratoconus (1147 eyes, 93.8%). A correlation was found between ectasia severity and medical assistance (p<0.001), and the most serious cases was treated by the Brazilian public health system. No complications were found in a total of 1155 surgeries, and after surgery, 959 patients were satisfied. Among the 164 dissatisfied patients, the majority failed to show improved best-corrected visual acuity. CONCLUSION: Patients in the public health system underwent surgical intervention for keratoconus later than those with private sources of funding. In the vast majority of operated cases, the patients reported improvements in vision.
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Affiliation(s)
- Taíse Tognon
- Instituto Penido Burnier, Campinas, SP, BR
- Hospital Oftalmologico de Sorocaba, Sorocaba, SP, BR
- *Corresponding author. E-mail:
| | - Mauro Campos
- Universidade Federal de Sao Paulo, Sao Paulo, SP, BR
| | | | | | - Adriano Pasqualotti
- Universidade de Passo Fundo, Passo Fundo, RS, BR
- Universidade de Lisboa, Lisboa, Portugal
| | | | - Adriana dos Santos Forseto
- Hospital Oftalmologico de Sorocaba, Sorocaba, SP, BR
- Universidade Federal de Sao Paulo, Sao Paulo, SP, BR
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Giacomin NT, Mello GR, Medeiros CS, Kiliç A, Serpe CC, Almeida HG, Kara-Junior N, Santhiago MR. Intracorneal Ring Segments Implantation for Corneal Ectasia. J Refract Surg 2016; 32:829-839. [DOI: 10.3928/1081597x-20160822-01] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 07/05/2016] [Indexed: 12/20/2022]
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Abstract
To evaluate the biomechanics of corneal ring implants by providing a related mathematical theory and biomechanical model for the treatment of myopia and keratoconus.
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This issue at a glance. J Curr Ophthalmol 2015; 27:1-3. [PMID: 27239566 PMCID: PMC4877720 DOI: 10.1016/j.joco.2015.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Outcome of intrastromal corneal ring segment relative to depth of insertion evaluated with scheimpflug image. J Curr Ophthalmol 2015; 27:25-31. [PMID: 27239571 PMCID: PMC4877726 DOI: 10.1016/j.joco.2015.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To report the results of intrastromal corneal ring segment (KeraRing; Mediphcose, Belo Horizonte, Brazil) implantation relative to depth of insertion in keratoconic patients. METHODS In this retrospective, observational study, we evaluated 29 eyes of 27 patients with keratoconus who underwent implantation of KeraRing SI-5 with mechanical tunnel creation. In the mean follow-up of 8.8 months, all eyes underwent scheimpfluge image of pentacam (Oculus, Germany) to determine insertion depth. Based on the measured implantation depth, cases were categorized into: 40-59% thickness group, 60-79% thickness group, and ≥80% thickness group. Visual, refractive, and shape outcomes were evaluated relative to implantation depth. RESULTS The mean insertion depth was 61.7%.We had 41.4% of cases were in the 40-59% thickness group, 51.7% in the 60-79% group, and 6.9% in the >80% group. Results were similar in 40-59% and 60-79% thickness groups: uncorrected visual acuity (UCVA) and best spectacle corrected VA (BSCVA) improved 3 and 2 lines, respectively, maximum keratometry (Kmax) decreased 2.6 D, refractive cylinder improved 2.04 D, and Q value 8 mm anterior changed by 0.35. In the ≥80% thickness group, UCVA and BSCVA improved less than 1 lines, Kmax change was less than 0.5 D, and RC decreased less than 0.25 D. CONCLUSION Implantation of KeraRing with mechanical tunnel creation in 40-80% of stromal thickness despite the variable insertion depth is effective.
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McAlinden C. Corneal refractive surgery: past to present. Clin Exp Optom 2012; 95:386-98. [PMID: 22672114 DOI: 10.1111/j.1444-0938.2012.00761.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2011] [Revised: 04/07/2012] [Accepted: 04/17/2012] [Indexed: 12/20/2022] Open
Abstract
There have been many historical corneal refractive techniques and procedures developed over the years. From early techniques of radial keratotomy to modern excimer laser techniques, the field of refractive surgery is one of the most rapidly developing in ophthalmology. This review details the historical aspects of the many early techniques up to current techniques used on millions of eyes around the world.
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Affiliation(s)
- Colm McAlinden
- University of Ulster, United Kingdom and Flinders Medical Centre and Flinders University, Adelaide, South Australia, Australia.
