- Hello and welcome to our ninth and final installment
of Let's Learn How to Use the Lensmeter.
Today, we're going to talk about using it to neutralize
a pair of glasses.
What does that mean?
That means when somebody hands you a pair,
and you have absolutely no idea what's in them.
(rock ballad)
In your kit, this is going to be considered Lensmeter kit
number eight.
However, what it does is it reuses the complete pair
from kit number three.
So dig around in your box, Find kit number three,
make sure that you've got the three etched on the lens,
make sure you got the right frame and the right bag.
The other things that I want you to have at hand
are some scrap paper and a pen.
I can guarantee you with one hundred percent certainty
that this is going to happen to you
on a fairly regular basis as a working optician.
Somebody's gonna come up to you,
give you a complete pair of glasses and say,
"I need to know what's in here."
There are a few steps, we're not going to get
into the nitty gritty 'cause this is really
about the lensmeter, but there are a couple
of steps that you need to do
before you go jumping right in and trying
to determine the prescription that's in there.
You know, just kinda look at the glasses both ways,
upside-down, sideways.
You may pick up some telltale signs
as you develop your skill set
that tell you some things that'll be helpful.
Another is make sure that they're
in some kind of standard alignment.
I go over standard alignment in great detail
on the OpticianWorks website.
If they were sat on, bent,
that's the reason the person's there getting
a new pair of glasses.
You can't read them if they're bent
and twisted and crossed and one lens is like this.
They have to be almost perfect
to what the person was wearing
in order to read it correctly,
so pay attention to that, too.
Another one, which lens style is it?
If it's a single vision, you're good to go.
Lined bifocal, if the bifocal segments are level,
you're good to go.
If it is a progressive lens, you've gotta mark up the lens
using the lens-appropriate chart before you can go
to the Lensmeter and figure out what it is
that you have in there.
Last, but not least,
I know you don't readjust the Lensmeter
for individual use every time you go near the thing.
When you're handed a pair of glasses for neutralization,
make sure you take that step.
Take that minute.
Refocus it to zero for you before you go trying to
read that prescription.
After that, guys, really it's just kind of the
Lensmeter waltz.
Just right lens, right lens, right lens, rest
it against the lens stop, turn it on, get it
comfortable, get things lined up in there,
turn your axis wheel, turn your drum,
do whatever you need, move things around,
move your chrome knurled sleeve if you need to,
get yourself a good set of closed sphere lines, good.
Now, here is another place where you have to
be sure you're reading in the correct cylinder form.
We've been working on the assumption all along that
you're working in minus cylinder form, so if
you have sphere lines, turn your power drum
away from you and make sure you can get closed
cylinder lines.
In this instance, I can't, so I have to back up,
get my sphere lines, rotate my axis wheel
until I get closed cylinder lines, now my sphere
lines are there, I turn my drum in a minus
direction and get cylinder lines.
I've got good, beautiful, sharp sphere lines, good.
And, I'm gonna take my readers here, and I have got
a minus 225, so I'm gonna write that down,
and I'm gonna put my R here as well, make
sure I keep things straight as I write this,
And, I've got an axis of exactly 130,
and let me get my cylinder lines in focus.
Alright, and now I'm at 325, so I went from
225, that's one, two, three, four, so I got
a cylinder value of minus one.
So, my right lens is a minus 225, minus one at 130.
And, I'm lined up well, my reticle, so I can
dot that one, go from my right to my left,
get things centered up, and I'm gonna just do
the waltz all over again.
I'm gonna turn my power drum 'till I get some
sphere line, move my axis wheel around, make
sure that I can get...
I can't again, so I'm 90 degrees off, spin my
axis wheel until I get beautiful sphere lines,
rotate my power drum in a minus direction
so I have cylinder lines, and what have we got here,
we've got a left is a plus 150
at 48 degrees,
and cylinder is good I went from plus 150 to minus one,
that's one, that's 250,
so my left is a plus 150, minus 250 at 48.
That is what I read, that is what I see
in this particular pair of glasses.
Everything's lined up in the reticle,
I could mark it, I could double-check my PD,
monocular PDs, height, everything else that
I needed from there.
Again, practice, and don't forget, there is a certain
level of subjective measure here.
You may not be perfect, it's a manual instrument.
If you're split between quarter diopter steps,
you do it again, you're caught between quarter
diopter steps, you are gonna have to make the call
whether you go up or down.
Somewhat of a rule, over minus under plus, that's
really, again, kind of a subjective thing.
Get yourself some pairs, pull them out of the
donation box, whatever it might be, and just
practice your neutralization techniques.
Single vision as they are, line bifocals as they are,
progressives, you must mark them up using the
appropriate chart before you jump to the Lensmeter.
That kind of wraps up our introduction to
Learn How to Use the Lensmeter, thank you for watching
these, if you like this stuff, by all means,
be sure to check us out on the YouTube channel,
and, of course, there's always the OpticianWorks
website, and me an e-mail away.
I will see you next week with something new
and perhaps even a little bit more exciting
than what we've been doing.
Thanks.