Abstract:
PROBLEM TO BE SOLVED: To provide a progressive multifocal lens for spectacles which has wide near sight and intermediate visual field region at an admission rate of refracting power of >=2.5 and has a uniform distribution of spherical surface values and cylinder values. SOLUTION: This lens has a far sight visual field region (VL), the near sight visual field region (VP), the intermediate visual field region, a progressive main meridian passing these three regions and a mounting center (CM). The far sight visual field region includes an angle sector of 110 deg. in central angle of which the apex exists at the mounting center. The spherical surface value and cylinder value thereon are
Abstract:
PROBLEM TO BE SOLVED: To provide a multifocus eye lens, which secures improved peripheral view while satisfactory center visibility is maintained and to which a wearing person in easily corresponds, by distributing an equal spherical value line and an equal cylinder value line. SOLUTION: The main length of a progression shows a position along a meridian 2 equivalent to the change of an average spherical value, which is actually equal to a magnification increase. A spherical value is substantially held constant at a far sight area above a point L. Then, the spherical value substantially is held constant in a nearsight area near a point P. Namely, the main length of the progression is shorter than 16 mm and the maximum value |dS/dθ|max of the coefficient of the sine function of the average spherical value in a circle whose diameter is 40 mm, which is center-adjusted with the geometric center of the lens, is smaller than 1/4 of the maximum value Pmer of the inclination of the average spherical value along the meridian 2. That is |dS/dθ|max /Pmer
Abstract:
The invention relates to a lens with a horizontal prismatic refractive power which varies progressively along the principal meridian of progression (MM') with an addition of horizontal prismatic power greater than 2 prismatic dioptres in absolute terms. This addition of horizontal prismatic power is defined by the difference in power of horizontal prismatic refraction at a reference point (L) in the distant field of vision and the power of horizontal prismatic refraction at the point (P') of projection of the point of reference (P) in the near field of vision (VP) onto the vertical passing through the point of reference (L) of the distant field of vision.
Abstract:
A progressive multifocal ophthalmic lens having a far vision region, an intermediate vision region and a near vision region, a main meridian of progression passing through said three regions, and a power addition equal to a difference in mean sphere between a near vision region control point and a far vision region control point is provided. The lens has a progression length less than 12 mm, defined as the vertical distance between a mounting center and a point on the meridian where mean sphere is greater than mean sphere at the far vision control point by 85% of the power addition value. To ensure excellent optical performance of the lens despite this short length of progression, the ratio between the product of cylinder times the norm of sphere gradient, and the square of power addition is less than 0.08 mm-1 at every point within a 40 mm diameter disc centered on the center of the lens. Additionally, cylinder within that part of the disc situated above the mounting center is less than 0.5 times power addition.
Abstract:
The lens, which includes long and near vision zones, has an aspherical surface with a mean sphere and cylinder at all points defined by the relationship: L1/(-0.031 0.139R 0.014) where L is equal to the relationship (Smax - Smin)/gradSmax between the maximum and minimum values of the mean sphere in a zone with a circle of 40 mm diameter centred on the geometrical centre of the lens, and R is equal to the relationship Cmax/(Smax - Smin) between the maximum value of the cylinder inside the aforementioned circle and the difference between maximum and minimum values of the sphere in the zone.
Abstract:
A progressive multifocal ophthalmic lens is provided having an aspherical surface with a mean sphere and a cylinder at every point. The aspherical surface has a distance vision portion, with a control point for distance vision, a near vision portion with a control point for near vision, and an intermediate vision portion between the near vision portion and the distance vision portion. A power addition value A is defined as a variation in mean sphere between the control point for distance vision and the control point for near vision portion. A base B is defined as a value of mean sphere at the control point for distance vision. A width of the near vision portion varies not only as a function of the power addition value A, but also as a function of the value B of the base. The invention thereby ensures the presence of a substantially constant object field for all values of the power addition and of the base.
Abstract:
The lens has a mean sphere and a cylinder at each of points of an aspherical surface of the lens. A main progression meridian passes through far, near and intermediate vision regions. Differences between maximum cylinder values over a distance of 20 mm at both sides of the meridian have an absolute value less than or equal to 0.30 diopters. An absolute value of difference between maximum and minimum values of cylinder at each side of the meridian is less than or equal to the product of power addition and a constant having a value of 0.10. The power addition is defined as a difference in the mean sphere between a reference point (VP) of the near vision region and a reference point (VL) of the far vision region, and is greater than or equal to 2.50 diopters.
Abstract:
A progressive multifocal ophthalmic lens is provided having an aspherical surface comprising a distance vision portion, a near vision portion and an intermediate vision portion, in which the maximum mean sphere gradient value is situated in the intermediate vision portion of the principal meridian of progression of the lens, and the cylinder gradient over the whole aspherical surface of the lens is less than the product obtained by multiplying the power addition value at each point by a constant value coefficient.
Abstract:
LENTE OFTALMICA MULTIFOCAL PROGRESIVA. LA LENTE MULTIFOCAL PROGRESIVA DE LA INVENCION COMPRENDE UNA SUPERFICIE ESFERICA (S), CON UNA ZONA DE VISION DE LEJOS (VL), UNA ZONA DE VISION DE CERCA (VP), UNA ZONA DE VISION INTERMEDIA (VI), UNA MERIDIANA PRINCIPAL DE PROGRESION (MM''); TIENE UNA ADICION DE POTENCIA A IGUAL A LA VARIACION DE ESFERA MEDIA ENTRE UN PUNTO (L) DE LA ZONA DE VISION DE LEJOS (VL) Y UN PUNTO (P) DE LA ZONA DE VISION DE CERCA (VP), Y UNA BASE B O VALOR DE ESFERA MEDIA EN DICHO PUNTO (P). LA ANCHURA DE LA ZONA DE VISION DE CERCA (VP) VARIA NO SOLO EN FUNCION DE LA ADICION DE POTENCIA A, SINO TAMBIEN EN FUNCION DEL VALOR DE LA BASE B, A FIN DE ASEGURAR UN CAMPO OBJETO SENSIBLEMENTE CONSTANTE PARA TODOS LOS VALORES DE ADICION Y DE BASE.