Cov tsom iav bifocal yog qhov tsim nyog rau cov neeg laus siv, thiab tuaj yeem ua tiav qhov ze thiab deb. Thaum cov neeg laus, lawv qhov muag yuav poob thiab lawv qhov muag yuav dhau los ua neeg laus. Thiab cov tsom iav bifocal tuaj yeem pab cov neeg laus pom deb thiab pom ze.
Lub lens dual tseem hu ua bifocal lens, uas feem ntau suav nrog lub lens sab saum toj, puag ncig sab saum toj lens thiab pom tsis pom.
Lub lo ntsiab muag ntawm cov iav bifocal yuav tsum muaj xws li hyperopia diopter, myopia diopter lossis downlight. Nyob deb ntawm cov menyuam kawm ntawv, nyob ze ntawm cov menyuam kawm ntawv nyob deb.