PUBLISHERS' NOTICES 



4^7 



PUBLISHERS NOTICES 



'Tis Dot in mortals to COMMAND success, but we'll do more, bempronius, we'll DESERVE IT. 



— Addison: Cato. 



Punktal Lenses. 



These new lenses mark an important 

 epoch in the history of ophthalmic op- 

 tics. They are strictly analogous to the 

 photographic anastigmat, since they 

 render in their field the same service 

 that is performed by the latter in the 

 field of photography. They remove a 

 handicap under which the oculist and 

 the refractionist have been compelled 

 to labor for years, by enabling them to 

 prescribe for their patients lenses 

 •equally well corrected from the center 

 to the very margin. 



The word ''Punktal" is of German ori- 

 gin, meaning in this application a lens 

 which reproduces any given definite 

 point of an object as a distinct point in 

 the image. In other words, we have at 

 last obtained an ophthalmic lens which 

 is corrected for astigmatism in all pow- 

 ers. For many years past practically 

 the only improvements in ophthalmic 

 lenses have been in the technique of 

 manufacture. 



With the popularization of the Men- 

 iscus and Toric lenses, there was intro- 

 duced a better corrected lens, one in 

 which the angle of distinct view was 

 materially increased. This was brought 

 about largely through the publication 

 of the Ophthalmic Lens Chart by the 

 Bausch & Lomb Optical Company in 

 1912. 



The flat forms of lenses would be 

 satisfactory, if the eye always remained 

 stationary in its socket and used only 

 the center of the lens, but the eye ro- 

 tates in viewing surrounding objects, 

 and even in reading, and one compelled 

 to wear ordinary lenses can avail him- 

 self of this rotation within only restrict- 

 ed limits, according to the form of lens 

 used. As his line of sight moves to- 

 ward the margin of the lens, both blur 

 and distortion are noticed — very pro- 

 nounced in the fiat forms, less pro- 



nounced in the ordinary deep curved 

 types. This blur is caused by the as- 

 tigmatism of oblique pencils of light. 



Desiring to eliminate all this astig- 

 matism and recognizing the impossibil- 

 ity of doing so when using a fixed base 

 curve lens for all foci, Dr. Moritz von 

 Rohr, of the scientific staff of Carl 

 Zeiss, Jena, Germany, instituted exten- 

 sive investigations in this field, and 

 published his findings in 191 1. 



Problems of manufacture were then 

 undertaken and have now been solved 

 satisfactorily. The result is the new 

 Punktal lenses. The word has been 

 registered as a trade-mark in the Unit- 

 ed States by the firm of Carl Zeiss and 

 patents obtained upon the astigmatic 

 corrections, The exclusive manufact- 

 uring rights for the American conti- 

 nent are held by the Bausch & Lomb 

 Optical Company, American associates 

 of Carl Zeiss and among the instigators 

 in the development of this new type. 



The Punktal lens, by eliminating all 

 astigmatism, enables the wearer to see 

 objects distinctly within an angle of 

 view of about sixty degrees. The ob- 

 server is thus enabled to see through 

 the extreme margin of the lens as clear- 

 ly as through the center. 



Punktal lenses represent what may 

 safely be regarded as the highest pos- 

 sible achievement in ophthalmic optics. 

 They are the products of precise work- 

 manship, and a guarantee of the accu- 

 racy of their curves and surfaces is as- 

 sured. Each lens bears upon its sur- 

 face, near the margin, a small trade- 

 mark of the Bausch & Lomb Optical 

 Company, which is not easily distin- 

 guishable with the naked eye, but 

 which serves as a mark of identity upon 

 this product. We take real pleasure in 

 thus calling attention to the new lenses. 

 The Bausch & Lomb Optical Company 

 is always so kind, so courteous and so 



