ESTIMATION OF THE THICKNESS OF THE CRYSTALLINE LENS FROM ON-AXIS AND OFF-AXIS SCHEIMPFLUG PHOTOGRAPHS

Measurement of human lens biometry directly from Scheimpflug images of the anterior ocular segment may be impossible when pupil size preclud es an adequate Scheimpflug view of the posterior lens surface. The aut hors describe a simple and accurate geometric method of overcoming thi s problem by estimating the true lens thickness from pairs of on-axis and off-axis Scheimpflug images. The method is validated and the varia bility of the estimate is quantified. This new method has utility in t he study of lens biometry in subjects with large lenses whose pupils c annot be adequately dilated.