Medical Glasses (PDF)

MEDICAL GLASSES TECHNICAL. ALI ADNAN ABBREVIATED TERMS R.E _ right eye L.E _ left eye SPh _ spherical CYL _ cylindrical AX _ axis Add _ addition reading number I.P.D _ Inter pupillary distance Dia _ Diameter  ABBREVIATED TERMS B.C _ base curve O.C _ optical center G.C _ geomet...

MEDICAL GLASSES TECHNICAL. ALI ADNAN ABBREVIATED TERMS R.E _ right eye L.E _ left eye SPh _ spherical CYL _ cylindrical AX _ axis Add _ addition reading number I.P.D _ Inter pupillary distance Dia _ Diameter  ABBREVIATED TERMS B.C _ base curve O.C _ optical center G.C _ geometrical center S.V _ single vision B.F _ bifocal Tri _ trifocal DIST _ distance vision U.V _ ultraviole  ABBREVIATED TERMS N.V _ near vision F.V _ far vision D.B.L _ distance between tow lenses HI.N _ high index lens material I.O.L _ inter ocular lens I.O.P _ inter ocular presser S.R.C _ scratch resistant coating N. nasal T. temporal F.S _ frame size B.S _ bridge size  IMPORTANT TERMS o Spectacles : it is use for correct refractive errors in human eves, protect the eyes from becoming subject to direct light and cosmetic. o The lenses; is a transparent refracting medium, bounded by two surfaces that form a part of a sphere (spherical lens) or cylinder (cylindrical or Toric lens ) o Diopter; is the unit of measurement of the power of the lens D= 1/f Optical center: a point within the lens and laying on it is principal axis such that all the rays passing through it emerge un deviated o Center of curvature (C)f is the center of the sphere of which the refracting lens surface is a part Radius of curvature (R): is the radius of the sphere of which the refracting surface is a part o Principal axis (AB) : is the line joining the centers of curvatures of it is surfaces o Principal focus : is that point on the principal axis where parallel rays of light IMPORTANT TERMS o Medical lens : it is a condition of tow prisms from the base or from the top. o The tow prisms blades at the base form a convex lens , which is called a plus lens o The tow prisms at the top form a minus lens o The plus lens is used to correct hypermetropic eye o The minus lens is used to correct myopic eye WAYS TO DISTINGUISH THE TYPE OF LENS o Viewing by placing the lens in front of the eye and looking through it at a specific object o If the movement of the body is opposite to the movement of the lens, this indicates that the lens is convex o If the movement of the body coincides with the movement of the lens, this indicates that the lens is concave o By holding the lens from the center o If the center of the lens is thick, this indicates that the lens is convex o If the center of the lens is thin, this indicates that the lens is concave