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20 Cards in this Set
- Front
- Back
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Axis meridian |
The meridian of least power of a cylinder or spherocylinder lens |
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Axis of a cylinder |
An imaginary reference line used to specify cylinder orientation |
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Base curve |
The front surface curve of a lens which all other curves are based off of |
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Back base curve |
The weaker back surface curve of a minus cylinder lens |
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Nuetralize |
To find power of a lens |
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Cylinder |
A lens having a refractive power in one meridian only and used in the correction of astigmatism |
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Focal point |
The point at which Ray's of light passing through a lens are brought to focus |
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Minus cylinder form lens |
A lens with two curves on the back,expressed on a minus form |
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Nominal power |
An estimate of total lens power,calculated as the sum of front and back surface curves |
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Optical center |
The point at which light passes through a lens undeviated |
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Plus cylinder form lens |
A lens that the cylinder is expressed as a positive number |
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Power cross |
A schematic representation of the 2 major meridians of a lens surface |
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Power meridian |
The meridian of maximum power of a cylinder or spherocylinder lens |
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Refractive power |
The ability of a lens to bend light |
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Real image |
The focal point of a plus power lens |
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Virtual image |
The focal point of a minus power lens |
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Diopter |
The unit of refractive power of a lens |
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Convex curve |
The front outward curve of a lens,and sometimes the back curve in extremely high minus lenses |
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Concave curve |
The back inward curve of a lens,and sometimes the front curve in extremely high minus lenses |
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Meniscus lens |
A lens having both convex and concave curves, the most common lens |
