Ngecandelo kwindawo engezantsi ye-lens, i-lens ye-bifocal ibonisa amandla amabini ahlukeneyo e-dioptric, enika izigulane umbono ocacileyo okufutshane kunye nokude.
Nokuba sithini na isizathu sokuba ufune ummiselo wokulungiswa kombono okufutshane, ii-bifocals zonke zisebenza ngendlela efanayo.Inxalenye encinci kwindawo engezantsi yelensi iqulethe amandla afunekayo ukulungisa umbono wakho okufutshane.Ilensi eseleyo iqhelekile yeyombono wakho womgama.Icandelo lelensi elinikelwe kufutshane nokulungiswa kombono inokuba yenye yeemilo ezininzi.