 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Medical Forum / General / Vision / February 2007Age related myopic shift
I've read here that it's usual for myopia to decrease after say, age 50 but what is the usual shift? How much improvement to myopia is average or usual? And over what period? Does it stabilise again? Any info would be good.. google is not revealing much, probably because because I'm not using the right terms in the search. Ann > I've read here that it's usual for myopia to decrease after say, age > 50 but what is the usual shift? How much improvement to myopia is > average or usual? And over what period? Does it stabilise again? After 50, myopic shift is mostly lenticular, driven by changes in chemistry rather than geometry. For those who experience it, an "average" value might be -100 over 10 years. But it's accompanied by increasing blur so at some point there's a net loss of usable vision. The lens proteins are like the albumin in egg white. Over time, with oxidation and sunlight and "normal" aging, the lens proteins get hard, the classic cause of presbyopia. Presbyopia is remarkably predictable - these proteins seem to hold up remarkably well for the first 40 years. Beyond that, the changes vary with each individual. Most _monocular_ myopic excursion after age 50 is presumed to be lenticular. Wait another decade or two, and circumferential bundles of lens fiber cells turn white or blue-white. Their shape and location give rise to crescent-shaped "riders" and wedge-shaped opacities that are fortunately slow to reach the center. The oldest (fetal) cells are at the core, like an onion, and often they behave independently, forming a pill-shaped "nucleus" with different refractive index or color. Local variations in refractive index can easily create monocular diplopia, either from wedge-shaped irregularities or a dichotomy of index in the center vs the periphery. These may vary dramatically with pupil size. Myopic shift is how hyperopes and presbyopes get "second sight" up close. No doubt it contributed to some of Dr. Bates' success-stories. The lens color usually changes, toward yellow and eventually red. This makes little old ladies dye their hair blue. Eventually the whole lens becomes opaque and white, like boiling an egg. Wait too long (like age 90) and the lens protein liquifies inside the capsule, producing an allergenic protein mush. I hope to live long enough to have that problem. Hell I hope to live long enough to get cataracts. -MT >> I've read here that it's usual for myopia to decrease after say, age >> 50 but what is the usual shift? How much improvement to myopia is [quoted text clipped - 38 lines] >I hope to live long enough to have that problem. Hell I hope to live long >enough to get cataracts. Thank you. My vision has improved from -6.25 to -5.25 in exactly three years. Wearing glasses that are slightly too strong is far more difficult than wearing glasses that are slighty too weak which is what most of us are more used to. I am hoping it levles out. The report sent by Robert is interesting but will take a couple of reads to get my head round. Ann > My vision has improved from -6.25 to -5.25 in exactly >three years. Wearing glasses that are slightly too strong is far more >difficult than wearing glasses that are slighty too weak Especially for myopes (nearsighted). Even half of that change (.50) can make reading, intermediate, or the vision in general uncomfortable if you are older than about age 45. >The report sent by Robert is interesting but will take a couple of >reads to get my head round. Ann, In general, it says that myopes over age 50 tend to have a stable distance Rx. Hyperopes (farsighted) and those with very little distance Rx tend to drift towards more plus power. Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical Wauwatosa Wi. ~~~~~~~~~~~~~~~~~~ "Science is a way of trying not to fool yourself." - Richard Feynman >> My vision has improved from -6.25 to -5.25 in exactly >>three years. Wearing glasses that are slightly too strong is far more [quoted text clipped - 12 lines] >Hyperopes (farsighted) and those with very little distance Rx tend to drift >towards more plus power. That's what I thought it said but it doesn't seem to be what I've learnt before. I thought that myopes weren't stable after age 50 but there you go. Ann >I've read here that it's usual for myopia to decrease after say, age >50 but what is the usual shift? How much improvement to myopia is [quoted text clipped - 4 lines] > >Ann Search for "Hyperopic Shift". http://www.optometrists.asn.au/gui/files/ceo826236.pdf Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical Wauwatosa Wi. ~~~~~~~~~~~~~~~~~~ "Science is a way of trying not to fool yourself." - Richard Feynman |
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.