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Estudo dos parâmetros bioquímicos da película lacrimal
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Authors
Abstract(s)
Com o constante avanço da Contactologia a nível mundial, são cada vez mais os
usuários de lentes de contacto quer no mercado nacional, quer no internacional. Este
facto tem levado a uma incessante introdução de novos materiais, que trazem um maior
conforto e qualidade visual para os seus utilizadores. Ao mesmo tempo, multiplicam-se
os estudos que revelam que o uso de lentes de contacto está associado às alterações
fisiológicas e bioquímicas a nível ocular, e que estas serão eventualmente causadoras do
desconforto visual e sintomatologia referida pelos seus usuários, como é o caso da
síndrome de olho seco. Contudo é importante avaliar se essas alterações fisiológicas são
realmente resultantes do uso de lentes de contacto, ou se por sua vez são variáveis préexistentes,
habituais do ciclo fisiológico ocular, que ocorrem também em não usuários
de lentes de contacto.
Mediante tais dúvidas, o objectivo principal deste projecto de investigação foi estudar a
estabilidade e composição bioquímica do filme lacrimal sob o ponto de vista proteico e
fisiológico em não usuários de lentes de contacto. Um ponto crucial deste trabalho
consistiu na avaliação da manutenção das propriedades e composição do filme lacrimal,
nas condições ditas normais, como é o caso do ciclo diário.
A amostra foi constituída por vinte indivíduos pertencentes à população universitária,
com idades compreendidas entre os 20 e 28 anos, não usuários de lentes de contacto e
sem história clínica relevante.
A qualidade lacrimal foi avaliada em dois períodos do dia, um no início da manhã e
outro no fim da tarde, através da medida do tempo de ruptura lacrimal não invasivo
(NIBUT) medidos com o Tearscope. Procedeu-se também à recolha lacrimal de ambos
os olhos por capilaridade. O perfil proteico da lágrima foi analisado por electroforese
desnaturante, SDS-PAGE (Sodium dodecyl sulfate polyacrylamide gel electrophoresis)
e nativa, PAGE (polyacrylamide gel electrophoresis) . As proteínas IgA e TNF foram quantificadas por ELISA (Enzyme Linked Immuno Sorbent Assay), e a sua tensão
superficial da lágrima foi determinada pelo método de Langmuir -Blogdett.
Os resultados apresentados nesta tese mostram que existem variações diárias, na
composição e propriedades do filme lacrimal, o que pode indicar que as alterações na
sua composição, não têm que ser necessariamente provocadas pelo uso de lentes de
contacto ou pela presença de patologias oculares e sistémicas.
With the constant advancement of contact lens in the world, the users of contact lenses (CL) are increasing, either in the domestic or internationally market. This has led to a continual introduction of new materials that bring greater comfort and visual quality to their users. On the other hand, several studies reveal complications after lens use, at the physiological eye level, mainly at the biochemical point of view such as dry eye syndrome. However it is important to evaluate whether these physiological changes are actually resulting from the use of contact lenses, or if variables are in turn pre-existing customary ocular physiological cycle that also occur in non-contact lenses. Through such doubts the main objective of this research project was to study the biochemical composition of the tear film from the physiological point of view and protein contents in non-contact lenses users. A crucial point of this study was to assess the maintenance of the properties and composition of the tear film in called normal conditions, such as the diurnal cycle. The sample population consists of individual from the university population, aged between 20 and 28 years, non-users of contact lenses and, without clinical relevance. The tear quality was assessed twice during the day; one early in the morning and another in the evening, through the values measured with the non invasive break up time (NIBUT) Tearscope. The tear from both eyes was also collect by capillarity and its protein profile was analyzed by desnaturing polyacrylamide gel electrophoresis SDSPAGE (Sodium dodecyl sulfate polyacrylamide gel electrophoresis) and native electrophoresis PAGE (polyacrylamide gel electrophoresis); IgA and TNF-α were quantified by ELISA (Enzyme Linked Immuno sorbent assay) while tear surface tension was measured by Langmuir method. We conclude that there are daily variations in composition and properties of the tear film. What may indicate that changes in composition do not necessarily have to be caused by the use of contact lenses or by presence of ocular and systemic pathologies.
With the constant advancement of contact lens in the world, the users of contact lenses (CL) are increasing, either in the domestic or internationally market. This has led to a continual introduction of new materials that bring greater comfort and visual quality to their users. On the other hand, several studies reveal complications after lens use, at the physiological eye level, mainly at the biochemical point of view such as dry eye syndrome. However it is important to evaluate whether these physiological changes are actually resulting from the use of contact lenses, or if variables are in turn pre-existing customary ocular physiological cycle that also occur in non-contact lenses. Through such doubts the main objective of this research project was to study the biochemical composition of the tear film from the physiological point of view and protein contents in non-contact lenses users. A crucial point of this study was to assess the maintenance of the properties and composition of the tear film in called normal conditions, such as the diurnal cycle. The sample population consists of individual from the university population, aged between 20 and 28 years, non-users of contact lenses and, without clinical relevance. The tear quality was assessed twice during the day; one early in the morning and another in the evening, through the values measured with the non invasive break up time (NIBUT) Tearscope. The tear from both eyes was also collect by capillarity and its protein profile was analyzed by desnaturing polyacrylamide gel electrophoresis SDSPAGE (Sodium dodecyl sulfate polyacrylamide gel electrophoresis) and native electrophoresis PAGE (polyacrylamide gel electrophoresis); IgA and TNF-α were quantified by ELISA (Enzyme Linked Immuno sorbent assay) while tear surface tension was measured by Langmuir method. We conclude that there are daily variations in composition and properties of the tear film. What may indicate that changes in composition do not necessarily have to be caused by the use of contact lenses or by presence of ocular and systemic pathologies.
Description
Keywords
Película lacrimal Película lacrimal - Aspectos bioquímicos Filme lacrimal - Propriedades físico-químicas Lágrima basal - Lágrima reflexa