acuity versus error in refraction

To whom it concerns,

Wake up all nitwits, there is no excact conversion possible from diopters
into vision acuity
and vice versa, period.
There is a relation nothing more nothing less.
A clip and clear example ace or otis?
A blind eye with a refractive error zero (0 diopter) or a refractive error
plus ten (+10 diopters)
still possess both a vision acuity of zero, cappice?

--
Free to Marcus Porcius Cato: ''Ceterum censeo Carthaginem esse delendam"

In conclusion, I think that the "Otis therapy" should be destroyed

Jan (normally Dutch spoken)

 

A pretty good statistical correlation. Valid within limits,
of course. Go look up the "Dead Horse Equation" on google.

-- Robert

 

A blind eye would have LP or NLP or 20/infinate. A +10 depending on
accomodative amplitude has varable accuracy. Say he can accomodate +5
of the +10 diopters, the remaining +5 diopters would give him 20/400
UCVA from distance and worse from near. I heard of one college lady of
18 who was +6.5 and she could accomodate +4.5 diopters and had a
manifast refraction of +2 and 20/70 UCVA. She got lasik and is now +2
and is glasses free for now but will soon need glasses again as her
accomodative amplitude drops.

There is a very close correlation between the two. Diopter is a
measurement of the focal point. A +2 lens or an eye with +2 diopters is
in focus at half meter and needs a -2 lens to cancel out. Everyone
knows more diopters results in more defocus so therefore its
predictable. A -3 myope would see worse than a -2.5 myope if both have
the same BCVA

 

Dear Ace man,

Subject: A dumb comparision.

Jan has been taught the box-camera
theory.

Therefore there can be no relationship
between refractive state and visual
acuity.

And of course, what Jan says is
true, the dead eye can have
a refractive state of zero, and
a visual acuity of infinity -- in
a dead person.

And of course he is 100 percent
correct.

Aceman you are a wacco for not
recognizing Jans genius.

Jan feels much better -- now that
he has put you in your "place".

But Ace-man, do you feel
better for Jan's imparted knowledge?

Remember -- the primate data
tells the truth about the dynamic
behavior of the living eye.

Otis

 

One simple question Robert, can you tell me what the refraction error should
be when I say the vision acuity is 0.5 or as you might say 20/40?
And please tell me myopic or hyperopic (or maybe emmetropic?) or astigmatic.

To make it simple, layman (aceotisace) in this NG think they simply can
convert vision acuity in diopters and vice versa, forgetting there is more
to say when you have to explain for instance a low vision in an emmetropic.

 

The above is placed because ace refuses to make clear to whom and on what he
is responding, a bad habbit of ace.

Blind is blind ace, even when accomodating.
Besides, accomodating and having an error in refraction of +10 diopters
means more error.
The example of mine (in the above) is myopic, not hypermetropic.

--
Free to Marcus Porcius Cato: ''Ceterum censeo Carthaginem esse delendam"

In conclusion, I think that the "Otis therapy" should be destroyed

Jan (normally Dutch spoken)

 

Indeed, among a lot other interresting subjects on photography by my father
who was an exellent amateur photographer.
BTW, an eye and a box-camera are not two off a kind TMHO.

You are an incorrigible old man Otis, misquoting must be lifetime habbit of
yours.
This is what I stated:

Wake up all nitwits, there is no excact conversion possible from diopters
into vision acuity
and vice versa, period.
There is a relation nothing more nothing less.

Keep these two in mind Otis.

Absolutly true Otis!

Almost, one person to go, gues who.


--
Free to Marcus Porcius Cato: ''Ceterum censeo Carthaginem esse delendam"

In conclusion, I think that the "Otis therapy" should be destroyed

Jan (normally Dutch spoken)

 

_If_ the error is purely myopic, it is approximately -0.1 diopter.
If it is something else, you will have to go fish. Statistics are
tools for those who know how and when to use 'em.

-- Robert

 

Just the answer I needed, statistics don't tell you what type of ametropia
exist and what would be the best vision acuity possible.
BTW, -0.1 diopters ( about 1/8 dioptr) should make the difference from
20/40 to 20/20 to a myopic with an average BCVA of 20/20?
I agree with your ''Statistics are tools for those who know how and when to
use 'em"

 

20/40 correlates most often to -1 diopters but your BCVA plays a huge
factor. Have a 20/40 BCVA and you could be plano or -.25 and 20/40.
Have 20/20 and your typically a -1. Diopters to 20/something values are
taken based on a 20/20 BCVA. I know this guy whos 20/40, corrected to
20/15 with -1.5 diopters. -1 diopters gets him to 20/20, but since his
eyes are capable of better, -1 is too weak for him. I have heard of
people with -2 to -2.5 diopters having 20/40 UCVA, corrected better
than 20/15 but its rare!

A blind person by our standards is 20/200 or worse BCVA. Many (legally)
blind people here do have some vision, but very poor, nonfunctional. I
knew this lady in person who was blind but she could see light,
darkness, shadows and the outline of large objects. She has light
perception(LP)

 

"I know this guy whos 20/40, corrected to
20/15 with -1.5 diopters. -1 diopters gets him to 20/20, but since his
eyes are capable of better, -1 is too weak for him. I have heard of
people with"

and one time, there was this guy at band camp...

 

"Remember -- the primate data
tells the truth about the dynamic
behavior of the living eye."

what does the HUMAN data tell about the behavior of the living human
eye Otis?
at the very least it tells everyone that otis the engineer is pissing
in the wind with his plus lens theory.

just because a theory of how the eye works (the "excess accommodation
causes myopia" theory) sounds good, and it "feels" like it must be
right, and it partially explains some of the data, does not mean that
therefore it must be right! when you test it in humans and it doesn't
pan out, then its back to the drawing board. not very objective of you
to hang onto something thats disproven now is it otis? not very
scientific of you is it otis? but alas i forgot-- otis is not a
scientist, he's an engineer!

go build something otis. or go play some shuffleboard.

 

Graag! Yes, there are many different ways to impair vision,
and myopia is only one.

This is what the correlation would imply. _HOWEVER_, it is
nothing but a correlation with error bands, and most likely
centered much higher, around -3-5D. I think most practitioners
would report somewhat more for 20/40, say between -0.5-1.0D

Thank you. Unfortunately, people frequently misuse
them with malica a-forethought. "Figures don't lie,
byt liars figure" [Mark Twain].

-- Robert