old ppl use +power to see far can we called it hypermetropia. how bout for young ppl use +power to see far????? but hypermetropia is the image fall behind our retina ???
how bout prebyopia ?????
old ppl use +power to see far can we called it hypermetropia. how bout for young ppl use +power to see far????? but hypermetropia is the image fall behind our retina ???
how bout prebyopia ?????
if a distance prescription is positive (+) then the person is a Hyperope, or has hypermetriopa.
Regardless of distance pescription (the distance prescription could be myopic/hyperopic -/+), if the person has a reading ADDition or ADD in the prescription, the person is presbyopic, or has presbyopia
Hyperopia is when the shape of the eye is SHORT and thus, the image would fall behind the retina ... there is a limited ability to see up close but the patient can see the mole on the bunny on the hill over yonder :p Plus lenses are thicker in the middle of the lens (thin to the edge of the lens) and thus "slow down" the light as it passes thru the lens and makes the light hit on the retina. (I kind of picture a plus lens kind of like a "speed bump" ~ slowing things down)Originally Posted by cnet_baby
Myopia is where the shape of the eye is LONG and thus, the image would fall in front of the retina). The lens design is thinner in the middle and thicker to the edge. (I kind of picture a minus lens as "pushing" the light to the back of the eye ~ like standing in a swimming pool at using your hands to kind of push the water at someone else).
Presbyopia is a condition of the crystalline lens and the muscles that control and move the crystalline lens. As we age, those muscles lose the flexibility necessary for "accomodation " (the ability to change focus from far to near and vice versa). The patient loses the ability to see up close and thus a magnification lens is needed to allow them to see up close.
Astigmatism is almost exclusively related to the shape (or shall we say "mishape") of the cornea. Instead of a smooth, round shape (like a basketball or baseball) it is elongated, like a football. Light scatters in the eye ~ nothing is clear near or far.
I hope that explains it a little bit :cheers:
Last edited by GOS_Queen; 12-26-2005 at 11:12 AM.
only old hyperopes use + at far. old myopes still use minus at far.Originally Posted by cnet_baby
young hyperopes often need + for full time, especially if it is above 2.00 D.
yes, in hyperopia the image is virtual in that it doesn't actually get behind the eye, but if the eye were transparent, yes it would focus there.
presbyopes need an "add" to read. if they are hyperopes, their add results in more power at near; if myopes, less minus at near (or some plus if the add exceeds the distance Rx)
is it hypermetropia ppl see blur if reading????Originally Posted by William Stacy O.D.
am i right, if hypermetropia reading need more accomodation ??
There are two parts of a prescription - the main part, and the reading addition
the main part defines if the patiet is a hyperope or myope (long/shortshighted)
for example
Main (distance) RX:
R+1.00 DS
L -1.00 DS
R+1.00 the right eye is hyperopic, the patient is RE longsighted/hyperope
L -1.00 the left eye is myopic, the patient is LE shortsighted/myope
Then there is a ADD
If an add was prescribed the patient would be a presbyope
Lets say in this example the ADD is +2.00
Adding the ADD to the main RX will give us the NEAR RX
R+3.00
L+1.00
This does not mean the patient is LE hyperopic. The patient is still RE hyperope, LE myope, but presbiopic in both eyes
Example 2: using the above main RX, lets pretend the add was +0.75
Adding the new ADD to the main RX will give us the new NEAR RX
R +1.75
L -0.25
The patient is still RE hyperope, LE myope, but presbiopic in both eyes
(we would say this was an early presbyope)
summary
1. The words Hyperope/Myope, Hyperopic/Myopic, Longsight/shortsight - relate to the main distance prescription only
2. The words: Presbyope/presbyopic are only used if there is an ADD prescribed
3. The reading addition does not alter the facts established from the main distance prescription - no mater how the numbers change once the ADD has been added to the main prescription. A hyperope is a hyperope, a myope a myope regardless of the resultant near prescription
The first question is like asking "is it fat people who weigh a lot?"Originally Posted by cnet_baby
Often, it's true, but often it's not. A 230 lb linebacker may not be fat at all while a morbidly obese infant may only weigh 50 lbs.
Similarly, many hyperopes have problems with reading, many do not. Your second question is correct. Many young hyperopes can easily focus through their hyperopia, some cannot. However, all older hyperopes have a problem reading without glasses (presbyopia is universal).
Usually, but not always. Often a child or young adult has an add for reasons of binocular imbalance or accommodative insufficiency, and are not presbyopic. Only older folks are presbyopic.Originally Posted by QDO1
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