64% of adults in America wear prescription eyewear. That’s over 143 million people. Glasses cost hundreds of dollars, and most wearers have to replace them every 1-3 years. Typically, frames outlive lenses in glasses. Lenses get scratched, broken, or outdated due to prescription changes. Meanwhile, frames tend to be sturdier. For people who like the frames they have, replacement lenses are a cheaper alternative to new glasses.
The fun thing about replacement lenses is that they can include the latest in glasses technology. Multifocal lenses are divided into segments to correct vision near and far. Though typically more expensive than single vision lenses, individuals not buying frames may be able to snag multifocals. Lens coatings can also give glasses more protection against reflection, blue light, or fog. Today, most lenses are scratch-resistant and protect against UV radiation by default. For sunglasses, polarized or transitional lenses offer even greater eye protection.
Source: LensFactory