Anki Glossary: OPT127 (96 cards) Generated on 2021-02-18 1. The most commonly used number foridentifying the amount of chromatic aberration for a given lens material. Abbe’ Value 2. The higher the Abbe’ value, the less [...] present in the lens. The higher the Abbe’ value, the less chromatic aberration present in the lens. 3. Abbe’ value is thereciprocal of [...]. Abbe’ value is thereciprocal of ω (dispersive power). 4. The resulting degradation of an image whena point source of light does not resultin a single-point image after going through the lens or lens system. The resulting degradation of an image whena point source of light does not resultin a single-point image after going through the lens or lens system. Aberration 5. The ratio of the speed of light in a vacuumto the speed in another medium. The ratio of the speed of light in a vacuumto the speed in another medium. Absolute Refractive Index 6. A thin layer or series of layers ofmaterial applied to the surface of a lens for the purpose of reducing unwanted reflections from the lens surface and thus increasing the amount of light thatpasses through to the eye. A thin layer or series of layers ofmaterial applied to the surface of a lens for the purpose of reducing unwanted reflections from the lens surface and thus increasing the amount of light thatpasses through to the eye. Antireflection Coating 1 of 22 Anki Glossary: OPT127 (96 cards) 7. A thin, hard coating applied to plasticlens surfaces to make them more resistant to scratching. Generated on 2021-02-18 A thin, hard coating applied to plasticlens surfaces to make them more resistant to scratching. Antiscratch Coating (Scratch Resistant Coating) 8. The type of aberration that causes light ofdifferent wavelengths (colors) to be refracted differently through the sameoptical system. The type of aberration that causes light ofdifferent wavelengths (colors) to be refracted differently through the sameoptical system. Chromatic Aberration 9. An aberration that produces images ofslightly different sizes at the focal length of the lens, depending upon thecolor of the light. An aberration that produces images ofslightly different sizes at the focal length of the lens, depending upon thecolor of the light. Transverse (Lateral) Chromatic Aberration 10. Occurs when a point light source that iscomposed of several wavelengths (such as white light) forms a series of pointimages along the optical axis. Each ofthese images is a different color, and has a slightly different focal length. 11. A commonly used glass lens material havingan index of refraction of 1.523. Occurs when a point light source that iscomposed of several wavelengths (such as white light) forms a series of pointimages along the optical axis. Each ofthese images is a different color, and has a slightly different focal length. Axial (Longitudinal) Chromatic Aberration A commonly used glass lens material havingan index of refraction of 1.523. Crown Glass 12. A registered trademark of Pittsburgh PlateGlass Co. for an optical plastic known as Columbia Resin 39. It has been the standard material from whichconventional plastic lenses are made. A registered trademark of Pittsburgh PlateGlass Co. for an optical plastic known as Columbia Resin 39. It has been the standard material from whichconventional plastic lenses are made. CR-39 2 of 22 Anki Glossary: OPT127 (96 cards) 13. The process of increasing the impactresistance of glass lenses by immersing them in a bath of molten salt. Generated on 2021-02-18 The process of increasing the impactresistance of glass lenses by immersing them in a bath of molten salt. Chemical Tempering 14. The process of hardening a glass lens byfirst heating it in a kiln, then quickly cooling by blowing forced air againstboth front and back surfaces. The process of hardening a glass lens byfirst heating it in a kiln, then quickly cooling by blowing forced air againstboth front and back surfaces. Heat Treating 15. A test to determine impact resistance ofophthalmic lenses whereby either a 5/8thinch or 1 inch steel ball is dropped onto the front surface of a lens from aheight of 50 inches. A test to determine impact resistance ofophthalmic lenses whereby either a 5/8thinch or 1 inch steel ball is dropped onto the front surface of a lens from aheight of 50 inches. Drop-Ball Test 16. Alens with an index of refraction that is at the upper end of the range ofavailable indices of refraction for lenses, yielding a lens that is thinnerthan other lenses of the same size and power. 