New Lenses for My Glasses - Blind as a Bat

[larkspur]

Actually, the opposite is true, people with myopia (nearsightedness) can read up close without glasses, however as you age, the ability to focus decreases and people who could once read things up close now find they need corrective lenses to read. Bless Benjamin Franklin for the bifocal lense.

Nope, nearsighted people are naturally in focus without glasses at near hence the term "nearsighted". Depending on the amount of myopia, as a myopic person ages they will either need bifocals to read with their glasses on or they will need to take the glasses off to read. A person with a -3.00 Rx is naturally in focus(without glasses) at 1/3 meter in front of the eye. While they are wearing their glasses they are essentially emmetropic and if they are also presbyopic they will need bifocals to read. When they take their glasses off they have the same result as if they had placed a +3.00 lens(reading glasses) in front of the their own glasses.

 

[Evo]

Nope, nearsighted people are naturally in focus without glasses at near hence the term "nearsighted".

Yes, I'm nearsighted. However, as you age, a nearsighted person loses the ability to read up close.

Depending on the amount of myopia, as a myopic person ages they will either need bifocals to read with their glasses on or they will need to take the glasses off to read.

Exactly, they lose their ability to read up close. They become presbyopic.

 

[larkspur]

Yes, I'm nearsighted. However, as you age, a nearsighted person loses the ability to read up close.

Exactly, they lose their ability to read up close. They become presbyopic.

Depends on how much nearsightedness you have. If you only have -1.00 diopter then your natural point of focus would be at one meter and anything closer to you would require accommodation to focus. If you have lost all your accommodative abilities(completely presbyopic) then you would require reading glasses or hold the object 1 meter away from you to see it. This is further than most peoples arms can reach. If you have -2.00 diopters of myopia then it will need to be at 1/2m, -3.00 at 1/3 m etc. The higher the amount of myopia the closer you can hold the object to view it without accommodation or glasses.

 

[Evo]

Relax, I'm referring to what you said

When myopes hit the 40's they begin to notice they can read better without glasses because their eyes are naturally in focus without accommodation for near.

I've never seen a case where this was true, although it might be possible. Do you know of any cases where a person's eyesight improved with age? You yourself agreed that people with myopia need corrective lenses for near vision as they get older.

Not only do I find that I can no longer see clearly at close range, but I now need more light in order to see things clearly at close range. Here we go, wikipedia, the quick answer.

"Many people with myopia are able to read comfortably without eyeglasses. Myopes considering refractive surgery are advised that this may be an advantage after the age of 40 when the eyes become presbyopic and lose their ability to accommodate or change focus.

"Presbyopia is not a disease as such, but a condition that affects everyone at a certain age. The first symptoms are usually noticed between the ages of 40-50, though in fact accommodation reduces throughout life, from about 20 dioptres (ability to focus at 50 mm away) in a young person to 10 dioptres at 25 and levelling off at 0.5 to 1 dioptre at age 60 (ability to focus down to 1 -2 metres only). For those with good distance vision, it may start with difficulty reading fine print, particularly if the lighting is poor, or with eyestrain when reading for long periods."

http://en.wikipedia.org/wiki/Presbyopia

 

[larkspur]

Relax, I'm referring to what you said I've never seen a case where this was true, although it might be possible. Do you know of any cases where a person's eyesight improved with age? You yourself agreed that people with myopia need corrective lenses for near vision as they get older.

In a child with ,small to moderate amounts of hyperopia, as the eye grows larger the refractive error can go away completely. However, with myopia the opposite occurs. As the eye grows larger so does the refractive error. Later in life, when cataracts develop, the refractive error can change quite a bit but mostly this change is for the worse. I personally have never seen a fully grown adult get out of glasses without surgical intervention.

Not only do I find that I can no longer see clearly at close range, but I now need more light in order to see things clearly at close range.

Do you have any astigmatism?

 

[matthew baird]

I am -4.50 in my right eye and -8.00 in my left eye. When I was 2.5yrs old I was stabbed with an exacto knife in the eye! OUCH since then I have been through numerous surgeries and am very fortunate to not be blind. If it weren't for the great docs at the University of Utah childrens hospital I would probably be in that situation.

 

[turbo]

Not only do I find that I can no longer see clearly at close range, but I now need more light in order to see things clearly at close range. Here we go, wikipedia, the quick answer.

