Glasses Lenses: The Easy Guide
Plastic vs. Glass Lenses used to be made of glass. Now almost everyone uses plastic — it's lighter and won't shatter if you drop your glasses.
Farsighted vs. Nearsighted — What's the Difference?
Farsighted? Your lenses will be thicker in the middle. Your prescription has a plus sign (like +2.00).
Nearsighted? Your lenses will be thicker around the edges. Your prescription has a minus sign (like -2.00).
Types of Lenses — Which One Do You Need?
Single vision – Basic, affordable. Fixes either near OR far vision, not both.
Bifocals – Two prescriptions in one lens: distance on top, reading on bottom. Usually has a visible line.
Trifocals – Three prescriptions: distance, "arm's length" (like your computer or dashboard), and reading.
Progressives – Like bifocals/trifocals but smoother — no line, and the powers blend together. Downside: the "sweet spot" for each distance is a bit smaller.
Polycarbonate/Trivex – Tough and light. Great for sports or active kids. Comes with UV protection built in.
High-index – Thinner and lighter, especially good if you have a strong prescription.
Aspheric – Flatter, thinner lenses that don't make your eyes look magnified. Also sharpens side vision.
Computer/Blue light lenses – Cuts down eye strain and headaches from screens. Can get this with or without a prescription.
Photochromic (Transitions) – Clear inside, sunglasses outside. One less thing to carry.
Polarized – Cuts glare off water, snow, and roads. Great for driving.
Why High-Index Lenses Are So Popular If your prescription is strong, regular lenses get thick and heavy fast. High-index lenses bend light more efficiently, so you get the same correction in a thinner, lighter lens. This matters most if you're very farsighted — thick lenses can make your eyes look bigger through the glasses; high-index avoids that.
You can get high-index in almost any style: aspheric, progressive, polycarbonate, photochromic, or polarized.
Worth Adding On (Coatings)
Anti-scratch – Lenses last longer.
Anti-reflective – No annoying glare or halos around lights at night.
UV protection – Blocks harmful sun rays.
Why Are High-Index Lenses Thinner? It comes down to the material. Regular plastic has a refractive index of 1.50. High-index ranges from 1.53 to 1.74 — the higher the number, the thinner the lens. A 1.74 lens can be up to 50% thinner than standard plastic, at the exact same prescription.
So, Which Lens Is Right for You? Bring your current prescription to your eye doctor or optician — that's the starting point. From there, think about your lifestyle: Are you on screens all day? Playing sports? Need something for driving? That'll point you to the right combination of lens type and coatings.