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PURPOSE: To evaluate the feasibility and effects of the intrastromal implantation of chemically modified corneal stroma obtained from chicken into the corneas of rabbits for corneal thickening. METHODS: Chicken corneas were cut, debrided, treated with cross-linking and implanted in an intrastromal pouch created in the cornea of 10 white New Zealand rabbits with femtosecond laser. Slit-lamp biomicroscopy and optical coherence tomography were performed immediately, 7, 30 and 90 days postoperatively. Corneas were removed at 90 days and cut in two halves. One half was sent to histological analysis for the presence of necrosis, polymorphonuclear inflammatory cells, blood vessels and fibrosis, while the other half was evaluated with transmission electron microscopy to verify tissue organization and the presence of keratocytes and inflammatory cells. Corneal thicknesses were comparatively analyzed over time with Wilcoxon test (p ≤ 0.05). RESULTS: The chicken grafts were incorporated into the cornea of all animals over time. Mean rabbit cornea thickness increased from 338 µm preoperatively to 538 µm (p < 0.0077) at 90 days, while mean chicken graft thickness decreased from 350 to 215 µm (p < 0.0077). No clear signs of rejection attributable to the xenograft were observed in any of the implanted eyes. However, some macroscopic and histological events were observed in some of the eyes, probably due to procedural issues during implantation. CONCLUSION: The intrastromal implantation of chicken grafts was shown to be feasible and predictable to thicken the recipient rabbit cornea without apparent rejection. However, before being considered in humans, further meticulous clinical trials are required to establish the clinical utility, safety and efficacy of xenografts for the treatment of patients with advanced keratoconus.
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Trasplante de Córnea , Queratocono , Animales , Pollos , Córnea/cirugía , Sustancia Propia/cirugía , Humanos , ConejosRESUMEN
PURPOSE: To evaluate the clinical outcomes after implantation of a new 320°-arc length Ferrara intrastromal corneal ring segment (320-ICRS) in eyes of patients with keratoconus. METHODS: A multicentric nonrandomized study was conducted in which a new 320-ICRS was placed in 138 eyes of 130 patients with keratoconus. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometry, corneal volume, asphericity, lines of vision gain/loss, and vectorial analysis were assessed preoperatively and at the final follow-up visit after the procedure. RESULTS: The mean follow-up time was 6.2 ± 3.3 (SD) months (range 3-12 months). Mean UDVA improved from 20/250 to 20/60. Mean CDVA improved from 20/100 to 20/40. Mean Q improved from -1.12 ± 0.49 preoperatively to -0.28 ± 0.51 postoperatively (P < 0.001). Mean corneal volume increased from 56.2 ± 4.28 mm preoperatively to 57.6 ± 4.74 postoperatively (P < 0.001). Mean Km reduced from 53.3 ± 5.5 D preoperatively to 47.8 ± 4.6 D postoperatively (P < 0.001). The change in UDVA, CDVA, and topographic astigmatism was statistically significant (P < 0.0001). CONCLUSIONS: The 320-ICRS can efficiently and safely improve visual acuity in keratoconus, modifying the corneal shape to a more physiologic, aspheric shape.
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Sustancia Propia/cirugía , Queratocono/cirugía , Prótesis e Implantes , Adolescente , Adulto , Niño , Femenino , Estudios de Seguimiento , Humanos , Queratocono/fisiopatología , Láseres de Excímeros/uso terapéutico , Masculino , Persona de Mediana Edad , Implantación de Prótesis , Refracción Ocular/fisiología , Agudeza Visual/fisiología , Adulto JovenRESUMEN
AIM: To evaluate the clinical and tomographic outcomes after implantation of a new intrastromal corneal ring segment (ICRS) with 140-degrees of arc in eyes with corneal ectasia. METHODS: We evaluated patients with corneal ectasia implanted with Ferrara 140° ICRS from April 2010 to February 2015. Outcome measures included preoperative and postoperative corrected distance visual acuity (CDVA), keratometry simulated (K) reading, tomographic astigmatism and asphericity. All patients were evaluated using the Pentacam Scheimpflug system. RESULTS: The study evaluated 58 eyes. The mean follow-up was 16.81±10.8mo. The CDVA (logMAR) improved from 0.5±0.20 (20/60) to 0.3±0.21 (20/40) (P<0.01). The average K reduced from 49.87±7.01 to 47.34±4.90 D (P<0.01). The asphericity changed from -0.60±0.86 to -0.23±0.67 D (P<0.01). The mean preoperative tomographic astigmatism decreased from -8.0±3.45 to -4.53±2.52 D (P<0.01). CONCLUSION: The new ICRS model with 140-degrees of arc effectively improve the visual acuity and reduce the high astigmatism usually found in patients with corneal ectasia.
