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What are the best lenses for my prescription?
Medically reviewed by Sharon Copeland on 26 May 2021
- Why is choosing the right lens for your eye prescription so important?
- Prescription lens materials
- Treatments for optical lenses
- Which high index lens should I get?
When choosing a pair of glasses, it is important to consider the best lenses for your prescription to ensure long-lasting wear and optimal clarity of vision.
Finding the right glasses lenses can be quite confusing. As there are so many different choices for lenses, we've put together a guide for you.
Whether you're looking for single vision lenses, bifocal lenses, progressive lenses or occupational lenses, our guide will help you to decide on the best lenses for your prescription.
Why choosing the right lenses for your eye prescription is so important
Choosing the right glasses lenses is crucial as the lenses you choose will influence your appearance, comfort, vision and safety.
People often overlook their choice of lenses for glasses. However, it is important to carefully consider the lens material, design and coating.
No matter what prescription lenses you need, it is important to choose the best design for your needs. You should consider whether you're short-sighted, long-sighted or whether you have astigmatism or presbyopia.
Prescription lens materials
The table below details various lens materials and the range of prescriptions they are best suited to.
|Lens Material||Refractive Index||Prescription||Abbe Value||Key Benefits and Features|
|High-index plastics||1.60 to 1.67||From +/-2.00 to +/-8.00||36 (1.60) 32 (1.67)||
|Polycarbonate||1.586||From plano to +/-6.00||30||
|Trivex||1.54||From plano - +/-6.00||45||
|CR-39 plastic||1.498||Low prescriptions from plano - +/-2.00||58||
Please note that Polycarbonate and Trivex are only used to make sunglasses at Feel Good Contacts.
Glass lenses were the only choice available when vision correction first came about.
While they can offer exceptional clarity of vision, they are also extremely heavy and carry the risk of breaking. Both these factors pose a serious threat to your eyes. While glass lenses are still available, they are no longer a common choice for this exact reason.
The first plastic prescription lens was introduced in 1947 by the Armorlite Lens Company in California. These lenses were made from Columbia Resin 39 which is why they are also referred to as CR-39 lenses. They remain a popular choice today due to their high-quality optics and lightweight feel. They are also a cheap option of spectacle lenses.
Polycarbonate lenses were first introduced in the 1970s by Gentex Corporation. They were meant for safety glasses but became increasingly popular in the 1980s and remain a popular choice today.
The polycarbonate material was originally used for helmet visors for the US Air Force as they offered a strong bulletproof quality. Due to the high-impact resistant nature, it remains a popular choice for children’s prescription glasses, safety glasses and sports.
Polycarbonate lenses are lighter than CR-39 lenses. However, an even lighter weight prescription lens was introduced in 2001 called Trivex. This lens is also a high impact choice and has a higher Abbe value, giving it a further advantage.
High-index plastic lenses
High-index plastic lenses were introduced by popular demand for even thinner and lighter eyeglasses options. Their higher index of refraction makes them thinner and lighter than CR-39 prescription lenses.
Index of refraction
The index of refraction in a prescription lens for glasses measures the efficiency of the material to refract light. This depends on how fast the light travels through the material.
Light moves slowly through lenses with a higher refractive index. This means that the light ray will refract more. Thinner lenses tend to have higher refractive indexes than lenses made from a thicker material.
The refractive index of prescription lenses ranges from 1.498 in CR-39 plastic to 1.74 in a range of high index lenses. Therefore, lenses made from CR-39 plastic will be the thickest lens regardless of their prescription power or design. The thinnest lens will be a 1.74 high-index plastic lens.
The Abbe value measures the degree to which white, visible light is dispersed or separated into its colour components when passing through lenses. It is also known as the V-number.
A high V-number indicates a low dispersion. A low abbe value can result in chromatic aberration. This is an optical error which causes coloured halos/rainbow effect/colour fringing around objects and light. It is especially noticeable around the periphery/edge of the lenses. Abbe values of prescription lenses range from 59 (crown glass) to 30 (polycarb).