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Choi SW, Choae WS, Her J. Intrastromal Corneal Ring Segments (KeraRing®) Implantation for the Correction of Keratoconus. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2011. [DOI: 10.3341/jkos.2011.52.3.277] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Sung Wook Choi
- Department of Ophthalmology, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea
| | - Woo Seok Choae
- Department of Ophthalmology, Masan Samsung Hospital, Sungkyunkwan University School of Medicine, Masan, Korea
| | - Jun Her
- Department of Ophthalmology, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea
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Renesto ADC, Campos M. Intrastromal Corneal Ring Segments. Cornea 2011. [DOI: 10.1016/b978-0-323-06387-6.00176-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Piñero DP, Alio JL. Intracorneal ring segments in ectatic corneal disease - a review. Clin Exp Ophthalmol 2010; 38:154-67. [DOI: 10.1111/j.1442-9071.2010.02197.x] [Citation(s) in RCA: 146] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Coskunseven E, Kymionis GD, Tsiklis NS, Atun S, Arslan E, Jankov MR, Pallikaris IG. One-year results of intrastromal corneal ring segment implantation (KeraRing) using femtosecond laser in patients with keratoconus. Am J Ophthalmol 2008; 145:775-9. [PMID: 18291344 DOI: 10.1016/j.ajo.2007.12.022] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Revised: 12/12/2007] [Accepted: 12/14/2007] [Indexed: 11/26/2022]
Abstract
PURPOSE To report the results of intrastromal corneal ring segment [ICRS] (KeraRing; Mediphacos, Belo Horizonte, Brazil) implantation using a femtosecond laser (IntraLase Corp, Irvine, California, USA) in keratoconic patients. DESIGN Retrospective, noncomparative, interventional study. METHODS Thirty-two keratoconic patients (50 eyes) who underwent ICRS insertion using a femtosecond laser for channel creation and completed at least one year of follow-up were included in this study. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, topographic findings, and adverse events were assessed. RESULTS No intraoperative complications were demonstrated in this series of patients. At the first postoperative day, segment migration to the incision site was seen in three eyes (6%; early postoperative complication). To avoid melting, we repositioned the migrated segment away from the incision site. Serious second migration was not seen and we did not need to reposition any segment again. At the last postoperative examination, there was a statistically significant reduction in the spherical equivalent refractive error compared with that observed at the examination before implantation (mean +/- standard deviation, -5.62 +/- 4.15 diopters [D; range, -23.62 to 0.50 D] to -2.49 +/- 2.68 D [range, -11.12 to 3.5 D]; P < .001). The UCVA before implantation was 20/40 or worse in 47 eyes (94%; range, counting fingers to 20/30), whereas at the last follow-up examination, 14 (28%) of 50 eyes had a UCVA of 20/40 or better (range, counting fingers to 20/25). Nine eyes (18%) maintained the preimplantation BSCVA, whereas 39 eyes (68%) experienced a BSCVA gain of one to four lines at the last follow-up examination. Only in two eyes (4%; two patients) with advanced keratoconus (stage III) was there a decrease of up to two lines. Despite this deterioration in BSCVA, the patients did not want to remove the ICRSs, because there was an increase of UCVA. No late postoperative complications were observed during the follow-up period. CONCLUSIONS ICRS (KeraRing) implantation using femtosecond laser for tunnel creation is a minimally invasive procedure for improving visual acuity (both UCVA and BSCVA) in keratoconic patients.
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Corneal intrastromal implantation surgery for the treatment of moderate and high myopia. J Cataract Refract Surg 2008; 34:194-8. [DOI: 10.1016/j.jcrs.2007.10.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Accepted: 10/25/2007] [Indexed: 11/24/2022]
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Ertan A, Bahadir M. Intrastromal ring segment insertion using a femtosecond laser to correct pellucid marginal corneal degeneration. J Cataract Refract Surg 2006; 32:1710-6. [PMID: 17010872 DOI: 10.1016/j.jcrs.2006.06.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Accepted: 06/03/2006] [Indexed: 11/16/2022]
Abstract
PURPOSE To assess the outcomes of intrastromal ring segment (Intacs, Addition Technology) implantation using a femtosecond laser in patients with pellucid marginal corneal degeneration. SETTING Kudret Eye Hospital, Ankara, Turkey. METHODS In this retrospective noncomparative case series, 9 eyes of 6 patients with pellucid marginal corneal degeneration had implantation of Intacs segments by a femtosecond laser technique. Preoperative and postoperative evaluations included slitlamp examination, uncorrected (UCVA) and best corrected (BCVA) visual acuities, and keratometry by a Pentacam Scheimpflug camera (Oculus Opticgerate GmbH). All parameters were reviewed within 6 months. RESULTS Intacs were successfully implanted in all eyes. The UCVA significantly improved from preoperatively to 6 months after Intacs implantation (mean 0.18 +/- 0.24 [SD] and 0.53 +/- 0.23, respectively). The mean difference between the preoperative and postoperative UCVA was 3.5 +/- 1.6 lines (P = .008). The BCVA also significantly improved from preoperatively to 6 months after implantation (mean 0.63 +/- 0.26 and 0.85 +/- 0.18 at 6 months, respectively). The Snellen BCVA was 1.0 in 5 eyes postoperatively. The mean difference between preoperative and postoperative BCVA was 2.3 +/- 51 lines (P = .011). The mean preoperative spherical refraction decreased from -3.86 +/- 2.91 diopters (D) to -2.77 +/- 1.43D (P = .091) and the mean cylindrical refraction, from -2.41 +/- 2.27 D to -0.94 +/- 1.07 D (P = .046). The mean central corneal curvature decreased from 48.20 +/- 4.19 D preoperatively to 46.90 +/- 5.00 D (P = .008) at 6 months and the mean posterior elevation, from 53.88 +/- 21.72 microm to 32.55 +/- 11.23 microm (P = .008). CONCLUSION Intacs insertion using a femtosecond laser was safe and efficient in the correction of pellucid marginal corneal degeneration.
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McAlister JC, Ardjomand N, Ilari L, Mengher LS, Gartry DS. Keratitis after intracorneal ring segment insertion for keratoconus. J Cataract Refract Surg 2006; 32:676-8. [PMID: 16698494 DOI: 10.1016/j.jcrs.2005.09.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2005] [Indexed: 11/26/2022]
Abstract
We report a case of sterile keratitis after Ferrara intracorneal ring (Ferrara Ophthalmics) implantation into the right cornea of a keratoconus patient who also suffered from atopic blepharoconjunctivitis. The keratitis resolved within a few days after removal of the Ferrara rings. Ocular atopy with sterile keratitis should be considered in the differential diagnosis of keratitis after the insertion of intracorneal ring segments, which can be easily treated by ring removal.
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Abstract
PURPOSE OF REVIEW This article reviews the latest data published and presented at international meetings about the use of intracorneal ring segments in corneal and refractive surgery. RECENT FINDINGS The long-term data on intracorneal ring segments in the correction of low to moderate myopia indicate that they seem clearly comparable with laser in-situ keratomileusis, the most common refractive procedure worldwide. There is increasing interest in the use of intracorneal ring segments for the treatment of some complications after laser in-situ keratomileusis and for the control of some degrees of primary corneal ectatic disorders such as keratoconus and pellucid marginal degeneration. SUMMARY Intracorneal ring segments are and will be useful in several corneal and refractive abnormalities. Concern still exists about their predictability and the long-term effects of their use in primary and secondary ectasia.
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Affiliation(s)
- José L Güell
- Department of Ophthalmology Autonoma, University of Barcelona, and Cornea and Refractive Surgery Unit, Instituto de Microcirugia, Ocular Munner, Barcelona, Spain.
