 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Medical Forum / General / Vision / August 2007Astigmatism changed?
Hello... My eye exam 3 years ago, resulted in this lens prescription: OD: -0.75 SPH (+1.25 ADD) OS: -0.50 SPH (+1.25 ADD) Last year, is was: OD: -0.75 SPH (+1.25 ADD) OS: -0.50 -.050 170 (+1.25 ADD) Last week, it was: OD: -1.00 SPH (+1.25) OS: -0.75 +.025 080 (+1.25 ADD) What would cause these astigmatitc changes to my left eye? How much astigmatism do I have with these prescriptions? I'm trying to understand astigmatism. Thanks, Ed > What would cause these astigmatitc changes to my left eye? Being alive. Astigmatism always varies a quarter diopter or so from year to year. > How much > astigmatism do I have with these prescriptions? Very little, almost negligible. > I'm trying to > understand astigmatism. There are good web resources if you simply google "astigmatism". Nature tries to make eyeballs perfectly spherical, but living tissue is never geometrically "perfect." Instead of perfectly spherical, most eyes are instead a little "spoon" shaped. Your spectacle lens is made with the same spoon shape, oriented to "neutralize" the optics of your eye, so it works as well as a spherical surface. -MT There is also a thing called bias. It is mosnswer on one day and a different on the next. There is such an inconsequential change it is not even worth bothering about. dr grant Thank you so much, Mike and Dr Grant, for the very quick (and understandable) responses! There is a wealth of knowlege in this forum! -Ed |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.