Which lenses are designed to correct nearsightedness, farsightedness, or astigmatism?

Single vision lenses are designed to correct specific vision problems, including nearsightedness, farsightedness, or astigmatism. They have a uniform focal length throughout the lens, which makes them effective for providing clarity at a specific distance based on the individual's prescription.

Nearsightedness, or myopia, requires lenses that reduce lens power to help focus distant objects more clearly, while farsightedness, or hyperopia, necessitates lenses that enhance lens power to aid in viewing nearer objects clearly. Astigmatism occurs due to an irregular shape of the cornea or lens, requiring specially shaped lenses to properly focus light onto the retina. Single vision lenses can be prescribed with specific curves to address these refractive errors, thus making them suitable for each condition independently or together.

In contrast, bifocal and trifocal lenses include multiple prescriptions in one lens for people who need vision correction at different distances, typically for presbyopia. Progressive lenses also serve a similar purpose but do so with a gradual transition between multiple focal lengths without distinct lines, catering primarily to those who require multifocal prescriptions. While all these lens types can correct vision problems, it's the single vision lenses that are directly aimed at addressing basic refractive errors comprehensively in one