GB2038020A - Ophthalmic Optical System, its Refraction Measurement, and Frame Therefor - Google Patents
Ophthalmic Optical System, its Refraction Measurement, and Frame Therefor Download PDFInfo
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- GB2038020A GB2038020A GB7932380A GB7932380A GB2038020A GB 2038020 A GB2038020 A GB 2038020A GB 7932380 A GB7932380 A GB 7932380A GB 7932380 A GB7932380 A GB 7932380A GB 2038020 A GB2038020 A GB 2038020A
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- G—PHYSICS
- G02—OPTICS
- G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
- G02C7/00—Optical parts
- G02C7/02—Lenses; Lens systems ; Methods of designing lenses
- G02C7/06—Lenses; Lens systems ; Methods of designing lenses bifocal; multifocal ; progressive
- G02C7/061—Spectacle lenses with progressively varying focal power
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- G—PHYSICS
- G02—OPTICS
- G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
- G02C2202/00—Generic optical aspects applicable to one or more of the subgroups of G02C7/00
- G02C2202/16—Laminated or compound lenses
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- Ophthalmology & Optometry (AREA)
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- General Physics & Mathematics (AREA)
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Abstract
An ophthalmic optical system of continuously variable refractive power in the meridian plane comprises a lens (1) having a refracting front surface (2) made spherical, and a coacting conicoid back surface (3). The front surface (2) may be located with respect to the back surface (3) such that thickness of the lens (1) decreases in the direction from the lower border to the upper distance portion. A frame comprises circular elements (20) formed by at least two segments (21, 22) whereof one of the segments (21, 22) is intended to install the thin edge of the lens and a nose strap (24) installed with due regard for the required face angle. A refraction measuring method comprises focusing a sight tube (37) at an object (44), placing an ophthalmic lens (43) under test between the sight tube (37) and the object (44), making the center of the entry pupil (41) of the sight tube (37) coincide with the center of rotation of the lens (43), turning the lens (43) about its center of rotation until thickness is obtained corresponding to the distance from the front surface of said lens to the object (44), measuring the lens power by the method of compensating the lens power of the lens (43) using a reference lens (45) until a sharp image of the object (44) is obtained in the focal plane of the eyepiece (39) of the sight tube (37), and subsequent determination of refraction by the lens power so measured. <IMAGE>
Description
SPECIFICATION
Opthalmic Optical System, Its Refraction Measurement Method, and Frame for This System
In an ophthalmic optical system, the change in refractive power of a spectacle lens required to relieve accommodative insufficiency or to help in the absence of accommodation in presbyopia and in aphakia, said change is to be effected in a continuous and regular manner, without discontinuities in the field of vision through the lens and with minimal distortion in said field.
In gaze at distant objects through the upper distance portion of the ophthalmic lens, it is necessary to obtain on the human reticle a clear image of objects located at infinity with respect to the spectacle wearer.
And as objects are observed through lower and lower portions of the ophthalmic lens, they must be closer and closer to the spectacle wearer to be seen clearly.
Thus, refractive power of the ophthalmic optical system should increase gradually from the upper border of the lens down to its lower border, with the image quality retained good.
The present invention provides an ophthalmic optical system of variable refractive power in the meridian plane, comprising a lens with the front and back refracting surfaces, whereof the latter is conicoid, wherein, according to the invention, the front surface is made spherical and located with respect to the back surface in such a manner that the lens thickness decreases from the lower border to the upper distance portion, thereby providing a gradual change in the focal distance of said opthalmic optical system in the meridian plane within the required accommodation of the human eye.
The front surface of said lens being spherical and located with respect to said back surface In such a manner that the thickness of said lens gets decreased, the distance from said front surface of said lens to its focal point along its optical axis differs from the distance between the front surface of said lens to its focal point along the main beam of light.
Maximum difference between said distances, corresponding to the minimum magnitude of refractive power, is obtained at the thin border of said lens.
Positioning said lens with its thin border facing up in said ophthalmic optical system permits observation of distant objects through a zone in said lens, characterized by the Ibast refractive power.
It is desirable that the proposed ophthalmic optical system be provided with another lens manufactured in a manner analogous to that for aforesaid first lens, with both lenses being positioned so that their optical axes are aligned and the refractive power signs of each lens are identical in any section.
Provision of said ophthalmic optical system with two lenses positioned in such a manner that their optical axes are aligned and the refractive power signs of each lens are identical in any section, said provision permits an increase in the refractive power of said ophthalmic optical system, with the total thickness of two lenses being smaller than that of one lens having the refractive power equal to the sum of refractive powers of two lenses, which phenomenon is permitted by the presence of four refracting surfaces.
It is desirable that in the ophthalmic optical system intended for the correction of the refractive error in presbyopia and in hypermetropia, the optical axis of said system be passing centrally through the sagittal section of the lens and be located in close proximity to the lower thick border of said lens.
The lens optical axis passing centrally through the sagittal section of the lens and being in close proximity to the lower thick border of said lens permits, in an ophthalmic optical system of positive refractive power, the lens optical axis to be displaced in its lower thick border, thus creating thereon a greater refractive power required to observe near objects. In this case, the lens thin border features the least positive refractive power required to watch distant objects.
It is also desirable that in the ophthalmic optical system intended for the correction of the refractive error in presbyopia and in myopia, the optical axis of said system be passing centrally through the sagittal section of the lens and be located in close proximity to the upper thin border of said lens.
The lens optical axis passing centrally through the sagittal section of the lens, located in close proximity to the upper thin border of said lens permits in an ophthalmic optical system of negative refractive power, the lens optical axis to be displaced to its upper thin border, thus creating thereon a greater negative refractive power required to watch distant objects. In this case the lens thick border will feature the least negative refractive power required to observe near objects.
It is desirable that in the ophthalmic optical system intended for the correction of the refractive error in presbyopia and in aphakia, the optical axis of said system be passing centrally through the sagittal sections of the lenses and be located in close proximity to the lower thick borders of said lenses.
