This technique is well-worth mastering for home cooks, as it's an easy way to cope successfully with thick steak and chop-style cuts of beef, pork and other meats. Step 1 Take the sirloin filets out of the refrigerator 45 to 120 minutes before you plan to cook them; chilled beef doesn't cook evenly.
The refractive index of current eyeglass lens materials ranges from 1.498 (CR-39 plastic) to 1.74 (a specific variety of high-index plastic). So for the same prescription power and lens design, a lens made of CR-39 plastic will be the thickest lens available, and a 1.74 high-index plastic lens will be the thinnest.
However, the lightness and stiffness of aluminum in some eye glasses designs offers great advantages. For example, for metal frames that are thicker in design, and larger in design, aluminum is the toughest material and can accommodate the thickest and heaviest lenses. Aluminum frames last a long time and can take a lot of abuse compared to plastic frames, or thin metal frames.