17. An aberration that is present even whenlight is made up of only one wavelength (one color). Alens with an index of refraction that is at the upper end of the range ofavailable indices of refraction for lenses, yielding a lens that is thinnerthan other lenses of the same size and power. High-Index Lens An aberration that is present even whenlight is made up of only one wavelength (one color). Monochromatic Aberration 18. A lens that changes its transmissioncharacteristics when exposed to light. A lens that changes its transmissioncharacteristics when exposed to light. Photochromic Lens 3 of 22 Anki Glossary: OPT127 (96 cards) 19. A 1.586 index lens material known for itsstrength. Generated on 2021-02-18 A 1.586 index lens material known for itsstrength. Polycarbonate 20. The ratio of the speed of light in a medium(such as air) to the speed of light in another medium (such as glass). The ratio of the speed of light in a medium(such as air) to the speed of light in another medium (such as glass). Refractive Index 21. Aterm used to describe a material that will bend when heated and will return toits original shape when reheated. Aterm used to describe a material that will bend when heated and will return toits original shape when reheated. Thermoelastic 22. A term used to describe a material thatwill bend when heated, but does notreturn to its original shape when reheated because it does not have a “plasticmemory”. A term used to describe a material thatwill bend when heated, but does notreturn to its original shape when reheated because it does not have a “plasticmemory”. Thermoplastic 23. The brand name for a PPG Industries plasticlens material known for its high impact resistance and ability to be processedin a manner similar to that of other plastic lenses. The brand name for a PPG Industries plasticlens material known for its high impact resistance and ability to be processedin a manner similar to that of other plastic lenses. Trivex 24. A lens whose surface power graduallychanges in power from the center to the edge for the purpose of optimizing theoptical quality of the image or reducing the thickness of the lens. A lens whose surface power graduallychanges in power from the center to the edge for the purpose of optimizing theoptical quality of the image or reducing the thickness of the lens. AsphericLens 4 of 22 Anki Glossary: OPT127 (96 cards) 25. A lens with a cylinder component whosesurface gradually changes in power from the center to the edge. Each of the two major meridians changes inpower by different amounts based on the cylinder power of the lens and for thepurpose of optimizing the optical quality of the image in both meridians. 26. The surface curve of a lens that becomesthe basis from which the remaining curves are calculated. In the United States and most other parts ofthe world, this is usually the front surface spherical curve of the lens. 27. Aterm used to describe a lens that is inwardly curved on both surfaces. Generated on 2021-02-18 A lens with a cylinder component whosesurface gradually changes in power from the center to the edge. Each of the two major meridians changes inpower by different amounts based on the cylinder power of the lens and for thepurpose of optimizing the optical quality of the image in both meridians. Atoric Lens The surface curve of a lens that becomesthe basis from which the remaining curves are calculated. In the United States and most other parts ofthe world, this is usually the front surface spherical curve of the lens. Base Curve Aterm used to describe a lens that is inwardly curved on both surfaces. Biconcave 28. A term used to describe a lens that isoutwardly curved on both surfaces. A term used to describe a lens that isoutwardly curved on both surfaces. Biconvex 29. A straight line that intersects two pointsof an arc. A straight line that intersects two pointsof an arc. Chord 30. A lens whose surface curvatures have beencarefully chosen with the intent of reducing those peripheral lens aberrationsthat are troublesome to the spectacle lens wearer. A lens whose surface curvatures have beencarefully chosen with the intent of reducing those peripheral lens aberrationsthat are troublesome to the spectacle lens wearer. CorrectedCurve