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| Effect on Optometry for Decentration and Tilt of Lenses in Phoropters |
| ZHANG Ji-yan1,2,LIU Wen-li1,SUN Jie1 |
1. Division of Metrology in Ionizing Radiation and Medicine, National Institute of Metrology, Beijing 100013, China
2. Information and Technology School, Beijing Institute of Technology, Beijing 100081, China |
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Abstract With the basic principle of geometric optics and ophthalmic dioptrics, the effect on decentration and tilt of lenses in phoropters is analyzed theoretically and verified by ZEMAX software. Results show that decentration in lenses will introduce extra prismatic power, and tilt will introduce error not only in prismatic power but also in spherical and cylindrical power. Moreover, if front and back surface of one single lens are tilted from two opposite directions, the error will be much bigger than that tilted from the same direction. Besides, the effect of decentration is a little more significant than that of tilt in assembly. Therefore, decentration and tilt from two opposite directions for front and back surface of a lens should be avoided possibly in production and assembly of phoropters.
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2010, Vol. 31 