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Background. To evaluate the change in corneal astigmatism after intrastromal corneal ring segment (ICRS) implantation in keratoconus patients with previous deep anterior lamellar keratoplasty (DALK). Design was a longitudinal, retrospective, interventional study. The study included 25 eyes of 24 patients with keratoconus who had DALK performed at least two years prior to ICRS implantation. All patients had a clear corneal graft with up to 8.00 D of corneal astigmatism and intolerance to contact lenses. The studied parameters were age, sex, corrected distance visual acuity (CDVA), maximum keratometry (K1), minimum keratometry (K2), spherical equivalent, and astigmatism. There was a statistically significant decrease in the postintervention analysis as follows: 3.5 D reduction in K1 (p < 0.001); 1.53 D in K2 (p = 0.005); and 2.52 D (p < 0.001) in the average K. The spherical equivalent reduced from -3.67 D (±2.74) to -0.71 D (±2.35) (p < 0.001). The topographic astigmatism reduced from 3.87 D preoperatively to 1.90 D postoperatively (p < 0.001). The CDVA improved from 0.33 (±0.10) to 0.20 (±0.09, p < 0.001). ICRS implantation is a useful option for the correction of astigmatism after DALK as it yields significant visual, topographic, and refractive results.
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AIM: To evaluate corneal parameters measured with a dual Scheimpflug analyzer in keratoconus patients implanted with intrastromal corneal ring segments (ICRS). METHODS: Fifty eyes of 40 keratoconus patients had Ferrara ICRS implantation from November 2010 to April 2014. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction, keratometry, asphericity, elevation, pachymetry, root mean square (RMS), spherical aberration and coma were studied. All patients were evaluated using a dual Scheimpflug system. RESULTS: The mean follow-up time after the procedure was 12.7mo. The mean UCVA improved from 0.82 to 0.31 (P<0.001); the mean BCVA improved from 0.42 to 0.05 (P<0.0001), the mean spherical refraction changed from -3.06±3.80 D to -0.80±2.5 D (P<0.0001) and the mean refraction astigmatism reduced from -4.51±2.08 D to -2.26±1.18 D (P<0.0001). The changes from preoperative to postoperative, in parameters of the anterior and posterior surface of the cornea, were statistically significant except the elevation posterior at the apex of the cornea and posterior asphericity. CONCLUSION: The implantation of Ferrara ICRS induces changes in both anterior and posterior surfaces of the cornea.
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AIM: To evaluate the clinical outcomes after Ferrara intrastromal corneal ring segments (ICRS) reoperation in patients with keratoconus. METHODS: A total of 37 keratoconus eyes implanted with intrastromal corneal ring segments, which had an ICRS exchange, addition, reposition or removal were evaluated. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), keratometry (K), asphericity (Q) and pachymetry at the thinnest point (PTP) of the cornea were evaluated using a corneal tomography (Oculus Pentacam, USA). RESULTS: The mean follow-up time after the reoperation was 30.5±9.7 months. The mean UCVA improved from 20/300 to 20/80 (P=0.005); the mean BCVA improved from 20/160 to 20/50 (P=0.0002), the mean keratometry reduced from 49.33±4.19D to 46.16±3.90D (P=0.0001), the mean pachymetry at the thinnest point increased from 450±42.9µm to 469±40.8µm (P=0.0001). The asphericity increased from -0.84±0.74 to -0.35±0.81 (P=0.15) and the spherical equivalent reduced from -4.64±4.87D to -3.04±3.45D (P=0.137). The changes in the asphericity and spherical equivalent were not statistically significant. CONCLUSION: Ferrara ICRS implantation showed to be a reversible and readjustable surgical procedure for keratoconus treatment. Good outcomes can be obtained even after removal, addition, reposition or exchange of ICRS.
