I have had "Toric" lenses for a while now and they are great..........didn't know they were also called "weighted lens" (thanks Ali). Bit uncomfortable for a couple of weeks but they do give me good vision and am able to keep them in for 10 hours or so.
Sas x
Weighted lens...
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Knight
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Ali Akay wrote:...
The term "weighted lens" is what is usually referred to as "toric lens"...
Yeah the doctor I saw that day was not the usual consultant, due to some emergency but she was very thorough in testing and examining my eye. I had to stop her halfway through though to explain what she meant as I hadn't heard of it before, so she just refered to it as a weighted lens but I suppose 'toric' is the correct term. My usual consultant is more open with the details and has often shown me samples and pictures in the past to get the information across when I ask specific questions. Normally I take a notepad with me, but I presumed that appointment would have been routine ...
When I go back to have it fitted, I've arranged it the same day I have the stitches removed in my left eye, so I dont have to wait and my usual consultant will be there to fit my right eye with this new lens instead of the doctor I saw last week. I'll be able to get more information then if only to clarity the type of lens - but toric lens - sounds about right so I'm looking that up as the term weighted lens, seems to be more of a generic description than an actual type of lens.
Anyway, thanks everyone for replying.
Sas, I'm curious how you mean uncomfortable? Was the lens catching your eyelid, or sitting flat against the bottom of the eye? The RGP I have now is very comfortable and I normally wear it for around a max of 17hours - obviously I depend on it that long for everything so its some relief to know it can be worn for 10hours, as I've been concerned about that specifically.
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Michael P
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About 35 years ago when I first started to wear hard lenses (before KC had been diagnosed my contact lens practitioner was tearing his hair out trying to improve the vision out of my right eye. He said I had astigmatism and prescribed a lens which I now understand was weighted. It was thicker at one end. It did not help and it was at this point he referred me to a consultant.
I thought the lens was called a prismatic ballistic lens but that must be wrong! Could it have been prismatic balance lens or just prismatic? It was all such a long time ago and my memory is probably playing tricks with me.
I thought the lens was called a prismatic ballistic lens but that must be wrong! Could it have been prismatic balance lens or just prismatic? It was all such a long time ago and my memory is probably playing tricks with me.
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Ali Akay
- Optometrist
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Michael
You are almost right, the proper term is "prism ballast".Making the bottom of the lens thicker than the top ie. like a wedge results in a prismatic effect and the lens effectively shifts the light downwards very slightly like a prism but this doesnt normally cause any problems. The issue with comfort is a bit more complicated as not all toric lenses are weighted. For ordinary astigmatism, the astigmatic correction is normally ground on the inside surface of the lens and this doesnt need to be weighted as the shape of the cornea is sufficient to keep the lens in a stable position.The lens needs to be weighted only if the astigmatic correction is on the front surface and this could cause more lower lid sensation due to increased thickness
You are almost right, the proper term is "prism ballast".Making the bottom of the lens thicker than the top ie. like a wedge results in a prismatic effect and the lens effectively shifts the light downwards very slightly like a prism but this doesnt normally cause any problems. The issue with comfort is a bit more complicated as not all toric lenses are weighted. For ordinary astigmatism, the astigmatic correction is normally ground on the inside surface of the lens and this doesnt need to be weighted as the shape of the cornea is sufficient to keep the lens in a stable position.The lens needs to be weighted only if the astigmatic correction is on the front surface and this could cause more lower lid sensation due to increased thickness
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Andrew MacLean
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Andrew MacLean
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