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Hofling-Lima AL, Branco BC, Romano AC, Campos MQS, Moreira H, Miranda D, Kwitko S, de Freitas D, Casanova FH, Casanova F, Sartori M, Schor P, Souza LB. Corneal Infections After Implantation of Intracorneal Ring Segments. Cornea 2004; 23:547-9. [PMID: 15256990 DOI: 10.1097/01.ico.0000126434.95325.24] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To report risk factors, clinical course, and outcome in patients with infectious keratitis following implantation of intracorneal ring segments (ICRS). METHODS The records of 8 patients with culture-proven infectious keratitis after ICRS (Ferrara or Intacs) implantation were retrospectively reviewed. Age, gender, corneal findings, ocular abnormalities, the condition that led to ICRS implantation, immediate prior use of a contact lens, elapsed time between implantation and the onset of symptoms, previous medications, and systemic disorders were noted. RESULTS Culture-positive infectious keratitis developed in 7 eyes of 7 patients (2 men and 5 women) with a mean age of 35 years who underwent Ferrara implantation for the treatment of keratoconus and in a 29-year-old man who underwent Intacs implantation for correction of low myopia. Contact lens use, diabetes, and trauma were factors possibly associated with the risk of infection in three cases. Microorganisms, identified in all cases, included Staphylococcus aureus, Streptococcus viridans, Streptococcus pneumoniae, Pseudomonas sp, Nocardia sp, Klebsiella sp, and Paecylomices sp. Onset of symptoms of infection varied from less than 1 week to 22 months postoperatively, depending on the infecting organism. CONCLUSIONS Infectious keratitis following ICRS implantation is a sight-threatening complication for which early recognition and rapid institution of appropriate treatment may result in a better visual outcome.
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Affiliation(s)
- Ana Luisa Hofling-Lima
- Department of Ophthalmology, Federal University of São Paulo/Paulista School of Medicine, Brazil.
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Hladun L, Harris M. Contact lens fitting over intrastromal corneal rings in a keratoconic patient. ACTA ACUST UNITED AC 2004; 75:48-54. [PMID: 14717280 DOI: 10.1016/s1529-1839(04)70010-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
BACKGROUND Intrastromal corneal ring segments have been used as a refractive surgery method for treatment of myopia. More recently, attempts have been made to use this surgical procedure in patients with keratoconus. CASE REPORT A 51-year-old man with keratoconus came to the clinic for a contact lens refit. He had undergone surgical insertion of intrastromal corneal rings in his right eye 7 months earlier in an attempt to obtain acceptable vision without contact lenses. At the time of presentation, the patient was not satisfied with his vision in the right eye and requested an attempt to improve his vision with a contact lens. The resulting corneal shape after surgery presented some complications, but the patient was able to achieve 20/25-vision and adequate comfort in his right eye with a piggyback contact lens system. CONCLUSIONS Insertion of intrastromal corneal rings may be beneficial in patients with early keratoconus or who are contact lens-intolerant. However, patients with more-advanced keratoconus are not likely to achieve adequate vision after the surgery and will require a contact lens. In addition, changes in the corneal anatomy created by the intrastromal rings may make contact lens fitting more challenging. The corneal irregularity may be exacerbated due to drastic variations in corneal elevation over the intrastromal ring and directly adjacent to the ring. This irregularity in elevation leads to difficulty in centering the lens on the eye and problems with bubbles forming under the contact lens over areas of corneal depression. When successfully fitted, contact lenses over intrastromal corneal rings can improve vision significantly.
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Affiliation(s)
- Larisia Hladun
- University of California at Berkeley, College of Optometry, Berkeley, California, USA.
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Güell JL, Velasco F. Topographically guided ablations for the correction of irregular astigmatism after corneal surgery. Int Ophthalmol Clin 2003; 43:111-28. [PMID: 12881654 DOI: 10.1097/00004397-200343030-00011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- José L Güell
- Departmento de Cornea, Instuto de Microcirugia, Barcelona, Spain
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Twa MD, Ruckhofer J, Kash RL, Costello M, Schanzlin DJ. Histologic evaluation of corneal stroma in rabbits after intrastromal corneal ring implantation. Cornea 2003; 22:146-52. [PMID: 12605051 DOI: 10.1097/00003226-200303000-00014] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE Previous refractive corneal implants have produced histologic changes characteristic of nonspecific lipid keratopathy. Intacs intrastromal corneal ring segments are polymethylmethacrylate (PMMA) corneal inserts approved for the correction of low myopia by the U.S. Food and Drug Administration. The purpose of this study was to describe histologic changes associated with these corneal implants in rabbit eyes. METHODS Two 150-degree PMMA arc segments, 0.30 mm thick, were surgically implanted through a single radial incision at two-thirds stromal depth in the mid-peripheral cornea of five New Zealand white rabbits. We collected corneas 6 months after implantation that were prepared for light and electron microscopy. We analyzed tissue with oil red O, filipin, and periodic acid-Schiff (PAS) staining. Additional studies with energy-dispersive x-ray analysis and autofluorescent microscopy were conducted. RESULTS In all samples, we observed new collagen formation with lamellar organization adjacent to the implant and increased keratocyte density. Intracellular accumulations of osmophilic and saturated lipid material corresponded to stromal opacification visible by slit-lamp microscopy. These same regions were autofluorescent and stained positively with oil red O, and filipin but negatively with PAS. Granular lipid inclusions characteristic of lipofuscinosis were absent on transmission electron microscopy. Energy-dispersive x-ray analysis demonstrated elevated levels of calcium compared with adjacent tissue. CONCLUSION Tissue response to these corneal inserts includes keratocyte activation, intracellular lipid accumulation, and new collagen formation. Our histologic findings suggest that these deposit formations are not lipofuscin accumulations.
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Affiliation(s)
- Michael D Twa
- College of Optometry, The Ohio State University, 338 West 10th Avenue, Columbus, OH 43210-1240, USA.
