referring to fig1 - 3 , an ophthalmic test lens holder 10 is shown to include a first clamping member 12 attached to a second clamping member 14 by a u - shaped compression spring 16 . in this embodiment , clamping members 12 and 14 include a base portion 18 and 20 , respectively , to which is attached an elongated loop of wire 22 and 24 , respectively . the area of space inwardly bounded by the loops of wire define a viewing aperture , as will be discussed in greater detail subsequently . it is not necessary to use wire , but strong , flexible materials are preferable . many plastics are acceptable . u - shaped compression spring 16 is connected to base portion 18 by a fastener assembly 26 and is connected to base portion 20 by a fastener assembly 28 . the compression spring serves to bias the ends 30 of the clamping members together , as shown in solid lines in fig3 . when base portions 18 and 20 are pressed together , usually between the thumb and forefinger of the practitioner &# 39 ; s hand , so as to be positioned at 18 &# 39 ; and 20 &# 39 ;, the ends 30 of the elongated loops of wire will spread apart as shown at 22 &# 39 ; and 24 &# 39 ;. when pressure is removed from the base portions , spring 16 will return the clamping members to their original , closed positions . thus , as configured , lens holder 10 is constructed to have a cliplike action , as will be more fully discussed later with reference to fig4 . attached to loop 24 is a test lens bracket which , in this embodiment , includes a pair of bracket pieces 32a and 32b and an elongated spring bracket piece 34 . as best seen in fig2 a test lens 36 can be held to loop 24 by placing it against the pair of bracket pieces 32a , 32b and by latching the hooked end of spring bracket piece 34 over the top of it . the spring bracket piece exerts a sufficient force upon the lens to securely hold it against the pair of bracket pieces 32 . the ophthalmic test lens holder 10 as described above may be constructed from a wide variety of materials . the base portions 18 and 20 can be formed from metal , plastic or other materials , although plastic is preferable for large scale production . the elongated loops of wire are preferably formed from a strong , resilient material such as spring steel . spring bracket piece 34 , of course , would have to be formed from spring steel or from some other rugged spring material . either or both of the elongated loops may be covered or coated with a material having a higher coefficient of friction than that of the loop material itself so as to help prevent the test lens holder from slipping when clamped to a pair of spectacle frames . in this preferred embodiment , elongated loop 22 is coated by a dip applied plastic material . with reference to fig4 the operation of ophthalmic test lens holder 10 can be discussed . as it is most normally used , test lens holder 10 is clamped to a pair of empty spectacle frames 40 by pressing the base portions between the thumb and forefinger to separate ends 30 , by disposing the clamping members on either side of a lens socket , and by releasing the pressure on the base portions . the bottom of a test lens is usually aligned with the bottom of a lens socket in a pair of spectacle frames if the position of a bifocal line is to be measured . the spectacle frames are placed on the face of a patient so that he or she can look at a mirror through the test lens held by the test lens holder . referring now to fig5 - 9 , another embodiment of a test lens holder is shown . in this embodiment , a first clamping member 44 , seen in fig6 is connected to a second clamping member 46 by a u - shaped compression spring 48 in a manner analogous to that of the previous embodiment . in this embodiment , at least one of the clamping members 44 or 46 is constructed from an elongated piece of flat , transparent plastic material which has a general overall shape similar to the loop , previously described and having a viewing aperture 52 in the center thereof , shown in fig5 which is a round hole slightly smaller than a test lens , but approximately the same size . clamping member 46 has a length which is greater than the distance across any socket of a spectacle frame . preferably , the member is at least 30 % greater than the vertical distance across a spectacle frame . attached to the base portion 47 of member 46 is a thumb plate 54 . base portion 47 is used to secure spring 48 thereto by means of fasteners 50 . the test lens support bracket consists of an arc - shaped spring 60 which is fastened to member 46 by an l - shaped pad 62 on one side , as seen in the detail of fig9 . at the opposite end of the bracket is a guide pad 64 which is free to move at the end of spring 60 . pads 62 and 64 have grooves 63 and 65 adapted to receive a test lens . while only two grooves are shown , more grooves can be provided if desired . the number of grooves is not critical . the reason that additional grooves may be desired is that it is very common for a practitioner to use two or more lenses to help determine the exact specification of a permanent correction lens . the grooves 62 and 65 are intended to lie in a semicircular arc since test lenses are usually circular . a test lens is held against a third pad 66 , seen in fig5 which is on the opposite side of aperture 52 with respect to spring 60 . the pad 66 also has a corresponding number of grooves therein for seating test lenses . the grooves