Flexure effects of double-thin zone toric soft contact lenses

We use a new model for describing the flexure of hydrogel lenses in situ to evaluate toric hydrogel lenses. The mathematical development of the model precludes use of prism ballasted lenses (because of differential thickness in the vertical meridian and possible lenticulation in the midperiphery), and so double-thin zone lenses were used here. Our results suggest that such lenses (low-minus power) align almost perfectly with the anterior corneal surface creating minimal tear layers.