The Abbe value is named after the German physicist Ernest Abbe, who defined this optical measurement.
An aspheric design will give your lenses a slimmer profile, making them more attractive.
An aspheric lens will feature a change in curvature from the centre of the lens to its edge. Due to the flat nature of aspheric lenses, they do not magnify your eyes as much as spherical lens designs. They can also enhance the clarity of the wearer’s peripheral vision as flatter lenses have less aberrations.
Aspheric designs are featured in most high index plastic lenses for the best appearance and optical performance. An aspheric design will increase the cost of the lenses with Polycarbonate or CR-39 lenses.
Minimum Centre Thickness
Due to the BS/EN (166:2002 and 167:2002) British standards for impact resistance, a laboratory can only make the lenses so thin.
Lenses to correct myopia (short-sightedness) are concave lenses which are thinnest in the middle at the optical centre with a bigger edge thickness. Convex lenses feature a lens which is thinner at the edges but have more centre thickness. These are used to correct hyperopia (long-sightedness).
Polycarbonate and Trivex lenses for myopia are high-impact resistant and can afford to have a centre thickness of just 1.0mm. Other lenses for myopia must be thicker at the centre to pass the BS/EN 166/167 standards for impact resistance.
The thickness of your lenses will depend on the size and shape of your optical frames. A small and well-centred frame will allow you to have a thinner and lighter lens. This is crucial for higher prescriptions.
Aspheric lenses made of a high index material and worn in a small/roundish frame are the thinnest option of lenses available.
The lenses you choose will also influence your choice of frames. For example, if you have a high prescription which requires thick lenses concave lenses, you may decide against rimless frames or metal frames for aesthetic reasons. It’s best to opt for plastic/acetate frames if you have a high prescription as these hide the thickness of the lenses more.
Treatments for optical lenses
There are many lens treatments available which can optimise the comfort, durability and appearance of your lenses. The following eyeglass lens coatings are highly recommended:
Lightweight glasses lenses are more prone to scratching and abrasions than glass lenses and require a scratch-resistant coating.
Anti-scratch coatings, also known as hard coats, can make your glasses lenses almost as scratch resistant as glass. However, it’s always worth considering lenses which offer a warranty against scratches.
Looking after your glasses is essential to avoiding scratches. Never place them face down and store them away safely in a case or pouch when not in use. When cleaning your glasses, make sure you use a microfibre cloth and avoid other materials as they may cause micro-fine scratches on the lenses.
Anti-reflective coating (AR or MAR coating) improves contrast and clarity of spectacle lenses by getting rid of reflections. This makes them perfect for night driving and using computer screens. They will also make your lenses less visible.
An anti-reflective coating is necessary for high index lenses as these lenses reflect more light, therefore increasing glare.
Exposure to ultra-violet radiation from the sun has been linked to many eye-related problems including cataracts and macular degeneration. It is therefore important to protect your eyes from the sun with a UV-blocking treatment on your lenses.
Almost all high-index plastic lenses include 100% UV protection. However, CR-39 plastic lenses will need an additional coating applied to ensure that they offer UV protection.
Photochromatic treatment allows lenses to automatically darken in response to the suns UV rays and return to clear when indoors. Photochromatic treatment is available in all lenses no matter what their material or design. This treatment also comes with 100% UVA and UVB protection.
Which high index lens should I get?
High index lenses will suit any prescription and are highly recommended for those who have a strong glasses prescription.
When choosing high index lenses, you should take the advice given to you by your optician. There are a variety of high index materials to choose from. The higher the index, the higher the cost of the lenses.
You may also want to consider whether you want photochromatic lenses or use tints instead.
No matter what you decide, we recommend choosing an anti-reflective (AR) lens coating. This will ensure optimal clarity of vision as an AR coating will eliminate reflections.
Should you have any further questions, please contact our helpful optical team on 01 514 3614.
Quick links:Lens packages explained
Eyeglass lens coatings guide
Glasses lens options for vision types