Navegando por Palavras-chave "Reagentes para ligações cruzadas"
Agora exibindo 1 - 4 de 4
Resultados por página
Opções de Ordenação
- ItemAcesso aberto (Open Access)Effect of corneal epithelium on ultraviolet-A and riboflavin absorption(Conselho Brasileiro de Oftalmologia, 2011-10-01) Bottós, Katia Mantovani [UNIFESP]; Schor, Paulo [UNIFESP]; Dreyfuss, Juliana Luporini [UNIFESP]; Nader, Helena Bonciani [UNIFESP]; Chamon, Wallace [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)PURPOSE: To determine if the corneal epithelium prevents the collagen cross-linking effect. Using immunofluorescence microscopy after CXL, we indirectly analyzed the role of the epithelium as ultraviolet-A (UVA) shield as well as a barrier to riboflavin penetration. METHODS: Fifteen freshly enucleated porcine eyes were divided into 3 groups. The corneal epithelium was kept intact in all groups. Five eyes served as control (Group 1). On group 2, eyes received tetracaine anesthetic drops and topical 0.1% riboflavin solution (10 mg riboflavin-5-phosphate in 10 mL 20% dextran-T-500). On Group 3, riboflavin was injected into the anterior chamber to allow penetration of the drug through the endothelium. Groups 2 and 3 were exposed to UVA (365 nm, 3 mW/cm²) for 30 minutes. Ultra-thin sections (8 µm) of the corneas were stained with anti-collagen type I and DAPI (4,6-diamidino-2-fenilindole dihydrocloride) and analyzed with fluorescence microscopy. RESULTS: Corneas treated with UVA irradiation and intracameral injection of riboflavin (Group 3) showed greater pattern of collagen organization compared to groups 1 (Control) and 2 (riboflavin and tetracaine eye drops). A yellow stromal staining, which represents the riboflavin diffusion into the stroma, was only observed in eyes injected with riboflavin into the anterior chamber. CONCLUSION: Using immunofluorescence microscopy in porcine corneas, we demonstrated that the corneal epithelium reduces the effectiveness of CXL by preventing the penetration of the drug and not by limiting the UVA transmittance. An inadequate intrastromal concentration of riboflavin may impair CXL effect.
- ItemAcesso aberto (Open Access)Induction of corneal collagen cross-linking in experimental corneal alkali burns in rabbits(Conselho Brasileiro de Oftalmologia, 2014-10-01) Colombo-Barboza, Marcello; Colombo-Barboza, Guilherme; Felberg, Sergio; Dantas, Paulo Elias Corrêa; Sato, Elcio Hideo [UNIFESP]; Hospital Oftalmológico Visão Laser; Santa Casa de Misericórida de São Paulo; Centro Universitário Lusíada; Universidade Federal de São Paulo (UNIFESP)Objective: To evaluate the effect of riboflavin-ultraviolet-A-induced cross-linking (CXL) following corneal alkali burns in rabbits. Methods: The right corneas and limbi of ten rabbits were burned using a 1N solution of NaOH and the animals were then divided into two groups: a control group submitted to clinical treatment alone and an experimental group that was treated 1 h after injury with CXL, followed by the same clinical treatment as administered to the controls. Clinical parameters were evaluated post-injury at 1, 7, 15, and 30 days by two independent observers. Following this evaluation, the corneas were excised and examined histologically. Results: There were no statistically significant differences in clinical parameters, such as hyperemia, corneal edema, ciliary injection, limbal ischemia, secretion, corneal neovascularization, symblepharon, or blepharospasm, at any of the time-points evaluated. However, the size of the epithelial defect was significantly smaller in the CXL group (p<0.05) (day 15: p=0.008 and day 30: p=0.008) and the extent of the corneal injury (opacity lesion) was also smaller (day 30: p=0.021). Histopathology showed the presence of collagen bridges linking the collagen fibers in only the CXL group. Conclusions: These results suggest that the use of CXL may improve the prognosis of acute corneal alkali burns.
- ItemAcesso aberto (Open Access)Intrastromal crosslinking in post-LASIK ectasia(Conselho Brasileiro de Oftalmologia, 2014-06-01) Moscovici, Bernardo Kaplan [UNIFESP]; Campos, Mauro Silveira de Queiroz [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Descrevemos um caso de ectasia de córnea precoce após cirurgia de LASIK, detectado no primeiro semestre pós-operatório. Nós optamos tratar este paciente com crosslinking embaixo do flap , sem desepitelização com bons resultados. A paciente permaneceu sem progressão da ectasia até o momento atual, dois anos após o procedimento.
- ItemAcesso aberto (Open Access)Ultra B2 - Promoção de ligações covalentes do colágeno corneal (Corneal cross-linking) no tratamento de ceratocone: resultados preliminares(Conselho Brasileiro de Oftalmologia, 2008-12-01) Jankov Ii, Mirko R.; Hafezi, Farhad; Beko, Maja; Ignjatovic, Zora; Djurovic, Branislav; Markovic, Vujica; Schor, Paulo [UNIFESP]; Institute of Refractive and Ophthalmic Surgery; US Medical School Medical Academy Milos Eye Hospital; Univerziteta u Beogradu Medicinski Fakultet Ocna Klinika; Universidade Federal de São Paulo (UNIFESP)PURPOSE: To present early visual and keratometric results for corneal cross-linking with riboflavin and UV irradiation in patients with progressive keratoconus. METHODS: Twenty-five eyes of twenty patients (15 males and 5 females) with a progressive keratoconus in the previous 6 months were followed. Unaided visual acuity (UVA), best spectacle corrected visual acuity (BSCVA), spherical equivalent (SEQ), manifest cylinder, and maximal corneal curvature (max K) values were followed at 1, 3 and 6 months. All patients were submitted to corneal cross-linking using riboflavin (vitamin B2) as the photosensitizer and ultraviolet light (UV, wavelength 370 nm). Epithelium was removed with 20% alcohol, cornea was soaked with vitamin B2 for 15 min, and then irradiated with UV light for 30 min, after which a bandage contact lens (BCL) was placed. RESULTS: UVA increased after one month (from 0.15 ± 0.15 to 0.23 ± 0.20), and went on increasing at 3 and 6 months, reaching statistical significance (p=0.025 e p=0.037, respectively). BSCVA increased from 0.41 ± 0.27 to 0.49 ± 0.29 at month six, without reaching statistical significance at any time point. Progression of keratoconus stopped in all patients, in contrast with progression in all of them in the six-month period prior to the surgery. Max K decreased by more than 2 D (from 53.02 ± 8.42 to 50.88 ± 6.05 D), SEQ less that 1 D (from -3.27 ± 4.08 to -2.68 ± 3.02 D), while refractive cylinder decreased less than 0.5 D (from -2.29 ± 1.77 to -1.86 ± 0.92 D), without reaching a statistically significant difference. None of the eyes lost any line of BSCVA, 12 maintained the preoperative BSCVA, 7 gained one line, 5 gained two lines, and 1 patient gained three lines of BSCVA. CONCLUSIONS: Corneal cross-linking with riboflavin and UV light seems to be a safe (no loss of BSCVA) and effective (anatomical and optical properties maintained) procedure, which has shown to stop the progression of the keratoconus: a reduction, although not statistically significant, of the corneal curvature, spherical equivalent and refractive cylinder took place in patients where previous progression of keratoconus had been described.