How to perform retinoscopy

-- deleted messages --

-- deleted messages --

-- deleted messages --

-- deleted messages --

-- deleted messages --

-- deleted messages --

Re: How to perform retinoscopy

On Thu, 1 May 2008 21:55:28 -0700 (PDT), douglas <Protoman2050@gmail,com >
wrote in
<news:c16a62fb-75de-470d-b9e5-9fe4bade665d@a9g2000prl.googlegroups,com >:

> Please tell me you mean that sarcastically...I'm not Einstein by any
> stretch of the imagination. I'm just an obsessive planner. My Dr-
> friend, Dr Sleiman, says I'll probably invent some revolutionary
> medical device or treatment...well, maybe, maybe not. I absolutely
> hate it when people are overconfident in my abilities..,it 's like
> reverse arrogance.

Not to mention more than a little scary!

--
- Nic.

Re: How to perform retinoscopy

Zetsu wrote:
>Well, I am a local from the UK, and from my personal and experiential
>perspective, 'Mister' is a lot less prestiguous sounding than
>'Doctor'! But then we have other titles that are really high up, like
>'Sir', or 'Lord', or 'Your Highness'. OK, I made the last one up.
>Anyway, I doubt there's a lot of difference between here and the US. I
>mean, it's us Brits who discovered your land in the first place isn't
>it? Oh well, I can't remember (not a good historian).

"Us Brits"? My recollection is that you are actually a Norwegian girl with a
Japanese name who lives now in the UK. Oh well, what's the heck...

--
MsBrainy

Message posted via MedKB,com
http :// www .medkb,com /Uwe/Forums.aspx/vision/200805/1

Re: How to perform retinoscopy

On 2 May, 06:55, "MsBrainy via MedKB,com " <u33689@uwe> wrote:
> Zetsu wrote:
> >Well, I am a local from the UK, and from my personal and experiential
> >perspective, 'Mister' is a lot less prestiguous sounding than
> >'Doctor'! But then we have other titles that are really high up, like
> >'Sir', or 'Lord', or 'Your Highness'. OK, I made the last one up.
> >Anyway, I doubt there's a lot of difference between here and the US. I
> >mean, it's us Brits who discovered your land in the first place isn't
> >it? Oh well, I can't remember (not a good historian).
>
> "Us Brits"? My recollection is that you are actually a Norwegian girl with a
> Japanese name who lives now in the UK. Oh well, what's the heck...

As a citizen of the UK, I am privileged with the respectful title of
'Brit'!
Just like you can call yourself 'American' even if you are from
Portugal, because you live in the US. Well, that's how I thought it
works!

Who is Zetsu

In article <8389354a0078e@uwe>, "MsBrainy via MedKB,com " <u33689@uwe>
wrote:

> "Us Brits"? My recollection is that you are actually a Norwegian girl with a
> Japanese name who lives now in the UK. Oh well, what's the heck...

For those who don't know, Zetsu is a villainous giant (cannibalistic)
man-eating venus flytrap from the manga series "Naruto." Zetsu can merge
with objects and travel to many locations. He has a split personality
(represented by a black side and a white side) and often argues with
himself.

In this respect, the Zetsu on this list is surprisingly in character.
Do a google images search of "Zetsu Naruto" and you can see what our
resident venus flytrap looks like. Puts his posts in clearer perspective.

--
~RT

Re: Who is Zetsu

This is an exceptionally qood question to ask on Mother's Day.

Don W.

