By LensPT Team · Published November 4, 2026
1.61, 1.67 and 1.74 are nominal refractive indices, not complete material names or finished-lens thickness specifications. A higher-index material can support a thinner lens for a defined optical requirement, but the finished result also depends on the lens design, prescription, frame geometry and processing constraints.
For an optical buyer comparing 1.61 vs. 1.67 vs. 1.74 lenses, start with the product requirement and ask suppliers to quote identifiable configurations. Then compare thickness, appearance and commercial scope on the same basis. Choosing the largest index number first can leave the more important order details unresolved.
Publisher disclosure: LensPT supplies optical lenses and publishes this guide. It uses public manufacturer explanations and LensPT product listings, with an original purchasing comparison record. No physical lens tests or thickness calculations were performed. The cover is an existing LensPT catalog image, not a measured comparison of different indices.
What do 1.61, 1.67 and 1.74 mean?
Refractive index describes how a material refracts light. It is one part of a lens specification, alongside the actual substrate, optical design and treatments. ZEISS’s lens ingredients guide explains the role of index in lens selection and the potential for higher-index materials to reduce thickness.
The index does not identify every material property. Ask for the supplier’s material designation and data sheet rather than assuming that two products carrying the same index have the same formulation, dispersion, density or processing instructions.
| Candidate index | What it establishes | What the buyer still needs |
|---|---|---|
| 1.61 | A nominal refractive-index designation for the quoted configuration. | Material identity, design, available prescription range, diameter, finish and comparison results for the intended job. |
| 1.67 | A higher nominal index than 1.61. | The same fields, plus a documented comparison if reduced thickness is the reason for changing the specification. |
| 1.74 | A higher nominal index than the other two candidates. | Confirmation that the exact design, prescription, coating and finishing requirements are supported, together with the resulting geometry. |
The table does not assign prescription cutoffs or promise a thickness saving. Those decisions require the actual lens and frame information, reviewed by the parties responsible for dispensing and processing.
Keep material identity separate from index
Mitsui Chemicals’ MR material information illustrates the distinction: its product family includes 1.60, 1.67 and 1.74 materials, and it identifies different grades within the 1.67 group. Those are Mitsui material references, not evidence that every lens at those indices uses MR material.
LensPT’s published single-vision range includes a 1.61 designation. Do not silently replace it with 1.60 in an inquiry or label it MR-8 without product-specific confirmation. If the quotation, package label and data sheet use different values or names, ask the supplier to reconcile them before sample approval.
Use separate order fields for material name, nominal index, supplier product code and specification revision. This makes a proposed substitution visible even when the headline index stays the same.
Ask what changes on the finished job
A thinner sample is useful only when the comparison answers the buyer’s actual question. Define the same job for each candidate and ask the processing partner to identify the constraints used. Keep an estimate separate from a measurement of a finished sample.
| Comparison field | What to hold constant or record | Result to request |
|---|---|---|
| Prescription and design | The same prescription inputs and named design, or an explicitly documented design difference. | Confirmation that each candidate covers the job. |
| Frame and centration | Frame identity, shape or trace, dimensions and the centration information supplied by the responsible professional. | The frame basis used for the comparison. |
| Geometry limits | Supplier-approved minimum thickness, blank requirements, base-curve choice and finishing constraints. | Thickness at defined reference points, in mm, with the calculation or measurement basis. |
| Mass and appearance | The same delivered stage, coating and frame context where possible. | Mass in g if measured, plus controlled appearance photographs or a retained sample. |
| Evidence identity | Product code, material, index, revision and sample or calculation reference. | A traceable result for the configuration actually quoted. |
This is an editorial comparison record. It does not prescribe manufacturing limits or tell a dispenser which lens to select for an individual wearer.
For example, a brand might receive a smaller-frame 1.74 sample beside a larger-frame 1.67 sample. That may show two possible products, but it does not isolate the effect of changing index. Request a comparison using the same frame basis before making a percentage claim. This is a hypothetical review situation, not a reported LensPT test.
Compare properties beyond thickness
Where optical dispersion matters to the program, request the documented Abbe value and material reference. Where weight matters, compare the finished item at the same endpoint. Neither field should be inferred from the index alone.
Check the proposed frame application and processing instructions with the lens supplier and receiving laboratory. An index number does not confirm drilling, tinting, coating or mounting compatibility. If the program has an impact or other performance requirement, request evidence for the relevant configuration rather than treating “high index” as a qualification.
Coating is a separate purchasing choice. Identify the actual finish and appearance requirement on each candidate. Our HC, HMC and SHMC coating guide explains how to compare the treatment package without relying on its abbreviation alone.
What LensPT currently lists
The clear single-vision product page lists nominal indices of 1.499, 1.56, 1.59, 1.61, 1.67, 1.70 and 1.74, with UC, HC, HMC and custom finishes. The blue cut single-vision page includes the same index list and identifies HMC, SHMC and custom coatings.
These listings were checked on November 3, 2026. They establish published product routes, not a complete availability matrix for every material, power, diameter and treatment combination. Ask LensPT to identify the current configuration being offered at each requested index.
For a made-to-order discussion, the RX lens page is another starting point. Confirm the design and service scope for the job; a general listing does not replace the receiving laboratory’s order specification.
Compare the commercial offer on the same basis
Before comparing prices, state whether the quote concerns finished uncut lenses, semi-finished blanks or another agreed endpoint. The finished vs. semi-finished lens guide explains why different amounts of processing can sit behind two unit prices.
For an assortment, group the inquiry by required configuration and quantity. Ask each supplier to return available ranges, substitutions, packaging, sample terms and delivery scope against the same specification revision. Keep a material change visible even when it is offered as a commercial alternative.
| Decision | Evidence that supports the next step |
|---|---|
| Keep an existing index | The current approved configuration meets the program requirement; no documented reason for changing it has been established. |
| Evaluate another index | A defined geometry, appearance or product-range requirement needs comparison using identifiable candidates. |
| Hold approval | Material identity, design availability, comparison conditions or quotation scope remains unresolved. |
These are purchasing decisions, not universal recommendations that 1.61, 1.67 or 1.74 belongs to a particular wearer category.
Questions buyers often ask
Is 1.74 always the best choice?
The highest index does not settle the full order. Compare the resulting lens, supported design, processing requirements, coating and commercial scope against the program’s needs.
Can a supplier quote thickness from index alone?
Index alone does not define the finished geometry. Ask which prescription, frame, design and thickness constraints are required for a useful estimate, then retain them with the result.
Are 1.60 and 1.61 interchangeable names?
Keep the supplied designation on the order until the supplier confirms the exact material and specification. Do not relabel a product by borrowing a name from another manufacturer’s material range.
Send LensPT an index comparison request
Include the candidate indices, lens design, material information already available, prescription or assortment scope, diameter, frame context, coating, quantity, packaging and destination market. If thickness is the reason for the comparison, identify the common job and ask what inputs are needed to assess it.
Discuss your 1.61, 1.67 or 1.74 lens requirements with LensPT. Request written confirmation of the product code, material identity and available configuration before using the quotation as an approved repeat-order specification.