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#121
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A screen question.
"J. P. Gilliver (John)" wrote:
The original poster Peter Jason didn't say he only had [astigmatism] in one eye. Are your palm prints exactly the same for your right hand as for your left hand? Nope. Same for your right and left fingerprints for the matching fingers. Same for your eyes. Irregularities in the shape of the cornea that generate refractive error (astigmatism) do not progress equally in both eyes because the tissues are separate, not common. Many folks with astigmatism have it in only one eye. While astigmatism usually occurs concurrently in both eyes (bilateral), it is not necessarily equal in both eyes (i.e., it can be asymmetrical). Astigmatism in only one eye is often caused by injury (which is my case due to a cat scratching my right eye when I was a kid) or by degenerative eye conditions or disease; however, eyes do not degenerate equally. No pair of disconnected tissue will degenerate equally. Regardless of astigmatism, how often do eyeglass wearers get exactly the same prescription for both eyes? Most users don't even know the specs for their specs; that is, they go to the optometrist, get their exam, and get their eyeglasses, and the bill they get never mentions the sphere, cylinder, and axis measurements. If they want to keep their own history of how their eyesight has degenerated, they have to ask for a copy of the measurements to know what they are. Several times when I've asked for the specs, they'd look mildly surpised and asked "Why do you need to know?". I'd respond "Why shouldn't I know?" In any case, for a monitor to correct vision impairment would mean the screen would need to place a lens at your face to correct the refractive error at the distance for where the pixels are painted. Don't know about you, but having a large bubble of glass protrude from the monitor against which I would have to press my face seems extreme compared to putting on a pair of eyeglasses. Remember the function of the lens is to correct your focus at a specific distance. My eyeglasses for outside and driving would be impossible to use for reading or the computer monitor, so I use prescription eyeglasses for reading and computer. Likewise, my reading eyeglasses would make everything slightly out of focus at distances. I did this once when I went to a reunion and wore the wrong eyeglasses. They look almost identical. I was wondering why my vision suddenly got so bad beyond my arm's length. I don't like bifocals. I get a sore neck tilting back my head to use the bottom lens portion for computer monitor viewing. |
#122
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A screen question.
On 2019-09-14 8:56 a.m., VanguardLH wrote:
"J. P. Gilliver (John)" wrote: The original poster Peter Jason didn't say he only had [astigmatism] in one eye. Are your palm prints exactly the same for your right hand as for your left hand? Nope. Same for your right and left fingerprints for the matching fingers. Same for your eyes. Irregularities in the shape of the cornea that generate refractive error (astigmatism) do not progress equally in both eyes because the tissues are separate, not common. Many folks with astigmatism have it in only one eye. While astigmatism usually occurs concurrently in both eyes (bilateral), it is not necessarily equal in both eyes (i.e., it can be asymmetrical). Astigmatism in only one eye is often caused by injury (which is my case due to a cat scratching my right eye when I was a kid) or by degenerative eye conditions or disease; however, eyes do not degenerate equally. No pair of disconnected tissue will degenerate equally. Regardless of astigmatism, how often do eyeglass wearers get exactly the same prescription for both eyes? Most users don't even know the specs for their specs; that is, they go to the optometrist, get their exam, and get their eyeglasses, and the bill they get never mentions the sphere, cylinder, and axis measurements. If they want to keep their own history of how their eyesight has degenerated, they have to ask for a copy of the measurements to know what they are. Several times when I've asked for the specs, they'd look mildly surpised and asked "Why do you need to know?". I'd respond "Why shouldn't I know?" In any case, for a monitor to correct vision impairment would mean the screen would need to place a lens at your face to correct the refractive error at the distance for where the pixels are painted. Don't know about you, but having a large bubble of glass protrude from the monitor against which I would have to press my face seems extreme compared to putting on a pair of eyeglasses. Remember the function of the lens is to correct your focus at a specific distance. My eyeglasses for outside and driving would be impossible to use for reading or the computer monitor, so I use prescription eyeglasses for reading and computer. Likewise, my reading eyeglasses would make everything slightly out of focus at distances. I did this once when I went to a reunion and wore the wrong eyeglasses. They look almost identical. I was wondering why my vision suddenly got so bad beyond my arm's length. I don't like bifocals. I get a sore neck tilting back my head to use the bottom lens portion for computer monitor viewing. I am in the same boat regards sore neck syndrome, especially reading the top of the display, my bifocals are +9. My ophthalmologist always gives me a copy of the Specs and also sends a copy to my medical Doctor. Rene |
#123
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A screen question.
