Position of Wear

By Darryl Meister, ABOM, Carl Zeiss Vision
Wednesday, May 1, 2013 2:50 PM POW or "position of wear" is a term that is used to describe the way that an eyeglass frame positions lenses in front of the eye.

Adapted from the Evolution of Anti-Reflective Coatings, Part 1

By Darryl Meister, ABOM, Carl Zeiss Vision
Monday, September 17, 2012 12:07 AM Each surface of a spectacle lens reflects a significant amount of incident light, resulting in both cosmetic and visual consequences.

Adapted from the Evolution of Anti-Reflective Coatings, Part 2

By Darryl Meister, ABOM, Carl Zeiss Vision
Sunday, September 16, 2012 11:00 PM In 1935, the first anti-reflective (AR) coating was invented at Carl Zeiss. These coatings significantly reduced annoying lens reflections while increasing light transmittance and visual clarity.

Adapted from the Evolution of Anti-Reflective Coatings, Part 3

By Darryl Meister, ABOM, Carl Zeiss Vision
Sunday, September 16, 2012 10:58 PM Anti-reflective lenses usually have three or more thin layers of ceramic or metal oxide on each side of the lens. By varying the refractive index of each layer, reflections from one layer can be made to interact with reflections from the next layer.

Lens Design

By Darryl Meister, ABOM
Thursday, November 10, 2011 9:03 PM The ability of a lens to refract and focus light—by either converging or diverging it—is referred to as its focal power or refractive power.

Base Curve Selection

By Darryl Meister, ABOM
Tuesday, November 8, 2011 9:25 PM The form of a given lens is determined by "base curve selection." The base curve of a lens is the surface curve that serves as the basis or starting point from which the remaining curves will be calculated.

Mechanical Factors of Lens Form

By Darryl Meister, ABOM
Tuesday, November 8, 2011 7:33 PM The maximum thickness of a lens, for a given prescription, varies with the form of a lens. Flatter lens forms are slightly thinner than steeper lens forms, and vice versa.

Optical Factors of Lens Forms

By Darryl Meister, ABOM
Monday, November 7, 2011 5:33 AM The principal impetus behind lens form selection is optical performance. Base curves are typically chosen to provide a wide field of clear vision.
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