Lens (Best Form Lens) 5 of 22 Anki Glossary: OPT127 (96 cards) 31. The reciprocal of the radius of curvatureof a curved surface, quantified in reciprocal meters (m-1) and abbreviated by R. Generated on 2021-02-18 The reciprocal of the radius of curvatureof a curved surface, quantified in reciprocal meters (m-1) and abbreviated by R. Curvature 32. An expression of the extent to which thecurve in the frame front varies from the classical four-point touch position,taking on the curved form of the face. An expression of the extent to which thecurve in the frame front varies from the classical four-point touch position,taking on the curved form of the face. Face Form 33. A lens having a convex front surface and aconcave back surface. A lens having a convex front surface and aconcave back surface. MeniscusLens 34. That line which passes through the centerof a lens on which the radii of curvature of the front and back surfaces fall. That line which passes through the centerof a lens on which the radii of curvature of the front and back surfaces fall. Optical Axis 35. That point on an ophthalmic prescriptionlens through which no prismatic effect is manifested. That point on an ophthalmic prescriptionlens through which no prismatic effect is manifested. Optical Center 36. In fitting: that angle that the frame frontmakes with the frontal plane of the wearer’s face when the lower rims arecloser to the face than the upper rims. In fitting: that angle that the frame frontmakes with the frontal plane of the wearer’s face when the lower rims arecloser to the face than the upper rims. PantoscopicTilt (Pantoscopic Angle) 6 of 22 Anki Glossary: OPT127 (96 cards) 37. A lens that is plano (flat) on one surfaceand inwardly curved on the other surface. Generated on 2021-02-18 A lens that is plano (flat) on one surfaceand inwardly curved on the other surface. PlanoconcaveLens 38. A lens that is plano (flat) on one surfaceand outwardly curved on the other surface. A lens that is plano (flat) on one surfaceand outwardly curved on the other surface. PlanoconvexLens 39. The height or depth of a given segment of acircle. The height or depth of a given segment of acircle. SagittalDepth 40. Alens having a single refractive power in all meridians. Alens having a single refractive power in all meridians. Sphere 41. The sum of the spherical component and onehalf of the cylinder component of an ophthalmic lens prescription. The sum of the spherical component and onehalf of the cylinder component of an ophthalmic lens prescription. SphericalEquivalent 42. Blackconcentric circles and numbers that are present whether or not the lensometeris on. Blackconcentric circles and numbers that are present whether or not the lensometeris on. Reticle 43. Presentonly when lensometer is on and focused. Presentonly when lensometer is on and focused. Illuminated mires 7 of 22 Anki Glossary: OPT127 (96 cards) Generated on 2021-02-18 44. Mostof Mostof the time, clinicians neutralize the right lens first. Technically, though,you should neutralize the strongest lens first to find the most precise opticalcenter. You're less likely to miss any prism this way. 45. Power Power in an oblique meridian is estimated by sphero-cylinders and toric by the following equation, in which alpha is the degree distance from the axis meridian to the meridian of interest. 46. Calculate Calculate the power of the following lens in the 180 meridian: +10.00 -6.00 x 140. the time, clinicians neutralize the [...] lens first. Technically, though,you should neutralize the [...] lens first to find the most precise opticalcenter. You're less likely to miss any [...] this way. in an oblique meridian is estimated by sphero-cylinders and toric by the following equation, in which alpha is the degree distance from the [...] to the [...]. the power of the following lens in the 180 meridian: +10.00 -6.00 x 140. 8 of 22 Anki Glossary: OPT127 (96 cards) an oblique meridian is 30 degrees from the axis meridian, it will have [...] of the total cylinder power. Generated on 2021-02-18 47. If If an oblique meridian is 30 degrees from the axis meridian, it will have 25 percent of the total cylinder power. 48. If If an oblique meridian is 45 degrees from the axis meridian, it will have 50 percent of the total cylinder power. an oblique meridian is 45 degrees from the axis meridian, it will have [...] of the total cylinder power. 