Hi. I'm online and happy to answer your question today.
Hi. Lets deal with your questions in turn:
1. Yes, it is correct. It is just a different way of doing the same thing.....like skinning a cat -- lots of different ways to get the same result.
2. yes, that is how it is done. It is a math thing. A spherical equivalent is the sphere power plus half of the cylinder power added together....it works out, so what you were given is correct.
3. The toric lens corrects both the sphere and the cylinder, but it has to sit just so on your eye. This can be a problem, for instance, if you lay on your side and try to read as the lens shifts and things get blurry. The "non-toric", or spherical equivalent lens, uses the above math, and other things to do with a lens formed by your tear film etc (more then you want to know :o), to take care of the majority, if not all, of your astigmatism with a "spherical equivalent" lens
So, try not to focus on the numbers......yes, they are different numbers, but they are all "equivalent" lens powers per established mathmatics. What your optician is doing is correct.
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