What are the best lenses for my prescription?

• 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.

Glass lenses

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.

Plastic lenses

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.

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.

Abbe value

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.

Aspheric design

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).

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 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:

Scratch-resistant coating

Lightweight plastic 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.

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

An anti-reflective coating (AR or MAR coating) improves contrast and clarity by almost eliminating reflections. This makes them perfect for night driving and using computer screens. They will also make your lenses less visible and therefore more cosmetically appealing.

An anti-reflective coating is necessary for high index lenses as these lenses reflect more light, therefore increasing glare.

UV-blocking treatment

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

Photochromatic treatment allows lenses to automatically darken in response to the sun’s UV rays and return to clear when indoors. Photochromatic treatment is available in all lenses no matter what their material or design. The light reactive lenses in our range come in a variety of lens colours, such as graphite green, grey, and brown. All our photochromatic lens options provide 100% UVA and UVB protection.

Light reactive

Lenses remain clear whilst indoors and darken when outdoors.

Transitions Signature Gen8

These lenses darken outside and become clear indoors more quickly. They provide Blue Light protection. These lenses won’t darken enough in the car, so they aren’t ideal for driving.

Transitions XTRACTIVE New Generation

Excellent for bright and hot sunny days, these lenses turn extra dark in hot temperatures, they turn darkest in the car. They fade from dark to clear 35% faster. These lenses have a mild tint whilst indoors to protect you against Blue Light.

Transitions Drivewear

Enjoy enhanced colour perception and sharper vision with these lenses, which is especially useful when driving. These polarised lenses prevent glare from the sun. They darken outdoors and fade to a very mild tint indoors. The lenses are yellow/green in low light, copper in moderate to bright light, and dark reddish brown in bright light.

Sun tint – prescription sunglasses

You can choose any pair of glasses from our range and choose the ‘sun tint’ option at checkout to create prescription sunglasses. This is a great option for those who spend a lot of time outdoors as they’ll have the benefit of full sun protection as well as their prescription within the lens, providing clear vison.

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.

No matter what you decide, we recommend choosing an anti-reflective (AR) and ultraviolet (UV) lens coating. This will ensure optimal clarity of vision as an AR coating will eliminate reflections and UV coating will protect your eyes from harmful UV sun rays.

Should you have any further questions, please contact our helpful optical team on 01 514 3614.