Pre-lens tear film evaluation scale: a tool for analyzing the tear film-lens interaction with respect to the material used

In clinical practice, to avoid or reduce the failure rate among users of contact lenses, it is necessary to obtain a detailed patient case history, information concerning symptoms, and a complete eye examination. In addition, application of an auxiliary photographic reference scale might increase the chances of improving initial success or, for existing contact lens wearers, provide insight into the extent or severity of symptoms. Patient symptoms are often directly related to contact lens failure, which in turn is related to the quality of the pre-corneal tear film as well as the wettability of the contact lens surface. We describe the relationship between the quality of the tear film, with particular attention to pre-contact lens tear film, variability in contact tolerance, and the material of which the contact lens is made.