• Question: what are contact lenses made of and how do they help people see if they need different lenses from each other.

    Asked by to Andrew, Elaine, Emma, Michael, Nancy on 17 Jun 2014. This question was also asked by .
    • Photo: Nancy Carlisle

      Nancy Carlisle answered on 17 Jun 2014:

      A similar question was asked earlier, check out the response there!
      /visionj14-zone/2014/06/16/how-do-contact-lenses-work-do-they-hurt-when-you-put-them-over-my-eyes-or-would-they-just-take-some-getting-used-to/#comment-26

    • Photo: Elaine Gardener

      Elaine Gardener answered on 17 Jun 2014:

      Soft contact lenses are made of a mixture of different chemicals which make up a silicone monomer which then goes through different processes before being packed as a lens. Each lens is made using a mould to make it the correct shape ‘strength’ for different people’s needs. Like with glasses, people can be given a different strengths for each eye.

    • Photo: Michael Kelly

      Michael Kelly answered on 21 Jun 2014:

      Contact lenses work in the same way as your glasses, they focus the light so that a clear image falls on the light sensitive layer, the retina, at the back of the eye. Its just that contact lenses are very steeply curved to fit on the front of the eye, the cornea. There are two main types of lenses soft and rigid. They correct different eye conditions. Soft lenses are made of materials that love water (hydrophilic) and contain between 38% and 70+% water. This makes them slippery and very soft. Rigid lenses are made of polymers (plastics) that allow gases to pass through them. The lack of flexibility allows them to correct very complicated problems of focussing, such as severe astigmatism.

      The experience of pain is very personal, and it depends upon lots of factors. Fear often makes pain worse, so if someone is scared by the optician or the thought of their eye(s) being touched then it can make the initial fitting of contacts more unpleasant. We can often overcome unpleasant things if we are very motivated to do something.

      However, within 30 seconds most people don’t notice anything after a soft lens is applied to the eye. The sensation is a little like having an eyelash in the lower part of the eye, you can feel it but its not unpleasant and after ten minutes there is hardly any sensation at all. Often the excitement of seeing without spectacles helps people forget that are wearing lenses at all.

      The sensation/discomfort of rigid lenses can be managed using a drop that reduces the touch sensitivity of the front of the eye, an anaesthetic such as benoxinate. This allows the patient to become comfortable and appreciate the improved vision. Over an hour or so the drops wear off and the eye gets used to the presence of the contact lens. The discomfort with rigid lenses usually comes from the upper eyelid bumping over the edge of the lens, so sometime a larger lens is fitted to reduce this.

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