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Which type of spectacle lens do I need?

Two people with the same prescription can need very different lenses. A schoolboy playing football in Chicalim, a shopkeeper in Vasco market reading bills all day, and a retired teacher who mostly reads the newspaper and watches television each use their eyes differently. This guide explains the choices so that you can talk them through with the eye hospital team.

Lens designs: how many distances do you need to see?

Single-vision lenses

The same power runs across the whole lens. They are used for distance (for short or long sight and astigmatism), for reading only, or for one fixed working distance such as a computer. Most children and adults under 40 need only single-vision lenses. They give the widest clear view and are the easiest to get used to.

Bifocal lenses

The top part has your distance power and a small segment at the bottom has your reading power, with a visible line between them. Bifocals give a wide, steady reading area but have no zone for middle distances such as a computer screen or a shop counter, and the view jumps as your eyes cross the line.

Progressive lenses

Also called varifocals or multifocals, progressive lenses change power smoothly from distance at the top, through middle distance, to reading at the bottom, with no visible line. The sides of the lens are softer in focus, so you learn to turn your head rather than your eyes. Most people get used to them within a few days to two weeks; a small number never feel comfortable. They need careful measurement of your pupils in the chosen frame. Our page on progressive vs bifocal lenses compares the two in detail.

Office or computer lenses

These lenses are set for the desk and screen: clear at arm's length and for reading, with a much wider middle zone than a progressive lens. They suit people over 40 who spend long hours at a computer or a counter, but they are not meant for driving or walking about.

Reading glasses

Single-vision lenses with reading power only, for people over 40 who see well in the distance. Our guide to reading glasses after 40 explains when ready-made readers are enough and when they are not.

Lens materials: thickness, weight and strength

• Standard plastic: light and optically clear, used for most low and moderate powers. It scratches without a hard coat.
• Polycarbonate: much more impact-resistant than standard plastic, light, and it blocks UV rays by itself. It is a good choice for children, sports and anyone who works where things can fly into the eye. At higher powers some people notice slight colour fringes near the edges.
• High-index plastic: bends light more strongly, so the lens can be thinner and lighter for the same power. It is useful for higher powers. High-index lenses reflect more light, so an anti-reflection coating is usually advised.
• Glass: very clear and hard to scratch, but heavy and it can shatter. It is rarely used now, and not for children.

Many lenses also have an aspheric design, which makes them flatter and thinner and reduces the way strong plus lenses make the eyes look bigger. If your power is high, a smaller, rounder frame keeps the lenses thinner too.

Coatings and treatments

• Hard coat: makes plastic lenses resist scratches. It does not make them scratch-proof; sand and grit still scratch lenses.
• Anti-reflection (anti-glare) coating: reduces reflections from the lens surfaces, so more light reaches your eye and there are fewer ghost images from headlights and tube lights. It helps at night and at screens, and other people see your eyes, not reflections. It needs gentle cleaning and should be kept away from heat.
• Water- and dust-repellent layers: make the lens easier to clean and help raindrops run off, which is useful in the monsoon.
• UV filtering: many modern lens materials and coatings block UV rays. Ask whether the lens you choose does.
• Blue-light filtering (blue cut): often recommended for screens, but research has not shown that it reduces eye strain or protects the eyes. Read our balanced guide, are blue light glasses worth it?

Lenses that darken in the sun

Photochromic lenses darken outdoors when UV light falls on them and clear again indoors. They take a few minutes to clear after you come in. They darken less behind a car windscreen, which blocks most UV, and less in hot weather, so on a hot Goa afternoon they may not get as dark as sunglasses. They are handy for people who go in and out all day, but they do not fully replace sunglasses for a day at Bogmalo beach or a long ride. For tinted and polarised lenses, see power sunglasses in Goa.

Some common situations

• A schoolchild with short sight: single-vision polycarbonate lenses with a hard coat, in a flexible frame.
• A 45-year-old who works at a computer: progressive lenses for daily wear, sometimes with office lenses for long screen days.
• A retired person who mostly reads and watches TV: bifocals, progressives or two separate pairs, depending on what feels comfortable.
• Someone with high power: high-index aspheric lenses in a smaller frame.
• Someone who drives or rides at night: clear lenses with anti-reflection coating. Tinted lenses should not be worn at night.

These are only examples. The final choice depends on your eye test, your work and what you find comfortable.

Lenses and frames work together

The frame decides how thick the lens edges look, whether a progressive lens has enough height, and whether the lenses sit at the right distance from your eyes. Choose the lens type first and then the frame, or choose them together at the Vision Correction Centre. See our guide to spectacle frames.

What decides the cost of lenses?

The lens design (single vision, bifocal, progressive or office), the material and thickness your power needs, and the coatings you add. The Vision Correction Centre explains the cost of each option before you order. We do not show prices on this website.

Questions patients ask

Are anti-glare lenses worth having?

For many people, yes. An anti-reflection coating reduces reflections and ghost images from headlights and lights, which helps at night and at screens. It needs gentle cleaning with water and a microfibre cloth, and it should be kept away from heat.

Do I need thin high-index lenses?

Usually only if your power is high. For low powers the difference in thickness is small. For higher powers, high-index lenses are thinner and lighter, and they look better in most frames.

Can photochromic lenses replace sunglasses?

Partly. They darken outdoors and clear indoors, but they darken less inside a car and in hot weather. For long hours at the beach, on the water or riding in the sun, dedicated sunglasses with UV protection are more reliable.

Which lens material is safest for children?

Polycarbonate is commonly advised for children because it is very impact-resistant and light, and it blocks UV rays. It should be fitted in a well-fitting, flexible frame.

Why do my new lenses feel strange at first?

A new power or a new lens design can make the floor look tilted or the edges blurred for a few days. This usually settles. If it has not settled in about two weeks, or you feel dizzy or get headaches, come back so the power and fitting can be checked.

This page is general eye-health information, not personal medical advice. Your eye doctor advises you after examining your eyes.