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Contact lenses

Contact lenses are one of those over looked marvels of modern science that just make life easier. It wasn’t until the late 70s that contact lenses were really readily available to the general public and that they wouldn’t cost you a small fortune. At the end of the 1800s the first version of contact lenses as we know them appeared. They were made out thick glass and could only be worn for a couple of hours without extreme discomfort. In the 50s and 60s the thinner, lighter plexi glass lenses were developed but they were so expensive people used to get them insured. Since then we have come a long way and now more than 3 million people wear contacts in the UK. So we decided to have a closer look at the advantages of contacts, the type of contacts available and the proper care for contacts and your eyes.

+   What are they?

You probably know what contact lenses are but just to clarify. A contact lens is a thin plastic lens (hard or soft) that you place over your cornea (the middle bit of your eye). Contacts are most commonly used to correct vision in replacement of glasses. However, contact lenses can be used as therapy to correct other eye problems (such as astigmatism) or may just be cosmetic (such as tinted contacts).

+   Advantages

There are a number of reasons why you may prefer contacts to standard glasses:

  • They provide better peripheral vision basically making it easier to see things out of the corner of your eye
  • They don’t fog up of collect moisture in bad weather
  • They are more practical for playing sports, especially contact sports
  • They make it easier to wear sunglasses of goggles (and mean you don’t have to get prescription sunglasses or goggles)

If you think that you would maybe prefer contact lenses to glasses talk to your optician. They will discuss with you whether your prescription will work well with contacts and what it will cost you. You may be entitled to an NHS voucher depending on your age and employment/student status.

+   Different types of contact lenses

Contact lenses come in a number of different forms are generally classified based on their use, their wear schedule and their replacement schedule.

Different Uses of Contacts

  • Corrective Contacts
    • These are the most standard contact lenses and they are designed to improve your vision
    • They do this by focusing (refracting) light in such a way that it enters your eye in a way that gives you correct vision
  • Toric Lenses
    • These lenses are designed to correct astigmatism
    • Astigmatism is a defect of the eye preventing it from bringing objects into proper focus causing blurry vision. It is caused either by genetics or by a scar on the cornea
    • Toric lenses fix astigmatism as they have a different focusing power horizontally then they do vertically
    • For this reason toric lenses have to be put in the right way up and stay the right way up. This is often done by slightly weighting the bottom of the lens
  • Multifocal Lenses
    • These are similar to bifocal or multifocal glasses
    • Different parts of the lens have different corrective power allowing you to see far or close through the same lens
  • Monovision lenses
    • These lenses work to provide a variety of distances
    • One lens will allow you to see distance
    • The other lens will allow you to see close up
  • Colour blindness
    • In recent years some work has been done to develop contact lenses that can help correct for colour blindness
    • Though they do not completely cure colour blindness and they are not suitable for all types of colour blindness they have been successful to help colour blind people distinguish better between colours

Wear Schedules

  • Daily Wear
    • These are contacts that are worn during the day and then removed before sleeping
    • Wearing them for an extended period of time without removing them can increase the risk of infection or even cause permanent damage
    • The risk of wearing these longer than recommended is that they can limit the oxygen supply to the eye
  • Extended Wear
    • Designed for continuous overnight use
    • Usually for up to 6 nights and 7 days
    • They can be worn for longer as they allow more oxygen to get to the eye
    • They have a higher risk of eye infections then daily wear lenses

Replacement Schedule

  • Daily
    • The lenses are designed to be used only once for the day then discarded
    • They tend to be thinner and more comfortable than longer use lenses but are also less durable
    • They collect less allergens or deposits making them a good option for very sensitive eyes
  • 2 or 4 weeks
    • These lenses are more robust and durable and are designed to be replaced every 2 or 4 weeks
    • If you have daily wear lenses like this you should clean them before you put them back in each morning

+   Complications

Putting a foreign body in your eye regularly does not come without complications however, if used correctly contact lenses are very safe.

  • Infection
    • Infection is the most common complication of contact lens use
    • An infection may affect your eyelid or your eyeball
    • Infections can be caused by improper cleaning of the contact or by transfer of some bacteria from your hands when putting in the contact
    • You may also get conjunctivitis if your contact doesn’t fit right
  • Long term corneal damage
    • If you do not replace your contact as recommended then you can cause long term damage to your cornea as you may starve it of oxygen
  • Temporary Discomfort or Blurring of vision
    • This is especially true if it’s the first time you have worn contacts or if you have particularly dry eyes

+   How to use contacts safely

You should always use your contacts as directed by your optician or optometrist. You should wear them for the amount of time recommended, replace them as suggested and clean them regularly.

  • Wash hands thoroughly before inserting or removing contact lenses
  • Avoid drying your hands on a towel before touching lenses as you may transfer fluff or dust to the lens
  • Keep the case clean
    • Wash out thoroughly at least once a week
  • Use cleanser and disinfectant to clean contacts
    • There are a number of different cleansing options
    • Saline solution can does not disinfect lenses but will rinse particles off them and keep them moist overnight
      • It is good for sensitive eyes as it won’t cause an allergic reaction
    • Hydrogen Peroxide is a good disinfectant but must be used carefully as instructed and must be given time to react fully. If the hydrogen peroxide is not properly neutralised not only may it be incredibly uncomfortable but it can cause serious damage to your eye.
    • Do not reuse cleaning solution
  • If your eyes seem to be irritated or uncomfortable try taking a day off from contacts and replacing them for new ones before next wearing them

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