Annual Eye Test

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Simon Dean - 04 Dec 2007 00:17 GMT

Just been to the optician for annual eye test.

Slight astigmatism, but the other major component between short/long
sightedness (Cylinder?) has returned to plano.

Ok.

I explained though how I was a little bewildered about a few years back
how I had a pair of slight glasses made up for the slight
longsightedness and slight astigmatism and how they made everything
incredibly sharp.

He suggested glasses will do that, and there is a danger of over
pre-scribing as it creates an artificial contrast which can cause eye
strain, and therefore perhaps the problems I experienced last year or so
with regards to problems looking at a piece of paper and feeling like
the text is jumping off the paper at me.

I left fairly happy with that explanation, makes sense, and yes, perhaps
those eye issues were related to when I got the glasses made up.

Obviously the question is, how can you make sure you're slightly
undercorrected to avoid this "artificial contrast" of which he describes?

Cheers
Simon

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Mike Tyner - 04 Dec 2007 06:56 GMT

> Obviously the question is, how can you make sure you're slightly
> undercorrected to avoid this "artificial contrast" of which he describes?

The symptoms and the management are different for specific refractions (and
ages). In any case, if he was discussing it, he was probably checking for
it.

"Too bright" and "contrast" usually mean you're accommodating more than
necessary, or more than you're used to. It isn't always a problem. When it
exceeds capacity, you get tired, blurry, or double, or achey.

I avoid it by assuring that one step more plus, or less minus, creates blur
at 20 feet. That should be enough, except that the answers can be different
in dim vs bright, one eye vs two, farsighted or nearsighted, morning or
evening, tense vs relaxed, young vs old, or one doc vs another.

The best test, once you have the glasses on, is a +0.25 hand-held lens. If
it doesn't make roadsigns blurry, then something is off. But be sure it's
"off" under all conditions, and be sure there are symptoms before asking for
remakes.

Most young people reflexively accommodate a little more than required, and
all semivoluntary autonomic reflexes vary by nature. What's precisely
"right" in your glasses is based on subjective comfort, catering to your
reflexes, rather than conforming to a static anatomical snapshot. With
presbyopia, most of the variability disappears.

-MT

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Simon Dean - 04 Dec 2007 22:55 GMT

>> Obviously the question is, how can you make sure you're slightly
>> undercorrected to avoid this "artificial contrast" of which he describes?
[quoted text clipped - 6 lines]
> necessary, or more than you're used to. It isn't always a problem. When it
> exceeds capacity, you get tired, blurry, or double, or achey.

So just to fill you in, to avoid any ambiguity... three years ago ish, I
went to my optician and had my usual excellent eye exam, with marginal
long sightedness and marginal astigmatism:

Right +0.50 Sph, -0.75 Cyl, 135 Axis
Left +0.75 Sph, -0.50 Cyl, 35 Axis

I suffer constantly from the tired, blurry, achey eyes that you speak
of, so thought it might be a great idea to see about getting some
glasses made up to see what things would be like.

Sure enough, things were incredible. Text was sharp, crystal clear, I
felt like I had less eye strain and things were great. Grey text was
black everything wonderful. But distance vision in those glasses was non
existant.

So, as you know, six months, to a year after having these glasses, I
started experiencing my odd effects of text jumping off a page at me,
disorientated reading etc and that's when I went to the eye clinic and
had all the electrical tests and MRI's done for the doc just to tell me
he can't find anything wrong but suggested a light sensitivity and
recommended comfort 41 lenses (that I gather, is a rather old idea and
is perhaps surpassed by the rather expensive Meares Irlen approach?).

Constantly over the past four years or so, I'd also say I believe that I
have various contrast issues. Various objects around me appear dull and
lifeless and a pair of sunglasses really make things come alive.

So my recent eye test, all I have now is very slight astigmatism again.
The optician only ran the standard tests, but we did talk about eye
strain, and I discussed about why a pair of glasses to counter those
previous "mild" results from a few years back, would give such amazing
results.

And he was almost suggesting that far from returning my vision to
"normal", that they'd be creating an almost artificial contrast and
thereby stressing my eyes out more than needs to be and therefore
possibly creating those odd vision issues I experienced. He was almost
suggesting a bit of blurriness is normal, and pristine sharp vision isn't.

> I avoid it by assuring that one step more plus, or less minus, creates blur
> at 20 feet. That should be enough, except that the answers can be different
> in dim vs bright, one eye vs two, farsighted or nearsighted, morning or
> evening, tense vs relaxed, young vs old, or one doc vs another.

This is where I get confused. You seem to be suggesting that adding a
little but more plus (in my case) will reduce eye strain, though my
optician was suggesting that the contrast generated by too much can
cause problems.

> The best test, once you have the glasses on, is a +0.25 hand-held lens. If
> it doesn't make roadsigns blurry, then something is off. But be sure it's
[quoted text clipped - 6 lines]
> reflexes, rather than conforming to a static anatomical snapshot. With
> presbyopia, most of the variability disappears.

That's over the top of my head :-)

Cya
Simon

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Mike Tyner - 04 Dec 2007 23:41 GMT

> This is where I get confused. You seem to be suggesting that adding a
> little but more plus (in my case) will reduce eye strain, though my
> optician was suggesting that the contrast generated by too much can cause
> problems.

Too much plus creates blur at distance, for most people. Others are used to
providing some of their own "plus" (tonic accommodation) and trying to move
that correction into glasses only screws up the balance between
accommodation and convergence, typically causing headache or double vision.

But the symptoms are so variable and individualized that it's very hard to
give you any significant answers without having you in my exam room. Even
then, I'm not sure I could have offered any better explanation. I hate it
when they reach into the twilight zone for answers.

-MT

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