Comparative study of silicone-hydrogel contact lenses surfaces before and after wear using atomic force microscopy

Purpose: The aim of this study was to analyze surface changes of three silicone-hydrogel contact lenses after daily wear. The lenses used in this study were balafilcon A, lotrafilcon B (both surface-treated), and galyfilcon A (non surface-treated). Methods: To understand how and where proteins, lipids, and other contaminants change contact lenses, surface roughness was assessed through Atomic Force Microscopy Tapping ModeTM. Roughness parameters were Mean Surface roughness (Ra), Mean-square-roughness (Rq), and Maximum roughness (Rmax). The surface topography of unworn and worn lenses was also mapped in great detail. Results: Contact lenses roughness parameters exhibited different values before and after wear and the surface appearance also changed. After wear, balafilcon A and galyfilcon A showed a significant increase on surface roughness parameters, being this increase more accentuated to galyfilcon A. In lotrafilcon B materials no significant changes were observed with wear. Conclusions: The present study suggests that surface treatment of silicone-hydrogel contact lenses can play a role in the prevention of a significant increase in roughness, and contribute to the better clinical tolerance of these lenses.University of PortoIBM

The effect of lens wear on refractive index of conventional hydrogel and silicone-hydrogel contact lenses: a comparative study

Purpose: The purpose of this work was to evaluate the ability of four silicone-hydrogel contact lenses (galyfilcon A, balafilcon A, lotrafilcon A and lotrafilcon B) to retain their equilibrium water content before and after wear, through measurements of refractive index and compare with that of a conventional disposable hydrogel contact lens (etafilcon A). Methods: The refractive indices of 115 contact lenses were measured using an automated refractometer (CLR 12-70, Index Instruments, Cambridge, U.K.) before and after a schedule of daily wear by 58 patients for 30 days in the case of silicone-hydrogel lenses and 15 days for the conventional contact lenses. Results: In the silicone-hydrogel contact lenses the changes on the refractive indices were not statistically significant, however after being worn the refractive index of the conventional etalfilcon A hydrogel contact lens increased significantly ( p < 0.001). Conclusion: The results presented here show that after being worn the silicone-hydrogel contact lens, show more capacity to retain or to reach their initial equilibrium water content than conventional hydrogel contact lenses. This suggests that the silicone-hydrogel contact lenses are less susceptible to spoilation over time maintaining its biocompatibility and contributing to the clinical success of lens performance.Vision and Johnson & Johnson.Bausch & Lom

The effect of silicone-hydrogel and conventional hydrogel contact lenses wear on the tear film: a comparison between de lenses

