1.61 vs 1.67 vs 1.74 Index Lenses: Cost vs Benefit

Once you move beyond a standard lens, the next question is which high-index option is actually worth choosing for your prescription. The difference between 1.60, 1.67, and 1.74 is not just a number — it translates into real, visible differences in lens thickness, weight, appearance, and daily comfort. But the benefit of upgrading from one index to the next is not linear, and the right choice depends entirely on where your prescription sits. This guide breaks down exactly what each index delivers, who gains the most from each step up, and how to decide which represents genuine value for your specific situation.

1.60 vs 1.67 vs 1.74 Index Lenses: Direct Comparison

Key Points at a Glance

• The benefit of moving to a higher index grows with prescription strength — the stronger the Rx, the more visible the improvement
• For mild prescriptions, 1.60 delivers a clear improvement over standard; jumping straight to 1.74 adds cost without proportional benefit
• For moderate prescriptions, 1.67 is usually the sweet spot — meaningfully thinner than 1.60 with a cost that reflects genuine optical improvement
• For strong prescriptions of ±6.00 and above, 1.74 is not a luxury — it is the practical choice that makes the prescription wearable and visually acceptable
• All three index options at ELUNO include the full set of Essential Coatings at no additional cost — AR coating, blue light, UV, scratch resistance, water repellent, smudge and dust resistance
• Higher index materials have greater surface reflectivity — which makes the anti-reflective coating included with every ELUNO lens functionally important, not decorative
• Lens shape and frame size affect how much index matters — larger lenses show more edge thickness at any index, making higher index choices more impactful in wider frames

The Complete Guide: 1.60 vs 1.67 vs 1.74 Index Lenses

Why the Index Steps Are Not Equal

Before comparing the three indexes directly, it helps to understand why the benefit of each step up is not uniform. Lens thickness is not a simple linear function of refractive index — it is determined by the interaction between the index, the prescription power, and the physical dimensions of the lens. For a mild prescription, even moving from 1.56 to 1.74 produces a relatively modest visible difference. For a strong prescription, the same step produces a dramatic one.

This is why index advice that ignores prescription strength is not particularly useful. The question is never just "which index is thinnest?" It is "for my specific prescription and frame choice, which index produces a meaningful enough improvement to justify the step?" The answer is different depending on where your eyes sit on the prescription scale.

1.60 Index — Who Gets the Most from It

ELUNO's 1.60 index lens — Thin and Light — is made from MR resin and delivers a clear, noticeable improvement over the standard 1.56 for wearers in the mild to moderate prescription range. For prescriptions up to approximately ±3.00 sphere, 1.60 is typically the right first upgrade from standard. The lens is thinner and lighter than 1.56 in a way that most wearers can see and feel, without the cost associated with the higher indexes.

The practical benefit at this prescription range is primarily about comfort and appearance. The edge thickness that a 1.56 lens shows at ±2.00 or ±2.50 — visible beyond the frame edge, slightly heavier on the nose bridge — is reduced noticeably in a 1.60. The lens sits more cleanly in the frame, the pair feels lighter on the face, and the overall appearance of the finished glasses is more refined.

For wearers at the lower end of this range — prescriptions around ±1.00 or ±1.50 — the visible difference between 1.56 and 1.60 is less dramatic. At very mild prescriptions, all index options produce relatively thin lenses, and the incremental benefit of each step up diminishes. For a prescription of ±1.00, the practical case for going beyond 1.60 is limited unless there is a specific frame or aesthetic reason to do so.

For full-rim frames in the mild to moderate range, 1.60 is genuinely the value sweet spot — meaningful improvement over standard, appropriate cost for the prescription level, and fully compatible with all standard frame designs.

1.67 Index — The Broad Versatility Option

ELUNO's 1.67 index — Super Thin and Light — is where the index conversation becomes most significant for the largest number of wearers. Prescriptions in the ±3.00 to ±6.00 range represent a very common zone of myopia and hyperopia, and it is precisely in this range that 1.67 delivers its most compelling value proposition.

