High-index lenses use materials that bend light more efficiently than standard plastic, so less material can be used to make the same prescription. For stronger prescriptions, this can reduce thick edges in short-sighted lenses or a thick centre in long-sighted lenses.
Prescription strength, frame size, lens design, measurements, impact-resistance needs and budget can all change which material offers the best balance.
At a glance
- Higher index numbers generally allow a prescription lens to be made thinner.
- The main benefit is reduced thickness, not automatically sharper vision.
- A higher index may cost more and can involve optical or impact-resistance trade-offs.
- Frame choice and accurate fitting remain important, even with a thin lens material.
What does lens index mean?
Refractive index describes how light travels through a material and how strongly the material bends it. It is an optical property, not simply the physical weight or density of the material.
In practical terms, a higher-index material can provide the required prescription with a flatter or thinner lens profile. Common plastic lens options are often labelled 1.50, 1.59, 1.60 or 1.61, 1.67 and 1.74. Availability and naming can vary between laboratories and practices.
Illustrative comparison
1.50 standard plastic
A common baseline material. In stronger prescriptions, the lens profile may appear bulkier than higher-index alternatives.
Lens index is only one part of the result. The final thickness also depends on the full prescription, lens diameter, frame shape, how the frame sits, the position of the eyes within the frame and the lens design.
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Start Free Checklist TestCommon lens materials compared
This table is a general comparison rather than a prescribing chart. An optometrist or optical dispenser needs the full prescription and chosen frame before recommending a material.
| Material or index | Possible advantage | Points to discuss |
|---|---|---|
| 1.50 standard plastic | Good optical quality and a common option for lower prescriptions. | Can become thicker as prescription strength and lens size increase. |
| 1.59 polycarbonate | Lightweight and impact resistant; often considered for children, sport or safety needs. | Optical dispersion and scratch resistance should be discussed; coatings may be recommended. |
| 1.60 or 1.61 high-index plastic | A thinner option that may balance appearance, performance and cost. | The benefit depends on the prescription and frame. |
| 1.67 high-index plastic | Can reduce thickness further for stronger prescriptions. | Usually costs more than lower-index plastic; ask about coatings and expected thickness. |
| 1.74 ultra-high-index plastic | Among the thinnest commonly offered plastic options. | May not provide a meaningful extra benefit for every prescription or frame; cost and material trade-offs matter. |
What are the benefits of high-index lenses?
Reduced lens thickness
This is the main reason people choose high-index lenses. A stronger short-sighted prescription can create thick outer edges, while a stronger long-sighted prescription can create a thick centre. A higher index can reduce that visible bulk.
A more balanced appearance
Thinner lenses may sit more neatly within the frame. They can also reduce some of the eye-size effect seen through stronger plus or minus prescriptions, although the result still depends on lens design and frame choice.
Potential comfort benefits
Using less material may reduce the weight of the finished lenses. It is not guaranteed, because the density of the material, lens size and frame also affect total weight. My Kids Vision’s explanation of high-index lenses provides a useful overview of how index can affect thickness, weight and appearance.
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Find an OptometristWhat are the limitations?
A higher price
Higher-index materials generally cost more. CHOICE’s Australian prescription-glasses guide notes that higher index numbers usually mean thinner, lighter, and more expensive lenses. The best value is the option that produces a worthwhile difference for your prescription and chosen frame.
Optical trade-offs can vary by material
Lens materials disperse light differently. Materials with a lower Abbe number can produce more colour fringing toward the edge of vision, particularly in stronger prescriptions. This does not mean every wearer will notice it, but it is worth asking about if you have been sensitive to peripheral colour or distortion before.
Impact resistance is not the same as thinness
A very thin lens material may not be the most suitable choice for sport, safety eyewear or an active child. Polycarbonate and Trivex are often considered when impact resistance is a priority. The recommendation should reflect how the glasses will be used, not only how thin they can be made.
