IN THE 1920s, the only commercially available contact lenses were German: the Zeiss ground glass lenses manufactured in Jena and the Müller Söhne blown-glass lenses fabricated in Wiesbaden (Bowden, 2009).

In 1930, Zeiss released the Zeiss-Dallos scleral design, incorporating design changes suggested by 26-year-old Hungarian ophthalmologist Josef Dallos (Bowden, 2009). Thus began Dallos’s lifelong obsession with contact lenses, and from 1930 to 1960 he was the driving force behind much of the worldwide innovation in contact lens design, fitting, and manufacturing.

Perhaps Dallos’s greatest contribution to the emerging contact lens industry took place in 1933, when, after much experimentation, he perfected a technique for taking impressions (molds) of the eye. The molding compound he used was Negocol (a material derived from seaweed) that was heated to 106° to 108° and injected onto the anesthetized eye (1% tetracaine) (Sabell, 1988).

The Negocol “fixed” or set as it cooled, and Dallos converted the mold into a positive cast with a wax-like preparation called Hominite. Later he used a positive cast made of brass, molding the glass lens over the brass mold and made any necessary adjustments to the fit by grinding (Sabell, 1988). Many historians believe this was the first modern scleral lens custom-made for the individual patient’s eyes. In later years, the Negocol was replaced with a molding compound called Moldite and the brass mold was replaced with a positive casting compound called Castone (Mann et al, 1996) (Figure 1). 

In the late 1930s, Dallos moved from Hungary to England, where he perfected the technique for manufacturing glass sclerals. Soon, individuals from around the world were flocking to London to replicate Dallos’s manufacturing and fitting techniques (Mann et al, 1996). One of these individuals was Philip Beilby from Perth, Australia, who began manufacturing glass and later plastic contact lenses for industry pioneers Ida Mann, Donald Ezekiel, and Kenneth Brown.

Our story now shifts to 2017, when the authors were contacted by Donald Ezekiel and told that Philip Beilby had given him his original “Dallos” scleral lens manufacturing bench, complete with the molding and grinding devices for the fabrication of glass scleral lenses (Figure 2). The bench consists of the molding device in which a square piece of glass was heated through a mixture of natural gas and oxygen.

As the glass began to sag and become malleable, the brass mold was plunged into the glass and left to cool (Figure 3A available online). The residual glass was removed with a grindstone until the appropriate diameter had been achieved. The edges were rounded and polished and, finally, the power was ground onto the anterior surface of the glass lens (Figure 3B available online).

The bench was donated to the Contact Lens Museum in Oregon, where today it stands as the only remaining glass scleral lens manufacturing apparatus in the world. CLS

References

1. Bowden TJ. Contact Lenses the Story: A Historical Development of Contact Lenses. Bower House Publications. 2009;68-87.
2. Sabell, T. 100 Years of Contact Lenses. Optician. 1988 May;17-21.
3. Mann I, Potter D, Buckley EI. Ida and the Eye: A Woman in British Ophthalmology From the Autobiography of Ida Mann. Parapress. 1996; 155-158.