Optical glasses (prescription eyeglasses) are corrective lenses in frames that fix refractive errors like nearsightedness, farsightedness, astigmatism, and presbyopia by properly focusing light on the retina.
Main types:
Single-vision: One power for distance or reading.
Bifocal: Two zones (distance + near) with a visible line.
Trifocal: Three zones (distance, intermediate, near) with two lines.
Progressive: Seamless, no-line multifocal for gradual focus shift.
Specialty: High-index (thinner), photochromic (auto-tint), blue-light blocking, anti-reflective.
