Plus-minus Cylinder Converter

Convert plus cylinder prescriptions to minus cylinder prescriptions or vice-versa.

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Oblique Fresnel Calculator

Calculate what magnitude and orientation of Fresnel prism when both horizontal and vertical prism is needed.

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Contact Lens Vertexing Calculator

Calculate contact lens power needed based off refraction data.

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Javal's Rule Calculator

Calculate estimated residual astigmatism based off corneal Ks.

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Visual Acuity From Letter Size Calculator

Calculate visual acuity from letter size and distance

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Cycles Per Centimeter to Visual Acuity Calculator

Calculate visual acuity from cy/cm and distance.

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