Metal printing with modified polymer bonding lithography

SOFT CONTACT LAMINATION; LIGHT-EMITTING DEVICES; LIFT-OFF; FABRICATION; TRANSISTORS; DIODES; FILMS; STAMP

Facetas sem preparo

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária

3D refraction correction and extraction of clinical parameters from spectral domain optical coherence tomography of the cornea.

Capable of three-dimensional imaging of the cornea with micrometer-scale resolution, spectral domain-optical coherence tomography (SDOCT) offers potential advantages over Placido ring and Scheimpflug photography based systems for accurate extraction of quantitative keratometric parameters. In this work, an SDOCT scanning protocol and motion correction algorithm were implemented to minimize the effects of patient motion during data acquisition. Procedures are described for correction of image data artifacts resulting from 3D refraction of SDOCT light in the cornea and from non-idealities of the scanning system geometry performed as a pre-requisite for accurate parameter extraction. Zernike polynomial 3D reconstruction and a recursive half searching algorithm (RHSA) were implemented to extract clinical keratometric parameters including anterior and posterior radii of curvature, central cornea optical power, central corneal thickness, and thickness maps of the cornea. Accuracy and repeatability of the extracted parameters obtained using a commercial 859nm SDOCT retinal imaging system with a corneal adapter were assessed using a rigid gas permeable (RGP) contact lens as a phantom target. Extraction of these parameters was performed in vivo in 3 patients and compared to commercial Placido topography and Scheimpflug photography systems. The repeatability of SDOCT central corneal power measured in vivo was 0.18 Diopters, and the difference observed between the systems averaged 0.1 Diopters between SDOCT and Scheimpflug photography, and 0.6 Diopters between SDOCT and Placido topography.

Successful medical treatment of Acanthamoeba keratitis

Purpose: To describe the outcome of a series of Acanthamoeba keratitis treated with a similar regimen. Methods: All cases diagnosed with Acanthamoeba keratitis in a referral centre from June 1994 through June 1997 were included. Diagnosis of Acanthamoeba keratitis was based in clinical presentation and laboratory results. Positive laboratory identification of Acanthamoeba from corneal scraping or contact lens was required, unless the patient had very characteristic symptoms (severe pain) and signs of the infection, including perineural infiltrates. Initial intensive treatment included topical polyhexamethylene biguanide (PHMB) 0.02%, propamidine isothionate 0.1% and broad-spectrum antibiotics. The treatment was gradually tapered. After documented response to anti-acanthamoeba therapy, topical steroids were introduced; they were discontinued before cessation of the antiAcanthamoeba regimen. Results: Six males and four females, with a mean age of 30.0 ± 7.4 years were included in this study. All cases weared contact lenses. On presentation all cases had severe pain, and epitheliopathy was associated with stromal infiltrate in most (seven of ten) cases. Four patients had anterior uveitis. Perineural infiltrates were present in three cases and ring infiltrate in one patient. Anti-amoebic treatment was started 12.7 ± 7.2 days after beginning of symptoms. The clinical response to therapy was very satisfactory in all patients. Within two to three weeks all patients had remarkable lessening of pain and photophobia, and improvement of clinical signs. At two to three months, visual acuity had improved in all patients. Two patients required penetrating keratoplasty for visual rehabilitation. Conclusion: The use of PHMB and propamidine cured all cases of Acanthamoeba keratitis. Cautious introduction of steroids was associated with expedited resolution of inflammation and provided symptomatic relief.

Comparación: injerto libre o cierre primario más lente de contacto, en resección de tumores de conjuntiva limbar

