VALIDATING A PILLAR AND COLLAR TECHNIQUE FOR MEASURING THE EDGE LIFT OF RIGID CONTACT-LENSES

Purpose. The clinical importance of the edge lift of rigid contact len ses is often neglected, possibly due to previous difficulties in its m easurement, A new method of measuring axial edge lift (AEL) and radial edge lift (REL) using standard contact lens verification equipment, s uch as an optical spherometer, a thickness gauge, and contact lens V g auge, is described, Methods. The technique was validated for trueness (accuracy) and precision (repeatability) by measuring the edge lift of a number of monocurve lenses, manufactured both with and without a no rmal edge finish. Results, Edge lift was measured to an accuracy of 0. 01 mm. Conclusions. As long as a mean of eight independent measurement s of back optic zone radius (BOZR), sagitta, and one measurement of ce nter thickness are taken, the pillar and collar technique is capable o f producing accurate and repeatable measurements of the edge lift of a rigid contact lens.