Fitting & Verification
Fitting Methods

Trial Lens Method:

The trial lens or �diagnostic lens� method is the most accurate method of fitting contact lenses. It allows for a close estimate of proper lens size, power, and curvature and it enables the fitter to evaluate what if any edge modifications may be necessary. Since only about half the population can tolerate sensitivity to any type of rigid contact lens, a trial lens allows the wearer to evaluate their particular sensitivity to hard lenses. Although trial lenses are generally composed of PMMA they can approximate the fitting characteristics of most gas permeable rigid lenses. However some gas permeable materials such as CAB are lighter in weight and this needs to be taken into account. Trial lenses made of the actual gas permeable materials are available and may be used but at a higher cost., elimination of edge flare because it can be fitted larger (about 9mm); better for sports—can be fitted tighter so there is less chance of loss; very tough and difficult to break; greater gas permeability; lower wetting angle.