INTRODUCCION: Existe controversia en cuanto a la técnica quirúrgica para el manejo de tumores del limbo conjuntival. El uso de cierre primario con uso de lente de contacto puede ofrecer una mejor cicatrización y tener ventajas adicionales sobre la técnica tradicional con el uso de plastia. OBJETIVOS: Comparar los resultados en cuanto a grado de dolor, picadas, prurito, porcentaje de epitelización y cicatrización, comodidad del paciente, grado de quemosis y tiempo de retorno a actividades diarias en ambas técnicas quirúrgicas. MATERIALES Y METODOS: Experimento clínico controlado aleatorizado en dos grupos: Al primer grupo se le realizó cirugía de resección de la lesión más plastia. Al segundo grupo se le practicó la resección de la lesión cierre primario y lente de contacto. El seguimiento se realizó al primer y cuarto día, y cada semana durante el primer mes de postoperatorio. Se utilizó el SPSS 20.0 ® para análisis estadístico de datos y se utilizó estadística no paramétrica. RESULTADOS: Se conto con 10 pacientes por grupo. El dolor y porcentaje de cicatrización al primer día postoperatorio fueron mayores en el grupo usando lente de contacto (p=0.048). Al cuarto día postquirúrgico se encontró un mayor porcentaje de cicatrización en el grupo usando lente de contacto. (p=0.075). CONCLUSIONES: El cierre por afrontamiento con uso de lente de contacto mostró dolor y picadas mayores al primer y cuarto día postoperatorio. Pero la epitelización y cicatrización fueron tempranas con un retorno corto a actividades cotidianas.

Advances in ophthalmic drug delivery

Various strategies for ocular drug delivery are considered; from basic formulation techniques for improving availability of drugs; viscosity enhancers and mucoadhesives aid drug retention and penetration enhancers promote drug transport into the eye. The use of drug loaded contact lenses and ocular inserts allows drugs to be better placed where they are needed for more direct delivery. Developments in ocular implants gives a means to overcome the physical barriers that traditionally prevented effective treatment. Implant technologies are under development allowing long term drug delivery from a single procedure, these devices allow posterior chamber diseases to be effectively treated. Future developments could bring artificial corneas to eliminate the need for donor tissue and one-off implantable drug depots lasting the patient’s lifetime.

Biomedical applications of hydrogels: a review of patents and commercial products

Hydrogels have become very popular due to their unique properties such as high water content, softness, flexibility and biocompatibility. Natural and synthetic hydrophilic polymers can be physically or chemically cross-linked in order to produce hydrogels. Their resemblance to living tissue opens up many opportunities for applications in biomedical areas. Currently, hydrogels are used for manufacturing contact lenses, hygiene products, tissue engineering scaffolds, drug delivery systems and wound dressings. This review provides an analysis of their main characteristics and biomedical applications. From Wichterle’s pioneering work to the most recent hydrogel-based inventions and products on the market, it provides the reader with a detailed introduction to the topic and perspective on further potential developments.

Twenty Years of Acanthamoeba Keratitis

Purpose: We described the rate of Acanthamoeba keratitis (AK) in a referral eye center in Sao Paulo, Brazil, through a retrospective review of clinical and laboratorial records of patients over 2 decades. Methods: From 1987 to 2006, a total of 581 requests for amoebic laboratory workup in cases of infections keratitis were investigated. Statistical analyses were applied to analyze a tendency of AK cases. Results: Acanthamoeba species were cultured from corneal scrapings of 185 patients, 5 of them with bilateral infection. Eighty-three percent of those patients were related with contact lens wear. Conclusions: The results suggested that patients with AK have persisted and increased over time at our ophthalmology center. Contact lenses showed to be a potential risk factor. Amoebic corneal infection can be considered as a new but well-established disease ill Brazilian ophthalmology and visual sciences.

Automedicação em oftalmologia

Purpose: To analyze the conditions, consequences and risks of self-medication in patients attended in ophthalmology emergency room at Hospital das Clínicas de Botucatu (UNESP). Methods: Sixty patients who had used any form of self-medication were studied according: age, sex, professional activity, mainly complain, visual acuity (best-corrected vision), who administrated the self-medication (friends/parents, pharmacy clerk, advertisement, or the person himself), sort of medication or product used (eyedrops/ointments/contact lenses), cost (R$), time expenditure to medical attention, ocular complications, risk of visual loss and final diagnose. Results: The majority of patients with self-medication were male (72%). The mean age was 40,9 years (7-77 years). Patients usually used eyedrops that they had at home and delayed 3 days to the first medical evaluation. The most frequently kind of topical eyedrop used was vasoconstrictor (17%). However, many patients even knew what kind of medication they had dropped in their eyes (21%). The great majority of the patients (68%) were exposed to the risk of visual loss. According to our results, self-medication may cause visual complications in 12% of patients, in which, 42% was related to the contact lenses fit without ophthalmologic assistance. Conclusion: The majory of the patients used medication that they had in home. The topical vasoconstrictor was the most frequently used drug, however, they did not know which medication were dropping in their eyes (21%).

