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Asked by to Andrew, Elaine, Emma, Michael, Nancy on 16 Jun 2014. This question was also asked by .
Question: How do contact lenses work, do they hurt when you put them over my eyes, or would they just take some getting used to?
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Andrew French answered on 16 Jun 2014:
Hi,
Sorry I don’t work with or wear contact lenses so I’m not the best person to ask. 🙂
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Michael Kelly answered on 17 Jun 2014:
They work in the same way as your spectacles. The contact lenses change the focussing of the light entering your eye so that there is a clear image on the light sensitive layer at the back of the eye, the retina. Two big differences between spectacles and contact lenses are, contact lenses are very steeply curved to fit onto the front of the eye the cornea, and they can rotate when placed on the eye.
There are two main types of CL, soft and rigid. Soft lenses are the commonest, they correct the vast majority of eyesight focussing conditions, e.g. short sight (myopia), long sight (hypermetropia) or mild astigmatism. They are made of a water loving material (hydrophilic) so are floppy, slippery and a bit like a thin film of jelly. Rigid lenses are made of plastics that allow gases to pass through them.
The surface that lays on the cornea is carefully designed, in soft lenses the lens is quite large (13.8mm) and covers the whole of the cornea and drapes over the surface. For rigid lenses the surface is designed to be in near alignment with the front of the eye. Rigid lenses are about 9mm in diameter and tend to sit between your eyelids when the eye is in a natural open position. It is these differences that explain the different feelings people have when trying lenses for the first time. Because soft lenses are sloppy and fit under the lids when you blink there is very little feeling but because rigid lenses sit between the eyelids, blinking causes the eyelid to bump over the top (and/or bottom) edge of the contact lens.
Pain and discomfort are very personal things and are affected by other factors besides the mechanical interactions between the eyelids and the lenses. Its important to consider your motivation and fear. If you really want to wear lenses so that you can do something you like,for example, football, dancing or not wearing glasses, then usually the discomfort passes really quickly whatever type of contact lens you need. Also if you are frightened by the thought of your eye being touched then it is likely that you will experience a greater degree of discomfort than you would otherwise.
Most people get used to lenses very quickly within in a minute for some soft lenses.
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Elaine Gardener answered on 17 Jun 2014:
Unclean hands can add extra germs to your eyes which can cause problems so be sure to wash your hands before putting them in and before taking them out.
Comments
Michael commented on :
I’ve fitted contact lenses for over twenty years. I can answer this if you’d like?
Michael commented on :
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.
Nancy commented on :
When we try to focus on an object, an oval/round part of our eye called the ‘lens’ changes shape in order to ensure that the object is appropriately focused on our retina (where light gets transferred into nerve signals). When we look at things close up vs. far away, our lens needs to change it’s shape- kind of like how you need to hold a magnifying glass at a specific distance from the thing you’re looking at in order for it to come into focus, or how you have to focus a microscope before the image you are trying to look at becomes clear. In people who need glasses or contacts, the lens doesn’t change as much as it should, meaning that they never get that ‘perfectly clear’ image. Just like glasses, contacts change the way light is focused on the back of your eye to try to make the image appear sharper. It’s kind of like putting a low-powered magnifying glass in front of your eye to make everything more clear.
Like Andrew, I don’t wear contacts, but I know plenty of people who do! Most people get used to wearing them after a little while. 🙂