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Lens index guide: 1.56 to 1.76, which one for your prescription and what it costs in Hanoi

Written by Alvin, Store Manager · Manh Long Optical, 147A Le Duan, Cua Nam, Hanoi · Updated 10 September 2026

Lens index is labelled the same way everywhere, so a 1.67 in Hanoi is a 1.67 at home and you can hold these numbers against any quote you already have. Here all seven indices we sell sit side by side, with September 2026 prices in Vietnamese đồng; your phone's currency converter gives today's figure.

1. What is lens index?

Index is a number for how strongly the lens material bends light. The higher it is, the thinner the lens at the same prescription.

It does not make you see sharper. Sharpness comes from an accurate prescription; index decides how thick the lens sits in the frame. On price lists you will also see SP or SPH (spherical surface) and ASP or AS (aspheric) after the index.

We sell single-vision lenses at seven indices: 1.56, 1.60, 1.61, 1.67, 1.70, 1.74 and 1.76. Our list also has an Essilor 1.59 impact-resistant polycarbonate lens (2,980,000₫) and ZEISS photochromic lenses at 1.50 and 1.59. Those sit outside the table.

2. Which index suits my prescription?

Our store guidance has four steps: 1.56 under 2.5 dioptres of short-sight, 1.60 under 3, 1.67 from 3 to 5, and 1.74 above 5. For 1.61, 1.70 and 1.76 there is no index-by-prescription guidance yet, so ask in store after your eye test.

September 2026 prices for a pair of single-vision lenses, clear or blue-light filtering (not photochromic), frame not included; the final price is confirmed after your eye test. Sources: our counter price list (Essilor, ZEISS) and the Chemi, Elements and Tokai retail list confirmed by the owner on 8 September 2026.
The edge column is our own approximate calculation, not a measurement and not a maker's claim: the edge thickness of a lens for short-sight is inversely proportional to (n − 1) at the same prescription and diameter, with 1.56 = 100%. Formula: 0.56 ÷ (n − 1). Example for 1.67: 0.56 ÷ 0.67 ≈ 84%. It ignores surface curve, aspheric design and centre thickness, so the real figure in your frame will differ.

Price tracks more than index. At 1.67 alone, a pair runs from 700,000₫ to 4,500,000₫. The rest comes from brand, coating, and whether the lens is taken from stock or made to your prescription. Brand by brand, see lens brands compared: Essilor, ZEISS, Tokai, Chemi and Elements.

3. How much thinner is each step?

Each step takes a few percent off the edge, by the same formula: 1.56 to 1.60 about 7%, 1.60 to 1.67 about 10%, 1.67 to 1.74 about 9%. From 1.74 to 1.76 it is about 3%.

These are proportions, not millimetres. On a mild prescription the edge is thin to begin with, so 10% of it is hard to see. On a strong one the same 10% shows. Our advice moves up the index as the prescription rises.

The frame matters too. A smaller frame hides edge thickness better than a large one.

4. When is a higher index worth the money?

Under 3 dioptres we suggest 1.60, and paying for a higher index there mostly buys thinness you will not notice. Above 5, 1.74 is worth weighing, but what it costs over 1.67 varies a lot by brand.

Edge thinner = 1 − (old n − 1) ÷ (new n − 1). Example, 1.67 to 1.74: 1 − 0.67 ÷ 0.74 ≈ 9%. Extra = higher price minus lower price, same brand, same line, September 2026.

In the Essilor line the 1.67 to 1.74 step costs almost five times the 1.60 to 1.67 step, for slightly less thinning. ZEISS follows the same pattern. For that money the 1.74 lenses of both brands go to -18.00 (Essilor) and -20.00 (ZEISS) with astigmatism to 6.00, where their 1.67 stops at -10.00 and 2.00. The two brands side by side: Essilor vs ZEISS lenses.

Chemi stock lenses are different. Moving up to 1.74 adds a little over one million đồng, as long as your prescription is inside the stock range: Chemi U2 1.74 in stock covers -1.00 to -10.00 with astigmatism to 4.00.

5. What are 1.70 and 1.76 for?

On our list both come from Tokai: 1.70 from 3,700,000₫ to 5,300,000₫ and 1.76 from 7,000,000₫ to 9,300,000₫ a pair, depending on the prescription. We do not have guidance yet on which prescriptions they suit, so we do not assign one.

What the formula does say: 1.76 is about 3% thinner at the edge than 1.74, and 1.70 about 4% thinner than 1.67. The top step is small.

6. Can it be ready before you fly?

Single-vision lenses in stock are usually cut the same day. Ordered lenses take longer. How long depends on the lens.

Tell us the day you leave Hanoi at the start, and we suggest lenses that can be finished in time. If you fly out first, international shipping can be arranged; we confirm the destination, cost and a realistic delivery time before you order. Delivery within inner Hanoi is free, hotels included.

7. What does a whole pair cost?

A finished single-vision pair, frame and lenses together, runs from 850,000₫ to 3,500,000₫. The 850,000₫ pair uses a standard lens, not a branded one.

Every other price on this page is for lenses alone. Visitors from abroad usually spend between 1,500,000₫ and 4,000,000₫ on a pair. You get the full figure before anything is cut. Cards are accepted.

8. Who does not need a high index?

Mild prescriptions. Under 3 dioptres we suggest 1.60; in Essilor Blue UV Capture a 1.60 pair is 2,280,000₫ and a 1.74 pair is 12,380,000₫, and the thinning at that level is hard to see.

On a tight budget, look at stock lenses before a higher index. At 1.67, Chemi U1 in stock is 700,000₫ and Essilor Blue UV Capture is 3,980,000₫. The other way round, above 5 dioptres a low index to save money means a thicker edge and a heavier pair all day. Weigh both.

Common questions

What is the difference between 1.60 and 1.67 lenses?

By the formula, at the same prescription and lens diameter, the edge of a 1.67 lens is about 10% thinner than a 1.60. Our usual advice is 1.60 under 3 dioptres and 1.67 from 3 to 5; in Essilor Blue UV Capture, a 1.67 pair costs 1,700,000₫ more than a 1.60 pair.

Do I need 1.74 lenses for a -2.00 prescription?

Usually not. Under 3 dioptres we suggest 1.60, and in Essilor Blue UV Capture a 1.60 pair is 2,280,000₫ while a 1.74 pair is 12,380,000₫.

Is 1.76 much thinner than 1.74?

By the formula, a 1.76 edge is about 3% thinner than a 1.74 at the same prescription and diameter. On our price list 1.76 comes from Tokai, from 7,000,000₫ to 9,300,000₫ a pair depending on the prescription.

Can I get high-index lenses before I leave Hanoi?

Single-vision lenses in stock are usually cut the same day. Chemi lenses made to order take 10 to 15 days, and other ordered lenses get a date once your prescription is checked, so tell us your departure date when you walk in.