The frame still matters
Large lenses require more material than smaller lenses. Frame shape, eye position and lens measurements can all affect edge or centre thickness. Ask to compare the expected result in the frame you actually plan to buy.
Who may benefit from high-index lenses?
High-index lenses are mainly considered when a standard material would produce noticeable thickness. They may be worth discussing when:
- your prescription is moderate or strong
- your current lenses have thick outer edges or a thick centre
- your glasses feel front-heavy or slide because of lens weight
- you want a frame that leaves the lens edge more visible
- you have a combined prescription, such as short-sightedness with astigmatism
Astigmatism does not automatically mean you need high-index lenses. The full sphere, cylinder, and axis values matter, along with the frame.
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Start Free Checklist Test1.67 vs 1.74: is the higher index worth it?
A 1.74 lens can usually be made thinner than a 1.67 lens for the same prescription. The visible difference may be modest in some frames and more useful in others.
Rather than choosing by number alone, ask the practice to compare the expected centre or edge thickness, finished weight, coatings and price for your selected frame. A well-chosen 1.67 lens can offer better value when the extra thinning from 1.74 would be small.
Do high-index lenses need special coatings?
Many buyers add an anti-reflective coating because it reduces surface reflections and can make the lenses look clearer. A scratch-resistant coating may also be recommended because plastic lenses can mark during everyday use.
Coatings do not correct the chromatic dispersion of the lens material, and no lens is completely scratch-proof. Ask which coatings are included, what the warranty covers and how the lenses should be cleaned.
You may also want to compare single vision lenses if your prescription is intended for one viewing distance.
What affects the cost of high-index lenses in Australia?
There is no single national price for a high-index upgrade. The total can change with the index, prescription, lens design, coatings, frame, laboratory, warranty and aftercare offered by the practice.
Healthdirect’s eye-test information states that Medicare does not cover glasses or contact lenses. Private health insurance may contribute, depending on the insurer and level of cover.
Ask for an itemised quote that separates the frame, lenses, index upgrade, coatings and any other features. Also confirm the remake or adaptation policy before ordering.
Questions to ask an optometrist or optical dispenser
- Why are you recommending this index for my full prescription?
- Can you compare the expected thickness and weight in this frame?
- Would a smaller or differently shaped frame improve the result?
- What are the optical and impact-resistance trade-offs of this material?
- Which coatings are included, and which are optional?
- What is the total price after any private health insurance benefit?
- What warranty, adjustment and remake support does the practice provide?
The answers should relate to your prescription, daily use and chosen frame. Services, products, prices, and policies vary between Australian practices.
The practical next step
High-index lenses can be a useful upgrade when lens thickness is a real concern. The highest index is not automatically the best value, and a good result depends on the frame, measurements, lens design, and fitting as well as the material.
Use the Australian Made Vision directory to compare participating independent optometry practices near you. Contact the individual practice to confirm which lens materials, coatings, prices and health-fund arrangements are available.
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Find an OptometristHigh Index Lenses FAQs
Are high-index lenses better than standard lenses?
Not for everyone. Their main advantage is reduced thickness for stronger prescriptions. A lower-index material may offer better value or a different balance of optical quality and impact resistance for a mild prescription.
Do high-index lenses make vision sharper?
Index alone does not make a prescription more accurate. Clear vision depends on the correct prescription, lens design, measurements, manufacturing and fitting. The index mainly changes the material needed to produce the lens.
Are high-index lenses always lighter?
They use less material and may be lighter, but the finished weight also depends on material density, frame size and lens design.
What index should I choose?
There is no universal cut-off. An optometrist or optical dispenser can compare suitable materials after reviewing the full prescription and frame.
Can children wear high-index lenses?
They can be considered for strong prescriptions, but impact resistance is also important. The practice should balance thickness, weight, safety, frame fit and the child’s daily activities.
Are 1.74 lenses worth the extra cost?
They may be worthwhile when the prescription and frame would otherwise produce substantial thickness. Ask for a comparison with 1.67 rather than assuming the highest number is necessary.
