. Spectacles and eyeglasses, their forms, mounting, and proper adjustment . hat of the first, to obtain the interpupillary procedure is also of advantage in revealing and meas-uring any difference in the distance of the pupils from the PRESCRIPTION OF FRAMES. 57 median line, due to asymmetry of the face. The use of atrial frame for making accurate measurements requires thebestowal of considerable attention to see that the supportof the nose-piece is vertical, the joints close and tight, andthe markings correct; otherwise it may readily introducethe errors its use is intended to
. Spectacles and eyeglasses, their forms, mounting, and proper adjustment . hat of the first, to obtain the interpupillary procedure is also of advantage in revealing and meas-uring any difference in the distance of the pupils from the PRESCRIPTION OF FRAMES. 57 median line, due to asymmetry of the face. The use of atrial frame for making accurate measurements requires thebestowal of considerable attention to see that the supportof the nose-piece is vertical, the joints close and tight, andthe markings correct; otherwise it may readily introducethe errors its use is intended to obviate. There are, in theshops, many special forms of the pupillometer constructedon the principle of a rule held before the eyes and a singlesight for each pupil. Two of these are shown in Figs. 31and 32. The interpupillary distance as registered by themrequires, of course, the same correction as does that ob-tained by the simple graduated rule. Height of the Bridge.—This is the distance of the topof the bridge above a line joining the centers of the lenses. Fig. x m ,t • H In Fig. 27, it is the distance from K to F, which is theheight of K above a line joining a and b; not the heightof K above a line joining c and d, which is sometimeserroneously supposed to represent the height of the a rule be held horizontally before the patients eyes,wdth the lower edge touching the nose at the natural posi-tion for the spectacle bridge, the height of this edge of therule above the pupil on either side will show at a glanceabout how high the top of the future bridge must be. Wemay then select from our sample frames that one whosebridge corresponds most nearly with this supposed height,and being sure to place it in the natural position, we care-fully note whether the pupils are above or below thecenters of the eyes of the frame. If they are below thesecenters, sufficient must be added to the height of the bridge 58 SPECTACLES AND EYEGLASSES. now upon the face to allow t
Size: 2023px × 1235px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjecteyeglasses, bookyear1
