Question about how much astigmatism affects vision? please answer!?!
Question: I am 18 and my contacts perscription is -1.00 on the left and -1.25 on the left. For a while I have thought my vision had gotten worse because I have a hard time seeing signs on the road when I am driving especially at night and a lot of things aren't very clear in the distance. Recently I looked at the perscription for my glasses, I don't have any glasses but I do I have a perscription for some, and it said that I had -.5 astigmatism in each eye. Could this be what is causing my vision to be unclear? It seems like it was clearer before but I could be wrong. So do you think my vision has gotten worse or it is the astigmatism that is making me see blurry? How much would it affect it? why isn't that correction on my contacts?Thanks
Answers: I am 18 and my contacts perscription is -1.00 on the left and -1.25 on the left. For a while I have thought my vision had gotten worse because I have a hard time seeing signs on the road when I am driving especially at night and a lot of things aren't very clear in the distance. Recently I looked at the perscription for my glasses, I don't have any glasses but I do I have a perscription for some, and it said that I had -.5 astigmatism in each eye. Could this be what is causing my vision to be unclear? It seems like it was clearer before but I could be wrong. So do you think my vision has gotten worse or it is the astigmatism that is making me see blurry? How much would it affect it? why isn't that correction on my contacts?Thanks
As a *rough* guide the amount of astigmatism causes half as much blur as as a sphere of the same strength.
So if you have 0.50 DC uncorrected, that would cause about 0.25 DS of spectacle blur, barely perceptible.
Since astigmatism correcting contacts are more expensive, thicker and not always stable in the eye, it's very common to compromise and stay with a spherical contact lens for small degrees of astigmatism.
Some people with 0.75 cyls will be happier being corrected, some will be happier with sphere lenses...
With poor vision or starriness at night with contacts, apart from the possibility that your Rx has shifted a little, the chief suspect would be your pupils getting larger than the optical zone of the contact lenses, so your eyes are accepting light that has passed through part of the lens not shaped for optical quality.
(but for reduced thickness, and transition towards the edge curve)
yes astigmatism (football shaped eyeball-oposed to round) commonly causes difficulty while driving at night-makes lights in darkness have a spiderwebbing effect. are your contacts specificly for astigmatism? if so, and your having the same problem, glasses may be more ideal for driving. i had astigmatism as a teenager, but years ago, i switched my birth control, and for what ever reason, that reversed it.
Yes, basically in your glasses there is a little line of power that is added on to your regular Rx, that and the angle it cuts through the lens is what makes up your astigmatism. If your astigmatism has gotten worse it is really easy to see the difference. Best thing to do is to get and updated Rx, and see how much it has changed. Most contacts don't correct for astigmatism, and those that do, don't always do it well, plus, they're more expensive.