Ophthalmic progressive addition lens for an emmetropic and presbyopic wearer and method of providing same

A method implemented by computer means for providing an ophthalmic progressive addition lens to an emmetropic and presbyopic wearer having a prescribed far vision mean refractive power greater than minus 1 Diopter and less than plus 1 Diopter and a non nil prescribed addition, ADDp, comprising the step of calculating a mean refractive power repartition, PPO(α, β), a module of resulting astigmatism repartition, ASR(α, β), an acuity loss value repartition ACU(α, β), where said (α, β) functions are calculated in as-worn conditions of the lens by the wearer, so as to fulfil following requirement of a first acuity criterion, AcuityCriterion1:

• AcuityCriterion1≥435 D2.deg2;
• “D” refers to Diopter, “deg” to degree, AcuityCriterion1 is defined as a combination of PPO(α, β), ASR(α, β), ADDp, and ACU(α, β), wherein the method further comprising the following steps:
• calculating or defining a meridian line, ML(α, β),
• calculating or defining a fitting cross, FC(αFC, βFC),
• calculating the mean refractive power, PPO(α, β), and the module of resulting astigmatism, ASR(α, β), determined in as-worn conditions of the lens by the wearer for gaze directions (α, β) joining the center of rotation of the eye, CRE, and the lens, where α is a lowering angle in degree and β is an azimuth angle in degree, an acuity loss value ACU(α, β) is expressed in logMAR and defined according to following equation:
• ACU(α,β)=−log(AC %(α,β)/100), where:
• AC %(α, β)=100−63×P(α, β)−44.3×ASR(α, β)+7.2×P(α, β)2+19.5×P(α, β)×ASR(α, β)+ASR(α, β)2;
• when P(α, β)≥0;
• and
• AC %(α, β)=100−44.3×ASR(α, β)+ASR(α, β)2;
• when P(α, β)<0;
• P(α, β)=PPO(α, β)−PPO(α, β_α_mer):
• β_α_mer is the value of the azimuth angle β on the meridian line, ML(α, β), at the lowering angle α;
• and where AcuitvCriterionl=Numerator1/Denominator:
• Numerator1=LAcuSub85(0.1)×LAcuAlpha85(0.1)×ADDp4;
• Denominator=AsrGradMax×PeaksMean×PVL2;
• LAcuSub85(0.1) is the angular extent (in deg2) of the zone where ACU(α, β)≤0.1 logMAR, inside a circle, CIR, centered on (α, β)=(12,0), which radius is 35 degrees, and where α≥α85%, α85% being the lowering angle where 85% of the prescribed addition is perceived by the wearer on the meridian line;
• LAcuAlpha85(0.1) is the acuity width (in deg) at α85% between two iso-acuity loss lines corresponding to 0.1 logMAR and is equal to:
• β+(ACU(α85%, β)=0.1)−β−(ACU(α85%, β)=0.1), where β+ is greater than β_α_mer(α85%) and β− is less than β_α_mer(α85%);
• PVL is the power variation length is expressed in deg and defined as being equal to (α85%−α15%), α15% being the lowering angle where 15% of the prescribed addition is perceived by the wearer on the meridian line;
• AsrGradMax is the maximum value of the norm of the gradient of resulting astigmatism, ASR(α, β), expressed in Diopter per degree, calculated inside a circle, CIR, centered on (α, β)=(12,0), which radius is 35 degrees;
• PeaksMean is the mean maximum module of resulting astigmatism (in Diopter) which is equal to [ASRmax(αL, βL)+ASRmax(αR, βR)]/2, where ASRmax(αL, βL) is the maximum module of resulting astigmatism on a side (left side) of the meridian line, and ASRmax(αR, βR) is the maximum module of resulting astigmatism on the other side (right side) of the meridian line that are both determined inside a circle, CIR, centered on (α, β)=(12,0), which radius is 35 degrees.