Varifocal describes glasses whose lenses change strength gradually from top to bottom, so one pair of glasses lets you see far away, at middle distance, and close up. You look through the top of the lens to see across the street, the middle for a computer screen, and the bottom to read your phone. The change is smooth — there is no visible line on the lens. That smoothness is what separates varifocals from bifocals. Bifocals have two clear zones with a line you can see across the lens. Varifocals blend everything together, so they look like ordinary glasses. In American English these are usually called progressive lenses or progressives, and that name is also common in Taiwanese optical shops. Varifocal is the more British word. Most people who wear them are over about forty, when the eye gets slower at focusing on close things. New wearers often need a week or two to get used to them, because the sides of the lens can look slightly blurred and stairs can feel strange at first. Opticians warn everyone about this. Grammar: it is nearly always used before a noun — varifocal lenses, varifocal glasses. The glasses themselves are often just called varifocals, a plural noun, like jeans or scissors.

漸進多焦點（鏡片）；台灣眼鏡行多說「漸進多焦點鏡片」