Compounding & Resolving Prism Calculator

This calculator converts ophthalmic prism prescriptions between a single oblique (diagonal) prism and its separate horizontal and vertical components, using vector mechanics to handle prism that acts across two planes at once. It works in two directions: compounding separate horizontal and vertical prism values into one resultant diagonal power and base angle, or resolving a single oblique prism back into its horizontal and vertical parts.

Enter either horizontal and vertical prism values (to compound) or a single prism power and base angle (to resolve), and the calculator handles the trigonometric conversion automatically. Use this to verify prism prescriptions on a lensometer, split prism between lens surfaces, or manufacture the exact combined effect a doctor has prescribed for patients with binocular vision dysfunction or eye alignment issues.

Unlike calculators that only deal with standard lens power, this tool operates on the principles of vector mechanics to handle how light bends through a lens simultaneously across two planes. It features two distinct functions depending on the direction of your workflow:

  • Compounding Prisms: This mode takes separate horizontal prism (Base In/Out) and vertical prism (Base Up/Down) values for one or both eyes and "compounds" them. It calculates the net diagonal prism force (the resultant) and the exact 360-degree base angle required to manufacture that exact combined effect into a single lens.
  • Resolving Prisms: This mode does the exact opposite. If an eye doctor prescribes a single prism power at an oblique, diagonal base angle, lab software or an optician can "resolve" that value. The calculator breaks it back down into standard horizontal and vertical components, making it easier to verify on a lensometer or split between different lens surfaces.

By automating the trigonometric vector equations required for these shifts, the calculator ensures that optical labs can precisely surface or finish intricate prism prescriptions for patients dealing with binocular vision dysfunctions or eye alignment issues.

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