Abstract: A method and apparatus for modifiying corneal refractive properties includes a laser source, computer control, and a plurality of deflectors including at least one rotating and translating deflector. A beam emitted from the laser source is deflected by the rotating and translating deflector in a controlled manner such that the beam strikes the cornea tangentially, ablating or lathing the contacted surface. The apparatus is computer controlled to intra-operatively determine the visual axis, monitor fixation, monitor changing refractive error, adjust the rotating and translating deflector and activate and deactivate the laser. The invention allows the radius of curvature of the cornea to be modified in vivo or in vitro. The cornea is lathed tangentially in either a natural or frozen state in an area centered about its optical axis, encompassing its optical zone.

Abstract: A spectacle lens comprises a liquid crystal layer and electrode assembly sandwiched between a pair of identically curved glass plates and layers of polarization material on the outer surfaces of the plates. The optical density of the lens is controlled by applying across the electrodes variable duty cycle voltage pulses having a magnitude greater than a threshold voltage of the liquid crystal layer and a frequency at least as great as the critical flicker fusion frequency of the eye. The duty cycle of the pulses is controlled in response to ambient light intensity measured by a photocell. In order to reduce response time and increase operating lifetime of the liquid crystal layer, tir-level (+V, 0, -V) rather than bilevel (+V, 0) pulses may be applied to the liquid crystal electrodes.