The optical axis of said lenses passing centrally through the sagittal sections of the lenses, located in close proximity to the lower thick borders of said lenses permits, in the ophthalmic optical system of positive refractive power, the optical axis of said lenses to be displaced to their lower thick borders, thus creating thereon a greater refractive power required to observe near objects. In this case, the thin borders of said lenses feature the least positive refractive power required to watch distant objects.
The present invention provides also a frame for said ophthalmic optical system, comprising circular elements adapted to fit lenses therein and interconnected by means of a nose strap, and earpieces connected to said circular elements, wherein, according to the invention, said circular elements are formed by at least two segments, one of the segments being intended to install the thin edge of said lens, while said nose strap ic curved in the direction opposed to that of said earpieces and is installed with due regard for the required face angle.
The circular elements composed of at least two segments permit the replacement of ophthalmic optical systems therein with negligible efforts required for so doing.
The curvature of said nose strap in the direction opposed to that of said earpieces and installation thereof with due regard for the required face angle provide the proper orientation of said lens with respect to the human eye due to the alignment of the entry pupil of said ophthalmic optical system with the center of rotation of the human eye.
The present invention provides also a frame for said ophthalmic optical system, comprising circular elements adapted each to fit therein at least two lenses and interconnected by means of a nose strap, and earpieces connected to said circular elements, wherein, according to the invention, the circular elements in their sectional plane have the shape of a segment, whose height is greater than the internal radius of said circular element, said circular segment-shaped elements being further provided on the internal surface thereof with at least two grooves to fit therein the thin edge of the respective lens, and with slots formed between said grooves in close proximity to the plane passing through the chord of said segment normal to its height, said nose strap being curved in the direction opposed to that of said earpieces and installed with due regard for the required face angle.Since the height of each segment-shaped circular element, the internal surface whereof is provided with at least two grooves to fit therein the thin edge of the respective lens, is greater than its internal radius, said lenses can be replaced with negligible efforts required for so doing.
Between said grooves intended to fit spectacle lenses, there are provided slots in close proximity to the plane passing through the chord of said segment normal to its height, said slots, due to resilience of said circular elements, providing a possibility to fit spectacle lenses separately into said frame.
The present invention further provides a refraction measuring method for an ophthalmic lens, residing in that a sight tube is focused at an object, a lens under test is placed between said sight tube and said object, said lens under test is rotated about its center of rotation, and the power is measured of said lens to find refraction thereof, wherein according to the invention, after said lens under test has been placed between said sight tube and said object, the center of entry pupil of said sight tube is aligned with the center of rotation of said lens under test, said lens under test being rotated until thickness is obtained which corresponds to the distance from its front surface to said object, and the lens power measurement is conducted by the method of compensating the power of said lens under test with a reference lens until a sharp image of said object has been obtained in the focal plane of the eyepiece of said sight tube.
Alignment of the center of rotation of said lens under test with the center of entry pupil of said sight tube and the rotation of said lens until thickness is obtained which corresponds to the distance from its front surface to said object, all this will provide better accuracy during refraction measurements conducted on said lens, owing to the fact that said lens under test is kept under natural conditions during said measurements.
The invention will now be described in greater detail taken in conjunction with the accompanying drawings, wherein:
Fig. 1 is a cross-sectional view illustrating schematically the opthalmic optical system of the present invention;
Fig. 2 is a cross-sectional view illustrating schematically one of the embodiments of the ophthalmic optical system embodying the features of the present invention;
Fig. 3 is a cross-sectional view illustrating schematically another embodiment of the opthalmic optical system of the present invention;
Fig. 4 is a cross-sectional view illustrating schematically yet another embodiment of the ophthalmic optical system of the present invention;
Fig. 5 is a diagrammatic view showing the height of the entry pupil of the ophthalmic optical system versus the magnitude of longitudinal spherical aberration in the system of the present invention; ;
Fig. 6 is a diagrammatic view showing the angle of the field of vision through the ophthalmic optical system versus the magnitude of the meridian and sagittal curvature of an image produced by the system of the present invention;
Fig. 7 is a diagrammatic view showing the transverse spherical aberration of the ophthalmic optical system versus the magnitude of the exit pupil expressed in radians, with the angle of the field of vision being at its maximum in the system of the present invention;
Fig. 8 is the same as in Fig. 7, with the angle of the field of vision being under its maximum magnitude;
Fig. 9 is the same as in Fig. 7, with the angle of the field of vision being equal to zero;
Fig. 10 is a front elevational view illustrating schematically a frame for the ophthalmic optical system of the present invention;;
Fig. 11 is a sectional view taken along the line Xl-Xl of Fig. 10;
Fig. 12 is a plan elevational view of the same as in Fig. 10;
Fig. 13 is a front elevational view illustrating schematically one embodiment of the frame for the ophthalmic optical system of this invention;
Fig. 14 is a plan elevational view of the same as in Fig. 13;
Fig. 15 is a schematic sectional view taken along the line XV-XV of Fig. 13;
Fig. 1 6 is a front elevational view illustrating schematically another embodiment of the frame for the ophthalmic optical system of the present invention;
Fig. 17 is a schematic sectional view taken along the line XVll-XVll of Fig. 16;
Fig. 18 is a plan elevational view of the same as in Fig. 16;;
Fig. 1 9 is a diagrammatic view illustrating the refraction measuring method for the ophthalmic optical system with an object located at a distance of best vision from a lens under test, i.e. at a distance of 250 mm; and
Fig. 2Q is a diagrammatic view of the setup illustrating refraction measuring method for the ophthalmic optical system with an object located at infinity.
Referring now to the accompanying drawings and initially to Fig. 1, the proposed ophthalmic optical system of variable refractive power in the meridian plane comprises a lens 1 having the refracting spherical front surface 2, whose radius of curvature is Rt, and with the conicoid refracting back surface 3, whose radius of curvature is R2 (C1 and C2 are, respectively, the centres of curvature of the front and back refracting surfaces 2 and 3), with R,=R2 at the apex of the lens 1.
Thickness of the lens 1 gradually decreases from its one border to the other.
Optical axis of the lens 1 passes through the thick border of the lens 1 and centrally through the sagittal section of the lens 1.