In message , VanguardLH
writes: "J. P. Gilliver (John)" wrote: The original poster Peter Jason didn't say he only had [astigmatism] in one eye. Are your palm prints exactly the same for your right hand as for your left hand? Nope. Same for your right and left fingerprints for the matching fingers. Same for your eyes. Irregularities in the shape of the cornea that generate refractive error (astigmatism) do not progress equally in both eyes because the tissues are separate, not common. Many folks with astigmatism have it in only one eye. While astigmatism usually occurs concurrently in both eyes (bilateral), it is not necessarily equal in both eyes (i.e., it can be asymmetrical). Astigmatism in only one eye is often caused by injury (which is my case due to a cat scratching my right eye when I was a kid) or by degenerative eye conditions or disease; however, eyes do not degenerate equally. No pair of disconnected tissue will degenerate equally. Like you (though for different reason - mine's from birth), I have dissimilar eyes (to the extent that I don't have 3D vision; both eyes worked fine when I was younger, but my brain never developed the ability to use both images at once). I will admit I'd got used to thinking _most_ other people had eyes that were more similar than mine are. Regardless of astigmatism, how often do eyeglass wearers get exactly the same prescription for both eyes? Most users don't even know the specs for their specs; that is, they go to the optometrist, get their exam, and get their eyeglasses, and the bill they get never mentions the That's _probably_ still true here (UK), but less so: several of our optometry chains offer free eye tests as a marketing exercise from time to time, and also certain classes (children below a certain age, pensioners above one, and I think those on certain kinds of benefit [welfare]) are entitled to free ones too. So the more savvy of us - or, even those entitled to free glasses as well as tests, but who don't like the options (frames, coatings, ...) offered at a particular branch - go for a free test, then take the prescription elsewhere. sphere, cylinder, and axis measurements. If they want to keep their own One that's often left off the card is intraocular distance, i. e. how far apart your pupils are. history of how their eyesight has degenerated, they have to ask for a copy of the measurements to know what they are. Several times when I've asked for the specs, they'd look mildly surpised and asked "Why do you need to know?". I'd respond "Why shouldn't I know?" Indeed! In any case, for a monitor to correct vision impairment would mean the screen would need to place a lens at your face to correct the refractive error at the distance for where the pixels are painted. Don't know about you, but having a large bubble of glass protrude from the monitor against which I would have to press my face seems extreme compared to putting on a pair of eyeglasses. With the one exception of the sort of astigmatism that is purely an aspect ratio distortion, and similar in both eyes. A monitor and graphics card combination _could_ sort that, by simply using the "wrong" ratio - _if_ a ratio "error" that countermatched the astigmatism was achievable (including by rotating the monitor if necessary). _Maybe_ that type of astigmatism is actually very rare; I don't know. I based my naïve thoughts on the matter on being told (decades ago) that the reason some famous painters painted pictures of a stretched world (e. g. tall thin people) was that they had astigmatism. (I was always suspicious of that explanation, because surely if they had, and looked at a picture they'd painted in that manner, it'd still look wrong to them.) Remember the function of the lens is to correct your focus at a specific One function ... distance. My eyeglasses for outside and driving would be impossible to .... and for most practical glasses, for a _range_ of distances - though ones for specific occupations, including display screen use, may be optimised for quite a narrow range. [] -- J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf As for cooking, what a bore that is. It's such a faff, thinking of what to have, buying it and cooking it and clearing up, then all you do is eat it - and have to start all over again next day. Hunter Davies, RT 2017/2/4-10 |
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