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Ruckhofer J, Stoiber J, Twa MD, Grabner G. Correction of astigmatism with short arc-length intrastromal corneal ring segments: preliminary results. Ophthalmology 2003; 110:516-24. [PMID: 12623814 DOI: 10.1016/s0161-6420(02)01773-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE To evaluate the refractive effect of 130 degrees short arc length intrastromal corneal ring segments (ICRS) designed to correct myopia concurrent with astigmatism. DESIGN Prospective, nonrandomized, comparative (self-controlled) trial. PARTICIPANTS Ten eyes of 6 patients from one surgical center with manifest refraction spherical equivalent between -1.00 and -6.00 diopters (D), manifest cylinder correction between 1.00 and 6.00 D, and best spectacle-corrected visual acuity of 20/20 or better. INTERVENTION The patients were assigned to receive 1 of 6 ICRS thicknesses, ranging from 0.25 to 0.50 mm by 0.05 mm increments, with an arc length of 130 degrees. MAIN OUTCOME MEASURES Vector analysis of astigmatic correction. Efficacy was assessed by uncorrected visual acuity and by deviation of postoperative spherical and cylindrical refractive error from predicted correction. Safety was assessed by maintenance or loss of preoperative best spectacle-corrected visual acuity. Measurements were made before surgery and after surgery at days 1 and 7 and months 1, 2, 3, and 6. RESULTS At 6 months, uncorrected visual acuity was 20/20 or better in 80% of eyes (8/10) and 20/40 or better in all eyes. Eight of 10 eyes (80%) were within +/-0.25 D of plano spherical equivalent manifest refraction. There was no loss of best spectacle-corrected visual acuity, and 6 of 10 eyes (60%) gained a line. Reduction of keratometric cylinder by ICRS thickness was statistically significant (P = 0.039). CONCLUSIONS Preliminary results of visual and refractive performance after correction of compound myopic astigmatism using short arc length ICRS are promising.
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Affiliation(s)
- Josef Ruckhofer
- Landesklinik für Augenheilkunde und Optometrie-Salzburg, Müllner Hauptstrauss 48, A-5020 Salsburg, Austria.
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Rau M, Dausch D. Intrastromal corneal ring implantation for the correction of myopia: 12-month follow-up. J Cataract Refract Surg 2003; 29:322-8. [PMID: 12648644 DOI: 10.1016/s0886-3350(02)01818-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
PURPOSE To evaluate the efficacy, predictability, and stability of refraction obtained after intrastromal corneal ring segment (ICRS) implantation for low to moderate myopia. SETTING Single-center clinical practice. METHODS In this prospective 2-surgeon study, 9 patients (15 eyes) with low to moderate myopia were recruited to receive ICRS implants. RESULTS At 1 day, 10 of the 15 eyes had an uncorrected visual acuity (UCVA) of 20/40 or better. At 12 months, all eyes had this UCVA and 66.6% had 20/25 or better. The mean manifest refraction stabilized after the first week at <-0.5 diopter (D). At 12 months, all eyes were within +/-1.0 D of the intended manifest refraction; 67% were within +/-0.5 D. Sixty percent of eyes had no change from the preoperative best corrected visual acuity; 13.3% improved by 1 line, and 26.6% lost 1 line. The postoperative complications included lamellar channel deposits (n = 12), ICRS dislocation (n = 2), corneal infiltrates (n = 2), bleeding in the positioning ring hole (n = 1), 0.3 mm segment decentration (n = 1), and prolonged wound healing (n = 1). CONCLUSIONS Intrastromal corneal ring segment implantation for the correction of low to moderate myopia afforded good visual recovery and efficacy similar to that with laser in situ keratomileusis and superior to that with photorefractive keratectomy. However, light or blunt trauma and insufficient hygiene can have serious consequences and there is the potential for induced astigmatism. Corneal infiltrates can occur and must be treated immediately. The ring implantation technique is demanding. Advantages of ICRS implantation include rapid and stable visual recovery as well as reversibility.
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Affiliation(s)
- Magda Rau
- Fachärztin für Augenheilkunde, Furth im Wald, Germany
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Alió J, Salem T, Artola A, Osman A. Intracorneal rings to correct corneal ectasia after laser in situ keratomileusis. J Cataract Refract Surg 2002; 28:1568-74. [PMID: 12231313 DOI: 10.1016/s0886-3350(01)01275-5] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE To evaluate the potential of using intrastromal corneal ring technology (Intacs, KeraVision) to correct posterior ectasia after laser in situ keratomileusis (LASIK) for myopia. SETTING Department of Cornea and Refractive Surgery, Instituto Oftalmológico de Alicante, and Miguel Hernández University School of Medicine, Alicante, Spain. METHODS In this prospective noncomparative intervention case series, Intacs segments were implanted in 3 eyes that developed posterior ectasia after myopic LASIK with clear central corneas. Posterior ectasia and corneal thickness were tested using the Orbscan II Slit Scanning Corneal Topography/Pachymetry System (Orbtek Inc.). Segment thickness varied based on corneal topography analysis and refraction. The mean follow-up was 8.3 months (range 7 to 11 months). RESULTS The cases showed marked improvement after Intacs segment implantation. Postoperatively, there was a reduction in the magnitude of the posterior and anterior corneal surface steepening or ectasia and an increase in the topographical regularity index. In addition, the significantly enlarged optical zones resulted in a favorable visual outcome. In 2 eyes, the uncorrected visual acuity (UCVA) was 20/40 postoperatively. In the third eye, there was a residual refractive error; the UCVA was 20/50 and the best spectacle-corrected visual acuity, 20/40. CONCLUSIONS Intacs intrastromal corneal rings used as a mechanical device may alter the biomechanical properties of the cornea for the correction of iatrogenic keratectasia and the associated residual myopia.
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Affiliation(s)
- Jorge Alió
- Refractive Surgery and Cornea Unit, Alicante Institute of Ophthalmology, and Miguel Hernández University School of Medicine, Alicante, Spain.
