| 摘要 |
A method of designing a soft contact lens to correct a visual defect in the eye of a human subject caused by abnormal corneal topography, comprises the steps of: (a) defining the posterior topography of the lens over at least a central optic zone to conform to that of the subject's cornea as previously determined; (b) defining the posterior topography of the lens over an outer portion to provide a flatter curve than that of the cornea, whilst retaining the previously defined topography over the central optic zone of the lens; (c) using empirical or theoretical data to predict or model the path of light rays passing from the cornea into the contact lens, and thereby adapting the topography of the anterior surface of the contact lens, over at least the central optic zone, to cause the light rays passing through the lens to conform to a desired wavefront (typically planar); and (d) defining the anterior surface of the contact lens over the outer portion to join the anterior optic zone to the posterior outer portion, the anterior surface over the outer portion conveniently comprising one or more thickened regions to confer rotational and/or translational stability on the lens in ocula. The topology of the subject's cornea may have been previously determined using a corneal topographer. The results are used to make a contact lens which can be done by casting or cutting with a CNC lathe. |
