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Vertex Distance Conversion

Converts a spectacle lens power at one vertex distance to the equivalent power at another (e.g. spectacle plane to corneal plane) — most clinically relevant for powers beyond about ±4D.

For healthcare professionals.These calculate a score or a measurement from values you enter. They do not diagnose, and they are no substitute for clinical judgement. If you are a patient, discuss any result with your own doctor rather than acting on it.

Original Power (F1)D

Original Vertex Distancemm

New Vertex DistanceUse 0 for the corneal plane (e.g. for a contact lens equivalent).mm

Enter the values above to see the result.

Source

Standard clinical optics — vertex distance power conversion formula (thin lens equation applied at two vertex planes).

Shown for reference and checked against the source above. Confirm against current guidance before acting on it, and use your own clinical judgement.

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