Re: How to perform retinoscopy

On May 1, 7:14 pm, douglas <Protoman2...@gmail,com > wrote:
> On May 1, 3:31 pm, otisbr...@embarqmail,com wrote:
>
>
>
>
>
> > Dear Doug,
>
> > Subject:  Best Visual Acuity -- METHOD
>
> > This is the standard that is preferred by most ODs.
>
> > Using a trial lens kit (or Phoropter), and a minus lens -- you do the
> > following.
>
> > Have the person read the Snellen.  OK, 20/70
>
> > Now you place a weak minus lens in your trial-lens frame, of -1
> > diopter.
>
> > 20/30, OK
>
> > You then increase the power (asking 1 or 2 better) until you get the
> > sharpest
> > vision possible.
>
> > 20/20.  OK with a -1.5 diopter lens.
>
> > Now let is see if we can do better.  Using a cyl lens, you rotate the
> > lens
> > from zero to 90 degrees, looking for that to sharpen the image.
>
> > So you get to 20/15 for that person.
>
> > You think write the prescription for the Spherical and Cyl and angle.
>
> > Enjoy,
>
> > On May 1, 3:18 pm, douglas <Protoman2...@gmail,com > wrote:
>
> > > On May 1, 9:21 am, "Mike Tyner" <mty...@mindspring,com > wrote:
>
> > > > "douglas" <Protoman2...@gmail,com > wrote
>
> > > > > OK, I know how to check the base refractive error, but how do you
> > > > > check for astigmatism? I know the retinoscope has a protractor on it,
>
> > > > You don't see protractor markings on modern retinoscopes. The markings are
> > > > on the phoropter.
>
> > > > > I'm pretty sure you use it just for that, but...how?
>
> > > > Once you get a good reflex, you rotate the streak and sweep it in different
> > > > directions across the pupil. Many times it's obvious that the streak
> > > > neutralizes in one meridian (say, sweeping side-to-side) yet it's way off
> > > > 90 degrees away, when you sweep up-and-down. That's astigmatism, and the
> > > > trick is to determine the maximum and minimum meridians.
>
> > > > > If you did both a static cycloplegic and a dynamic non-cycloplegic
>
> > > > Dynamic retinoscopy isn't useful for determining refractive error. Many
> > > > doctors never use dynamic and have forgotten how, because it's only valuable
> > > > for determining accommodative response and there are other ways to do that.
> > > > A few years ago the "Prio system" was pushed out, basically an LCD nearpoint
> > > > card with a hole it it, thru which you could do dynamic retinoscopy. It was
> > > > gimmicky ("computer vision") and seldom indicated any unique sort of
> > > > treatment, but you were obligated to prescripe Prio lenses from it. It
> > > > wasn't that much better than a plastic nearpoint card with the same hole.
>
> > > > Retinoscopy is a dying art. Most retinoscopy used to be done to gain a
> > > > starting point for subjective refraction, an estimate. Many doctors now use
> > > > autorefractors for that, and consequently never pick up a retinoscope. I
> > > > wouldn't either, except sometimes I get ahead of my staff and patients
> > > > haven't had the autorefraction done yet.
>
> > > > Cycloplegic retinoscopy may be used to help determine latent hyperopia but
> > > > dry (non-cyclo) ret is often a good indicator of LH, revealing results that
> > > > are a half- or full diopter more plus than the patient's chosen subjective.
>
> > > > > Who makes good retinoscopes? Keeler?
>
> > > > Copeland and Welch-Allyn. Don't know the Keeler.
>
> > > > > And what's the diff b/w a
> > > > > retinoscope and an ophthalmoscope?
>
> > > > BIG diff. A ret just generates a streak of light. The streak can be focused
> > > > but it's designed to focus an image of the filament (the streak) to the
> > > > retina, such that you can see it moving in the pupil.
>
> > > > Ophthalmoscopes are illuminated too, but more important they have an
> > > > observation system that lets you see the details of what you're
> > > > illuminating. Direct and indirect o'scopes both produce an image of the
> > > > retina. In direct scopes, the image is upright and magnified. Indirect
> > > > scopes produce upside-down images that are wider-field (less detailed, not
> > > > as magnified.)
>
> > > > > Can you use a indirect
> > > > > ophthalmoscope for retinoscopy?
>
> > > > Not very well, I'm not sure it could be done because retinoscopes all focus
> > > > the streak in different planes. The ophthalmoscope generates only parallel
> > > > light for illumination.
>
> > > > >And has any beginning optometry student accidently held the
> > > > > retinoscope backwards, and temporarily blinded themselves?
>
> > > > Oh sure. Ophthalmoscopes are much brighter.  But with all hand-held scopes,
> > > > it's habit to turn it on, then shine it somewhere like your hand or the
> > > > wall, to make sure it's working. Putting it to your eye backwards is dumb
> > > > but even dumber is getting up in your patient's face then finding the scope
> > > > is dead.
>
> > > > -MT
>
> > > But I'm sure you could use a direct ophthalmoscope for retinoscopy, if
> > > you lacked a retnoscope, would the procedure be any different for
> > > using an ophthalmoscope for static retinoscopy? Which provides better
> > > bva, cyclo, or non-cyclo?- Hide quoted text -
>
> > > - Show quoted text -- Hide quoted text -
>
> > - Show quoted text -
>
> That's subjectively. And, according to House, patients lie. So, how do
> we use retinoscopy to *objectively* determine our patient's refractive
> error? I believe its as follows:
>
> Dim the lights, instill cyclopentolate into the patient's eyes, and
> have them look at at a target at optical infinity. You stand 67cm away
> from the patient, and set the phoropter to -1.50D --please explain to
> me exactly why this is done?