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PURPOSE: To evaluate the clinical outcomes of implantation of Ferrara intrastromal corneal ring segments (ICRS) in patients with astigmatism after penetrating keratoplasty (PKP). SETTING: Private clinic, Belo Horizonte, Brazil. DESIGN: Retrospective consecutive case series. METHODS: Chart records of post-PKP patients who had ICRS implantation from May 2005 to September 2009 were retrospectively reviewed. The following parameters were studied: corrected distance visual acuity (CDVA), keratometry (K) values, spherical equivalent (SE), spherical refractive error, corneal topographic astigmatism, minimum K, and maximum K. RESULTS: The study evaluated 59 eyes (54 patients). The mean CDVA (logMAR) improved from 0.45 ± 0.17 (SD) (range 0.18 to 1.00) to 0.30 ± 0.17 (range 0.00 to 1.00). The mean SE was -6.34 ± 3.40 diopters (D) (range 0.37 to -16.50 D) preoperatively and -2.66 ± 2.52 D (range 0.87 to -10.50 D) postoperatively. The mean spherical refractive error decreased from -7.10 ± 3.07 D (range 2.15 to 16.68 D) preoperatively to -3.46 ± 2.05 D (range 0.88 to 10.79 D) postoperatively. No patient lost visual acuity. The mean corneal topographic astigmatism decreased from 3.37 ± 1.51 D preoperatively to 1.69 ± 1.04 D postoperatively. The mean maximum K value decreased from 48.09 ± 2.56 D to 44.17 ± 2.67 D and the mean minimum K value, from 44.90 ± 2.54 D to 42.46 ± 2.63 D. All changes were statistically significant (P<.0001). CONCLUSION: Intrastromal corneal ring segments effectively reduced corneal cylinder in patients with astigmatism after PKP.
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Astigmatismo/cirugía , Sustancia Propia/cirugía , Queratoplastia Penetrante , Complicaciones Posoperatorias , Prótesis e Implantes , Implantación de Prótesis , Adulto , Astigmatismo/fisiopatología , Materiales Biocompatibles , Topografía de la Córnea , Femenino , Estudios de Seguimiento , Humanos , Masculino , Polimetil Metacrilato , Refracción Ocular/fisiología , Estudios Retrospectivos , Resultado del Tratamiento , Agudeza Visual/fisiologíaRESUMEN
PURPOSE: To evaluate the clinical outcomes of implantation of Ferrara intrastromal corneal ring segments (ICRS) in patients with corneal ectasia after refractive surgery. SETTING: Private clinic, Belo Horizonte, Brazil. METHODS: Charts of patients with corneal ectasia after refractive surgery were retrospectively reviewed. The following parameters were studied: uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometry, corneal asphericity, and pachymetry. All patients were evaluated by Scheimpflug scanning-slit tomography (Pentacam). RESULTS: Twenty-five eyes (20 patients) with corneal ectasia (20 after laser in situ keratomileusis, 4 after radial keratotomy, 1 after photorefractive keratectomy) were evaluated. Postoperatively, the mean UDVA increased from 20/185 to 20/66 (P = .005) and the mean CDVA, from 20/125 to 20/40 (P = .008). The mean asphericity decreased from -0.95 preoperatively to -0.23 postoperatively (P = .006). The mean pachymetry at the apex of the cornea increased from 457.7 microm +/- 48.7 (SD) preoperatively to 466.2 +/- 49.8 mum postoperatively (P = .025) and the mean pachymetry at the thinnest point, from 436.3 +/- 46.2 microm to 453.9 +/- 49.3 microm (P = .000). The mean keratometry decreased from 45.41 +/- 5.63 diopters (D) to 42.88 +/- 4.44 D, respectively; the decrease was statistically significant (P = .000). CONCLUSION: Intrastromal corneal ring segment implantation significantly improved UDVA and CDVA in patients with corneal ectasia.
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Enfermedades de la Córnea/cirugía , Sustancia Propia/cirugía , Prótesis e Implantes , Implantación de Prótesis , Procedimientos Quirúrgicos Refractivos/efectos adversos , Adulto , Materiales Biocompatibles , Enfermedades de la Córnea/etiología , Dilatación Patológica/etiología , Dilatación Patológica/cirugía , Femenino , Humanos , Queratomileusis por Láser In Situ/efectos adversos , Queratotomía Radial/efectos adversos , Masculino , Persona de Mediana Edad , Queratectomía Fotorrefractiva/efectos adversos , Estudios Retrospectivos , Resultado del Tratamiento , Agudeza Visual/fisiologíaRESUMEN
PURPOSE: To report the long-term follow-up of Ferrara intrastromal corneal ring segment (ICRS) implantation for the management of keratoconus. SETTING: Private clinic, Belo Horizonte, Brazil. METHODS: This study comprised patients with keratoconus who completed at least 5 years of follow-up. One or 2 ICRS were inserted in the cornea, embracing the keratoconus area. Statistical analysis included preoperative and postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and keratometry (K) values. RESULTS: Thirty-five eyes of 28 patients were evaluated. The mean UDVA improved from 0.15 preoperatively to 0.31 postoperatively and the mean CDVA, from 0.41 to 0.62, respectively; the increases were statistically significant (P = .003 and P = .002, respectively). Corneal topography showed corneal flattening in all eyes. The mean minimum K value decreased from 48.99 D preoperatively to 44.45 D postoperatively and the mean maximum K value, from 54.07 D to 48.09 D, respectively; the decreases were statistically significant (both P = .000). CONCLUSIONS: Five years after ICRS implantation, the UDVA and CDVA were improved in eyes with keratoconus. There was significant postoperative corneal flattening that remained stable over the follow-up period.
