Retinoscopy Lecture (Video)

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:


Retinoscopy.m4v (195mb)

ScreenShots/Notes from this Lecture:

Three Steps to Retinoscopy
Three Steps to Retinoscopy

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.

Retinoscopy With Motion
When the image is focused behind the retina, you see “with motion” as the reflection bounces off the retina.
Retinoscopy Reflex
When you use the perfect lens power, the reflection will be bright.
retinopathy - against motion
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.
retinoscopy working distance
You subtract a working distance to compensate for your arm-length. For most people this is -1.50
retinoscopy calculation
The Final Prescription: -2.50 + 5.00 at 045
Dr. Timothy Root is a practicing ophthalmologist and cataract surgeon in Daytona Beach, Florida. His books, video lectures, and training resources can be found at:


  1. 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)

    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°.

  2. 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!

    -Tim Root

  3. 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?
    Margherita M.

  4. 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.

  5. Brilliant approach, thanks so much. You are really making a difference in the ophthalmic education of many people across the world.

  6. DR.ROOT

  7. 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


    subtract wrokin distance
    thats how we work it out


    a small query. wud b kind of u if u cud reply…

    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?


    a small query. wud b kind of u if u cud reply…

    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?

  10. 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.

  11. How do I get the audio portion to work? Am I required to purchase a video? Can I just buy a download?


    Lynn S

  12. 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

  13. 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)

  14. 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!!

  15. hello doctor,

    Greetings from India. Thanks for the exhaustive explanation. very easy to understand ‘FINALLY’ .i will be looking forward to see many of your videos and lectures.
    Thank you

  16. hello doctor,

    Greetings from India. Thanks for the exhaustive explanation. very easy to understand ‘FINALLY’ .i will be looking forward to see many of your videos and lectures.
    Thank you

  17. hello..i have questions:
    how the distance between instrument and patient’s eye?
    what object seen by patient? & how the distance?
    the the last one how if i want to use minus cylinder, any different method?

  18. I,m a beginner from srilanka.i,m interesting about your explanation and need to be a professional in the trade and want some more information about retinoscopy.

  19. excellent lecture i am passing on this site to my fellow techs. I have switched from a + cyl phoropter to – cyl, how do i find the astigmatic power now?

    thank you

    Rodney in Boston

  20. Dear Dr. Root.

    You said the word “ALONG”the meridian right? so you need to convert it to ÄXIS” so if its along 90 or @ 90 and the AXIS would be 180? am I right? I’m sorry but I’m a little bit confused, as according to the book, they use the term “@”or ÄLONG” then should convert it to axis.

    Hoping for a quick respond regarding on this matter.

    Best Regards,


  21. Mark,
    In this video … I am using the “@” sign to mean “at.” In retrospect, perhaps I should have used the more traditional “x” sign or just spelled out “at” but I didn’t.

    I wouldn’t focus on the words ALONG or AT if I were you. As long as you remember that power and axis are 90 degrees from each other, you should be ok.

    Tim Root

  22. Hello Dr Root,

    Thank you so much for your AMAZING videos! They really help understand concepts from our ophthalmic technician training course!

    My doctor prefers minus cylinder, do you have instructions for doing retinoscopy in minus cylinder?


  23. Marissa,
    Most optometrists work in minus cylinder (which is fine). I’m not used to working in minus cylinder, however, so I don’t plan on making a minus video instruction (these videos take forever to put together). Thanks!

  24. Dear Dr. Root,

    Ive always believed reading up from a textbook is entirely different from whats to be practised, which is why I kept forgetting most of the things I read up prior to applying it in real life. Here, your lecture on something this interesting is as close as I could get to a practical experience. I hope to take it forward and learn the most from the foundation you’ve helped me ascertain. Thank you very much.

    Akansha Sinha.

  25. Their vidz help me a lot for understanding many things obout ohpthalmology a speciallity that soon i want to doit.. thanks ..greeting from panama!!!

  26. Thank you very much doctor. After long time I understood how to do Retinoscopy. This video is very helpful to many Optometrist. Hope to see more of your lectures. Thank you!

  27. Excellent. Concise and positive!

    We have a preference for starting with a working distance +1.50, neutralising the most with and then using -ve cyls. The rationale being that it minimises the probability of under-plussing due to the Px (particularly children) accommodating.

