Transitional zones causing distorted or blurred vision are a drawback of which lens type?

The correct answer highlights the nature of progressive-addition multifocal lenses, which are designed to accommodate various vision needs by offering a gradual change in lens power from the top of the lens to the bottom. This design allows the wearer to see clearly at different distances—far, intermediate, and near—without the visible lines found in bifocal lenses.

However, one of the challenges associated with progressive lenses is the presence of transitional zones between different prescription powers. These zones can cause distorted or blurred vision, particularly when a person is adjusting to the lens or when they are not properly aligned with the optical center of the lens. This blending of powers, while providing a smooth transition between vision types, can create areas of the lens that may not clarify vision as intended.

In contrast, single vision lenses provide a consistent prescription throughout, addressing only one type of vision correction and eliminating transitional zones. Bifocal lenses, while they do have distinct segments for different viewing distances, are less complex in terms of power transitions and therefore typically do not exhibit the same level of distortion or blurriness associated with progressive lenses. Contact lenses also do not have the transitional zones characteristic of progressive multifocal lenses and can offer clear vision without the same issues related to power variability.

Understanding these