Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: Karen W. on 22/04/2007 12:54:47
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I just heard something about that. I have astigmatisms in both eyes..LOL I don't evem know if you can have it happen to an individual eye! LOL I understand it is when your eyes are more football shaped then round. All I really know is that what I see with out my glasses seem less vivid then with them on. On things are crisp and bright off they seem softer around the edges! Can you explain this to me and if you know anything about the contacts let me know. My glasses are annoying, I seldonm wear them, and know it can cause me headaches sometimes not having them on.
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Well.. I'm not sure, but I'll try.. I think astigmatism is this.. Hang on.. I'll draw a diagram.
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[diagram=194_0]
Ahh.. I haven't drawn it well. But Astigmatism eyes, have a bumpy surface, which makes the images you look at, less clear and more fuzzy.
Some people say, that they have less astigmatism when they wear contact lenses, because water gets in between the eye and the lens, filling in the bumpy areas, so it smoothens the surface area of the eye.
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I think that there isn't a specific lens for astigmatisms, but most lenses tend to be comfortable for them.
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HUMMM That is interesting.. I wonder how anyone can put anything on their eyes, I was told these new lenses are like so soft you can't tell they are on your eyes..This is something supposedly new my friend told me about last week!
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Yep.. My sister has worn glasses for about 8-9 years. And she changed to contact lenses about 2 months ago. She loves it. She said it was so comfortable, even the first time she tried it, although she cried a bit [;)] She has a slight astigmatism as well, and she says its fine!
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Sean,
If I understand what you have written about astigmatism, it is not correct, but what Karen has written is closer to the truth (if one remembers that she is talking about American footballs, rather than European footballs).
What happens is that, as Karen says, the shape of the eye is not spherical, so its vertical curvature is different from its horizontal curvature, so when the lens of the eye tries to focus something in the vertical axis, it is out of focus in the horizontal axis, and visa versa (sometimes it isn't exactly a horizontal/vertical bias, but at some other angle).
For this reason, the corrective lenses for astigmatism is not circularly symmetric, so when you use contact lenses to correct for astigmatism, you have to be careful to orientate them the correct way, so the line up with the axis of the astigmatism (contact lenses for simple long or short sightedness do not matter which angle they lay on the eye, since the make the same correction both horizontally and vertically).
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Ah ok, thanks George..
I've heard somewhere about the bumpy surface, maybe it wasn't astigmatism. [;D]
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Thanks both of you. George have you heard about some newfangled lenses, contacts for astigmatism??
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Thanks both of you. George have you heard about some newfangled lenses, contacts for astigmatism??
Not sure that I had - I was assuming that people were telling me that they did exist - although I had not worked out how they would properly be aligned to the correct rotation when placed on the eye. Maybe if it is only a slight astigmatism, and the major correction is for simple long or short sightedness, then a slight misalignment on the eye is tolerable, but ofcourse if they were placed in 90 degrees misaligned, then far from correcting the astigmatism, they would only compound it.
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There are contacts useful for many cases of astigmatism. They are called "toric" and are made with multiple curvatures to the lens as well as a stabilizing system to keep them from rotating about. It may be advisable to find an eye doctor who specializes in contact lenses - fitting these is especially critical.
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Thank you for the information.. I missed this last post eh about 2 years ago!!