The entry pupil 4 of said ophthalmic optical system is located at a distance which provides for correction of the system aberrations (astigmatism) and which is convenient for placing a patient.
The main beam of light passes through the center of the entry pupil 4 and through the thin border of the lens 1.
Angle P between the main beam of light and the optical axis is essentially the angle of the field of vision through said ophthalmic optical system.
Said ophthalmic optical system is utilized for the correction of the refractive error in presbyopia.
In the embodiment shown in Fig. 2, the ophthalmic optical system comprises a lens 5 with the refracting spherical front surface 6, whose radius of curvature is R1, and with the conicoid refracting back surface 7, whose radius of curvature is R2, with R2 > R, (C, and C2 are, respectively, the centres of curvature of the front and back refracting surfaces 6, 7).
Optical axis of the lens 5 passes through the thick border of the lens 5 and centrally through the
sagittal section of the lens 5.
An exit pupil 8 of the ophthalmic optical system is located at a distance which provides for
correction of the system aberrations and which is convenient for placing a patient.
The main beam of light passes through the center of the exit pupil 8 of said ophthalmic optical
system and through the thin border of the lens 5.
Angle p between the main beam of light and the optical axis is essentially the angle of the field of vision through said ophthalmic optical system. Said ophthalmic optical system is utilized for the correction of the refractive error in hypermetropia and in presbyopia.
In the embodiment shown in Fig. 3, the ophthalmic optical system comprises a lens 9 with the refracting spherical front surface 10, whose radius of curvature is R1, and with the conicoid refracting back surface 11, whose radius of curvature is R2, with R, > R2 (C, and C2 are, respectively, the centres of curvature of the front and back refracting surfaces 10, 11).
Optical axis of the lens 9 passes through its thin border and centrally through the sagittal section.
The exit pupil 12 of the ophthalmic optical system is located at a distance which provides for correction of the system aberrations and which is convenient for placing a patient.
The main beam of light passes through the center of the exit pupil 12 of the ophthalmic optical system and through the thick border of the lens 9.
Angle P between the main beam of light and the optical axis is essentially the angle of the field of vision through said ophthalmic optical system. Said ophthalmic optical system is utilized for the correction of the refractive error in myopia and in presbyopia.
In the embodiment shown in Fig. 4, the ophthalmic optical system comprises a lens 13 with the refracting spherical front surface 14 and with the refracting spherical back surface 1 5, and a lens 1 6 with the refracting spherical front surface 1 7 and the conicoid refracting back surface 18, with R, and
R2 being, respectively, the radii of curvature of the front and back spherical refracting surfaces 14, 1 5 of the lens 13, and C, and C2 being, respectively, the centres of curvature of the front and back spherical refracting surfaces 14, 1 5 of the lens 13, R3 and R4 being, respectively, the radii of curvature of the front and back refracting surfaces 17,18 of the lens 16;C3 and C4 being, respectively, the centres of curvature of the front and back refracting surfaces 17, 1 8 of the lens 1 6. Thickness of the lens 13 and 1 6 gradually decreases from one border thereof to the other.
Optical axis of said ophthalmic optical system passes through the thick borders of the lenses 1 3, 1 6 and centrally through the sagittal sections of the lenses 13, 1 6.
An exit pupil 1 9 is located at a distance which provides for correction of the system aberrations and which is convenient for placing a patient.
The main beam of light passes through the center of the exit pupil 19 of said ophthalmic optical system and through the thin borders of the lenses 13 and 1 6. Angle p between the main beam of light and the optical axis is essentially the angle of the field of vision through said ophthalmic optical system.
In this embodiment the refractive powers of the lenses have identical signs in any section.
Said ophthalmic optical system is utilized for the correction of the refractive error in presbyopia
and in acute hypermetropia, and in aphakia.
When the use is made of any of the embodiments of the ophthalmic optical systems, shown in
Figs. 1, 2, 3 and 4, the centre of the exit pupil is aligned with the centre of rotation of the human eye.
Refractive power of the lens portion intended for observing distant objects at infinity is selected in such a manner that the rear focal point of said lens portion is aligned with the eye's fa-rthest point which, by the eye's optics proper, is conjugated with the reticule, while the refractive power of the-lens portion for viewing the objects at a distance of 250 mm is selected in such a manner that the rearfocai point of said lens portion is aligned with the eye's nearest point which is conjugated by the eye's optics with the reticule.
Given below are the embodiments of the ophthalmic optical systems of continuously variable refractive power in the meridian plane.
Embodiment 1
The ophthalmic optical system (Fig. 1 ) of continuously variable refractive power in the meridian plane from +0.2 to +2.7 diopters, intended for the correction of the refractive error in presbyopia
Radius of curvature of the lens front refracting surface R,=25.0 mm
Radius of curvature of the lens back refracting surface R2=25.0 mm
Thickness of lens gradually varying within the range d=0.5 to 5.0 mm
Index of refraction nD=1.6568
Refractive power on axis (do=5 mm) +2.7 diopters
Field of vision p=80o The front and back refracting surfaces of said lens are made spherical.
Embodiment 2
The ophthalmic optical system (Fig. 1) of continuously variable refractive power in the meridian plane from +0.3 to +3.94 diopters, intended for the correction of the refractive error in presbyopia.
Radius of curvature of the lens front refracting surface R,=22.0 mm
Radius of curvature of the lens back refracting surface R2=22.0 mm
Thickness of lens gradually varying within the range d=0.5 to 6.0 mm
Index of refraction nod=1.7440 Refractive power on axis (do=6 mm) +3.9 diopters
Field of vision p=80 The front and back refracting surfaces of said lens are made spherical.
Embodiment 3
The opthalmic optical system (Fig. 1) of continuously variable refractive power in the meridian plane from +0.2 to +2.54 diopters, intended for the correction of the refractive error in presbyopia.
Radius of curvature of the lens front refracting surface R,=25.0 mm
Radius of curvature of the lens back refracting surface R2=25.0 mm
Thickness of lens gradually varying within the range d=0.5 to 5.0 mm
Index of refraction nod=1.744 Refractive power on axis (do=5 mm) +2.54 diopters
Field of vision p=80o The front and back refracting surfaces of said lens are made spherical.