Purpose: The aim of this study was to evaluate the effect of one conventional hydrogel and four silicone-hydrogel contact lenses of 6-months daily wear on the quantity and stability of the tear film. The tests were performed with a group of patients with no previous contact lenses experience before and after wear on 96 eyes. Methods: The contact lenses tested were: 19 Galyfilcon A (Acuvue® Advance™), 15 Balafilcon A (PureVision™), 20 Lotrafilcon A (Focus® Night & Day™), 14 Lotrafilcon B (O2Optix™) and 28 Etalfilcon A (Acuvue®). Each silicone-hydrogel contact lens was used for 1 month and the conventional hydrogel for 15 days. Every patient used a different lens in each eye. Tear film stability was monitored by tear Break-up-time (BUT) and Non Invasive Break Up Time (NiBUT) and tear volume was measured by the Total Tear Meniscus Height and the Red Phenol Test. Results: The following tables summarize the difference between the measurements obtained in the first and in the last day of wear of each contact lens brand and the results were analyzed comparing the conventional hydrogel and the siliconehydrogel contact lenses (Table 1, 2, and 3), the lenses belonging to the first generation of silicone-hydrogel contact lenses (table 4) and the lenses belonging to the second generation of silicone-hydrogel (Table 5). The significance (p value) of 0.05 is considered statistically significant. Conclusions: Although there are some differences between the lenses, there are no statistically significant differences between the lenses and measurements obtained before and after contact lenses wear on the tear film tests.Objectivo: Avaliar o efeito de 6 meses de uso diário de uma lente de contacto de hidrogel convencional e quatro lentes de contacto de silicone-hidrogel na qualidade e estabilidade do filme lacrimal. Os testes foram realizados num grupo de pacientes (96 olhos) sem experiência prévia de uso de lentes de contacto, antes e depois do período de uso das lentes. Material e Métodos: As lentes de contacto estudadas foram: 19 Galyfilcon A (Acuvue® Advance™), 15 Balafilcon A (PureVision™), 20 Lotrafilcon A (Focus® Night & Day™), 14 Lotrafilcon B (O2Optix™) e 28 Etalfilcon A (Acuvue®). Cada lente de silicone-hidrogel foi usada durante 1 mês e a lente de hidrogel convencional durante 15 dias. Todos os pacientes usaram uma lente diferente em cada olho. A estabilidade do filme lacrimal foi avaliada pelo teste de ruptura lacrimal (BUT) e pelo teste de ruptura lacrimal não invasivo (NIBUT). O volume lacrimal foi medido pala altura total do menisco lacrimal e pelo teste vermelho fenol (Red Phenol Test) Resultados: Nas tabelas seguintes apresenta-se a diferença entre as medidas obtidas no 1º e último dia de uso para cada marca de lente de contacto e os resultados foram analisados comparando a lente de contacto hidrogel convencional com as lentes de silicone-hidrogel (Tabela 1, 2 e 3), as lentes pertencentes à 1ª geração de lentes de silicone-hidrogel (Tabela 4) e as lentes que pertencem à 2ª geração das lentes de silicone-hidrogel (Tabela 5). O valor da significância (p) é considerada estatisticamente significativa quando ≤0.05. Conclusões: Embora existam algumas diferenças entre as lentes de contacto estudadas, não há diferenças estatisticamente significativas entre os valores obtidos nos testes de avaliação do filme lacrimal antes e depois do uso das lentes de contacto

The effect of octylglucoside and sodium cholate in Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion to soft contact lenses

Purpose. In this study, the effect of the natural surfactants octylglucoside and sodium cholate in inhibiting Staphylococcus epidermidis and Pseudomonas aeruginosa adhesion to conventional and silicone-hydrogel contact lenses (CL) was assessed. Hydrophobicity was also evaluated to conditioned and nonconditioned CL. Methods. The inhibiting effect of the tested surfactants was determined through “in vitro” adhesion studies to conditioned and nonconditioned CL followed by image acquisition and cell enumeration. Hydrophobicity was evaluated through contact angle measurements using the advancing type technique on air. Results. Sodium cholate exhibits a very low capability to inhibit microbial adhesion. Conversely, octylglucoside effectively inhibited microbial adhesion in both types of lenses. This surfactant exhibited an even greater performance than a multipurpose lens care solution used as control. Octylglucoside was the only tested surfactant able to lower the hydrophobicity of all CL, which can explain its high performance. Conclusions. The results obtained in this study point out the potential of octylglucoside as a conditioning agent to prevent microbial colonization.Portuguese Foundation for Science and Technology (FCT

Sarcoma de Kaposi na Odontologia: Um levantamento epidemiológico no Brasil.

HIV-AIDS is a public health problem in the world. In 2014, 9,888 new cases were reported in Brazik and it is estimated that half of the patients are unaware of having the disease. Kaposi's sarcoma associated with AIDS (KS-AIDS) is a marker of disease progression and immunosuppression. Although the incidence of SK-AIDS in the oral cavity has decreased markedly since universal access to highly active retroviral treatment, studies in São Paulo have established a 5% incidence of this neoplasm. The immune reconstitution syndrome associated with KS-AIDS and facial lymphedema is a life-threatening complication. The lack of training in the oral diagnosis of SK-AIDS and its relatively low incidence can make this neoplasia go unnoticed by the clinician in the routine examination, which is a characteristic clinical sign of immunosuppression. This article examines oral KS associated with AIDS.HIV-AIDS é um problema de saúde pública no mundo.&nbsp;Em 2014, foram notificados 9.888 novos casos no Brasil e estima-se que metade dos pacientes desconhecem ser portadores da doença. O sarcoma de Kaposi associado à AIDS (KS-AIDS) é um marcador de progressão da doença e imunossupressão.&nbsp;Embora a incidência de SK-AIDS na cavidade oral tenha diminuído notavelmente desde o acesso universal ao tratamento retroviral altamente ativo, há estudos em São paulo que estabelecem uma incidência dessa neoplasia em 5%. A síndrome de reconstituição imunológica associada ao KS-AIDS e ao linfedema facial é uma complicação com risco de vida. A falta de treinamento no diagnóstico oral do SK-AIDS e sua incidência relativamente baixa podem fazer com que essa neoplasia passe despercebida pelo clínico no exame de rotina, sendo este um sinal clínico característico de imunossupressão. Este artigo analisa o SK oral associado à AIDS

