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| What are the 4 Base Curve Rules? |
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Definition
That curve from which all other curves are determined
For a cylindrical surface, the flattest (lowest) curve on that surface
In a single vision lens, the flattest curve on the front surface
In bifocals, the only curve on the same side as the segment (always a sphere) |
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Term
| What is the first rule of base curve |
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Definition
| That curve from which all other curves are determined |
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Term
| What is the second rule of base curve |
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Definition
| For a cylindrical surface, the flattest (lowest) curve on that surface |
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Term
| What is the third rule of base curve |
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Definition
| In a single vision lens, the flattest curve on the front surface |
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Term
| What is the fourth rule of base curve |
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Definition
| In Bifocals, the only curve on the same side as the segment (always a sphere) |
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Term
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R = N-1 D = N-1
D R
Inverse relationship |
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| Spherical Equivalent Formula |
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Definition
DS = Sph + Cyl
2
ex: RX: +1.00 -3.00 x90
DS = 1 + (-3.00/2) = -0.50 |
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Term
| True/Marked Power formula |
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Definition
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| Back Vertex Power formula |
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Definition
De = D1 + D2 + Tmeters (D1) ^2
N |
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| American National Standards Institute |
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| Occupational Safety and Health Administration |
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| Health Insurance Portability and Accountability Act |
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| Food & Drug Administration |
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Thicker at the edge
Minifies images
Has with motion
Diverges incident light rays
Corrects for myopia (nearsightedness) |
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Definition
Parallel light rays focus in front of the retina
The eye is too strong or the globe is too long |
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