ABO, ABO Study Guide QUESTIONS AND ANSWERS

ABO, ABO Study Guide Prentice Rule - (Power x distance in mm) /10 Cornea index of refraction - 1.37 Tear Film, Vitreous index of refraction - 1.33 Crystalline lens index of refraction - 1.42 Optical Standard index of refraction - 1.53 Crown Glass index of refraction - 1.523 High index of refraction - 1.74 CR-39 index of refraction - 1.49/1.50 Poly index of refraction - 1.586 Air - 1.00 How fast does light travel through air - 186,000 mi/sec MBS formula - ED+2 (decentration)+2 Focal length formula - 1/Dioptic Power power Dioptic Power formula - 1/Focal Length Antimetropia - Rx with unlike signs in both eyes Anisometropia - Difference of 2 diopters btwn OD & OS Anisiekonia - When images from right and left eye are so different the brain can not achieve fusion What is the Radius of a 1 diopter curve? - 530mm Radius formula - 530/Power = Radius Power formula - 530/Radius = Power Vertical Decentration formula - S. - B/2 How much HORIZONTAL prism tolerance is allowed? - 2/3 of a diopter -or- 0.667 How much VERTICAL prism tolerance is allowed? - 1/3 of a diopter -or- 0.333 Base Curve tolerance - +/-0.75 Sphere Tolerance up to 6.50 - +/- 0.13