What Do Contact Lenses Do?

A contact lens corrects visual impairments like:

  • Shortsightedness (myopia) – an inability to focus on objects at a distance.
  • Farsightedness (hyperopia) – a loss of focus on near objects.
  • Astigmatism – an abnormally shaped lens within the eye that results in blurred vision.
  • Presbyopia – a progressive loss of the ability to focus on nearer objects as a consequence of aging.

Unlike glasses, a contact lens needs no frame to support it as it is applied directly to the eye. Your eye has a natural layer of liquids (water, oils, and mucus) that forms what is called a tear film that lubricates and protects the eye. Contact lenses are placed on top of this layer, and so are essentially invisible and you can barely feel their presence.

Like lenses within spectacles, contact lenses are shaped to compensate for your visual impairment by correctly focusing light on the back of the eye, called the retina, where the signal your brain views as an image is generated. Contacts can be concave, which is to say curving inwards to correct for myopia, or convex (curving outwards) to treat hyperopia. There are a range of options to correct astigmatism and presbyopia, and technology has now gotten us to a point where you can have multifocal lenses. Multifocals include bifocals for example, which have two separate sections that accommodate near and far sight. You can also choose between rigid gas-permeable or soft lenses, each of which have their own advantages.

What types of contact lenses are there?

Contact lenses can be either disposable dailies or extended wear monthlies. You can also get tinted or coloured contact lenses if you so wish, and these can be cosmetic ones (non-prescription). Otherwise, you will generally be provided with a prescription after an eye test and some advice as to what kinds of lenses would best suit your needs.

Dailies are, as the name suggests, used for a day before being discarded. These tend to be thinner than their monthly counterparts and can be more costly as you will need quite a few lenses if you intend on wearing them every day! Monthlies are designed for long term use and have the advantage of being cheaper as you need fewer lenses. You do need to be careful with monthlies however, as you need to maintain the integrity and cleanliness of each lens as they are, after all, being put into your eyes!

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