9 of 22 Anki Glossary: OPT127 (96 cards) an oblique meridian is 60 degrees from the axis meridian, it will have [...] of the total cylinder power. Generated on 2021-02-18 49. If If an oblique meridian is 60 degrees from the axis meridian, it will have 75 percent of the total cylinder power. 50. If If an oblique meridian is 90 degrees from the axis meridian, it will have 100 percent of the total cylinder power. an oblique meridian is 90 degrees from the axis meridian, it will have [...] of the total cylinder power. 10 of 22 Anki Glossary: OPT127 (96 cards) the power at the following axes (170, 005,020, 050) of this prescription: +10.00 -6.00 x 140. Generated on 2021-02-18 51. Estimate Estimate the power at the following axes (170, 005,020, 050) of this prescription: +10.00 -6.00 x 140. 52. When When adding two spherocylinder lenses, how can the resultant cylinder axis be estimated? adding two spherocylinder lenses, how can the resultant cylinder axis be estimated? [[type:Back]] If cylinders are of the same power, resultant axis halfway between combining lens axes. If one cylinder stronger, resultant axis falls closer to the axis of the stronger cylinder. 53. What is the resultant spherocylindrical lens obtained by crossing a +4.00 DC axis 20° with a +2.50 DC axis 80°? Use estimation. a. +1.50 DS +3.50DC axis 39° b. +3.00 DS +3.50DC axis 15° c. +3.50 DS +1.50DC axis 60° d. +1.50 DS +3.50DC axis 78° What is the resultant spherocylindrical lens obtained by crossing a +4.00 DC axis 20° with a +2.50 DC axis 80°? Use estimation. a. +1.50 DS +3.50DC axis 39° b. +3.00 DS +3.50DC axis 15° c. +3.50 DS +1.50DC axis 60° d. +1.50 DS +3.50DC axis 78° The axis must be between 020 and 080. It will be closer to the stronger cylinder lens. Therefore, A is the only reasonable answer. 11 of 22 Anki Glossary: OPT127 (96 cards) Generated on 2021-02-18 54. Normally Normally the object of regard is viewed along the optical axis of the lens when the lens is tilted, the optical axis tilts. If you tilt a lens, the lens is now angled relative to the object of regard, resulting in oblique astigmatism being created. 55. When When you tilt a lens, the new sphere becomes stronger than the old sphere. Minus lenses become more minus and plus lenses become more plus. 56. When When you tilt a lens, cylinder will be induced in the spherical lens. It will be the same sign as the sphere and have axis equal to the meridian of rotation. 57. Most Most glasses have some tilt forward, called Pantoscopic tilt, thatslightly alters the prescription. 58. In In a tilted spherical lens, the sagittal and tangential meridian are the same. the object of regard is viewed along the optical axis of the lens when the lens is tilted, the optical axis tilts. If you tilt a lens, the lens is now angled relative to the object of regard, resulting in [...] being created. you tilt a lens, the new sphere becomes stronger than the old sphere. Minus lenses become [...] and plus lenses become [...]. you tilt a lens, cylinder will be induced in the spherical lens. It will be the same sign as the sphere and have axis equal to the [...]. glasses have some tilt forward, called [...], thatslightly alters the prescription. a tilted spherical lens, the sagittal and tangential meridian are [...]. 12 of 22 Anki Glossary: OPT127 (96 cards) Generated on 2021-02-18 59. In In a tilted spherocylindrical lens, thesagittal meridian is always the same meridian as the axis of the lens tilt. Thetangential meridian is perpendicular to the sagittal meridian. 60. For For pantoscopic tilt, the axis meridian is the 180° meridian, thereforethe sagittal meridian is the horizontal meridian. 61. For For face-form tilt (goggle-effect), the axis meridian is the 90° meridian, therefore the sagittal meridian is the vertical meridian 62. What What is the equation for effectivepower in a sagittal meridian when tilting a spherical lens? a tilted spherocylindrical lens, thesagittal meridian is always the same meridian as the [...]