Process For Determining A Pair Of Progressive Ophthalmic Lenses

摘要

A process for determining a pair of personalized progressive ophthalmic lenses. and a computer program product associated to these processes. Right-handed persons and left-handed persons behave very differently when executing certain near vision tasks, such as writing on a sheet of paper. However, current lens designs do not take into account these behaviour differences. The comfort of wearing a pair of ophthalmic lenses can be improved for the wearer for whom the lenses are intended by adapting his near vision according to his handedness.

主权项

1. A process for determining a pair of progressive ophthalmic lenses comprising the steps of:
determining a prescribed far vision mean power (PFV) for each lens of the pair; determining a prescribed addition (A) for each lens of the pair; determining laterality of a wearer; defining a temporal side and a nasal side on each lens of the pair; defining, on each lens being worn and for each gaze direction, a refractive power (Pα,β) and a module of resulting astigmatism (Asrα,β), each gaze direction corresponding to a lowering angle (α) and to an azimuth angle (β); defining a proximate vision gaze direction (αPV, βTP) for each lens of the pair; defining, for each lens of the pair, a temporal half-width field of refractive power (TP—LE, TP—RE) as the angular distance, at constant lowering angle (α), between the proximate vision gaze direction (αPV, βPV) and a gaze direction (αPV, βNP) on the temporal side of the lens where the refractive power reaches the value of the prescribed far vision mean power plus three quarters of the prescribed addition (PFV+¾*A); defining, for each lens of the pair, a nasal half-width field of refractive power (NP—LE, NP—RE) as the angular distance, at constant lowering angle (α), between the proximate vision gaze direction (αPV, αPV) and a gaze direction (αPV, βNP) on the nasal side of the lens where the refractive power reaches the value of the prescribed far vision mean power plus three quarters of the prescribed addition (PFV+¾*A); defining, for each lens of the pair, a temporal half-width field of module of resulting astigmatism (TA—LE, TA—RE) as the angular distance, at constant lowering angle (α), between the proximate vision gaze direction (αPV, βPV) and a gaze direction (αPV, βTA) on the temporal side of the lens where the module of resulting astigmatism reaches the value of one quarter of the prescribed addition (A/4); defining, for each lens of the pair, a nasal half-width field of module of resulting astigmatism (NA—LE, NA—RE) as the angular distance, at constant lowering angle (α), between the proximate vision gaze direction (αPV, βPV) and a gaze direction (αPV, βNA) on the nasal side of the lens where the module of resulting astigmatism reaches the value of one quarter of the prescribed addition (A/4);wherein the ratio of the difference over the sum of temporal and nasal half-width fields of refractive power ((TP—LE−NP—LE)/(TP—LE+NP—LE), (TP—RE−NP—RE)/(TP—RE+NP—RE)) and/or the ratio of the difference over the sum of temporal and nasal half-width fields of module of resulting astigmatism ((TA—LE−NA—LE)/(TA—LE+NA—LE), (TA—RE−NA—RE)/(TA—RE+NA—RE)) are determined for each lens of the pair based on the laterality of the wearer.