Spectacle lens selection method and spectacle lens selection system

1. A spectacle lens selection method to select a single spectacle lens including a distance portion, a progressive corridor, and a reading portion from a plurality of target spectacle lens, the method comprising:

determining a horizontal fixation field width Fw, the Fw extending from a distance eyepoint in a horizontal direction;

measuring an eyeball infraduction value Indih, the Indih being a length from the distance eyepoint to a reading eyepoint;

determining a ΔE from Equation (1) based on the Indih, a distance portion eyepoint height Fh from a boundary between the distance portion and the progressive corridor to the distance eyepoint, a progressive corridor length SPh, the SPh being a length from the boundary between the distance portion and the progressive corridor to a boundary between the progressive corridor and the reading portion, and a reading portion eyepoint height Nh from the boundary between the progressive corridor and the reading portion to an optical center of the reading portion;

determining a th from Equation (2) based on the Fh, the SPh, and the Nh;

determining an upper frame height Oh from the distance eyepoint to an upper end of a test spectacle lens from Equation (3) based on a lens portion height Bh of the test spectacle lens, the th, the ΔE, and a lower frame height Uh from a lower end of the test spectacle lens to the reading eyepoint,

Δ E=Indih −( Fh+SPh+Nh )  (1)

th=Fh+SPh+Nh   (2)

Oh=Bh −( th+ΔE+Uh )  (3);

judging a target spectacle lens satisfied the Fw and conditions of 0 mm≦ΔE≦2 mm and 0 mm<Oh; and

selecting a spectacle lens satisfied the Fw and the conditions.

2. The spectacle lens selection method according to claim 1 , wherein

judging the target spectacle lens is first carried out for a spectacle lens having narrow distance portion,

when the Fh does not satisfy a predetermined condition, judging the target spectacle lens is carried out for a spectacle lens having wider distance portion than the spectacle lens having narrow distance portion.

3. The spectacle lens selection method according to claim 2 , wherein

in selecting a single spectacle lens having a horizontal fixation field width Fw greater than 6 mm from three types of target spectacle lens, first spectacle lens having narrow distance portion, second spectacle lens having wide distance portion, and third spectacle lens having intermediate distance portion, the first spectacle lens is selected when 4 mm<Fh, the third spectacle lens is selected when 3 mm<Fh≦4 mm, and the second spectacle lens is selected when 1 mm≦Fh≦3 mm.

4. The spectacle lens selection method according to claim 2 , wherein

in selecting a single spectacle lens having a horizontal fixation field width Fw greater than 4.5 mm but smaller than or equal to 6 mm from three types of target spectacle lens, first spectacle lens having a narrow distance portion, second spectacle lens having a wide distance portion, and third spectacle lens having a intermediate distance portion, the first spectacle lens is selected when 3 mm<Fh, the third spectacle lens is selected when 2.5 mm<Fh≦3 mm, and the third spectacle lens is selected when 0.8 mm≦Fh≦2.5 mm.

5. The spectacle lens selection method according to claim 2 , wherein

in selecting a single spectacle lens having a horizontal fixation field width Fw greater than 3.75 mm but smaller than or equal to 4.5 mm from three types of target spectacle lens, first spectacle lens having a narrow distance portion, second spectacle lens having a wide distance portion, and third spectacle lens having a intermediate distance portion is intermediate, the first spectacle lens is selected when 2.5 mm<Fh, a third spectacle lens is selected when 2 mm<Fh≦2.5 mm, and the second spectacle lens is selected when 0.5 mm≦Fh≦2 mm.

6. The spectacle lens selection method according to claim 3 , wherein

the Fw is determined from Equation (4) based on a horizontal fixation field angle Fa and a spectacle fitting distance EL between the distance eyepoint and the eyeball:

Fw=EL ×tan Fa   (4).

7. The spectacle lens selection method according to claim 6 , wherein

the Fa is a predetermined range value.

8. A spectacle lens selection system to select a spectacle lens including a distance portion, a progressive corridor, and a reading portion, the system comprising:

a horizontal fixation field width determination unit that determines a horizontal fixation field width Fw, the Fw extending from a distance eyepoint of a test spectacle lens in a horizontal direction;

an eyeball infraduction value measurement unit that measures an eyeball infraduction value Indih, the Indih being a length from the distance eyepoint to a reading eyepoint; and

a selection unit that selects a single spectacle lens from a plurality of types of target spectacle lens based on information containing a value measured by the eyeball infraduction value measurement unit, the selection unit including;

unit a computation section that determines;

a ΔE from Equation (1) based on the Indih, a distance portion eyepoint height Fh from a boundary between the distance portion and the progressive corridor to the distance eyepoint, a progressive corridor length SPh, the SPh being a length from the boundary between the distance portion and the progressive corridor to a boundary between the progressive corridor and the reading portion, and a reading portion eyepoint height Nh from the boundary between the progressive corridor and the reading portion to an optical center of the reading portion;

a th from Equation (2) based on the Fh, the SPh, and Nh; and

an upper frame height Oh from the distance eyepoint to an upper end of a test spectacle lens from Equation (3) based on a lens portion height Bh of the test spectacle lens, the th, the ΔE, and a lower frame height Uh from a lower end of the test spectacle lens to the reading eyepoint,

Δ E=Indih −( Fh+SPh+Nh )  (1)

th=Fh+SPh+Nh   (2)

Oh=Bh −( th+ΔE+Uh )  (3); and

a judgment section that judges a target spectacle lens that satisfies the Fw unit and conditions of 0 mm≦ΔE≦2 mm and 0 mm<Oh, and selects a spectacle lens that satisfied the Fw and the conditions.

9. The spectacle lens selection system according to claim 8 ,

the eyeball infraduction value measurement unit further includes;

a sight line position detecting unit that detects a position of a sight line of a spectacle wearer that corresponds to the distance eyepoint and a position of the sight line of the spectacle wearer that corresponds to the reading eyepoint, and

a length calculating unit that calculates a length between the position of the distance eyepoint and the position of the reading eyepoint detected by the sight line position detecting unit and outputs a calculated value to the computation section.

10. The spectacle lens selection system according to claim 9 , further comprising

a forward inclination angle measuring unit that measures a forward inclination angle of a frame to which the test spectacle lens is attached.