Noteworthy is to mention that in the three embodiments described hereinabove the back refracting surface of said lens can be made conicoid with eccentricity zero or greater, or toric, for additional correction of ocular astigmatism.
Embodiment 4
The ophthalmic optical system (Fig. 2) of continuously variable refractive power in the meridian plane from +3.8 to +6.4 diopters, intended for the correction of the refractive error in presbyopia and in hypermetropia.
Radius of curvature of the lens front refracting surface R,=22.0 mm
Radius of curvature of the lens back refracting surface R2=25.0 mm
Thickness of lens gradually varying within the range d=0.5 to 5.0 mm
Index of refraction nod=1.6568 Refractive power on axis (do=6 mm) +6.4 diopters
Field of vision p=800 The front and back refracting surfaces of said lens are made spherical.
Embodiment 5
The ophthalmic optical system (Fig. 2) of continuously variable refractive power in the meridian plane from +7 to +9 diopters, intended for the correction of the refractive error in presbyopia and in hypermetropia.
Radius of curvature of the lens front refracting surface R,=22.0 mm
Radius of curvature of the lens back refracting surface R2=28.O mm
Thickness of lens, gradually varying within the range d=0.5 to 5 mm
Index of refraction
Refractive power (do=5 mm) +9 diopters
Field of vision p=800 The front and back refracting surfaces of said lens are made spherical.
Embodiment 6
The ophthalmic optical system (Fig. 2) of continuously variable refractive power in the meridian plane from +2.5 to +4.96 diopters, intended for the correction of the refractive error in presbyopia and in hypermetropia.
Radius of curvature of the lens front refracting surface R2=22.0 mm
Radius of curvature of the lens back refracting surface R2=24.0 mm
Thickness of lens gradually varying within the range d=0.5 to 6.0 mm
Index of refraction nod=1.6126 Refractive power on axis (do=6 mm) +4.96 to +5 diopters
Field of vision p=800 The front and back refracting surfaces of said lens are made spherical.
Noteworthy is to mention that in the three embodiments Nos. 4, 5, 6 described hereinabove the back refracting surface of said lens can be made conicoid with eccentricity zero or greater, or toric, for additional correction of ocular astigmatism.
Embodiment 7
The ophthalmic optical system (Fig. 3) of continuously variable refractive power in the meridian plane from -2.5 to +0.4 diopters, intended for the correction of the refractive error in presbyopia and in myopia.
Radius of curvature of the lens front refracting surface R,=22.0 mm
Radius of curvature of the lens back refracting surface R2=22.O mm
Thickness of lens, gradually varying within the range d=0.5 to 6.0 mm
Index of refraction
Refractive power on axis (d,=0.5) -2.5 diopters
Field of vision p=800 The front and back refracting surfaces of said lens are made spherical.
Embodiment 8
The ophthalmic optical system (Fig. 3) of continuously variable refractive power in the meridian plane from -6.3 to -2.7 diopters, intended for the correction of the refractive error in presbyopia and myopia.
Radius of curvature of the lens front refracting surface R,=22.0 mm
Radius of curvature of the lens back refracting surface R2=1 8.0 mm
Thickness of lens, gradually varying within the range d=0.5 to 6.0 mm
Index of refraction nD=1.6568
Refractive power on axis (d@=0.5) -6.3 diopters
Field of vision p=800 The front and back refracting surfaces of said lens are made spherical.
Embodiment 9
The ophthalmic optical system (Fig. 3) of continuously variable refractive power in the meridian plane from -4.6 to -0.9 diopters, intended for the correction of the refractive error in presbyopia and in myopia.
Radius of curvature of the lens front refracting surface R,=22.0 mm
Radius of curvature of the lens back refracting surface R2=1 9.0 mm
Thickness of lens, gradually varying within the range d=0.5 to 6.0 mm
Index of refraction nD=1.6919 Refractive power on axis (d,=0.5 mm) -4.6 diopters
Field of vision p=800 The front and back refracting surfaces of said lens are made spherical.
Noteworthy is to mention that in the embodiments Nos. 7, 8 and 9, described hereinabove, the back refracting surface of said lens can be made conicoid with eccentricity zero or greater, or toric, for additional correction of ocular astigmatism.
Embodiment 10
The ophthalmic optical system (Fig. 1) of continuously variable refractive power in the meridian plane from + 13.6 to + 11.5 diopters, intended for the correction of the refractive error in aphakia.
Radius of curvature of the front refracting surface of first lens R,=22.0 mm
Radius of curvature of the back refracting surface of first lens R2=27.0 mm
Radius of curvature of the front refracting surface of second lens R3=22.0 mm
Radius of curvature of the back refracting surface of second lens R4=27.0 mm
Thickness of first and second lenses, gradually varying within the range d=3.0 to 0.5 mm
Distance between lenses along the optical axis 0.5 mm
Index of refraction nD=1.6568
Refractive power on axis (do=3*0 mm; d011=3 .0 mm) +3.6 diopters
Field of vision ss=80
The front and back refracting surfaces of each lens are made spherical.
Embodiment 11
The ophthalmic optical system (Fig. 4) of continuously variable refractive power in the meridian
plane from + 13 to + 10.5 diopters, intended for the correction of the refractive-error in aphakia.
Radius of curvature of the front refracting surface of first lens R,=22.0 mm
Radius of curvature of the back refracting surface of first lens R2=26.0 mm
Radius of curvature of the front refracting surface of second lens R3=22.0 mm
Radius of curvature of the back refracting surface of second lens R4=26.0 mm
Thickness of first and second lenses, gradually varying within the range d=3.5 to 0.5 mm
Distance between the lenses along the optical axis 0.5 mm
Index of refraction nD=1.6919
Refractive power on the axis (do=3*0 mm; d011=3 .0 mm) +13 diopters Field of vision p=800 The front and back refracting surfaces of each lens are made spherical.
Embodiment 12
The ophthalmic optical system (Fig. 4) of continuously variable refractive power in the meridian
plane from + 13 to + 10.8 diopters, intended for the correction of the refractive error in aphakia.