The jump from 1.60 to 1.67 for a prescription of ±4.00 or ±5.00 is visible and meaningful. A 1.60 lens at -4.00 has edges that are noticeable — particularly in a larger frame or a frame style where the lens edge is partially exposed. A 1.67 lens at the same prescription has edges that are significantly thinner and considerably less prominent. The lens sits flatter in the frame. The pair looks less like a strong prescription and more like a considered eyewear choice.

This is also the index range where frame style compatibility expands meaningfully. At 1.60, thin metal frames and semi-rimless styles work tolerably for moderate prescriptions but show lens thickness more than ideal. At 1.67, those same frames work cleanly — the thinner lens profile matches the frame's design intent and the overall pair looks cohesive. For wearers drawn to minimal metal frames or semi-rimless designs, 1.67 is often the minimum index that produces the result they're imagining when they choose the frame.

For progressives wearers — those with a near addition on top of the distance prescription — 1.67 is particularly worth considering. Progressive lenses already add complexity to the grinding process that increases lens thickness in certain zones. A higher base index reduces this across the board, keeping the finished lens profile consistent and the pair comfortable for all-day wear.

If there is a single index that represents the best overall value across the widest range of prescriptions and frame styles, 1.67 makes the strongest case. It is the index ELUNO most often recommends for wearers in the moderate to strong prescription range who want a finished pair that looks genuinely good without necessarily needing the absolute thinnest lens available. You can explore exactly how this index looks and performs in the context of your frame options through ELUNO's lens guide.

1.74 Index — When Thinnest Is Not a Preference but a Necessity

ELUNO's 1.74 index — Ultra Thin and Light — is made with advanced MR resin and represents the thinnest and lightest lens available. For most of the prescription range, the step from 1.67 to 1.74 is an improvement but not a transformative one. For prescriptions of ±6.00 and above, however, 1.74 is a different proposition entirely — it is the index at which strong prescriptions become practically and aesthetically wearable in a way that lower indexes cannot fully achieve.

At -6.00 or -7.00 sphere, a 1.67 lens already looks considerably better than a 1.56 or 1.60 — but the edges are still present and visible, particularly in larger frames. A 1.74 lens at the same prescription is measurably thinner in a way that changes the character of the finished pair. The lenses no longer read as a strong prescription at a glance. They sit in the frame with a discretion that simply is not achievable at lower indexes for those power levels.

For wearers with prescriptions above ±8.00 or ±9.00, 1.74 is not a choice between options — it is the appropriate lens for the prescription. At these levels, anything lower produces lenses that are visually and physically heavy enough to affect not just appearance but comfort. The nose bridge carries that weight all day. The lens profile draws attention in a way that many wearers with high prescriptions have long since accepted as unavoidable. With 1.74, it largely ceases to be unavoidable.

The cost of 1.74 is the highest of the three indexes, and for wearers in the mild to moderate range, it represents a premium that doesn't return proportional visible benefit. But for strong prescription wearers, that cost calculation changes. The lens is thinner, lighter, more comfortable to wear all day, and opens up frame choices — including rimless and ultra-slim metal designs — that are not practical at lower indexes for high powers. Assessed against those benefits, the cost of 1.74 for a wearer who genuinely needs it is almost invariably worth it.

If you're considering 1.74 for a strong prescription and want to see the full range of frame options that work best with ultra-thin lenses, ELUNO's eyeglasses collection includes designs specifically suited to the clean, minimal aesthetic that high-index lenses make possible.

The Relationship Between Index and Anti-Reflective Coating

One technical detail that has direct practical relevance to this comparison is the relationship between refractive index and surface reflectivity. As the index of a lens material increases, so does its natural tendency to reflect light off the lens surface. A 1.74 lens without anti-reflective coating reflects a meaningfully higher proportion of incoming light than a 1.56 lens — producing more visible surface glare, a more noticeable sheen on the lens, and slightly less of the available light passing cleanly through to the eye.

Anti-reflective coating cancels this reflected light through destructive interference, restoring the lens's optical performance to where it should be. For higher index lenses, this is not a cosmetic benefit — it is functionally necessary to get the full optical performance from the lens material. A high-index lens without AR coating underperforms relative to what it is capable of.

