Current topographers cannot measure the shape of a rough corneal surface. The proposed instrument will measure the shape of a roughened corneal surface with sufficient accuracy to determine the refractive change to better than 1/4 diopter. The goal is to provide a measurement device which, when incorporated into a refractive laser system, significantly improves the accuracy of the delivered ablation. This will result in better patient vision and significantly reduce the number patients requiring additional ablations. Variations in excimer laser output energy, beam quality, and corneal hydration cause errors in the refractive correction from PRK and LASIK. In addition, the currently used techniques for laser ablation diagnostics are often less than adequate. Real time topography data from the proposed instrument will allow ablating laser systems to correct for variations and prevent system malfunctions from damaging a patient's cornea. Details of the measurement technique are presented including transverse and vertical resolution, signal to noise ration, and measurement speed. The vertical measurement range is sufficient to account for corneal curvature and the device can be located 20cm from the cornea. High speed sampling is used to minimize the effect of corneal movement.
The commercial applications of the technology being developed under this grant are: 1. Measurement and quality control of precision mechanical components. 2. Non-contact vibration measurement at frequencies up to 200 kHz. 3. Process control for precision grinding. 4. Feedback system for micro machining. 5. Measurement feedback for hard contact lens manufacturing.
