This video lecture describes the process of loose-lens retinoscopy from start to finish. You’ll learn the theory of how retinoscopy works to estimate glasses prescription, then run through 20 different patients with increasing complexity of astigmatism error. This is probably the best presentation on the internet to learn this difficult-to-learn skill:
SCREEN SHOTS FROM THIS VIDEO LECTURE:
(comments below)
Three Steps to Retinoscopy
1. Start with WITH motion
You need to the retina reflection to be “with” in all directions. If you see “against” motion in the beginning, you might need to hold up a -2.00, -4.00, or even a -10.00 lens in front of the eyes to get that “with” motion. Only then can you proceed without getting confused!!!
2. ADD power to neutralize reflex
Slowly add more power (plus power) until you neutralize the red-reflex. If you see “against” motion, you’ve gone too far. If the patient has astigmatism, you may get different powers for each axis … don’t worry. Just set the lenses aside so you can calculate the prescription later. Remember: the sphere power is your first lens, the cylinder power is the difference between the lenses. The axis is the angle your light beam ends up at (see example below)
3. SUBTRACT working distance at end
The last step is to subtract -1.50 from the sphere.
When the image is focused behind the retina, you see "with motion" as the reflection bounces off the retina.
When you use the perfect lens power, the reflection will be bright.
You add power until you neutralize the reflex. If you use too much power, like here, you see a "see-saw" movement of the light reflex. This is called "against" motion.
You subtract a working distance to compensate for your arm-length. For most people this is -1.50
Best explanation I have ever had on this topic, (I don’t know how many attempts I made to learn the retinoscopy in observing my prof)
thanks!!
Margherita Montali
p.s. only a question: can you determine accurately the axis with the retinoscopy?
I mean how can you be sure than what are you measuring, for example, in an axis of 60° instead of 70°? Because, I notice, in the prescription of glasses, normally the patient can appreciate a difference of 10°.
Comment by Dr. M. Montali — November 7, 2010 @ 8:32 pm
Thanks Dr. Montali,
In answer to your question … no, I can’t always tell the exact axis using retinoscopy, though we can often get close.
If I have an adult (who might notice these subtle axis issues) than I can usually get them up to the phoropter anyway. I start with my retinoscopy estimation, then using the phoropter I tweak my power and axis to the exact prescription.
In kids, I just do the best I can and trust my retinoscopy. I like to put my final prescription in a trial frame to make sure the kid likes it (if old enough). Good luck!
Thanks Dr. Root,
yes I see.
Can I take up your time once again?
When I was student (in Italy), my prof told me it was the best technique to measure the refractives troubles. Now I am in Switzerland, and I continue to be surprise they prefer do another kind of measuration: once obtained the cycloplegia they use the autorefratometer.
What do you think about?
Best,
Margherita M.
Comment by Dr. M. Montali — November 8, 2010 @ 10:08 am
The autorefractor is fine … we use it in our clinic prior to refracting new patients and children (if old enough). It gives a good place to start before manifest refraction with the phoropter. Plus, technicians can use the autorefractor with minimal training.
However, you can’t autorefract everyone … including young children, wheel-chair patients, or the demented. Also, the autorefractor is sometimes wrong or the machine refuses to take a good reading. In these cases, loose-lens refraction is the only way to go.
DR.ROOT
THANK FOR WONDERFUL EXPLANATION ABOUT RETINOSCOPY.AS OPHTHALOMOLGIST ETHIER WE DEPEND ON AUTOREF OR ON OPTOM ,BUT AFTER THIS AND WITH GOOD PRACTIVE WE ABLE TO GIVE CORRECT CORRECTION.
the video was good and simple to understand, however we at the moment in classess work, slightly different to whats on the video, for exmple, we choose the most positive value between the two values as a sphere, then we use a negative cycl to correct for the astigmatism with axis at the positive sphere. however in this video, what type of technique is being used in the video positive cycl form or negtative, as im getting the impression its positive cycl form.
for example: we have two different meridian powers
+4.00 axis90 and +2.00 axis 180
+4.00/-2.00/x90
subtract wrokin distance
+5.50/-2.00×90
thats how we work it out
Comment by waheed zaman — January 26, 2011 @ 2:03 pm
how do u select the the axis for spherical power from which the workin distance is subtracted in case of un-rule astigmatism? is it the first one whichever gives complete bright red reflex?
how do u select the the axis for spherical power from which the workin distance is subtracted in case of un-rule astigmatism? is it the first one whichever gives complete bright red reflex?
Thanks alot Dr. Tim. I’m an under grad and this video has become the standard study material for retinoscopy amongst all my friends. Have also seen all of your other videos. you made optha easy and interesting.
it was a very good demo.thank u so much.but i would like to know how u would do it in a keratoconus patient and how to appreciate oil drop reflex.
thank u
Brilliant lecture Dr Root. I think the best way to learn retinoscopy is using a practice model eye which you can make out of a toilet roll! Please contact me and I will send you some photos and more details.
Clive Novis (South Africa)
Comment by Clive Novis — September 7, 2011 @ 3:53 pm
could never have understood retinoscopy without this video..u’ve made it so understandabl that i’m so mch interested in smthn i earlier dreaded..
Today as i did retinoscopy fr d 1st time,i cn only thank u fr d knowledge u’ve given..Thank u so vry mch..lukn fwd to more of sch videos..obliged to b ur student..
al d best!!
Comment by Tulika Gupta — September 12, 2011 @ 3:23 pm
you are making difference to many people thank you very much i am from Egypt and i have learned a lot thank you again .
Comment by mohmedfawzy — October 24, 2011 @ 5:40 pm
iam an optometrist , i was see the vidoeo really iam fine . this teaching is not neglect in my life . thank u