At ELUNO, anti-reflective coating is included as standard on every lens regardless of index. This means whether you choose 1.60, 1.67, or 1.74, the AR coating that makes each lens perform at its best is already there — no additional selection required, no additional cost. The same applies to the full set of Essential Coatings: UV and blue light protection, scratch resistance, water repellent, smudge resistance, and dust resistance come standard across all indexes.

How Frame Choice Interacts with Index Selection

The frame you choose affects how much the index decision matters and which index produces the best result. Understanding this interaction before finalising both choices produces a more considered outcome than selecting frame and lens in isolation.

Lens diameter is the most important variable. A larger lens — in a wider frame or a design with generous lens coverage — has more physical surface area, and the edges of a minus lens extend further from the optical centre. This amplifies the edge thickness at any given index. For the same prescription, a compact round frame will show less edge thickness than a wide square frame. This means that wearers choosing larger frames benefit more from a higher index than those choosing compact designs — and should factor this into the decision.

Rimless and semi-rimless frames expose the lens edge entirely. In these designs, edge thickness is fully visible rather than concealed by the frame, making it a more prominent aesthetic variable. For any prescription above mild in a rimless frame, 1.67 is a practical minimum and 1.74 is appropriate for moderate to strong prescriptions. The clean, refined look of a rimless frame is only achieved when the lens is thin enough to match the frame's visual intention.

Full-rim frames conceal the lens edge and are more forgiving of index choice across the prescription range. A full-rim acetate or TR90 frame at a moderate prescription in 1.60 produces a perfectly acceptable result that a rimless frame at the same index and prescription would not. Whether you're browsing ELUNO's women's eyeglasses or men's eyeglasses, pairing the frame style and lens index as a combined decision — rather than independently — produces the best outcome.

A Practical Index Recommendation by Prescription Range

For prescriptions up to approximately ±2.00 sphere, 1.60 is the right choice for most wearers. The improvement over 1.56 is clear and the cost is proportionate. Moving to 1.67 or 1.74 at this prescription level adds cost without producing visible benefit in most frame styles.

For prescriptions from ±2.00 to ±4.00, 1.67 becomes the more compelling option. At the lower end of this range, 1.60 remains a good choice. At ±3.00 and above, 1.67 produces a noticeably cleaner, lighter result that most wearers in this range find worth the step up.

For prescriptions from ±4.00 to ±6.00, 1.67 is the practical recommendation for most frame types. 1.74 produces a further improvement that is visible and valued, particularly in larger frames or rimless designs.

For prescriptions above ±6.00, 1.74 is the appropriate choice. The benefit relative to 1.67 at these power levels is substantial — in thickness, weight, and overall appearance — and the cost reflects genuine optical necessity rather than incremental preference.

For progressive lens wearers, moving one index level higher than the above guide suggests is generally a sound approach, since the addition power and multi-zone design of progressive lenses adds to effective thickness across the lens.

Children and Index Selection

Children with moderate to strong prescriptions benefit from higher-index lenses in the same ways adults do, with the additional consideration that comfort directly affects whether a child wears their glasses consistently. Lighter, thinner lenses are more comfortable on smaller nose bridges and less prone to slipping during activity. For children with prescriptions above ±3.00, 1.67 is a meaningful upgrade worth considering. ELUNO's kids eyeglasses are available with the full range of index options, and the team can advise on the right choice for a child's prescription and frame.

Final Thought

The decision between 1.60, 1.67, and 1.74 is ultimately about matching the lens to the prescription it needs to serve. For mild prescriptions, 1.60 delivers honest, clear value. For moderate to strong prescriptions, 1.67 is the broad versatility choice that improves both the appearance and comfort of the finished pair in ways that most wearers in this range notice every day. For strong to very strong prescriptions, 1.74 is not an extravagance — it is the index at which the prescription becomes genuinely wearable and visually unobtrusive.

At ELUNO, all three indexes come with the full set of Essential Coatings included as standard. Choosing the right index for your prescription is the decision. Everything else — the coatings that make the lens perform at its best — is already taken care of.