Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: berty on 23/03/2014 19:06:22
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Just had eye test I am told i need one for driving. one for reading and one for watching my computer monitor. I no i need them but how come my 12 year old grandson who strugles to see without glasses has one pair for every thing. ps just cost me £300
Berty
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Just had eye test I am told i need one for driving. one for reading and one for watching my computer monitor. I no i need them but how come my 12 year old grandson who strugles to see without glasses has one pair for every thing.
Because of age Grandfather's eyes don't accommodate (https://en.wikipedia.org/wiki/Accommodation_%28eye%29) any more , grandson's still do ...
The young human eye can change focus from distance (infinity) to 7 cm from the eye in 350 milliseconds.
This dramatic change in focal power of the eye of approximately 13 diopters ...
... The age-related decline in accommodation occurs almost universally to less than 2 dioptres by the time a person reaches 45 to 50 years, by which time most of the population will have noticed a decrease in their ability to focus on close objects and hence require glasses for reading or bifocal lenses.
Accommodation decreases to essentially 0 dioptres at the age of 70 years.
https://en.wikipedia.org/wiki/Accommodation_%28eye%29
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My optometrist told me that unless one eye is different from the other or you have an astigmatism, you can use drug store glasses for various things. (They won't damage your eyes.) I have one pair of expensive prescription glasses, and several cheapies of varying strength, depending on whether I am watching tv or threading a needle.
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Because of age,you will require 3 glasses, as your grandson is too younger his eyesight will be more stronger than your eyesight.As in old age eyesight gets weaker and we are more dependent on glasses.As I am a doctor I would suggest you to wear glasses every time as without glasses you will harm your eyes.
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Consider varifocals, if you still have any degree of accommodation. I am very shortshighted and astigmatic but one pair of varifocals (admittedly with very large lenses - not a fashion item) allows me to watch the conductor and read the music at the same time, without the break line of bifocals.