First off, you've already found out about presbyopia, so you know why close-range vision is deteriorating. The reason that you can see better with more light is that the more light you have reflecting off a page (for instance, if you're reading a book), the smaller your pupils get, and that sharpens your vision. When your pupils are dilated, your eyes' optical flaws are exaggerated. I found out when I was a child (an old man told me) that if there was enough light and I had difficulty seeing something, I could get a sharper view by rolling my index finger into a circle and peering through the tiny gap in the center. Try it. Though I am nearsighted, I can clearly see the leaves on the trees across the road (75' or so) and though I have a problem reading print at less than about a foot (presbyopia) I can read fine print at a distance of less than 3" - all by peeking through the gap in my index finger. Since it's not a round aperture, some distortion is induced, but if you're into that kind of perfection, you can use a hot pin to poke a hole in one of your credit cards and tuck it back in your purse. People are going to look at you funny if you're trying to look up a number in a phone directory with a credit card held up to your eye, but if you have misplaced or broken your glasses...it'll get you out of a jam.

 

[Evo]

Though I am nearsighted, I can clearly see the leaves on the trees across the road (75' or so) and though I have a problem reading print at less than about a foot (presbyopia) I can read fine print at a distance of less than 3" - all by peeking through the gap in my index finger. Since it's not a round aperture, some distortion is induced, but if you're into that kind of perfection, you can use a hot pin to poke a hole in one of your credit cards and tuck it back in your purse. People are going to look at you funny if you're trying to look up a number in a phone directory with a credit card held up to your eye, but if you have misplaced or broken your glasses...it'll get you out of a jam.

I'm going to have to try that, ever since the Evo Child broke my tri-focals I've been dealing with my old single vision lenses and they're making me crazy.

 

[larkspur]

I am -4.50 in my right eye and -8.00 in my left eye. When I was 2.5yrs old I was stabbed with an exacto knife in the eye! OUCH since then I have been through numerous surgeries and am very fortunate to not be blind. If it weren't for the great docs at the University of Utah childrens hospital I would probably be in that situation.

Yes, you are very lucky and you must have great parents that did what the doctors recommended.

 

[larkspur]

I'm going to have to try that, ever since the Evo Child broke my tri-focals I've been dealing with my old single vision lenses and they're making me crazy.

How about a pair of these?
http://www.bernell.com/store/prodinfo.asp?number=BC1185PH&variation=&aitem=2&mitem=5"
http://www.bernell.com/store/images/BC1185PH.JPG

 

[fargoth]

that's very interesting, i wonder why pinhole sunglasses are so rare if they give better resolution then normal sunglasses for hyperopia/myopia...
you can't drive with them, but they seem better for main use in the outdoors...

http://us.st11.yimg.com/us.st.yimg.com/I/toolsforwellnesscom_1903_3429430

or better yet:

http://www.myopia.org/sunglasses.htm

 

[turbo]

that's very interesting, i wonder why pinhole sunglasses are so rare if they give better resolution then normal sunglasses for hyperopia/myopia...
you can't drive with them, but they seem better for main use in the outdoors...

If you have every photographed through a pinhole aperture (I have one for my OM-1) you will know that the images are "soft". You will not have great visual acuity with pinhole sunglasses, just a bit better than with no correction at all. If you already see well with no corrective lenses, looking through pinhole sunglasses will give you less visual acuity, not more.

Safety tip: do NOT buy cheap sunglasses that don't have good UV protection. They will allow your pupils to dilate due to the reduced amount of visible light, and that will allow a lot more UV into your eyes than if you had worn no sunglasses at all. This is especially important for little kids - do not buy them cute "novelty" sunglasses unless you are confident that they supply good UV protection - their pupils can dilate much larger than yours can.

 

[larkspur]

that's very interesting, i wonder why pinhole sunglasses are so rare if they give better resolution then normal sunglasses for hyperopia/myopia...
you can't drive with them, but they seem better for main use in the outdoors...

The pinhole has to be lined up exactly so the image through it lines up with the http://www.tedmontgomery.com/the_eye/macula.html" . Otherwise the image is still out of focus. If the object of regard moves or if you move, then the image is out of focus until you realign the pinhole with the fovea. Like Turbo said, the image is fuzzy around the edges of the pinhole, even when you do get it aligned.