You don't set it to -1.50 at the beginning. After you are finished
doing retinoscopy you add -1.50 to the result (if you are standing
67cm from the patient). This is because the patient is looking at the
chart 6 metres away and you are standing 67cm away. That creates a
+1.50 error in the measurement.


To set the effective curvature to zero,
> perhaps? And I know that -1.50D is the reciprical of 67cm--, and move
> the retinoscope across the pupil. If you see with-motion, add plus
> lenses; against-motion, add minus lenses. Stop when the pupil fills w/
> light, and there's no motion. Rinse and repeat for all meridians.
> Rinse and repeat for the other eye. Subtract -1.50D from the readings
> to get the prescription.
>
> How would you use the autorefractor to find an inital starting point
> for the static retinoscopy?-

An autorefractor is a substitute for retinoscopy. Both provide a
starting point for subjective refraction.
To use an auto refractor you line up the patients pupils with the
cross hairs and push the button.

Judy


Hide quoted text -
>
> - Show quoted text -

Re: How to perform retinoscopy


>Dim the lights, instill cyclopentolate into the patient's eyes, and
>have them look at at a target at optical infinity.

I seldom use cyclopentolate.

> You stand 67cm away
>from the patient, and set the phoropter to -1.50D --please explain to
>me exactly why this is done? To set the effective curvature to zero,
> perhaps?

Yes. You need to focus the streak on the retina while the eye is at rest. To
do this, you can stand at 20 feet away, or you can simulate infinity by
placing a +1.50 lens in front of the eye and holding your light at 67 cm. In
either case, the result is parallel light striking the eye.

> Subtract -1.50D from the readings
> to get the prescription.

+1.50 not -1.50

> How would you use the autorefractor to find an inital starting point
> for the static retinoscopy?

You wouldn't. You'd use retinoscopy or the autorefractor as an initial
starting point for subjective refraction. There's little benefit in doing
both ret and AR.

-MT

Re: How to perform retinoscopy

On May 1, 3:18 pm, douglas <Protoman2...@gmail,com > wrote:
> MT
>
> But I'm sure you could use a direct ophthalmoscope for retinoscopy, if
> you lacked a retnoscope, would the procedure be any different for
> using an ophthalmoscope for static retinoscopy? Which provides better
> bva, cyclo, or non-cyclo?

It's almost impossible to use a DO for ret; I've tried once or twice
while doing community screenings.

Best Visual Acuity is not related very well to cyclo or non cyclo. It
is a function of the eye, not the measurement system.

Judy

Re: How to perform retinoscopy


"douglas" <Protoman2050@gmail,com > wrote

>But I'm sure you could use a direct ophthalmoscope for retinoscopy, if
>you lacked a retnoscope, would the procedure be any different for
>using an ophthalmoscope for static retinoscopy?

The ophthalmoscope lacks any optics to focus the beam. I don't think I could
do ret with parallel light.
Your mileage may vary.

>Which provides better
>bva, cyclo, or non-cyclo?

"BVA" is a term usually applied to subjective refraction. Which ret techique
comes closer to the subjective refraction? Probably dry (non-cyclo.)

-MT