Estimation of Degree of Dehydration in Different Hydrogel Lenses Used During 10 Consecutive Hours

Abstract

Dehydration in contact lenses causes changes in the material, which provokes alterations in thelens’ characteristics. <em><strong>Objective</strong><em> To evaluate the degree of dehydration in three types of hydrogelcontact lenses after ten consecutive hours of use. <em><strong>Materials and methods:</strong></em> 24 hydrogel contactlenses were evaluated: 8 Polymacon, 8 Ocufilcon D and 8 Vasurfilcon A. The lens was evaluatedthrough a gravimetric method established by the ISO standards in order to determine the watercontent. Patients wore a contact lens in each eye for ten hours, after which the water content wasonce again evaluated at the laboratory in order to establish the dehydration percentages. <em><strong>Results</strong><em>The water content of the Polymacon lens was 41.83%, which is different from the one reportedby the manufacturer (38.6%), with a p-value of 0.015. The Omafilcon A lens showed a value of58.81% different from the one reported by the manufacturer (60%), with a p-value of 0.006. TheVasurfilcon lens showed a value of 74.0%, as reported by the manufacturer, with a p-value of 0.83. Asignificance level of 5% was used. The average dehydration percentage after ten hours of use for thePolymacon lens was 12.1%; 3.7% for the Omafilcon; and 6.5% for the Vasurfilcon A. <em><strong>Conclusions:</strong></em>The Varsulfilcon A lens showed the same value reported by the manufacturer. The Omafilcon Alens showed a lesser degree of dehydration after using it compared to the other hydrogel lensesunder study. No direct link was found between the water content and the dehydration percentage.