title: Design of imaging keratometer with annular object and charge-coupled device detector.
abstract: A novel imaging keratometer by the aid of modern optoelectronic technology is proposed. The optical system consists of an annular object, a first imaging subsystem, a second imaging subsystem, and a CCD detector. The measurement range of corneal refraction is from 30D to 60D (5.5-11 mm in radius of curvature), and the accuracy reaches 0.156D, 0.072D, and 0.036D, respectively, for the corneal surface of the steepest, the radius of curvature of 7.8 mm, and the corneal surface of the flattest. The accuracy of corneal astigmatism is verified to be 0.05D for cylindrical refraction of 0.75D. Compared with the traditional keratometer, the proposed keratometer possesses advantages of high accuracy.
authors: Yuanqing
authors: Y
authors: He
authors: Yan
authors: Y
authors: Wang
authors: Zhaoqi
authors: Z
authors: Wang
authors: Yao
authors: Y
authors: Wang
authors: Yongji
authors: Y
authors: Liu
authors: Lin
authors: L
authors: Zhang
authors: Yi
authors: Y
authors: Zhai
authors: Shengjiang
authors: S
authors: Chang
mesh_terms: D001251:Astigmatism / Q000175:diagnosis* / Q000503:physiopathology*; D003315:Cornea / Q000503:physiopathology*; D019781:Corneal Topography / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D010783:Photometry / Q000295:instrumentation* / Q000379:methods; D012029:Refraction, Ocular; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012666:Semiconductors; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation