Human tear film pre-rupture phase time (TP-RPT)--a non-invasive technique for evaluating the pre-corneal tear film using a novel keratometer mire.

A non-invasive method of assessing the stability of the human pre-corneal tear film is described using a novel keratometer mire designed in the form of a grid pattern (HIR-CAL Grid). In a laboratory environment, the technique measures with ease and little variability the time taken for the tear film to loose stability and enter the pre-rupture phase (TP-RPT) before rupturing (BUT). This technique may prove useful in evaluating the stability or otherwise of the pre-corneal tear film of prospective contact lens wearer and the pre-contact lens tear film stability on differing current and new contact lens materials.