Abstract
A hydrogel of high water content was applied for the soft contact lens capable of being worn continuously. The hydrogels prepared in this study contain methyl methacrylate units as hydrophobic component and N-viny1-2-pyrrolidone units as hydrophilic component. Oxygen permeability and tensile strength of the hydrogels were measured at 52% 90% water content. From the both properties mentioned above and the reported values of oxygen uptake by front surface of human cornea, it is anticipated that the contact lens of about 70% water content and 0.15 mm thickness can be worn continuously in sleep. In clinical tests, 69 myopic patients wore continuously the contact lenses of 70% water content and 0.15-0.20mm thickness at the center, without any symptom of hypoxia at the cornea for 1-25 months. On the other hand, several cases among the 78 aphakic patients were suspected of hypoxia at the corneas. They wore the contact lenses of the same material but of 0.50-0.60 mm center thickness continuously for the same period as the above.
