| 摘要 |
PURPOSE:To obtain the inexpensive bifocal contact lens which eliminates the need for moving the line of sight and for giving care to the upper and lower positions of the lens by consisting the lens of two kinds of stocks which are different in refractive index and consisting the lens in such a manner that two kinds of these stocks are concentrically disposed alternately from the center. CONSTITUTION:A 1st resin 11 of a cylindrical shape having the suitable refractive index is prepd. and the 2nd resin 12 of a cylindrical shape which has the diameter to be tightly fitted into this cylinder and the different refractive index is prepd. and is fitted into the hole of the 1st resin 11 to form the combined resin. The combined resin is heated to the temp. higher than the glass transition point of the resin and is elongated, by which a resin rod having a desired diameter is obtd. The rod is subjected to cutting, grinding and polishing to obtain the desired bifocal contact lens. A user views a far object with the part of the low refractive index resin and a near object with the high refractive index part. The inexpensive bifocal contact lens which eliminates the need for moving the line of sight and for giving care to the upper and lower position of the lens is obtd. in this way. |