. Thetangential meridian is [...] the sagittal meridian. [...] tilt, the axis meridian is the 180° meridian, thereforethe sagittal meridian is the horizontal meridian. [...], the axis meridian is the 90° meridian, therefore the sagittal meridian is the vertical meridian is the equation for effectivepower in a sagittal meridian when tilting a spherical lens? 13 of 22 Anki Glossary: OPT127 (96 cards) is the equation for effective power in a tangential meridian when tilting a spherical lens? Generated on 2021-02-18 63. What What is the equation for effective power in a tangential meridian when tilting a spherical lens? 64. What What are the equations for induced cylinder when tilting a spherical lens? 65. A A +8.00DS crown glass lens has a 20° pantoscopic tilt. What is the new power? are the equations for induced cylinder when tilting a spherical lens? +8.00DS crown glass lens has a 20° pantoscopic tilt. What is the new power? 14 of 22 Anki Glossary: OPT127 (96 cards) 66. A 10.00Dcrown glass lens has 10° face-form tilt. What is the new power? Generated on 2021-02-18 A 10.00Dcrown glass lens has 10° face-form tilt. What is the new power? 15 of 22 Anki Glossary: OPT127 (96 cards) 67. A +7.00 -2.00 x180 crown glass lens has 17 degree pantoscopic tilt. What is the effective power? Generated on 2021-02-18 A +7.00 -2.00 x180 crown glass lens has 17 degree pantoscopic tilt. What is the effective power? 16 of 22 Anki Glossary: OPT127 (96 cards) -10.00 -3.00 x 090 crown glass lens has 15 degree face-form tilt. What is the effective power? Generated on 2021-02-18 68. A A -10.00 -3.00 x 090 crown glass lens has 15 degree face-form tilt. What is the effective power? 69. Near Near SEQ can be calculated by the following equation: Near SEQ =ADD + Distance SEQ. SEQ can be calculated by the following equation: [...]. 17 of 22 Anki Glossary: OPT127 (96 cards) 70. A lens having two areas for viewing, eachwith its own focal power. Usually theupper portion of the lens is for distance vision, the lower for near vision. Generated on 2021-02-18 A lens having two areas for viewing, eachwith its own focal power. Usually theupper portion of the lens is for distance vision, the lower for near vision. Bifocal 71. A bifocal lens constructed from one piece of lensmaterial and having the demarcation line smoothed out as not to be visible toan observer. A bifocal lens constructed from one piece of lensmaterial and having the demarcation line smoothed out as not to be visible toan observer. Blended Bifocal 72. For the manufacture of fused-glasssemifinished bifocal and trifocal lenses, the countersink curve is that curvethat is ground into the main lens in the area where the segment is to beplaced. The countersink curve matchesthe back curve of the bifocal or trifocal segment. When the segment is placed on the countersinkcurve of the main lens, the two may then be fused together. 73. A bifocal lens having a segment that isround in the lower portion and gently curved on the top of the segment. For the manufacture of fused-glasssemifinished bifocal and trifocal lenses, the countersink curve is that curvethat is ground into the main lens in the area where the segment is to beplaced. The countersink curve matchesthe back curve of the bifocal or trifocal segment. When the segment is placed on the countersinkcurve of the main lens, the two may then be fused together. Countersink Curve A bifocal lens having a segment that isround in the lower portion and gently curved on the top of the segment. Curved-Top Bifocal 74. A multifocal lens with a flat-topbifocal-style segment in the upper portion of the lens. A multifocal lens with a flat-topbifocal-style segment in the upper portion of the lens. Double-D Lens 18 of 22 Anki Glossary: OPT127 (96 cards) 75. A bifocal having a segment that extends theentire width of the lens blank. Generated on 2021-02-18 A bifocal having a segment that extends theentire width of the lens blank. Executive Bifocal (AKA Franklin Bifocal) 76. A bifocal with a segment that is round inthe lower half, but flat on the top. A bifocal with a segment that is round inthe lower half, but flat on the top. Flat-Top Bifocal 77. Glass multifocal lenses in which the segmentcannot be felt because it is fused into the distance portion. Glass multifocal lenses in which the segmentcannot be felt because it is fused into the distance portion. Fused Multifocal 78. The sudden displacement of image as thebifocal line is crossed by the eye. The sudden displacement of image as thebifocal line is crossed by the eye. Image Jump 79. The point on a lens where the prism equalsthat called for by the prescription. The point on a lens where the prism equalsthat called for by the prescription. Major Reference Point 80. A lens having a sector or sectors