Laboratory studies in the management of soft contact lens use

Laboratory procedures may be of great value in dealing with lens spoilation and in monitoring the state of the cornea during lens wear. Deposition of calcium-rich material remains the only defined non-mechanical process involved in spoilation although other forms of deposit and discolouration occur. Excess calcium levels in tear fluid are not a feature of contact lens wear, but changes in the sodium-potassium concentration ratio of tears are found. The basis for this effect is obscure but ratio changes may be useful empirical indices of corneal function.