R. A. Lawley Opticians

Providing Personalised Optical Services Since 1981

Spectacle lenses

By | October 11, 2014


Spectacle lenses

What do I need to know about choosing lenses?

When you talk to the dispensing optician about your spectacles, they will explain to you about the different lenses that you can choose. Most people opt for plastic lenses today: they are lighter and safer. Plastic is softer than glass and can scratch more easily so you will be offered an anti-scratch coating. More and more people are opting for an anti-reflection coating. This allows more light to pass through the lens, with the dual benefits of letting you see more clearly, and allowing people to see your eyes clearly too.

I need glasses to help me read. What are my choices?

If you need glasses to help you read, you can opt for glasses that just focus your sight on close work. You may prefer bifocals or varifocals, where a portion of the lens is suitable for distance vision too. People who wear glasses for distance work all the time, and get to the age where they need a different prescription for reading often choose bifocal or varifocal lenses. These allow you to swap from distance to close work without changing spectacles. Like all new specs, they can take time to get used to. Some people prefer to have a different pair of glasses for distance and for close work. This can work well if you are unsteady on your feet, or if you do one task for a long period of time and don’t need to swap your glasses often.e, click edit button to change this text.

What are bifocal lenses?

A bifocal lens has a clear division between the top part, for distance vision, and the smaller segment in the bottom half of the lens that helps you focus on reading material. The reading segment can come in different shapes, some with a curved top and some with a flat top.

Curved Top / C segment bifocal

E-Line / Executive bifocal

Your dispensing optician can show you the different designs and help you decide if one is right for you.

What is a varifocal lens?

Varifocal (or ‘progressive’) lenses allow you to see clearly in the distance, then the focus of the lens changes gradually as you lower your gaze, giving you a portion of the lens for intermediate work and the lowest part for focussing on reading material. You can’t see the transition when you look at the lens, unlike bifocal lenses where there is a clear line. Some people choose varifocals because they feel they look less aging, while others like them because of the increased flexibility compared to bifocals. They are handier than having a pair of specs for distance vision and one for close up.

Varifocal / Progressive lens viewing zones – Picture: Rodenstock

Varifocals come in different designs. Some have a narrow central channel, which is ideal if you mainly look at things in the distance or close up. Others have a wider central portion which might be suitable if you do a lot of work at a middle distance, such as on a work bench or computer. Everyone’s needs will vary, so discuss your lifestyle with your dispensing optician and they will help choose the best lens for you.

Should I choose glass or plastic lenses?

Today, most people choose plastics lenses. They are lighter than glass lenses, and weigh less on your face. Glass lenses are a little thinner than a plastic lens of the same prescription. Plastic is more break resistant, so is significantly safer, provides more protection and cannot splinter. Plastic is softer and more likely to scratch, but the chance of scratches can be reduced with an anti-scratch coating. Plastic lenses are easier to tint in a range of colours too.

I have a high prescription. what lenses will be best for me?

If you are very short sighted, you may have noticed that your lenses have thick edges and appear to make your eyes smaller. Your spectacles may feel heavy and mark the bridge of your nose. Opticians can offer you lenses that are thinner at the edge and lighter too. These lenses are known as high index lenses, and bend light more efficiently than standard lenses. There are different high index lenses: some are only a little thinner than standard plastic lenses, while others are thinner still. Generally the thinnest and lightest lenses cost the most. High index lenses generally come with an anti-reflection coating as standard, as this improves the appearance of the lenses

High index and aspheric lenses can be dispensed to produce thinner lenses for higher prescriptions – Picture: Carl Zeiss Vision

If you are very long sighted, as well as benefitting from high index lens materials, your optician may suggest an aspheric design. Your lenses are likely to be thickest in the centre, which can magnify the appearance of your eyes. An aspheric design cuts down the central thickness, reducing the weight and magnification.