Effect of weathering and thickness on roughness of acrylic resin and ocular button

Purpose: The aim of this study was to evaluate the roughness of colorless ocular button and four brands of colorless acrylic resins designed to fabricate ocular prosthesis as a function of weathering (1008 h) and different thickness (1 and 3.5 mm). Materials and methods: One-hundred-and-twenty specimens were fabricated and distributed in 12 groups. The analysis was carried out by means of digital roughness meter. Results: Data were analyzed statistically by ANOVA and Tukey test at 1% significance. The results showed that there was no statistically significant difference after the weathering period. Both the Vipi Cril acrylic resin with 3.5 mm in thickness and ocular button with 1 mm in thickness presented the lowest roughness values (0.12. Ra). Conclusion: The roughness of the acrylic resins and the ocular button was not affect by the weathering of 1008 h. However, the thickness of the specimens proved to have a major influence on roughness property. © 2010.

Análise do comportamento da cor de restaurações cerâmicas sem metal avaliadas por diferentes métodos: estudo clínico prospectivo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Functional hydrogels

Hydrogels are used in a variety of applications in daily life, such as super absorbers, contact lenses and in drug delivery. Functional hydrogels that allow the incorporation of additional functionalities have enormous potential for future development. The properties of such hydrogels can be diversified by introducing responsiveness to external stimuli. These crosslinked polymers are known to respond to changes in temperature, pH and pressure, as well as chemical and electrical stimuli, magnetic fields and irradiation. From this responsive behavior possible applications arise in many fields like drug delivery, tissue engineering, purification and implementation as actuators, biosensors or for medical coatings. However, their interaction with biomaterial and way of functioning are yet not fully understood. Therefore, thorough investigations regarding their optical, mechanical and chemical nature have to be conducted. A UV-crosslinkable polymer, consisting of N-isopropylacrylamide, methacrylic acid and the UV-crosslinker 4-benzoylphenyl methacrylate was synthesized. Its composition, determined by a comprehensive NMR study, is equivalent to the composition of the monomer mixture. The chemical characteristics were preserved during the subsequently formation of hydrogel films by photo-crosslinking as proved by XPS. For the optical characterization, e.g. the degree of swelling of very thin films, the spectroscopy of coupled long range surface plasmons is introduced. Thicker films, able to guide light waves were analyzed with combined surface plasmon and optical waveguide mode spectroscopy (SPR/OWS). The evaluation of the data was facilitated by the reverse Wentzel-Kramers-Brillouin (WKB) approximation. The meshsize and proper motion of the surface anchored hydrogels were investigated by fluorescence correlation spectroscopy (FCS), micro photon correlation spectroscopy (µPCS) and SPR/OWS. The studied gels exhibit a meshsize that allowed for the diffusion of small biomolecules inside their network. For future enhancement of probing diffusants, a dye that enables FRET in FCS was immobilized in the gel and the diffusion of gold-nanoparticles embedded in the polymer solution was studied by PCS. These properties can be conveniently tuned by the crosslinking density, which depends on the irradiation dose. Additionally, protocols and components for polymer analogous reactions based on active ester chemistry of the hydrogel were developed. Based on these syntheses and investigations, the hydrogel films are applied in the fields of medical coatings as well as in biosensing as matrix and biomimetic cushion. Their non-adhesive properties were proved in cell experiments, SPR/OWS and ToF-SIMS studies. The functionality and non-fouling property of the prepared hydrogels allowed for adaption to the needs of the respective application.

