what is astigmatism? All the online definitions don’t make any sense. Ty
In: Other
Astigmatism is when your cornea has an irregular shape.
For regular short/long-sightedness the focal point is a bit back or forward of where it should be. But a normal round lens fixes the problem just fine.
In astigmatism however the cornea is curved a bit differently in one direction compared to the other, so you end up with a blurry focal point at all distances. In a simplified example (a 0 degree rotation lens), height and width have different focal points so letters for example would either be blurry in height, or in width or in both depending on how you focus your eye.
To fix astigmatism (as well as it can be fixed, you can rarely compensate 100% for astigmatism) you need a lens that corrects the light in a specific way. An astigmatic lens has the refractive value (how myopic/hyperopic is the eye in general), a cylindrical value (how much of a difference is it between refractive value in direction X vs direction Y) and then a specific axis (rotation of 0-180 degrees, because of course a biological eye is rarely perfectly aligned with just an X/Y up/down/left/right axis).
This also made it difficult to make contact lenses, but these days they have self-righting lenses that you just need to blink a few times and the lens corrects its axis so that it’s aligned with your eye.
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