Spectacle ⇄ Contact Lens Calculator
Vertex-distance compensated, power rounded to 0.25 D, axis rounded to the nearest 10°.
Direction
Spectacle → Contact lens
Spectacle → Contact lens
Right eye (OD)
Contact lens Rx—
Left eye (OS)
Contact lens Rx—
Method: each principal meridian is converted with F′ = F ÷ (1 − d·F) (spectacle → CL) or F = F′ ÷ (1 + d·F′) (CL → spectacle), then the cylinder is the difference between meridians. Always verify against clinical judgement and the lens manufacturer’s available parameters.