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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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Abstract
PURPOSE To evaluate the effect of removal and/or exchange of intrastromal corneal ring segments (ICRS, Intacs); specifically the risk factors, degree of reversibility, and visual outcomes. SETTING Gimbel Eye Centres, Calgary, Edmonton, and Vancouver, Canada. METHODS Prospective cohort data were collected on 71 eyes that had ICRS placement by 3 surgeons at the Gimbel Eye Centres between August 1998 and July 1999. Data included patient symptoms, best spectacle-corrected visual acuity, uncorrected visual acuity (UCVA), manifest refraction, reason for removal or replacement, keratometry, corneal topography, and complications. RESULTS Twenty-four eyes (33.8%) had exchange or removal procedures because of underresponse, 20 eyes; overresponse, 2 eyes; and induced astigmatism and shallow placement, 1 eye each. Secondary procedures were removal and replacement, removal with subsequent laser in situ keratomileusis, and segment repositioning. Two risk factors for secondary surgery were identified: high preoperative refractive astigmatism and postoperative spherical equivalent greater than +/-0.5 diopter (D). The 6 eyes that had ICRS removal stabilized to within +/-0.25 D of the original refractive error with no surgically induced astigmatism within 1 to 7 weeks (mean 4 weeks) and had a final UCVA of 20/20 or better. In the 15 eyes that had ICRS exchange procedures, the UCVA improved by at least 1 line and median UCVA improved from 20/40 to 20/20. CONCLUSION Preliminary data from this study indicate that removal of segments resulted in reversal of the refractive effect.
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Affiliation(s)
- Stanley M Chan
- Department of Ophthalmology, University of Alberta, Edmonton, Alberta, Canada
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Abstract
PURPOSE To evaluate the long-term visual results in patients having Intacs placement for the correction of mild myopia. SETTING Department of Ophthalmology, Mount Sinai School of Medicine and the Mount Sinai Hospital of Mount Sinai NYU Health, New York, New York, USA. METHODS Patients with mild myopia (spherical equivalent between -0.75 and -4.50 diopters [D]) were enrolled to have Intacs placement between May 1995 and March 1999 under United States Food and Drug Administration Phase II and Phase III clinical trials for intrastromal corneal ring segments (ICRS). Six insert thicknesses were evaluated: 0.21, 0.25, 0.30, 0.35, 0.40, and 0.45 mm. The long-term results evaluated were uncorrected visual acuity (UCVA), maintenance of best spectacle-corrected visual acuity (BSCVA), predictability and stability of the refractive effect, induced manifest refraction cylinder, slitlamp findings, self-reported visual symptoms, and maintenance of mesopic contrast sensitivity. RESULTS One hundred fourteen eyes of 73 patients were enrolled; 113 eyes of 72 patients received Intacs. There were no serious intraoperative or postoperative complications. The mean follow-up was 17.5 months +/- 8.9 (SD). At the end of this period (number of eyes evaluated = 100), the UCVA was 20/40 or better in 95 eyes (95.0%), 20/20 or better in 72 (72%), and 20/16 or better in 41 (41%). None of the 113 eyes lost 10 or more letters or 2 or more lines of preoperative BSCVA. The mean change in the cycloplegic refraction spherical equivalent for the 6 insert thicknesses was as follows: -0.75 +/- 0.00 D for 0.21 mm; -1.17 +/- 0.42 D for 0.25 mm; -2.00 +/- 0.54 D for 0.30 mm; -2.59 +/- 0.53 D for 0.35 mm; -3.09 +/- 0.54 D for 0.40 mm; and -3.82+/-0.80 D for 0.45 mm. The refractive correction was within +/-1.0 D of the predicted outcome in 103 eyes (92.0%) and within +/-0.5 D in 72 eyes (63.7%). Intacs were removed from 6 eyes (5.3%). All 4 eyes for which data were available 3 months after removal returned to within +/-0.5 D of their preoperative manifest refraction spherical equivalent. Intacs were exchanged because of undercorrection in 2 eyes (1.8%). These eyes gained 3 and 5 lines of UCVA 12 months and 18 months, respectively, after the exchange procedure. Overall, 85.7% (36/42) of the patients were satisfied with the results of the Intacs procedure. CONCLUSION Intacs safely and effectively corrected mild myopia. Placement is a brief, easy outpatient procedure. The refractive effect was predictable and stable over long-term follow-up. Results from a limited number of removal and exchange procedures indicate that Intacs are removable and adjustable.
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Affiliation(s)
- P A Asbell
- Department of Ophthalmology, Mount Sinai School of Medicine and the Mount Sinai Hospital of Mount Sinai NYU Health, New York, 10029-6574, USA.
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Schanzlin DJ, Abbott RL, Asbell PA, Assil KK, Burris TE, Durrie DS, Fouraker BD, Lindstrom RL, McDonald JE, Verity SM, Waring GO. Two-year outcomes of intrastromal corneal ring segments for the correction of myopia. Ophthalmology 2001; 108:1688-94. [PMID: 11535474 DOI: 10.1016/s0161-6420(01)00692-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
OBJECTIVE To evaluate the safety and efficacy of Intrastromal Corneal Ring Segments (ICRS) for the correction of myopia. DESIGN Nonrandomized, comparative trial. PARTICIPANTS Patients enrolled in the United States Food and Drug Administration phase II and phase III clinical trials of the ICRS had best spectacle-corrected visual acuity (BSCVA) of 20/20 or better, myopia of -1.00 to -3.50 diopters (D), and a cylindrical correction of 1.00 D or less as measured by manifest refraction. INTERVENTION Surgical correction of myopia with an ICRS. MAIN OUTCOME MEASURES Efficacy was assessed by predictability of refractive outcome (deviation from predicted cycloplegic refraction spherical equivalent), stability of refractive effect, and postoperative uncorrected visual acuity. Safety was assessed by adverse events, maintenance or loss of preoperative BSCVA, and induced manifest refraction cylinder. RESULTS Four hundred fifty-two patients were enrolled at 11 investigational sites in both studies. Of the 454 surgical attempts, 449 received an ICRS in one eye (0.25, 0.30, and 0.35 mm in 148, 151, and 150 eyes, respectively). First surgeries were attempted in 452 patients. An ICRS was successfully implanted in 447 initial eyes, and 5 surgeries were discontinued. Of the five discontinued surgeries, three patients subsequently exited from the study, and two patients went on to have the ICRS implanted in the second eye, bringing the total number of successful implants to 449 patient eyes. Month 24 postoperative follow-up was completed on 358 patients (80%). At month 24, 328 of 354 eyes (93%) were within +/-1.00 D of predicted refractive outcome. Refraction changed by 1 D or less in 97% of eyes (421/435) between 3 and 6 months after implantation and in 99% (343/348) between months 18 and 24. Before surgery, 87% of eyes (390/448) saw worse than 20/40 uncorrected; 24 months after surgery, 55% of eyes (196/358) saw 20/16 or better, 76% (271/358) saw 20/20 or better, and 97% (346/358) saw 20/40 or better. Although two eyes (2/358; 0.5%) lost two or more lines of BSCVA at 24 months; visual acuity in both was 20/20 or better. Intraoperative complications included anterior corneal surface perforation (three eyes) and anterior chamber perforations (two eyes, one during an attempted exchange procedure); all healed spontaneously without suturing and without loss of BSCVA. The ICRS was repositioned in five eyes to increase correction. Postoperative complications in one eye each were infectious keratitis, shallow segment placement, and loss of two lines of BSCVA at two or more consecutive examinations (subsequently regained). CONCLUSIONS The ICRS safely, predictably, and effectively reduced or eliminated myopia of -1.00 to -3.50 D. The refractive effect was stable over time.
