Abo study Test Summary

Abo study Abbe Value - A numerical expression of how prone a lens material is to causing chromatic aberration. The higher the Abbe Value the lower the chance it will cause aberration Aberration - An unclear image of an object when viewed through a lens. ABO - American Board of Opticianary an agency that provides various levels certification for persons in the field. It is only a written exam not a practical. Accommodation - The ability for the eye's crystalline lens to change shape and add and reduce power to see things at different distances. Amblyopia - Visual acuity difficulties without a specific or detectable refraction error. Anisometropia - A substantial difference in the refractive powers of each eye. Aphakia - A person that has had their crystalline lens removed. Aspheric - Not spherical or not perfectly round. Asthenopia - Eye fatigue Astigmatism - A misshapen cornea that causes light entering the eye to focus on many points instead of one. Auto-refractor - A specialized instrument used to provide a doctor or tech with a baseline patient RX Axis - A numeric expression of the position of the spherical portion of the prescription when it is the place in front of the eye. Base Curve - The front curve of an ophthalmic lens. In older and now outdated surfacing it is/was the curve from which all other curves are/were measured. Bi-Centric Grind - Another term for slab-off. Boxing System - A way of dividing a frame into geometric shapes for measuring. Box-O-Graph - A tool used in labs to measure lenses and frames. Brow-Bar - The bar or bars that connect the tops of the eyewires in traditional men's frames. C-Sizer - A tool used to measure the circumference of a cut lens. Caliper - The tool used to measure the thickness of a lens. Cataract - Clouding of a crystalline lens caused by age. Chromatic Aberration - The breaking down of white light into its component colors due to a lens material optical properties. (R,O,Y,G,B,I,V)