How do teeny-tiny bits of plastic help you see better? Here’s an explainer on how contact lenses work.
Your vision plays a key role in your quality of life, and for many people contact lenses are a no-brainer. They’re comfortable, convenient and, for some conditions, give better vision than glasses. Keen to find out more? Here’s some information to get you started.
First invented more than 100 years ago, contact lenses are small pieces of a complex type of plastic that help to correct vision problems. Instead of sitting on your nose like glasses, contact lenses float on a film of tears in front of the cornea – a part of the eye that helps us focus.
There are two main types of contact lenses: soft lenses and hard lenses. Soft contact lenses are made from light, flexible plastic that conforms to the eye shape, while hard contact lenses are made from firmer plastic that covers only part of the cornea.
Soft contact lenses – which are usually disposable – are by far the most common, says Bupa optometrist Karen Makin. “One of the main types of materials used in soft lenses is what’s called ‘hydrogel’,” she says. “It’s been around for a lot of years and is still being used to manufacture contact lenses.
“A newer material is ‘silicon hydrogel’, a breathable material that allows more oxygen through to the cornea.”
Most people who wear glasses can opt for contact lenses – including those who need multifocal lenses. The benefits are many, says Makin.
“Your vision is unobstructed as you don’t have something on your face that may be a barrier, so you get a more natural field of vision,” she says. “Physical activities and sport are also much easier in most cases with contact lenses.”
And for those with a higher prescription, contact lenses give a better result than glasses due to ‘spectacle magnification’, which means their lenses change the size of what they are seeing.
“Someone with a high long-sighted prescription gets a lot of spectacle magnification, making things look bigger than they actually are,” Makin says. “Those with a high short-sighted prescription get the opposite – images become much smaller than they actually are. With contact lenses you see things in their natural size, as the lens correction is on the surface of the eye, not sticking out in front.”
For vision conditions like keratoconus, a progressive condition of the cornea, contact lenses can provide better results than glasses. “With keratoconus, the cornea is in a cone-like shape rather than being spherical,” explains Makin. “Because of the irregular surface often contact lenses do give better vision. In the early stages we would suggest soft contact lenses, but if the disease is progressing sometimes rigid or hard contact lenses are needed to give the best visual results.”
And then there are the practical and aesthetic benefits. “It’s easier to apply makeup with contact lenses because you can see what you’re doing,” says Makin. “Plus, you don’t need to buy prescription sunglasses. With contact lenses you can just buy off-the-shelf sunglasses and put them on over the top.”
Compared to glasses, there’s a little more involved in maintaining contact lenses. Keeping them clean is really important. “If you’re wearing reusable contact lenses, you need to clean and disinfect them after each wear,” says Makin. “You shouldn’t use tap water, bottled water or saliva – use a proper contact lens solution.”
What’s more, Makin says it’s crucial to stick to your optometrist’s wearing time instructions. “If they’re daily, replace them daily; if they’re monthly, replace them monthly,” she says. “Don’t try to sneak extra time out of them.”
And because you’re likely to encounter situations where you may not want to wear contact lenses, like on a long-haul flight or when you’re unwell, it’s worthwhile hanging onto your glasses. “Always have a good pair of glasses that you can wear just in case,” says Makin.