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Affiliation(s)
- D J Schanzlin
- Department of Ophthalmology, University of California San Diego, San Diego, California, 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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Twa MD, Ruckhofer J, Shanzlin DJ. Surgically induced astigmatism after implantation of intacs intrastromal corneal ring segments. J Cataract Refract Surg 2001; 27:411-5. [PMID: 11255053 DOI: 10.1016/s0886-3350(00)00754-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PURPOSE To analyze surgically induced astigmatism (SIA) after implantation of Intacs intrastromal corneal ring segments. SETTING Multicenter clinical trials in the United States. METHODS Data from 11 investigational sites involved in the Phase II and III trials of Intacs for the United States Food and Drug Administration were retrospectively analyzed. The distribution of Intacs thicknesses implanted in 449 eyes was 0.25 mm in 148 eyes, 0.30 mm in 151 eyes, and 0.35 mm in 150 eyes. Refractive astigmatism was measured by subjective manifest refraction preoperatively and 1 week and 1, 2, 3, 6, 9, and 12 months postoperatively. The mean simple change in astigmatism and the surgically induced refractive change were determined by vector analysis. RESULTS Mean induced astigmatism at 12 months was 0.13 diopter (D) +/- 0.52 (SD). Induced astigmatism was more frequently with the rule (44%) than against the rule (26%) or oblique (30%). Maximal mean astigmatism was 0.50 +/- 1.09 D and occurred at 7 days. Mean induced astigmatism increased with segment thickness (0.01 D, 0.17 D, and 0.21 D for the 0.25 mm, 0.30 mm, and 0.35 mm segments, respectively). Mean surgically induced refractive change in cylinder power in all eyes at 12 months by vector analysis was 0.17 D x 92. CONCLUSION Mean SIA was not clinically meaningful 12 months after Intacs implantation.
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Affiliation(s)
- M D Twa
- University of California San Diego, Shiley Eye Center, La Jolla, California 92093-1805, USA.
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Affiliation(s)
- E J Linebarger
- Department of Ophthalmology, UCSD Shiley Eye Center, La Jolla 92093, USA
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Ruckhofer J, Stoiber J, Alzner E, Grabner G. One year results of European Multicenter Study of intrastromal corneal ring segments. Part 1: refractive outcomes. J Cataract Refract Surg 2001; 27:277-86. [PMID: 11226796 DOI: 10.1016/s0886-3350(00)00749-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE To assess the efficacy, predictability, stability, and safety of correcting myopia with intrastromal corneal ring segments (ICRS, KeraVision, Inc.). SETTING Twelve European investigational sites. METHODS Patients with myopia of -1.0 to -6.0 diopters (D) and best spectacle-corrected visual acuity (BSCVA) of 20/20 or better (except in 3 eyes) were assigned to receive 1 of 5 ICRS thicknesses (0.25, 0.30, 0.35, 0.40, or 0.45 mm). Efficacy was assessed by postoperative uncorrected visual acuity (UCVA), predictability of refractive outcome (deviation from predicted cycloplegic refraction spherical equivalent), and stability of refractive effect (manifest refraction spherical equivalent [MRSE]). Safety was assessed by maintenance or loss of preoperative BSCVA and induced manifest refraction cylinder. Measurements were made preoperatively and 1 and 7 days and 1, 2, 3, 6, and 12 months postoperatively. RESULTS One hundred fifty-nine ICRSs were implanted in the eyes of 107 patients (52 patients had bilateral implantation). Preoperatively, UCVA was worse than 20/40 in 98% of eyes (155/159); 12 months postoperatively, it was 20/20 or better in 63% of eyes (83/132) and 20/40 or better in 96% (127/132). Predicted refractive corrections for each ICRS thickness generally correlated with achieved corrections. At 12 months postoperatively, 90% of eyes (124/138) were within +/-1.00 D of plano (MRSE). Two or more lines of BSCVA were lost in 6% of eyes (8/135); all 8 eyes had BSCVAs of 20/25 or better. CONCLUSION The ICRS safely, effectively, and predictably reduced or eliminated low to moderate myopia. Refractive correction was stable through the 12 month follow-up.
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Affiliation(s)
- J Ruckhofer
- Landesklinik für Augenheilkunde und Optometrie, Landeskliniken Salzburg, Austria.