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Sustancia Propia/cirugía , Queratocono/cirugía , Prótesis e Implantes , Implantación de Prótesis , Sustancia Propia/fisiopatología , Topografía de la Córnea , Estudios de Seguimiento , Humanos , Queratocono/fisiopatología , Polimetil Metacrilato , Estudios Retrospectivos , Agudeza Visual/fisiologíaRESUMEN
OBJETIVO: Este trabalho tem como objetivo relatar experiência com utilização do crosslinking após implante de anel intracorneano de Ferrara (Ferrara Ophtalmic) visando a melhora refrativa e estabilização corneana. MÉTODOS: Seis pacientes com idade entre 26 e 38 anos foram submetidos ao tratamento com crosslinking após implante de anel de Ferrara. Cinco pacientes receberam 2 segmentos de anel e um paciente recebeu um segmento. Depois de 4 a 55 meses os pacientes foram submetidos a aplicação do "crosslinking" com ultra-violeta de acordo com o protocolo estabelecido por Seiler & cols. RESULTADOS: Quatro olhos apresentaram alteração progressiva da refração e 2 apresentaram refração sem alteração progressiva. A topografia mostrou queda acentuada da curvatura e o estudo da lâmpada de fenda mostrou anel em boa profundidade durante um ano de pós-operatório em 100 por cento dos olhos. A microscopia especular não mostrou alteração significativa e a acuidade visual se mostrou semelhante ao pré-operatório. CONCLUSÃO: O crosslinking poderá ajudar a manter ceratocones estáveis, não-somente nos casos de progressão, mas também nos cones evolutivos com implante de anel.
PURPOSE: To describe our experience with crosslinking after Ferrara ring implant for better vision and corneal stabilization. METHODS: six patients with age of 26 - 38 years old had treatment with crosslinking after Ferrara ring implant. Five patients had 2 ring segments implanted and one patient had one segment implanted. After 4 to 55 months the patients were submitted to crosslinking with UVA light according to Seiler et al protocol. RESULTS: Four eyes had progressive alteration of refraction and 2 patients had no alteration of refraction. The topography showed flattener curvature and at the slip lamp 100 percent of the eyes had good depth after one year post operatively. The specular microscopy didn't show any significant alteration and the visual acuity was similar before the procedure. CONCLUSION: The crosslinking may help to maintain stable keratoconus, not only in progression cases, but also in evolutive keratoconus with ring implant.
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PURPOSE: Intrastromal Ferrara ring segments were inserted in eyes with severe keratoconus to evaluate safety and efficacy of this procedure. METHODS: Intrastromal Ferrara ring segments were placed in 36 eyes of 35 patients with severe keratoconus, who were evaluated after 12 months of follow-up. All patients had highly disabling visual acuity, contact lens intolerance, and a previous indication for penetrating keratoplasty. Statistical analysis included preoperative and postoperative uncorrected visual acuity, best spectacle-corrected visual acuity, manifest refraction, anterior chamber depth, keratometry, and pachymetry. RESULTS: No patient had a loss of visual acuity. Uncorrected visual acuity improved in 28 eyes (77.78%) and best spectacle-corrected visual acuity improved in 29 eyes (80.56%). Spherical equivalent refraction decreased from -7.29 +/- 3.12 D to -4.80 +/- 3.04 D at 12 months after Ferrara intrastromal ring segment implantation. Corneal topography and ultrasound biomicroscopy showed corneal flattening, demonstrated by thinning of the central cornea and a reduction in anterior chamber depth. Segment decentration occurred in one eye (2.7%), asymmetric positioning of the segments in two eyes (5%), inadequate depth in two eyes (5%), migration of the segments in two eyes (5%), segment extrusion in five eyes (13.8%), conjunctivitis in one eye (2.7%), bacterial keratitis in one eye (2.7%), and hydrops in one eye (2.7%). CONCLUSIONS: With these early results, Ferrara intrastromal ring segments appear to be an alternative for the treatment of severe keratoconus.