opticalc

Rust utilities for common clinical optics calculations used in optometry and ophthalmic settings.

Features

• Index conversion: Convert measured lens powers between assumed and actual refractive indices.
• Rx conversion: Scale full sphero‑cyl prescriptions between indices while preserving axis.
• Lensmeter simulation: Predict what a lensmeter would read for a true Rx at a different index.
• Induced prism: Compute horizontal/vertical prism from decentration using the full power matrix.
• Crossed cylinders and oblique meridian helpers.

Examples

use opticalc::*;

// Convert a measured power from 1.523 to 1.586
let true_power = convert_power(-4.463, 1.523, 1.586);

// Convert a full sphero‑cyl Rx between indices
let measured = SpheroCyl { sphere: -2.00, cylinder: -1.00, axis_deg: 180.0 };
let true_rx = convert_rx(measured, 1.523, 1.586);

// Simulate what a lensmeter @1.523 would read for a true Rx @1.586
let reading = simulate_lensmeter_reading(true_rx, 1.523, 1.586);

Induced prism from decentration (Prentice’s rule, full toric matrix):

use opticalc::*;

let lens = SpheroCyl { sphere: 2.0, cylinder: -1.0, axis_deg: 25.0 };
let dec = Decentration { horizontal_mm: 2.0, vertical_mm: -1.0 };
let p = induced_prism(Eye::OD, lens, dec);

// Access signed or magnitude/base components
let h_signed = p.horizontal.signed();
let v_signed = p.vertical.signed();
let mag = p.magnitude();