Static Fracture Resistance of Schott S‐1005 Lenses as a Function of Thickness

High‐Lite S‐1005 lenses (Schott Optical Company) of various center thicknesses were tested for static load fracture resistance. Chemically tempered High‐Lite lenses of 1.7‐mm center thickness were found to be equivalent in strength to 3.0‐mm heat‐tempered crown lenses; 1.34‐mm chemically tempered High‐Lite lenses were equivalent in strength to 2.07‐mm heat‐tempered crown lenses. These findings agree closely with earlier data on chemically tempered crown glass and therefore illustrate that chemically hardened lenses can be made significantly thinner than Z‐80 specifications and still meet FDA strength requirements.