Automated ocular wavefront analyzer for clinical use

摘要

Higher-order optical errors of the human eye are often responsible for a reduced visual acuity in spite of an optimal sphericla or cylindrical refraction. These optical aberrations are of natural origin or can result from operations in the eye involving optical structures. The presented wavefront analyzer bases on Tscherning's aberroscope. A collimated laser beam (532 nm, 10 mW)illuminates a mask with a regular matrix of 0.3 mm diameter holes which forms a bundle of thin parallel rays. These rays are focused by a lens in front of the eye that their intraocular focus point is located in a certain distance in front of the retina generating a corresponding pattern of light spots on it. According to the existing ocular errors, this spot pattern is more or less distorted in comparison to the mask matrix. For a 6 mm pupil diameter 68 retinal spots are plottabel for the assessment of optical aberrations. The retinal spot pattern is imaged onto the sensor of a low-light CCD video camera by indirect ophthalmoscopy. the deviations of all psots from their ideal regular positions are measured by means of a PC, and from these values the introocular wave-front aberrations is computed in the form of Zernike polynomials up to the 6~th order.