Radius of curvature of the front refracting surface of first lens R,=22.0 mm
Radius of curvature of the back refracting surface of first lens R2=27.0 mm
Radius of curvature of the front refracting surface of second lens R3=22.0 mm
Radius of curvature of the back refracting surface of second lens R4=27.0 mm
Thickness of first and second lenses, gradually varying within the range d=3.5 to 0.5 mm
Distance between the lenses along the optical axis 0.5 mm
Index of refraction nD=1.6126
Refractive power on axis (d01=3.5 mm; d011=3,5 mm) + 13 diopters
Field of vision ss=80
The front and back refracting surfaces of each lens are made spherical.
Noteworthy is to mention that in the embodiments described hereinabove, the back refracting
surface of the second lens can be made conicoid with eccentricity zero or greater, or toric, for
additional correction of ocular astigmatism.
Image quality obtained by the use of the ophthalmic optical system described in the Embodiment
10, intended for the correction of the refractive error in aphakia, is further explained by Tables 1, 2, 3
and 4, and by the diagrams in Figs. 5, 6, 7, 8 and 9.
For clarity sake, the calculation for aberrations in said ophthalmic optical system has been conducted on the return travel of the beam of light.
Table 1 illustrates the ophthalmic optical system aberrations for an object located on the system optical axis. In Table 1: height of beams of light on entry pupil; AS'-longitudinal spherical aberrations in rear focal plane of said ophthalmic optical system; #g-transverse spherical aberrations in rear focal plane of said ophthalmic system; #-values characterizing departure from the law of sines;
w-wave spherical aberration;
tan u'-aperture angles in image space.
From Table 1 it is clear that in case of the ophthalmic optical system entry pupil of up to 3 mm, the longitudinal spherical aberration #S' does not exceed-0.293 mm, while the transverse spherical aberration #'g=-0.004 mm.
Table 1
h AS' #g' Ti W tan U'
1.50 -0.293 -0.0044 -0.096 -0.104 0.024
1.30 -0.220 -0.0029 -0.064 -0.046 0.019
1.06 -0.147 -0.0016 -0.032 -0.012 0.014
0.75 -0.073 -0.0006 -0.020 -0.005 0.011
0 0
Table 2 illustrates the ophthalmic optical system aberrations for an object located away from the
optical axis, with the main beam of light passing through the system.In Table 2:
ss-fields of vision in degrees;
tan ss'-tangents of fields of vision in image space; y'-image sizes in rear focal plane of ophthalmic optical system;
xt'-curvature of image in the meridian plane;
xs'-curvature of image in the sagittal plane;
Sin-distances between system entry pupil and rear surface;
S'out-distances between system exit pupil and front surface; A%-relative distortion expressed in percent.
From Table 2 it is clear that in case of the entry pupil placed at Sin=-14 mm, the magnitude of astigmatism equal to xs'-xt' does not exceed circa 3 diopters.
Table 2
ss tan ss' y' xt' xs' Sin S'out %
-80 -1.540 162.68 -34.49 -36.55 -14.0 -9.10 -60.27
-69 -1.139 120.38 -21.14 -25.24 -14.0 -9.15 -36.92
-56 -0.894 86.60 -10.80 -15.43 14.0 -9.20 -20.78
-40 -9.523 55.13 -3.88 -7.08 -14.0 -9.27 -8.98 -14.0 -9.35
Table 3 illustrates the ophthalmic optical system aberrations for an object located away from the optical axis, with the inclined beams of light passing through the meridian plane of said system. In this table for various fields of vision p there is provided the relation of entry pupil m of said system versus transverse spherical aberration in the meridian section.From Table 3 it is clear that the maximum transverse spherical aberration for the maximum field of vision p does not exceed 0.2 mm.
Table 3
ss=80 ss=-69 ss=-36 ss=-40 m #y' m #y' m #y' m #y' -147.56 -0.200 -109.25 -0.206 -78.59 -0.155 -49.80 -0.090 -147.64 -0.172 -109.37 -0.175 -73.75 -0.130 -49.97 -0.073 -147.73 -0.140 -109.51 -0.140 -78.93 -0.102 -50.18 -0.055 -147.85 -0.098 -109.69 0.096 -79.16 -0.068 -50.46 -0.035 -148.12 0 -110.12 0 -79.70 0 -51.11 0 -148.40 -0.093 -110.54 0.083 -80.24 0.049 -51.75 0.016 -148.51 0.130 -110.71 0.114 -80.45 0.064 -52.01 0.017 -148.55 0.157 -110.84 0.136 -80.62 0.073 -52.21 0.017 -148.67 0.180 -110.95 0.154 -80.76 0.080 -52.38 0.015 Table 4 ss=-80 ss=-69 ss=-56 ss=-40
M #g' #G' M #g' #G' M #g' #G' M #g' #G' -148.04 -0.099 -0.643 -110.07 -0.061 -0.414 -79.67 -0.037 -0.224 -51.09 -0.020 -0.112 -148.06 -0.074 -0.558 -110.08 -0.046 -0.358 -79.68 -0.028 -0.210 -51.10 -0.015 -0.096 -148.08 -0.050 -0.455 -110.10 -0.031 -0.292 -79.69 -0.018 -0.171 -51.10 -0.010 -0.078 -148.10 -0.025 -0.321 -110.11 -0.015 -0.206 -79.70 -0.009 -0.120 -51.11 -0.005 -0.054 0 0 0 0 0 0 0 0 0 0 0 0 Table 4 illustrates the ophthalmic optical system aberrations for an object located away from the optical axis, with the inclined beams of light passing through the sagittal section of said system. In
Table 4: M-size of entry pupil in the sagittal section for inclined pencils of light rays; dG'-transverse spherical aberrations of said ophthalmic optical system in the sagittal section; #g'-system coma.
The diagram in Fig. 5 shows a curve A illustrating relation of the ophthalmic optical system entry pupil height versus longitudinal spherical aberration of said system for an object located on the optical axis of said ophthalmic optical system, wherein plotted on the y-axis, the entry diameter in millimetres (h), and on the x-axis, the longitudinal spherical aberration in millimetres (AS').
