Vectofocimetry: Dioptric power measurement in manual focimeters using power vectors

Highlights

• Power vectors are used for direct dioptric power measurement in ophthalmic lenses.

• Validation is implemented in a manual focimeter including the needed modifications showing comparable results with the conventional procedure.

• The proposed device/methodology is also valid for marking the lenses prior to being assembled in spectacle frames.

• The main advantages are the improvement in usability in focimeters and the elimination of the error during wrong annotation of the results.

• The proposed concept can be the background technology of a new generation of automatic focimeters.

Abstract

Dioptric power measurement is classically achieved using manual focimeters. In this contribution, we present vectofocimetry as a novel methodology to be easily implemented in manual focimeters for improving their capabilities regarding dioptric power measurement. The new procedure is conceptually based on power vector formalism of dioptric power which represents the dioptric power as three values in the form of [M, J₀, J₄₅], it uses an iterative process of blur reduction, and it only requires a few modifications in the device that are easy-to-adapt and cost-effective. As a result, dioptric power measurements are easily and quickly obtained with comparable results to the reported ones using the traditional method but with some improvements concerning: i) comfortability/usability (no need to see through the device), ii) elimination of the accommodation user's error (no need to adjust the ocular for every user), and iii) elimination of the measurement error coming from wrong interpretation/annotation of the cylinder axis (the test reticle is focused at once as a whole). The new device is presented, the measurement methodology is rigorously described, and proof-of-principle validation is included showing comparable results between the proposed procedure/device and the conventional ones for dioptric power determination. In addition, definition of the marking methodology has been also included and described. Next steps can be directed towards automatization of the measurement process at both levels (decision for final measurement point and avoiding the manual use of the device) thus opening the gate as a potential technology for a new generation of automatic focimeters.