Evaluación del grado de deshidratación en diferentes lentes de hidrogel usados durante diez horas / Estimation of degree of dehydratation in different hydrogel lenses used during 10 consecutive hours

La deshidratación en lentes de contacto produce cambios en el material ocasionando alteraciones en las características del lente. Objetivo: evaluar el grado de deshidratación de tres diferentes tipos de lentes de contacto de hidrogel luego de diez horas de uso. Materiales y métodos: se evaluaron veinticuatro lentes de contacto de hidrogel: ocho de Polymacon, ocho de Ocufilcon D y ocho de Vasurfilcon A. un lente de cada material fue evaluado mediante un método gravimétrico establecido por la norma ISO para determinar el contenido acuoso, los pacientes utilizaron un lente de contacto nuevo en cada ojo durante diez horas luego de las cuales se evaluó nuevamente el contenido de agua en el laboratorio para así establecer porcentajes de deshidratación. Resultados: el contenido acuoso del lente Polymacon evaluado fue de 41,83%, diferente al reportado por el fabricante (38,6%), con un valor p = 0,015. el lente Omafilcon A indicó un valor de 58,81%, diferente al reportado por el fabricante (60%), con un valor p = 0,006. el lente Vasurfilcon indicó un valor igual a 74,0%, el cual fue el reportado por el fabricante, con un valor p = 0,83. se usó nivel de significancia de 5%. el porcentaje de deshidratación promedio después de diez horas de uso, para el Polymacon fue del 12,1%; para Omafilcon del 3,7% y para el Vasurfilcon A del 6,5%. Conclusiones: el lente de Varsulfilcon A reportó el mismo valor indicado por el fabricante. el lente de Omafilcon A demostró menor deshidratación después de su uso, en relación con los demás lentes de hidrogel estudiados. no se encontró relación directa entre el contenido acuoso y el porcentaje de deshidratación.

Dehydration in contact lenses causes changes in the material, which provokes alterations in the lens’ characteristics. Objective: to evaluate the degree of dehydration in three types of hydrogel contact lenses after ten consecutive hours of use. Materials and methods: 24 hydrogel contact lenses were evaluated: 8 Polymacon, 8 Ocufilcon D and 8 Vasurfilcon A. the lens was evaluated through a gravimetric method established by the ISO standards in order to determine the water content. Patients wore a contact lens in each eye for ten hours, after which the water content was once again evaluated at the laboratory in order to establish the dehydration percentages. Results: the water content of the Polymacon lens was 41.83%, which is different from the one reported by the manufacturer (38.6%), with a p-value of 0.015. the Omafilcon A lens showed a value of 58.81% different from the one reported by the manufacturer (60%), with a p-value of 0.006. the Vasurfilcon lens showed a value of 74.0%, as reported by the manufacturer, with a p-value of 0.83. A significance level of 5% was used. the average dehydration percentage after ten hours of use for the Polymacon lens was 12.1%; 3.7% for the Omafilcon; and 6.5% for the Vasurfilcon A. Conclusions: the Varsulfilcon A lens showed the same value reported by the manufacturer. the Omafilcon A lens showed a lesser degree of dehydration after using it compared to the other hydrogel lenses under study. no direct link was found between the water content and the dehydration percentage.

Bacterial colonization of hydrogel disposable contact lenses / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To determine the rate of bacterial colonization in hydrogel disposable contact lenses and solutions and to identify the contaminating organisms.METHODS:A cross sectional study with purposive sampling was carried out.One hundred hydrogel contact lenses were collected from wearers among undergraduate students of Health Campus,University Sains Malaysia.All lenses and storage solutions were sent for microbiological culture and gram staining.RESULTS:The majority of study participants were females(98%).The mean age was 21.36±1.63 years.Forty-one subject participants(82%)showed positive bacterial colonization of the lenses.From storage solutions 32% yielded positive colonization by bacteria.The most common organisms were coagulase negative staphyJococcus,Staph aureus and streptococci while Pseudomonas sp.and Serratia sp.were isolated more frequently from contact lenses.CONCLUSION:Contact lens wearing is potentially dangerous as a result of high rate of bacterial colonization of the lenses and its storage solutions.Extreme precaution and adherence to strict hygienic practice is recommended during lens handling and wearing.