From the curve A it is clear that the longitudinal spherical aberration AS' rises smoothly with an increase in the pupil diameter h: the longitudinal spherical aberration AS'=-0.2 mm at the pupils border (h=hbrd)- The diagram in Fig. 6 shows a curve B illustrating the relation of the field of vision through the ophthalmic optical system versus image curvature in the meridian plane, and a curve C illustrating the relation of the field of vision versus magimage curvature in the sagittal plane, wherein plotted on the yaxis is the field of vision (P) in degrees, and plotted on the x-axis are xt and x5, the image curvatures in the meridian plane and in the sagittal plane, respectively.
From the curves B and C it is clear that as the angle expands, the image curvature in the meridian and sagittal planes grows gradually up and has the same sign. From these diagrams it is clear that such an ophthalmic system has a negligible magnitude of astigmatism equal to x'-)4, required for optical observation instruments.
The diagram in Fig. 7 shows a curve D illustrating the relation of the ophthalmic optical system transverse spherical aberration versus exit pupil diameter at the maximum field of vision, i.e. at p=800; in this case, plotted on the y-axis are transverse spherical aberrations (Ay') in millimetres and on the xaxis, in radians (# tan B'= tans B--tan Bo'), wherein tan Bk is the magnitude of the tangent for the exit angle of the field of vision for a beam of light passing through the border of the exit pupil, while tan BO is the magnitude of the tangent for the exit angle of the field of vision for a beam of light passing centrally through the exit pupil.
The magnitude A tan B' characterizes the value of the exit pupil of said ophthalmic optical system in radians.
From the curve D for p=800 it is clear that there is no coma in said ophthalmic optical system, while the transverse spherical aberration is negligibly small all over the pupil.
The diagram in Fig. 8 shows a curve E illustrating the relation of the ophthalmic optical system, transverse spherical aberration versus exit pupil size at the field of vision of 40 , in this case, plotted on the x-axis are transverse spherical aberrations (Ay') in millimetres, while on the x-axis, in radians (h tan
B'=tan Bhutan B0,), wherein tan Bk is the magnitude of the tangent for the exit angle of the field of vision for a beam of light passing through the border of said exit pupil, and tan B0,- is the tangent for the exit angle of the field of vision for a beam of light passing centrally through the exit pupil.
The diagram in Fig, 9 shows a curve F illustrating the relation of the ophthalmic optical system transverse spherical aberration versus the exit pupil size at the field of vision p equal to zero, in this case, plotted on the x-axis is the magnitude of transverse spherical aberration (Ay') in millimetres, while on the x-axis, in radians (h tan B'=tan Bktan Bó) From the curves E and F it is clear that the transverse spherical aberration is small and that there is no coma in said ophthalmic optical system.
Shown in Figs.10,11 and 12 is a frame for said ophthalmic optical system, comprising circular elements 20 (Fig. 10) formed by two segments 21 and 22. Installed into the segment 21 is the thin edge of the ophthalmic lens, while the segment 22 is used to receive the thick edge of the ophthalmic lens. The circular elements 20 are manufactured of a resilient material, for instance, of brass.Fixed to the circular elements 20 are earpieces 23 (Fig. 11). A nose strap 24 interconnects the circular elements 20 and is curved in the direction opposed to that of the earpieces 23 and is installed with due regard for the required face angle P (Fig. 12). For proper orientation of the ophthalmic optical system with respect to the face of the spectacle wearer, the nose strap 24 is inclined toward the face plane through the face angle , which is equal to an angle between the patient's face plane and the nose shape generatrix.
A frame of this design is used primarily for installation of negative ophthalmic systems.
Shown in Figs. 13, 14 and 1 5 is one embodiment of the frame for the ophthalmic optical system.
The frame comprises circular elements 25 (Fig. 13) formed by segments 26, 27, 28 and 29. Installed into the segment 26 is the thin edge of the ophthalmic lens. Fastened to the circular elements 25 are earpieces 30 (Fig. 14).
A nose strap 31 interconnects the circular elements 25 and is curved in the direction opposed to that of the earpieces and is installed with due regard for the required face angle P (Fig. 1 5).
The frame mentioned hereinabove is used primarily for installation of positive ophthalmic optical systems.
Shown in Figs. 1 6, 17, and 1 8 is another embodiment of frame for the ophthalmic optical system comprised of two lenses.
The frame comprises circular segment-shaped elements 32 (Fig. 1 6). Segment height h is greater than the inside radius R5 of the circular element 32. Two grooves 33 (Fig. 1 7) are made on the internal surface of the circular element 32. Fitted into the grooves 33 is the thin edge of the ophthalmic lenses.
Slots 34 (Figs. 1 6, 1 7) are made between the grooves 33 from the plane passing through the segment chord. Earpieces 35 are fastened to the circular elements 32 (Fig. 1 8).
A nose strap 36 interconnects the circular elements 32 and is curved in the direction opposed to that of the earpieces 35 and is installed with due regard for the required face angle q7 (Fig. 1 7). For proper orientation of the ophthalmic optical system with respect to the face of the spectacle wearer, the nose strap 36 is inclined toward the face plane through the face angle , which is equal to an angle between the patient's face plane and the nose shape generatrix.
Such a design of the frame is used primarily for installation of the ophthalmic optical systems intended for the correction of the refractive error in aphakia.
The lens refraction measuring method is illustrated by a device shown in Figs. 19, 20, wherein a device shown in Fig. 19 implements the refraction measuring method for the lens portion intended for gaze at (observation of) objects located at a distance of best vision, i.e. 250 mm, while a device shown in Fig. 20 implements the refraction measuring method for the lens portion intended for gaze at (observation of) objects located at infinity.
The device comprises a sight tube 37 (Figs. 1 9, 20), consisting of an objective lens 28 with the rear focal point Fóbi and an eyepiece 39 with the front focal point Focu. A graticule 40 is placed in the focal plane of the eyepiece 39 of the sight tube 37. The sight tube 37 has an entry pupil 41 and an exit pupil 42.
A lens 43 under test is placed in front of the entry pupil 41 of the sight tube 37.
