Statement of a "concerned" Parent of 3 year-old:

I have posted several threads about my 3 year old on this site(-10.5
but sees
20/60 without glasses). My question is that a year ago when I brought
my
daughter in to the pediatric opthalmologist he originally had her
perscription at -12.50 each eye. He gave her a lighter perscription to
start
out with though(-10.00). About 3 months later she was -11.50 each eye.
About
3 months later he had her at about -11.00 each eye. Then about 3 months
later
he had her at -10.50 each eye. Just recently when she went back she was
-10.
25 in one eye and -10.00 in the other. The astigmatism has been about
the
same for all perscriptions. I was not at the last visit and would have
asked
him why its going down. I am not posting this in ANYWAY to start any
controversy. We have not been doing ANY sort of vision therapy or
trying to
improve her vision in anyway, shape, or form. I was wondering if it
made any
difference that she has lenticular myopia or if because she is young
maybe
her lens could be changing still.

Signed,

A concerned parent

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,

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
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?