Abstract:
A method of designing and evaluating a progressive power lens where the intersection of the wearer's line of sight, and the refractive surface of the lens is the primary line of fixation (L), the positions upon the primary line of fixation corresponding to far-field vision and near-field vision are the points (F) and (ON), respectively, and the distance of the displacement of (ON) toward the nose in the horizontal direction relative to (F) is the inward shift (OI). Upon the principal meridian curve (M) passing through (F), the point at which the profile curve (H) passing through (ON) in the horizontal direction and (M) is (DN), the displacement of (DN) towards the nose in the horizontal direction relative to (F) is the inward shift (DH), and OI
Abstract:
To provide a bi-aspherical type progressive-power lens which provides an excellent visual acuity correction for prescription values and a wide effective visual field with less distortion in wearing, by reducing a magnification difference of an image between a distance portion and a near portion of a lens, and a method of designing the same.A progressive action of a progressive-power lens is divided in the vertical direction and the horizontal direction of the lens and then an optimal sharing ratio between the front and rear two surfaces of the object side and the eyeball side is set in each direction to configure one bi-aspherical type progressive-power lens, a sharing ratio of a progressive action in the horizontal direction of a rear surface (eyeball side surface) is set higher so that an advantage of increasing the visual field in the horizontal direction can be obtained, a sharing ratio of a progressive action in the vertical direction of a front surface (object side surface) is set higher so that a disadvantage of increasing an eyeball turning angle between the distance and near portions in the vertical direction can be restrained, also a wide effective visual field with less distortion in wearing can be provided by reducing a magnification difference of an image between the distance portion and the near portion on the progressive-power lens, further making it possible to obtain a bi-aspherical type progressive-power lens capable of reducing a machining time and cost by making it possible to machine only the surface of an eyeball side as a bilaterally asymmetrical curved surface coping with a convergence action of an eye in near vision after receiving an order, by using “bilaterally symmetrical semi-finished product” as an object side surface of the progressive refractive power lens.
Abstract:
An improved ophthalmic lens for presbyopia is disclosed in which the refractive power is progressively changed to provide a natural visual target arrangement. In the opthalmic lens, rotation of the head of a wearer for binocular lateral vision is taken into account to permit comfortable binocular lateral vision closer to vision with the naked eyes.
Abstract:
A method provides for manufacturing progressive-power lenses in a manner in which an inventory burden of semis can be reduced. A progressive-power lens is designed by arranging a progressive-power surface on a convex surface and combining the convex surface with a concave surface so as to meet prescription values of a spectacles wearer. The method for manufacturing progressive-power lenses includes previously preparing the concave surface side as a concave surface semi group based on a predetermined classification table, selecting a most suitable semi-finished lens according to an order, designing a progressive-power surface on the convex surface side by adding the difference between cylindrical component of a most suitable concave surface semi selected based on an order and cylindrical component of the prescription values to the concave surface side so as to meet the prescription values, and finishing the lens by performing free-form processing.
Abstract:
A method of designing and evaluating a progressive power lens where the intersection of the wearer's line of sight, and the refractive surface of the lens is the primary line of fixation (L), the positions upon the primary line of fixation corresponding to far-field vision and near-field vision are the points (F) and (ON), respectively, and the distance of the displacement of (ON) toward the nose in the horizontal direction relative to (F) is the inward shift (OI). Upon the principal meridian curve (M) passing through (F), the point at which the profile curve (H) passing through (ON) in the horizontal direction and (M) is (DN), the displacement of (DN) towards the nose in the horizontal direction relative to (F) is the inward shift (DH), and OI
Abstract:
To provide a bi-aspherical type progressive-power lens which provides an excellent visual acuity correction for prescription values and a wide effective visual field with less distortion in wearing, by reducing a magnification difference of an image between a distance portion and a near portion. The lens is characterized in that when on a first refractive surface being an object side surface, a surface refractive power in a horizontal direction and a surface refractive power in a vertical direction, at a far vision diopter measurement position F1, are DHf and DVf respectively, and on the first refractive surface, a surface refractive power in a horizontal direction and a surface refractive power in a vertical direction, at a near vision diopter measurement position N1, are DHn and DVn respectively, relational equations, DHf+DHn
Abstract:
There is provided a group of bi-aspherical type progressive-power lenses for which the processing costs are reduced. In a bi-aspherical type progressive-power lens(es), the relationships DHf+DHn ADD/2 and DHn−DHf
Abstract:
There is provided a group of bi-aspherical type progressive-power lenses for which the processing costs are reduced. In a bi-aspherical type progressive-power lens(es), the relationships DHf+DHn ADD/2 and DHn−DHf
Abstract:
To provide a bi-aspherical type progressive-power lens which provides an excellent visual acuity correction for prescription values and a wide effective visual field with less distortion in wearing, by reducing a magnification difference of an image between a distance portion and a near portion. The lens is characterized in that when on a first refractive surface being an object side surface, a surface refractive power in a horizontal direction and a surface refractive power in a vertical direction, at a far vision diopter measurement position F1, are DHf and DVf respectively, and on the first refractive surface, a surface refractive power in a horizontal direction and a surface refractive power in a vertical direction, at a near vision diopter measurement position N1, are DHn and DVn respectively, relational equations, DHf+DHn
Abstract:
To provide a bi-aspherical type progressive-power lens which provides an excellent visual acuity correction for prescription values and a wide effective visual field with less distortion in wearing, by reducing a magnification difference of an image between a distance portion and a near portion. The lens is characterized in that when on a first refractive surface being an object side surface, a surface refractive power in a horizontal direction and a surface refractive power in a vertical direction, at a far vision diopter measurement position F1, are DHf and DVf respectively, and on the first refractive surface, a surface refractive power in a horizontal direction and a surface refractive power in a vertical direction, at a near vision diopter measurement position N1, are DHn and DVn respectively, relational equations, DHf+DHn