How to choose the right contact lenses

Contact lenses provide a virtually weightless and invisible alternative to glasses. They're available in different types, and it's a good idea to know what your options are before you visit your optometrist.

Contact lenses correct vision in exactly the same way as glasses, and the technology has advanced by leaps and bounds since the days of rigid, daily-wear lenses that took weeks to get accustomed to and also required a medicine chest full of cleaning, disinfecting and storage products.

Today's lenses are so comfortable that you can forget you're wearing them within seconds of insertion. They also give you an unobstructed view across the whole visual field.

Contact lenses are available in soft, disposable, gas-permeable, extended-wear and even tinted varieties. They are made of a variety of materials, and length-of-wear times and disposal periods also vary.

In the past, you may have been told that lenses were not suitable for you; today, that is probably no longer true. If you have presbyopia, you may now be able to wear either bifocal or varifocal contact lenses. Lenses can now be made to counteract astigmatism, although if your cornea is too uneven, you may have to wear hard lenses rather than soft ones, which would simply mould to the irregular shape.

Your optometrist can help you decide on the best option for your eyes.

Now rarely prescribed, rigid lenses can be difficult to get used to. They deprive the cornea of oxygen and can be worn only during the day. They are sometimes recommended for people with severe astigmatism.

These lenses are made of a material that allows oxygen to pass through them. However, since they are hard, gas-permeable contacts take time to get accustomed to. Less widely used than soft lenses, they may be recommended for people with severe astigmatism or presbyopia.

Soft contact lenses were originally made from a material called hydrogel, which combines water and plastic. Though hydrogel is not gas permeable, it allows oxygen to reach the eye through its water content.

Newer variants combine water with silicone, making them gas permeable, so they can be worn even when you are sleeping.

You can also get versions that alter the colour of your eyes. A soft lens is slightly larger than the eye's iris, so it can be seen if someone looks closely.

Some lenses have a soft outer rim combined with a rigid, gas-permeable centre. This allows them to provide comfort in addition to the slightly superior visual qualities of a hard lens.

Hard and gas-permeable lenses must be removed and cleaned every night; you can't sleep in them. On the plus side, they last for about a year before you need to replace them.

You can also get daytime-wear soft lenses that last from three to twelve months and soft "disposable" lenses designed for daytime wear for shorter periods before planned replacement.

Sometimes called "continuous wear" lenses, these are soft lenses that you can sleep in. Depending on the type, you can keep them in for between a week and a month before they need to be replaced. They are more expensive than daytime-wear lenses, but you save on cleaning products.

The ultimate in consumer eyewear are soft lenses that you simply throw away at the end of each day. Disposable lenses are the most expensive type of contacts if you wear them all the time. However, many users swear by this option and say they are worth every penny.