A NOVEL-APPROACH TO MEASURING THE WETTABILITY OF RIGID CONTACT-LENSES- MASS MEASUREMENT OF THE ADHERENT LIQUID ON THE RIGID LENS SURFACE .1.

A novel approach and the equilibrium sessile drop (laser assisted) met hod were used to determine the wettability of hydrated and unhydrated PMMA, Polycon II, Boston IV, Equalens and Boston RXD rigid contact len s materials. In the new method the ability of the contact lens surface to attract the liquid is evaluated by measuring the adhered mass of l iquid on the front lens surface. The mass has a direct relationship to contact lens wettability, so the greater the lens surface hydrophilic ity the more liquid adheres to the contact lens surface. In the hydrat ed state, Equalens and Boston IV showed the greatest hydrophilicity of all five materials, although there was no significant difference betw een them (P > 0.9). Boston RXD had a lower ability to attract liquid a nd there was a significant difference between it and the next higher m aterial which was Boston IV (P < 0.005) and also the next lowest Polyc on II (P < 0.00001). PMMA had the lowest capability to adhere liquid a nd there was a significant difference between PMMA and Polycon II (P < 0.00001). The new method is simple and quick to use and gives greater discrimination and repeatability than other current methods.