    …a great lecture and the visuals make this method totally clear.

    Thank you.

  28. Brilliant Dr Root

    If you work in minus cilinder, jose, you must do the same process.

    You can use the second lens to obtain the sphere value(please, don’t forget to substrat 1.50)

    The difference between the fist and the second lens is the cylinder. Is always the same absolute value.

    And the axis: you can determinate the value
    adding or substracting 90
    or using the first lens, not the second lens for test the axis

    Other way?,…. you can use the Optician tips for convert positive cilinder in negative cylinder.

    I’m sorry. I’m spanish and my English is not fluent enough, jose, but if you can speak my language, I could explain it with more detail.

    Gerardo Bellas Spain

  29. I’ve attempted for several years to learn retinoscopy. I’ve even had a workshop where I thought I finally understood the with and against, however that and no other means of learning ever stuck. It felt like learning calculus … having to memorize complex formulas to apply every step of the way. This is the first explanation/demonstration that flipped the switch on … and it be brightly lit rather than a flickering dimmer bulb that even moths weren’t attracted to. It finally makes complete sense. Sense enough that I’m wondering why it was so hard for me to get before. Thanks so much for putting this together! I’m taking my COT in 5 days and this was the last thing for me to learn … the only thing that has been holding me back for years!

  30. Hi Dr,

    Firstly excellent video.
    2ndly, what do u mean by writing down the
    rx as “at [axis in degrees]”?

    Is it the same as “X [axis in degrees]”

    for example +0.50 +1.00 at 90 = +0.50 +1.00 X 90 ?

    Thanks and keep up the awesome vids.

  31. hello dr root
    some one ask me why we substract sphere only after doing retinoscope
    will you please give me the correct answer i should reply to the the person

  32. I just recently did a COT practical exam (computer simulated) and part of the exam was various instructions that you would give to the patients prior to retinoscope and refraction?

    1)Is telling the patient to keep both eyes open during retinoscope and refraction a required instruction? I figure since they are behind the phoropter naturally the eye not being looked at the moment would be occluded anyway, since one eye is always retinoscope and refracted first at a time. When one eye is done you go on to the other one and occluded the eye not being looked at. Am I right?

    2) Is telling patient to keep both teeth together reguired during retinoscope and refraction?

  33. sir this is very supportive lecture i learned more from this weakness is on astigmatism that is when i do retinoscopy on oblique case i get confuse to determine the actual axis so. can u plz add more videos for astigmatisam.plz add more videos for how to use jackson cross cylinder to find out the axis of prescription glasses .

  34. thanks,sir
    for the wonderful class,iam a resident from india.any videos regarding indirect ophthalmoscope ,perimetry, ffa kindly post it sir

  35. Hi Dr Root,
    Would the prescription of practitioner affect the working distance?
    I am with +1.50. If my working distance is 67cm, will there be any effect?

  36. When correcting the astigmatism (2nd Axis) in your example, are you using spherical lenses, or, cylindrical lenses placed at the axis of the direction of light?

  37. Dear Dr Root,

    I’m a french student in Optometry who’s trying to grow up his comprehension in Ophtalmology.
    First of all I would like to thank you for the great and really complete job you made which is helping me a lot in my studies. (Website and book)
    I have one question remaining about this topic : I was wondering if starting with “against” reflects in both axis couldn’t be better for inhibate the subject’s accommodation and find the most convex prescription than starting with “with” reflect. Can you help me to make the good choice with your experience ?

    Thanks again for all your helpfull work all around the world.
    Vincent Carpentier

  38. Oh, such a brilliant explanation!!! Thank you so much!!!
    I had a problem to find something similar in russian language, but was lucky to find yours.

  39. Give more examples for this, like -ve sphere & -ve sphere,-ve sphere &+ve sphere,low -ve & high +ve,high -ve & low +ve sphere s

  40. thank u so much Dr. Root for this Amazing video.
    i just wanna ask a question that in which cases we can find scissor reflex other than keratoconus?

  41. HI,
    I love your lecture. Just curious when working with a phoropter do we still take the difference of the sphere and cyl power to come up with the final cyl. power or do you document the cyl. that shows on the phoropter when working with (+) cyl.


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