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Asbell PA, Uçakhan OO, Abbott RL, Assil KA, Burris TE, Durrie DS, Lindstrom RL, Schanzlin DJ, Verity SM, Waring GO. Intrastromal Corneal Ring Segments: Reversibility of Refractive Effect. J Refract Surg 2001; 17:25-31. [PMID: 11201774 DOI: 10.3928/1081-597x-20010101-03] [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: 11/20/2022]
Abstract
PURPOSE To evaluate the reversibility of refractive effect following removal of the ICRS (intrastromal corneal ring segments; Intacs). METHODS Data from 34 eyes from which ICRS were removed during United States FDA Phase II and III clinical trials were evaluated with regard to segment size, loss or change of best spectacle-corrected visual acuity (BSCVA), any change of uncorrected visual acuity (UCVA), manifest spherical equivalent refraction, manifest cylinder refraction, stability of manifest cylinder refraction, and subjective visual symptoms. RESULTS Out of 725 initial or contralateral eyes placed with the ICRS during Phase II and III clinical trials, segments were removed from 34 eyes (4.7%). Other than one (1/725, 0.1%) safety related ICRS removal, 30/725 (4.1%) were due to visual symptoms. ICRS removal was accomplished under topical anesthesia without complications in all eyes. The mean length of time the segments remained in the cornea after initial surgery was 10.3 +/- 5.4 months. At 3 months after ICRS removal, 21 eyes had monitored data available and were within +/-1 line or 10 letters of their preoperative BSCVA. Twenty eyes (20/21, 95%) returned to within +/-1.00 D of their preoperative manifest spherical equivalent refraction. All eyes had a stable refraction at the 3-month examination after removal, and a manifest spherical equivalent refraction within +/-1.00 D of their 1-month examination after removal. Nineteen eyes (19/21, 90%) returned to within +/-2 lines and 16 eyes (16/21, 76%) returned to within +/-1 line of preoperative UCVA. CONCLUSION The ICRS (Intacs) was easily and safely removed, and eyes returned to preoperative refractive status within 3 months.
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Affiliation(s)
- P A Asbell
- Department of Ophthalmology, Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
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Ruckhofer J, Böhnke M, Alzner E, Grabner G. Confocal microscopy after implantation of intrastromal corneal ring segments. Ophthalmology 2000; 107:2144-51. [PMID: 11097586 DOI: 10.1016/s0161-6420(00)00387-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
OBJECTIVE Confocal in vivo real-time microscopy was used to study the corneal morphologic features in eyes after Intrastromal Corneal Ring Segments (ICRS; now called KeraVision INTACS, KeraVision, Inc., Fremont, CA) implantation. DESIGN Noncomparative, interventional case series. PARTICIPANTS The authors performed confocal real-time microscopy on a total of 21 eyes from 11 patients. Seventeen eyes from 10 patients (five female, five male; mean age 32.3 years; range 22-42 years) underwent uncomplicated ICRS surgery to correct myopia and were examined after surgery (average 8.6 months; range 2-15 months). Three patients had the ICRS implanted into only one eye, and those eyes were compared with the untreated fellow eyes. One eye of another patient was examined 1 and 6 months after ICRS removal. INTERVENTION Flying slit-confocal microscopy was performed with water immersion objectives in the corneal center and near the nasal or temporal ICRS. Corneal optical sections were recorded in real time without further digital processing and were reviewed frame by frame. MAIN OUTCOME MEASURES Video frames selected from all corneal layers were evaluated qualitatively and quantitatively. RESULTS In the central cornea, we found normal morphologic features at all layers. In peripheral sections, epithelial cells with highly reflective nuclei in the basal cell layer were observed in six of 17 eyes (35%) implanted with ICRS. We found an intact corneal nerve plexus and undisturbed corneal endothelium immediately underneath the ICRS. Around the ICRS, moderate fibrosis was seen. In one eye, linear structures in bamboo-like orientation were detected after ICRS removal in the last keratocyte layer underneath the collapsed tunnel. CONCLUSIONS Whereas the central corneal zone appears unchanged, the corneal stroma adjacent to the ICRS displays a slight, but distinct, activation of wound healing. Epithelial cells with highly reflective nuclei in this region may be an indicator for an increased biologic stress caused by the device.
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Affiliation(s)
- J Ruckhofer
- Landesklinik für Augenheilkunde und Optometrie, Salzburg, Austria. Department of Ophthalmology, University of Bern, Bern, Switzerland.
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Ruckhofer J, Twa MD, Schanzlin DJ. Clinical characteristics of lamellar channel deposits after implantation of intacs. J Cataract Refract Surg 2000; 26:1473-9. [PMID: 11033393 DOI: 10.1016/s0886-3350(00)00575-7] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To report the frequency, location, and severity of biomicroscopically evident intrastromal deposits that may accumulate in the lamellar channel after implantation of Intacs corneal ring segments. SETTING United States Food and Drug Administration multicenter clinical trial conducted at 10 sites. METHODS Two-year follow-up data from a phase III clinical trial (N = 359) were reviewed. Examiners at 10 study sites described the location and severity (density) of deposits, grading severity on a standardized scale from absent (0) to severe (4). At 24 months, the incidence of deposits was 74% overall and 61%, 73%, and 89% with the 0.25, 0.30, and 0.35 mm Intacs, respectively (P <.001). The incidence increased sharply at first and more slowly after 6 months. RESULTS At 12 months, deposits were located along the inner curvature of the segments in 47% of patients, along the outer curvature in 5%, along both inner and outer curvatures in 38%, and anterior to the segments in 10%. The severity of the deposits increased with segment thickness (P <.001 at 6, 12, and 24 months). CONCLUSIONS Lamellar channel deposits occurred frequently after Intacs implantation. The incidence and density of deposits increased with segment thickness and duration of implantation. The presence of this material did not result in alteration of the optical performance of Intacs or anatomical or physiological corneal deterioration.
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Affiliation(s)
- J Ruckhofer
- Shiley Eye Center, University of California, San Diego, California, USA.
