Lenses with three powers are called?

Lenses with three powers are called?

• A. Trifocals
• B. Bifocals
• C. Monovision
• D. Progressives

Answer: (A)

In eyeglass optics, lenses that provide multiple focal lengths are described by how many distinct powers they contain. When a lens has three separate focal powers, it’s arranged to give distance, intermediate, and near vision in three zones. This setup is called trifocals. The top portion is for distance, the middle for intermediate tasks, and the bottom for near tasks like reading. Bifocals, in contrast, have two powers with a single boundary between distance and near. Progressives offer a smooth, gradual change between many powers with no visible lines, and monovision refers to correcting each eye differently rather than a single lens with three powers.

In eyeglass optics, lenses that provide multiple focal lengths are described by how many distinct powers they contain. When a lens has three separate focal powers, it’s arranged to give distance, intermediate, and near vision in three zones. This setup is called trifocals. The top portion is for distance, the middle for intermediate tasks, and the bottom for near tasks like reading. Bifocals, in contrast, have two powers with a single boundary between distance and near. Progressives offer a smooth, gradual change between many powers with no visible lines, and monovision refers to correcting each eye differently rather than a single lens with three powers.