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.
Principal photography on the film began on April 25, 2016, in Pittsburgh, Pennsylvania, in the Hill District, and wrapped in mid-June 2016. Fences was released in the United States on December 16, 2016, by Paramount Pictures, received positive reviews and grossed $64 million.
Fences is a 1983 play by American playwright August Wilson. Set in the 1950s, it is the sixth in Wilson's ten-part  Pittsburgh Cycle . Like all of the Pittsburgh plays, Fences explores the evolving African-American experience and examines race relations, among other themes.The play won the 1987 Pulitzer Prize for Drama and the 1987 Tony Award for Best Play.he fence referred to by the play's title is revealed to be finished in the final act of the play, and Bono has bought his wife a refrigerator as he promised Troy he would do if he finished building it.