Alterações na transmitância UV-Visível induzidas pelo uso de lentes de contacto de silicone-hidrogel

Fundação para a Ciência e a Tecnologia (FCT) through Centro de Física da U

Adhesion of Pseudomonas aeruginosa and Staphylococcus epidermidis to silicone-hydrogel contact lenses

Purpose. The purpose of this study is to compare the adhesion capabilities of the most important etiologic agents of microbial ocular infection to the recently available silicone– hydrogel lenses with those to a conventional hydrogel lens. Methods. In vitro static adhesion assays of Pseudomonas aeruginosa 10,145, Staphylococcus epidermidis 9142 (biofilm-positive), and 12,228 (biofilm-negative) to two extended-wear silicone– hydrogel lenses (balafilcon A and lotrafilcon A), a daily wear silicone– hydrogel lens (galyfilcon A) and a conventional hydrogel (etafilcon A) were performed. To interpret the adhesion results, lens surface relative hydrophobicity was assessed by water contact angle measurements. Results. P. aeruginosa and S. epidermidis 9142 exhibited greater adhesion capabilities to the extended wear silicone– hydrogel lenses than to the daily wear silicone– and conventional hydrogel lenses (p < 0.05). No statistical differences were found between the adhesion extent of these strains to galyfilcon A and etafilcon A. The biofilm negative strain of S. epidermidis adhered in larger extents to the silicone– hydrogel lenses than to the conventional hydrogel (p < 0.05), but in much lower amounts than the biofilm-positive strain. The water contact angle measurements revealed that the extended wear silicone– hydrogel lenses are hydrophobic, whereas the daily wear silicone– and conventional hydrogel lenses are hydrophilic. Conclusions. As a result of their hydrophobicity, the extended wear silicone– hydrogel lenses (lotrafilcon A and balafilcon A) may carry higher risk of microbial contamination than both the hydrophilic daily wear silicone– hydrogel lens, galyfilcon A and the conventional hydrogel lens, etafilcon A.Fundação para a Ciência e a Tecnologia (FCT

The influence of lens material and lens wear on the removal and viability of staphylococcus epidermidis

Purpose: The aim of this study was to evaluate the influence of lens material and lens wear on the removal capability of Staphylococcus epidermidis. Assessment of viability of remaining adhered bacteria was another goal of this work. Four silicone hydrogel materials (galyfilcon A, balafilcon A, lotrafilcon A, lotrafilcon B) and one conventional hydrogel material (etafilcon A) were assayed. Methods: Detachment studies on S. epidermidis were carried out in a parallel plate flow chamber. Contact lenses (CLs) were fitted to the bottom of the flow chamber and a bacterial suspension was perfused into the system, promoting bacterial adhesion. Afterwards, detachment was stimulated using a multipurpose solution (MPS, ReNu Multiplus®) and the percentage of removed bacteria estimated through microscopic observation and enumeration. Remaining adhered bacteria were stained with propidium iodide (PI) and enumerated in order to assess their viability. Additionally, the worn lenses were observed by confocal laser scanning microscopy (CLSM) to visualize bacterial distribution along the lens surfaces. Results: Bacterial removal was significant ( p < 0.05) for both unworn and worn galyfilcon A and etafilcon A. Galyfilcon A exhibited a detachment percentage of 59.1 and 63.5 while etafilcon A of 62.6 and 69.3, both for unworn and worn lenses, respectively. As far as bacterial viability is concerned, it was found that worn lenses exhibit a superior amount of non-viable bacteria than unworn CLs. Images obtained by CLSM revealed an irregular bacterial distribution for all lens materials. Conclusions: It appears that surface and/or bulk structure of the lens material affects removal of S. epidermidis while CL wear influences their viability.Fundação para a Ciência e a Tecnologia (FCT