Reduced foveal vision enhances peripheral monitoring and peripheral event detection

Introduction: Although it seems plausible that sports performance relies on high-acuity foveal vision, it could be empirically shown that myoptic blur (up to +2 diopters) does not harm performance in sport tasks that require foveal information pick-up like golf putting (Bulson, Ciuffreda, & Hung, 2008). How myoptic blur affects peripheral performance is yet unknown. Attention might be less needed for processing visual cues foveally and lead to better performance because peripheral cues are better processed as a function of reduced foveal vision, which will be tested in the current experiment. Methods: 18 sport science students with self-reported myopia volunteered as participants, all of them regularly wearing contact lenses. Exclusion criteria comprised visual correction other than myopic, correction of astigmatism and use of contact lenses out of Swiss delivery area. For each of the participants, three pairs of additional contact lenses (besides their regular lenses; used in the “plano” condition) were manufactured with an individual overcorrection to a retinal defocus of +1 to +3 diopters (referred to as “+1.00 D”, “+2.00 D”, and “+3.00 D” condition, respectively). Gaze data were acquired while participants had to perform a multiple object tracking (MOT) task that required to track 4 out of 10 moving stimuli. In addition, in 66.7 % of all trials, one of the 4 targets suddenly stopped during the motion phase for a period of 0.5 s. Stimuli moved in front of a picture of a sports hall to allow for foveal processing. Due to the directional hypotheses, the level of significance for one-tailed tests on differences was set at α = .05 and posteriori effect sizes were computed as partial eta squares (ηρ2). Results: Due to problems with the gaze-data collection, 3 participants had to be excluded from further analyses. The expectation of a centroid strategy was confirmed because gaze was closer to the centroid than the target (all p < .01). In comparison to the plano baseline, participants more often recalled all 4 targets under defocus conditions, F(1,14) = 26.13, p < .01, ηρ2 = .65. The three defocus conditions differed significantly, F(2,28) = 2.56, p = .05, ηρ2 = .16, with a higher accuracy as a function of a defocus increase and significant contrasts between conditions +1.00 D and +2.00 D (p = .03) and +1.00 D and +3.00 D (p = .03). For stop trials, significant differences could neither be found between plano baseline and defocus conditions, F(1,14) = .19, p = .67, ηρ2 = .01, nor between the three defocus conditions, F(2,28) = 1.09, p = .18, ηρ2 = .07. Participants reacted faster in “4 correct+button” trials under defocus than under plano-baseline conditions, F(1,14) = 10.77, p < .01, ηρ2 = .44. The defocus conditions differed significantly, F(2,28) = 6.16, p < .01, ηρ2 = .31, with shorter response times as a function of a defocus increase and significant contrasts between +1.00 D and +2.00 D (p = .01) and +1.00 D and +3.00 D (p < .01). Discussion: The results show that gaze behaviour in MOT is not affected to a relevant degree by a visual overcorrection up to +3 diopters. Hence, it can be taken for granted that peripheral event detection was investigated in the present study. This overcorrection, however, does not harm the capability to peripherally track objects. Moreover, if an event has to be detected peripherally, neither response accuracy nor response time is negatively affected. Findings could claim considerable relevance for all sport situations in which peripheral vision is required which now needs applied studies on this topic. References: Bulson, R. C., Ciuffreda, K. J., & Hung, G. K. (2008). The effect of retinal defocus on golf putting. Ophthalmic and Physiological Optics, 28, 334-344.

The extraordinarily rapid disappearance of entoptic images.

It has been known for more than 40 years that images fade from perception when they are kept at the same position on the retina by abrogating eye movements. Although aspects of this phenomenon were described earlier, the use of close-fitting contact lenses in the 1950s made possible a series of detailed observations on eye movements and visual continuity. In the intervening decades, many investigators have studied the role of image motion on visual perception. Although several controversies remain, it is clear that images deteriorate and in some cases disappear following stabilization; eye movements are, therefore, essential to sustained exoptic vision. The time course of image degradation has generally been reported to be a few seconds to a minute or more, depending upon the conditions. Here we show that images of entoptic vascular shadows can disappear in less than 80 msec. The rapid vanishing of these images implies an active mechanism of image erasure and creation as the basis of normal visual processing.