Re: Can difference in vision be explained?

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Re: Can difference in vision be explained?

Neil Brooks	29 Dec 2006 20:05
> On 12/29/06 7:41 AM, in article > 1167406898.484719.25500@i12g2000cwa.googlegroups.com, "otisbrown@pa.net" [quoted text clipped - 4 lines] > > How can you even rely upon a 2 year-old to read a Snellen chart correctly? His mind is made up. Please do not try to confuse him with logic or facts. His head could explode....

Salmon Egg	29 Dec 2006 19:10
On 12/29/06 7:41 AM, in article 1167406898.484719.25500@i12g2000cwa.googlegroups.com, "otisbrown@pa.net" > For instance, one 2 year-old had a Snellen of > 20/60 -- which is functional for a child of that age -- and > a retinoscope/cycloplegic of -11 diopters. How can you even rely upon a 2 year-old to read a Snellen chart correctly? Bill -- Fermez le Bush

otisbrown@pa.net

29 Dec 2006 15:41

Dear Katy,

I would also add, that sometimes the difference between
Snellen and Retinoscope/cycloplegic can be profound.

For instance, one 2 year-old had a Snellen of
20/60 -- which is functional for a child of that age -- and
a retinoscope/cycloplegic of -11 diopters.

So what do you do? Tell the mother that 20/60 is
OK for now, or "prescribe" based on the retinoscope/cycloplegic.

For the case in question, the child is now wearing a -10 dioper
lens all the time.

Obviously there is a majority and second opinion on this
subject.

Just one man's opinion.

Best,

Otis

> Dear Katy,
>
[quoted text clipped - 44 lines]
> > Message posted via MedKB.com
> > http://www.medkb.com/Uwe/Forums.aspx/vision/200612/1

otisbrown@pa.net

29 Dec 2006 15:34

Dear Katy,

In fact there are two DIFFERENT methods of judging
a person's refractive STATE.

1. Use a Snellen and a trial lens kit. (The so-called
"subjective" measurement). In this method you
have the person read the snellen at say 20/50. You
then use stronger minus lenses until the 20/20
line is cleared, with say a -3/4 diopter lens.)

2. Measure with a retinoscope/cycloplegic (drops),
and determine a person's refractive STATE.

These two methods often do not agree -- and
can be profoundly different.

In fact it is possible to have 20/20 and a reafractive
STATE (cycloplegic) of -3/4 diopters.

This my explain some of the difference between
your refractive measurement and your current
visual acuity.

It is also true as suggested by the ODs on
sci.med.vision, that as you get older your
refractive STATE will change in a positive
direction, and your Snellen will clear.

That might also explain why you can
get along with no minus lens.

Obviously, opinions vary concerning your
distant visual acuity.

Best,

Otis

> Is there a scientific explanation for why two people with the same
> prescription appear to have different levels of vision? For example, I've
[quoted text clipped - 5 lines]
> Message posted via MedKB.com
> http://www.medkb.com/Uwe/Forums.aspx/vision/200612/1

katy	29 Dec 2006 07:22
Is there a scientific explanation for why two people with the same prescription appear to have different levels of vision? For example, I've read somewhere that two people who are -3 won't necessarily see the same without glasses, one might see better/worse than the other. What factors influence this?

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