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Affiliation(s)
- A Brahma
- Department of Ophthalmology, University of Dundee, Ninewells Hospital, Scotland, UK
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Baïkoff G, Maia N, Poulhalec D, Fontaine A, Giusiano B. Diurnal variations in keratometry and refraction with intracorneal ring segments. J Cataract Refract Surg 1999; 25:1056-61. [PMID: 10445190 DOI: 10.1016/s0886-3350(99)00129-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
PURPOSE To study refraction variations during the day in eyes with intrastromal corneal ring segments (ICRS) to correct low myopia. SETTING Monticelli Clinic, Marseille, France. METHODS Thirteen eyes with ICRS were included in the study; the ICRS was explanted from 3 eyes because of undercorrection. The minimum follow-up in all eyes was 1 year. The same observer measured refraction and keratometry at 9:00 AM, 1:00 PM, and 7:00 PM with the same autokeratorefractometer. To validate the analysis method, these eyes were compared with a group of emmetropic control eyes that had not had surgery and with a group of eyes that had photorefractive keratectomy for a similar degree of myopia. All measurements were done under the same conditions. RESULTS After 1 year, the ICRS eyes showed a tendency toward an evening myopic shift. This was confirmed by the objective keratometry study, which showed variations closely correlated with the myopia observed. These phenomena were not observed in the other groups. CONCLUSION The ICRS had satisfactory predictability in eyes with up to -3.50 diopters of myopia. However, the evening myopic shift appeared similar to that observed after radial keratotomy.
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Affiliation(s)
- G Baïkoff
- Centre d'Ophtalmologie, Clinique Monticelli, Marseille, France
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Schanzlin DJ, Asbell PA, Burris TE, Durrie DS. The intrastromal corneal ring segments. Phase II results for the correction of myopia. Ophthalmology 1997; 104:1067-78. [PMID: 9224455 DOI: 10.1016/s0161-6420(97)30183-3] [Citation(s) in RCA: 139] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
OBJECTIVE The purpose of the study was to evaluate the safety and efficacy of the intrastromal corneal ring segments (ICRS) for the correction of myopia. DESIGN A 2-year phase II clinical trial of ICRS was initiated in May 1995. The investigational plan specifies that 150 patients with sighted eyes, requiring myopic corrections from -1.00 to -6.00 diopters (D), will each receive ICRS in 1 eye. The patient population will be divided into approximately five patients per ICRS thickness (0.25, 0.30, 0.35, 0.40, and 0.45 mm) per site. Six investigational sites are participating in the trial. PARTICIPANTS Fifty-nine men and 43 women requiring myopic corrections were enrolled at four U.S. investigational sites. These 102 patients each received the ICRS product in 1 eye. INTERVENTION Correction of myopia. MAIN OUTCOME MEASURES Efficacy of ICRS was assessed with respect to the trial endpoints of predictability of refractive effect, uncorrected visual acuity (UCVA), stability of UCVA, maintenance of best spectacle-corrected visual acuity and stability of refractive effect. RESULTS As shown by the available month-3 data (99 patients; all device thicknesses), 95 (96%) of 99 patients had a UCVA of 20/40 or better. Ninety-eight (99%) of 99 patients were within 2 lines of their preoperative best spectacle-corrected visual acuity. The average change (with standard error) in cycloplegic refraction (spherical equivalent) achieved by ICRS thickness was -1.27 +/- 0.09 D (0.25 mm), -2.13 +/- 0.16 D (0.30 mm), -2.56 +/- 0.15 D (0.35 mm), -3.77 +/- 0.37 D (0.40 mm) and -4.16 +/- 0.24 D (0.45 mm). Seventy-seven percent (76/99) of the patients were within +/-1.00 D of their intended correction. When the ICRS was removed in two cases, both patients returned to within 0.75 D of their preoperative manifest refraction. CONCLUSIONS The ICRS appears to be a viable and effective alternative for the treatment of myopia. Additionally, as indicated by the explant data, the ICRS's refractive effect may be reversible upon removal of the device.
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Affiliation(s)
- D J Schanzlin
- St. Louis University's Anheuser-Busch Eye Institute, Missouri, USA
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Nosé W, Neves RA, Burris TE, Schanzlin DJ, Belfort Júnior R. Intrastromal Corneal Ring: 12-month Sighted Myopic Eyes. J Refract Surg 1996; 12:20-8. [PMID: 8963814 DOI: 10.3928/1081-597x-19960101-08] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND To evaluate the efficacy, predictability, and stability of the refractive effect produced by the Intrastromal Corneal Ring (ICR), the authors completed a 12-month study on 10 myopic eyes. METHODS Ten patients with preoperative refractive errors ranging from -2.63 diopters (D) to -4.25 D (mean, -3.30 D) participated in the study. The attempted correction was -2.50 D for a 7.0-mm diameter, 0.3-mm thick ICR. One eye of each patient received an ICR. RESULTS The average change in spherical equivalent at 12 months was -2.25 D (SD 0.54 D; range, -1.62 to -3.25 D). All patients maintained a spectacle-corrected visual acuity of 20/20 or better during the 12-month study period, with the exception of patient no. 6 who saw 20/30 at the 6-month examination. Her spectacle-corrected visual acuity returned to 20/20 a few days after the ICR was explanted and remained stable throughout the study. Uncorrected visual acuity had improved to 20/40 or better in all patients on postoperative day 1 and remained in this range for the 9 eyes (90%) during the 12 months of follow up. At postoperative month 12, 9 of 9 eyes (100%) had an uncorrected visual acuity of 20/40 or better with 3 of 9 eyes (33%) seeing 20/20 or better. The remaining patient, no. 6, experienced a tear in Descemet's membrane during the procedure and required explantation of the ring after 6 months due to induced astigmatism and deterioration of uncorrected visual acuity. Two patients developed infiltrates that resolved with the use of antibiotics. The most common postoperative ocular findings were peripheral corneal haze in all eyes that diminished over time, minute lamellar channel deposits (7 of 10 eyes, 70%), deep stromal neovascularization (5 of 10 eyes, 50%), and pannus (5 of 10 eyes, 50%). CONCLUSION This preliminary study shows that implantation of an intrastromal corneal ring of this dimension (0.3-mm thick) can reduce approximately 1.50 to 3.00 D of myopia and maintain spectacle-corrected visual acuity.
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Affiliation(s)
- W Nosé
- Department of Ophthalmology, Paulista School of Medicine, São Paulo Hospital, Brazil
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