Lens Thickness Explained: Choosing the Right Lens Index

When you add prescription lenses to a frame, you'll choose between Standard (1.5), Thin & Light (1.6), Super Thin (1.67) and Ultra Thin (1.74). Those numbers are the lens index — here's what they actually mean, and how to pick without overpaying. Whichever you choose, scratch-resistant and anti-reflection coatings are included as standard.

What “index” means

The index measures how strongly a lens material bends light. A higher-index material bends light more, so the lab needs less material to achieve the same correction — which means a thinner, lighter lens. The correction is identical at every index; only the thickness, weight and price change.

The four tiers

Standard (1.5) is the everyday choice, and for lower prescriptions (roughly ±2.00 and below) it's all most people need — the thickness difference at that strength is barely visible.

Thin & Light (1.6) is around 20% thinner. Worth it from around ±2.00–4.00, especially in larger frames where lens edges show more.

Super Thin (1.67) is around a third thinner than standard — the sweet spot for stronger prescriptions (roughly ±4.00–8.00). Edges stay neat even in bigger, fashion-led frames.

Ultra Thin (1.74) is our thinnest lens, for the strongest prescriptions. If your SPH is beyond ±8.00, this keeps lenses remarkably slim and light.

Why frame choice matters too

Lens thickness shows at the edge (for minus prescriptions) or the centre (for plus). Two tips: a smaller lens shape cuts edge thickness dramatically because the thickest part of the lens is simply cut away; and a full-rim frame — which is all we stock — hides the lens edge inside the rim, so you can often go one tier lower than you'd think.

Our honest recommendation

Enter your prescription on any frame page and our lens picker automatically shows which tiers are available for your numbers, with prices — it won't offer a combination our specialist glazing lab wouldn't make. As a rule of thumb: below ±2.00, save your money and take 1.5; ±2.00–4.00, consider 1.6; above that, thin lenses stop being a luxury and start being the difference between glasses you tolerate and glasses you love. Unsure? Add a note with your order and our eyewear specialists will advise before anything is glazed.