An object 44 is placed at infinity (Fig. 20) or at a distance of 250 mm (Fig. 19) from the front surface of the lens 43 under test. A reference lens 45 is placed between the lens 43 and the entry pupil 41 of the sight tube 37.
The lens refraction measuring method resides in the following steps, the objective lens 38 is moved along the optical axis of the sight tube 37 (Fig. 19) until the latter is focused at the object 44, by aligning the image of the object 44 with the collimator mark placed on the plane of the graticule 40 which is placed in the front focal plane of the eyepiece 39. The object 44 is located at a distance of 250 mm from the front surface of the lens 43.
Then the center of rotation of the lens 43 under test is aligned with the center of the entry pupil 41 of the sight tube 37 and the lens 43 is rotated as far as the zone corresponding to the distance at which is focused the sight tube 37.
By the method of compensation with a reference lens 45, the readings of refractive power ((p) are taken for the lens 43 under test. At the moment the reading is taken, a sharp image of the object 44 is obtained on the graticule 40 of the sight tube 37.
The rear apex refraction R of the lens differs from the lens refractive power by the value of K.
where: R=Kv
where: rrefractive power nbindex of refraction R1-radius of curvature of the front refracting surface dthickness of the lens.
To measure refraction for the object 44 (Fig. 20) located at infinity, the lens 43 under test is rotated as far as the zone corresponding to a distance at which is focused the sight tube 37.
Then by the method of compensation with the reference lens 45, the readings of refractive power P are taken for the lens 43 under test until a sharp image of the object 44 is obtained on the graticule 40 of the sight tube 37, and finally a reading of lens refraction is obtained from the formula stated hereinabove.
For an object located at any other distance from infinity to 250 mm, the refraction measurements can be conducted by the method described hereinabove. In so doing, the sight tube 37 should be focused at an object located at the required distance. The lens under test should be rotated with respect to the sight tube entry pupil as far as the zone suitable for observation of objects at the given distance.
Embodiment 13
The lens under test used herein is a lens intended for the correction of the refractive error in presbyopia.
Radius of curvature of front refracting surface R,=22.0 mm
Radius of curvature of back refracting surface R2=22.O mm
Thickness of lens gradually varies within d=0.5 to 5.0 mm
Index of refraction no=1.6126 Refractive power of lens thin border =+0.2 diopter
Refractive power of lens thick border +2.7 diopters
Refraction for lens thin border +0.2 diopters
Refraction for lens thick border +2.96 diopters
Embodiment 14
The lens under test used herein is a lens intended for the correction of the refractive error in hypermetropia and in presbyopia.
Radius of curvature of front refracting surface R,=22.0 mm
Radius of curvature of back refracting surface R2=25.0 mm
Thickness of lens gradually varies within d=0.5 to 6.0 mm
Index of refraction nod=1.6568 Refractive power of lens thin border +3.8 diopters
Refractive power of lens thick border +6.4 diopters
Refraction for lens thin border +3.8 diopters
Refraction for lens thick border +7.1 diopters
Embodiment 15
The lens under test used herein is a lens intended for the correction of the refractive error in
myopia and in presbyopia.
Radius of curvature of front refracting surface R1=22,0 mm
Radius of curvature of back refracting surface R2=20,0 mm
Thickness of lens gradually varies within d=0.5 to 6.0 mm
Index of refraction nD=1.6126
Refractive power of lens thin border -2.5 diopters
Refractive power of lens thick border +0.4 diopter
Refraction for lens thin border -2.5 diopters
Refraction for lens thick border +0.45 diopter
Although the particular embodiments of the invention have been described hereinabove it will be apparent to those skilled in the art that numerous modifications and other embodiments of the invention may be devised without departing from the true spirit and scope thereof, defined by the following claims.
The proposed ophthalmic optical system of continuously variable refractive power in the meridian plane provides a possibility to observe both distant and near objects.
The multifocal lenses known in the prior art are complicated to manufacture, expensive, and cause unpleasant image distortions.
The proposed ophthalmic optical systems are intended for permanent wear and do not cause the sensation of fatigue. The cost of spectacles does not differ substantially from that of regular monofocal spectacles utilized for the relief of the refractive error in myopia and in presbyopia. The proposed spectacles feature larger field of vision (80 ) and lack of unpleasant image distortions.
The proposed refraction measuring method for the ophthalmic lenses permits refraction readings to be taken in any lens zone for an object located at the required distance.
Claims (12)
1. An ophthalmic optical system of continuously variable refractive power in the meridian plane, comprising a lens with coating front and back refractingsurf-aceswbereof1he latter is conicoid, wherein the front surface is made spherical and located with respect to the back surface in such a manner that thickness of the lens decreases in the direction from the lower borderto the upper distance portion, thereby providing a gradual change in the focal distance of the ophthalmic optical system in the meridian plane within the required accommodation of the human eye.
2. An ophthalmic optical system as defined in Claim 1, comprising a further lens made similar to the first one, with both lenses being installed in such a manner that their optical axes coincide with one another and the lens power signs of each of the lenses are identical in any combination thereof.
3. An ophthalmic optical system as defined in Claim 1, wherein, for the correction of the refractive error in presbyopia and in hypermetropia, the optical axis of said lens passes centrally through the sagittal section of the lens and is located in close proximity to the lower thick border of the lens.
4. An ophthalmic optical system as defined in Claim 1, wherein, for the correction of the refractive error in presbyopia and in myopia, the optical axis of said lens passes centrally through the sagittal section of the lens and is located in close proximity to the upper thin border of the lens.
5. An ophthalmic optical system as defined in Claim 2, wherein, for the correction of the refractive error in presbyopia and in aphakia, the optical axis of said lens passes centrally through the sagittal sections of the lenses and is located in close proximity to the lower thick borders thereof.
6. A frame for the ophthalmic optical system as defined in Claim 1, comprising circular elements intended to install lenses therein, and interconnected by means of a nose strap, and earpieces connected to said circular elements, wherein the circular elements are formed by at least two segments whereof one is intended to install the thin edge of the lens, while the nose strap is curved in the direction opposed to that of the earpieces and is installed with due regard for the required face angle.