may be either machined into the pads or molded . it is preferable to have at least one groove , usually the outermost , with a greater thickness compared to the innermost groove to accommodate thicker lenses , such as those having greater corrective power for the near - sighted . the member 46 has a portion extending from the middle of lens aperture 52 to a point 70 , well below the furthest downward extent of lens aperture 52 . this portion is necessary for two reasons . first , it allows the test lens holder to completely span a lens socket , for even the largest of spectacle frames . secondly , the downwardly extending portion of the member , opposite the base bears a number of lateral rulings 72 which are used for marking distances of a test lens relative to the socket . the rulings may include indicia identifying individual rulings or groups of rulings . for example , rulings may be marked indicating millimeter or other distance intervals . one of the chief uses of the lateral ruling 72 is to indicate bifocal segment height relative to the bottom of a lens socket in a frame . an ophthalmic practitioner can first place the bottom of lens apeture 52 to coincide with the bottom of the socket in a spectacle frame . then , by moving the ophthalmic test lens holder of the present invention upwardly or downwardly , he can count the number of rulings or gauge the distance that a bifocal segment line should be placed with respect to the bottom of the spectacle frame . usually , a patient indicates a desired bifocal segment line height . this height can be accurately gauged by the present invention . the lateral rulings are parallel to each other and when used , are generally parallel to the direction of the bridge of spectacles , although this orientation is not the only possible one . the rulings may be engraved , painted or otherwise applied to base portion . while the extended tip portion of the member carries distance rulings 72 , the side of the member toward the base 47 carries angular rulings 74 which are used to indicate angular orientation of a test lens , for measuring the angular alignment of a test lens , as in astigmatism correction . with respect to fig7 the backside of the ophthalmic test lens holder of fig5 may be seen . in this case , the back member has the clamping member 44 which consists of a wire loop 73 held by base portion 75 . the wire loop 73 may be constructed in a manner similar to loop 24 in fig1 . while a wire loop is shown as the back clamping member , a second plastic clamping member , similar to member 46 may also be used . a wire member is preferred for the backside , because it is light weight and may be made relatively thin , so as not to cause discomfort to a patient . fig8 shows the test lens holder of fig5 - 7 positioned over a spectable frame 40 &# 39 ;. the base of aperture 52 is aligned with the bottom of the socket of the frame and then the lateral rulings 72 are observed to measure the desired location of a lens feature , such as a bifocal segment line height . angular alignment measurements are observed by reading the angular rulings 74 in a similar manner . the test lens holder may be moved by pressure against the thumb plate 54 relative to an index finger plate 55 on the back member 44 . this causes spring compression and an opening of the frame as indicated by the arrow a in fig6 . the test lens holder may be moved up or down as required by the practitioner or patient until desired measurements may be made . note that it is important that the length of the holder in the vertical direction be sufficient to allow upward movement of a test lens across the socket of a frame . for example , in the situation where a patient desires a relatively high bifocal line , a relatively small test lens must be supported in a high position relative to a big socket in a large frame . fig8 illustrates a medium size frame with a typical small test lens size . with larger frames , the test lens holder must have a length below the lens aperture of at least one centimeter and preferably two to four centimeter . with the test lens holder of this embodiment , it is possible for a practitioner to perform three important and distinct tests . first , the practitioner can determine by means of one or more test lenses exactly what the correctional formula for the permanent eyeglass lenses should be . secondly , he is able to determine exactly where to place the bifocal line prior to the preparation of a permanent lens . finally , the patient is allowed to view a number of frames with lenses equivalent to his regular prescription so that he can judge the frame style , even though the frames are without lenses .
a lens holder having a pair of spring connected clamping members with apertures therein mountable over a lens socket of spectacle frames . the clamping members have an extent which is sufficient to completely span lens sockets and extend a distance beyond . transverse lateral rulings on at least one of the clamping members permit gauging an aperture in a clamping member relative to a socket in a spectacle frame . in this manner , geometrical characteristics of a test lens may be measured and recorded for the purpose of making permanent lenses for a selected spectacle frame . in addition to transverse lateral rulings on a clamping member , angular rulings about an aperture in a clamping member may also be applied for determining angular orientations of a test lens .