where therefractive power is different from the rest of the lens, such as bifocals ortrifocals. A lens having a sector or sectors where therefractive power is different from the rest of the lens, such as bifocals ortrifocals. Multifocal Lens (AKA Multifocal) 19 of 22 Anki Glossary: OPT127 (96 cards) 81. The plus power a multifocal lens segment has that is added to the power alreadypresent in the main portion of the lens. Generated on 2021-02-18 The plus power a multifocal lens segment has that is added to the power alreadypresent in the main portion of the lens. Near Addition 82. The net lens power resulting from thecombination of the add power and the distance power. The net lens power resulting from thecombination of the add power and the distance power. Near Rx (AKA Near Power) 83. Multifocal lenses that are made of onematerial with any changes in power in the segment portion of the lens theresult of a change in the surface curvature of the lens. Multifocal lenses that are made of onematerial with any changes in power in the segment portion of the lens theresult of a change in the surface curvature of the lens. One-Piece Multifocals 84. That point on an ophthalmic prescriptionlens through which not prismatic effect is manifested. That point on an ophthalmic prescriptionlens through which not prismatic effect is manifested. Optical Center 85. Theapparent change in position of an object as the result of a change in viewingangle. Theapparent change in position of an object as the result of a change in viewingangle. Parallax 86. The vertical position in the lens throughwhich the wearer’s line of sight passes when reading. The vertical position in the lens throughwhich the wearer’s line of sight passes when reading. Reading Level (AKA Reading Depth) 20 of 22 Anki Glossary: OPT127 (96 cards) 87. Abifocal with a segment that resembles a circle with the top and bottom removed. Generated on 2021-02-18 Abifocal with a segment that resembles a circle with the top and bottom removed. Ribbon Bifocal 88. A bifocal with a segment that is perfectlyround. A bifocal with a segment that is perfectlyround. Round Seg Bifocal 89. An area of a spectacle lens with powerdiffering from that of the main portion. An area of a spectacle lens with powerdiffering from that of the main portion. Segment 90. The vertical distance from the majorreference point (MRP) to the top of the segment when the segment top is lowerthan the MRP. The vertical distance from the majorreference point (MRP) to the top of the segment when the segment top is lowerthan the MRP. Segment Drop 91. The vertically measured distance from thelowest point on the lens to the level of the top of the segment. The vertically measured distance from thelowest point on the lens to the level of the top of the segment. Segment Height 92. That location on the segment of a bifocallens that shows zero prismatic effect when no refractive power is in thedistance portion of the lens. That location on the segment of a bifocallens that shows zero prismatic effect when no refractive power is in thedistance portion of the lens. Segment Optical Center 21 of 22 Anki Glossary: OPT127 (96 cards) 93. The vertical distance from the majorreference point (MRP) to the top of the segment when the segment top is higherthan the MRP. Generated on 2021-02-18 The vertical distance from the majorreference point (MRP) to the top of the segment when the segment top is higherthan the MRP. Segment Raise 94. Thesize of a bifocal or trifocal segment measured horizontally across its widestsection. Thesize of a bifocal or trifocal segment measured horizontally across its widestsection. Segment Width 95. Multifocal lenses having a visible, clearlydemarcated bifocal or trifocal area. Nonsegmented multifocals would be progressive addition lenses. 96. Lenses having three areas of viewing, eachwith its own focal power. Usually theupper portion is for distance viewing, the lower for near, and the middle ofintermediate portion for distance in between. Multifocal lenses having a visible, clearlydemarcated bifocal or trifocal area. Nonsegmented multifocals would be progressive addition lenses. Segmented Multifocals Lenses having three areas of viewing, eachwith its own focal power. Usually theupper portion is for distance viewing, the lower for near, and the middle ofintermediate portion for distance in between. Trifocals 22 of 22
