I have astigmatism and want to know the best lens. Say I was Bill Gates and I have astigmatism. Money is not an issue, I just want the best lens, which lens is the best for astigmatism?
To answer this question, I am first going to explain how lenses for astigmatism work and then you will understand my response a little better. Lenses for astigmatism, referred to as toric lenses, have two distinct areas of different power. For simplicity sake, let’s say on your eye you need a lens that has a vision correction of -2.00 accross the horizontal plain and it needs a -3.00 along the vertical. Your eye would have astigmatism and need a toric lens.
Toric lenses (and I am focusing on soft lenses for this answer) have two methods staying oriented on an eye.
Type 1 is a prism ballast lens. Some common prism ballasted lenses are the Vertex Toric and Purevision Toric lenses. Picture these like a watermelon seed, thin on the top and thick on the bottom. These lenses will orientate properly by the lids applying pressure along the thin area and pushing the thick area down towards the lower lid.
Type 2 is a double slab off lens. A very common double slab off design is the Acuvue Advance for Astigmatism. These lenses have 2 thin zones that remain under the upper and lower lids while the thicker middle zone maintains it’s position between the lids.
Both styles require the lens fitter to choose the best design based on corneal measurements, then the lid structure (which you see is extremely important for toric lenses), the tear film, and vision correction. There are a lot of factors and variables to decide which will be the best lens.
Now to answer the question, which is the best lens for astigmatism?, well that all depends. Almost every soft toric lens works on some eyes, but there is not one that works on every eye. To find out which would work best on Bill Gates, trial and error is the only way to find out. (Ironically, it could potentially be the least expensive option… there is only one way to find out.)