7. A frame for the ophthalmic optical system as defined in Claim 2, comprising circular elements intended each to install at least two lenses and interconnected by means of a nose strap, and earpieces connected to said circular elements, wherein the circular elements in their sectional plane have the shape of a segment whose height is greater than the insde radius of the circular element, the internal surface of each segment-shaped circular element being provided with at least two grooves to install therein the thin edge of the respective lens and with slots formed between said grooves in close proximity to the plane passing through the chord of the segment and normal to its height, while the nose strap is curved in the direction opposed to that of the earpieces and is installed with due regard for the required face angle.
8. A refraction measuring method for the ophthalmic lens as defined in Claim 1, comprising the steps of focusing a sight tube at an object, placing an ophthalmic lens under test between the sight tube and the object, turning the ophthalmic lens under test about its center of rotation, and measuring the lens power to determine the refraction of said lens, wherein upon placing the lens under test between the sight tube and the object, the center of the entry pupil of the sight tube is made to agree with the center of rotation of the lens under test, the lens under test is rotated until thickness is obtained corresponding to the distance from the front surface of said lens to the object, and the lens power measurement is effected by the method of compensating the lens power of the ophthalmic lens under test using a reference lens until a sharp image of the object is obtained in the focal plane of the eyepiece of the sight tube.
9. An ophthalmic optical system of continuously variable refractive power in the meridian plane, essentially as hereinabove described with reference to Figures 1, 2, 3 and 4 of the accompanying drawings.
10. A frame for the ophthalmic optical system, substantially as hereinabove described with reference to Figures 10, 11 and 12 of the accompanying drawings,
11. A frame for the ophthalmic optical system, essentially as hereinabove described with reference to Figures 1 6, 1 7 and 1 8 of the accompanying drawings.
12. A refraction measuring method for the ophthalmic lens, essentially as described hereinabove with reference to Figure 1 9 or Figure 20 of the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SU2693979 | 1978-12-20 | ||
| SU2693978 | 1978-12-20 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2038020A true GB2038020A (en) | 1980-07-16 |
| GB2038020B GB2038020B (en) | 1983-06-15 |
Family
ID=26665715
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7932380A Expired GB2038020B (en) | 1978-12-20 | 1979-09-18 | Ophthalmic optical system its refraction measurement and frame therefor |
Country Status (5)
| Country | Link |
|---|---|
| DD (1) | DD146214A1 (en) |
| DE (1) | DE2937743A1 (en) |
| FR (1) | FR2444955A1 (en) |
| GB (1) | GB2038020B (en) |
| HU (1) | HU181900B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1411382A2 (en) * | 1999-07-02 | 2004-04-21 | E-Vision, L.L.C. | System, apparatus, and method for correcting vision using an electro-active lens |
| FR2881846A1 (en) * | 2005-02-08 | 2006-08-11 | Essilor Int | METHOD FOR DEFINING AN EXTRA FACE FOR EYEWEAR |
| US8047651B2 (en) | 1999-07-02 | 2011-11-01 | E-Vision Inc. | Electro-active opthalmic lens having an optical power blending region |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0578833A4 (en) * | 1992-02-03 | 1994-06-29 | Seiko Epson Corp | Variable focus visual power correction apparatus |
| US7775660B2 (en) | 1999-07-02 | 2010-08-17 | E-Vision Llc | Electro-active ophthalmic lens having an optical power blending region |
| EP4157146A1 (en) | 2020-06-01 | 2023-04-05 | Icares Medicus, Inc. | Double-sided aspheric diffractive multifocal lens, manufacture, and uses thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1112429A (en) * | 1953-09-21 | 1956-03-14 | Optical lens |
-
1979
- 1979-09-12 FR FR7922786A patent/FR2444955A1/en active Granted
- 1979-09-18 DE DE19792937743 patent/DE2937743A1/en not_active Withdrawn
- 1979-09-18 GB GB7932380A patent/GB2038020B/en not_active Expired
- 1979-09-18 DD DD21561379A patent/DD146214A1/en unknown
- 1979-10-31 HU HULE000844 patent/HU181900B/en unknown
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1411382A2 (en) * | 1999-07-02 | 2004-04-21 | E-Vision, L.L.C. | System, apparatus, and method for correcting vision using an electro-active lens |
| EP1411382A3 (en) * | 1999-07-02 | 2007-01-17 | E-Vision, L.L.C. | System, apparatus, and method for correcting vision using an electro-active lens |
| US8047651B2 (en) | 1999-07-02 | 2011-11-01 | E-Vision Inc. | Electro-active opthalmic lens having an optical power blending region |
| US9323101B2 (en) | 1999-07-02 | 2016-04-26 | E-Vision Smart Optics, Inc. | Electro-active opthalmic lens having an optical power blending region |
| US9411173B1 (en) | 1999-07-02 | 2016-08-09 | E-Vision Smart Optics, Inc. | Electro-active opthalmic lens having an optical power blending region |
| US9500883B2 (en) | 1999-07-02 | 2016-11-22 | E-Vision Smart Optics, Inc. | Electro-active opthalmic lens having an optical power blending region |
| FR2881846A1 (en) * | 2005-02-08 | 2006-08-11 | Essilor Int | METHOD FOR DEFINING AN EXTRA FACE FOR EYEWEAR |
| WO2006084986A1 (en) * | 2005-02-08 | 2006-08-17 | Essilor International (Compagnie Generale D'optique) | Method of defining a supplementary face for spectacles |
| US7775657B2 (en) | 2005-02-08 | 2010-08-17 | Essilor International (Compagnie Générale d'Optique) | Method for defining a supplementary face for spectacles |
| AU2006212096B2 (en) * | 2005-02-08 | 2011-08-11 | Essilor International (Compagnie Generale D'optique) | Method of defining a supplementary face for spectacles |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2444955B1 (en) | 1982-05-21 |
| DD146214A1 (en) | 1981-01-28 |
| HU181900B (en) | 1983-11-28 |
| FR2444955A1 (en) | 1980-07-18 |
| DE2937743A1 (en) | 1980-07-03 |
| GB2038020B (en) | 1983-06-15 |
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