How Opticians Use Lenses To Correct Refractive Errors

This week we look at how opticians use optical lenses to correct the refractive errors of the human eye. In part 3 of our series, we show simple lens shapes in front of the eye and how they redirect light to correct vision. Optician training includes an understanding of lens design and the refractive errors. We cover the topics of plus lenses, minus lenses, lenses that correct astigmatism and presbyopia.
Learn More: opticianworks.com/
Connect with us:
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This video lesson is sponsored by Laramy-K Optical
Laramy-K Optical is a digital uncut and coating lab unlike any other. The only exclusively uncut lab in the country; we provide our customers with independent, high-end alternatives to corporate brands. Through craftsmanship, technology, and independent, innovative vendors like Younger, IOT, A&R, and Quantum Innovations we offer our customers the Integrity portfolio of freeform lenses and coatings. Made in the USA, the Integrity brand is not a generic house-brand, but is the absolute best available, designed to give the wearer that “wow!” experience.
In addition to the digital line, we still offer conventional surfacing, including glass. Maintaining traditional equipment gives our customers vastly more flexibility in their dispensing, particularly when it comes to more difficult prescriptions.
Learn More: www.laramyk.com

[@alyssabarroga6518]

I’m a medical student and I’ve been struggling for years to understand these concepts, you explained them so effortlessly and comprehensively!

[@teresabrunson2528]

I am a 60 year old new optician. I love your videos for their information and entertainment. They help me with my customers, help me verify lenses, help me to understand and tell people about their refractive errors and how we can help them. I work for one of the largest (top 3) optical stores in the US. People who come to get glasses in our store are often unsure why they can't see and what we are doing to 'fix it'. They enter the store clutching a bit of paper with numbers they do not comprehend. Your diagrams help me to help them to understand. I love explaining to a little 5 year old boy why he can see better with his glasses or to a lovely 40 year old woman why she might like to have a bifocal or progressive lens. No greater joy than when the patient puts the lenses in front of their eyes and says, "I can see!" First time wearers bring tears to my eyes, as little baby fists try to push the glasses away, but then realize that they can suddenly see. The first thing they do is turn to their mother's face. No greater moment. Thank you.

[@LaramyKOptical]

Wow Teresa! Thanks for the note. Don't miss the actual OpticianWorks program. Plenty more to learn over there. John www.OpticianWorks.com.

[@teresabrunson2528]

@@LaramyKOptical I am doing it. I talked to your recently. So excited for the program!

[@monicaosorio9564]

Thanks for all the hours you have put in to help others!

[@kwesmichalak9742]

As an apprentice optician I find all these videos to be beneficial to my career- keep them coming! 😊

[@yuzufrio]

Thanks so much for making these videos available to us. They are all explained so well and in great detail and depiction.

[@deborahuhrina6881]

You crack me up! But I love your tutorials. Best I have found so far. Really helping to educate me, a fledgling optician. Thank you so much!!

[@aaronbaird3905]

Thank You for helping this mom understand her babies eyes much better!!!

[@brejinx9294]

Great presentation!

[@iurisemedo771]

Great work,the way that things are explained ,its amazing,kinds regards from England u.k

[@jennifergould1835]

I just started an optician program offered through my work, but it's all online and I was really struggling with grasping the concepts. I was on the verge of quitting until I found your videos. Getting to see what I"m trying to learn has improved my comprehension tremendously. Thank you!

[@LaramyKOptical]

If you think the videos are good try the actual program! www.OpticianWorks.com

[@clipon8613]

Greetings from Romania! Excellent work, thank you! :)

[@elhammatar4837]

It was so helpful.... thank you

[@priye_Love]

Great video, thanks

[@Gawandeakshay18]

Informative knowledge.👍🙂

[@amykiousis2727]

thank you for all of your videos they are helping me so much.

[@irmarincon2843]

Very helpful thank you so much 💗

[@RECOMMENDED_ACC_IMA]

Awesome explanation

[@ChiKitty24]

You are an exceptional teacher! ❤

[@fabiorodriguez2086]

This is so good!

[@LaramyKOptical]

Thanks

[@alikhanmohammadi9652]

Thank you for explaining this, I am an Optometrist student, and I found your videos much easy and clear.

[@chandrakanthalder1361]

Thanks a lot for explanation.😇

[@reyhaneahmadi1781]

thank you :) it was great

[@srgkzy1294]

Thanks for explaining =)

[@MsMadhwani]

Thanks a lot

[@mbbrooks123]

Thank you for explaining this. I have Anti reflective coating on some of my prescription glasses, and sometimes it interferes while viewing certain types of surfaces, which can be a pain. I can see how it could be a positive on watches and also a negative, I have Anti reflective coating on some of my watches, and some do not.

[@dydx3741]

thank you .....very informative .. just came here to know more about my prescription :D

[@chewlah]

dy dx Saaaame! My eyes are so ridiculous, and total opposites. It’s so interesting to me 😂

[@javiermillanes1315]

You are an inspiration. I truly enjoy watching all your videos and I have no more doubts....... I will enroll in your course and I will try to become the best optician I can with your help and with your passion for teaching. Thank you very much. Muchas gracias from Japan.

[@LaramyKOptical]

Doumo Arigatou!

[@NoneMechanic101]

Javier Millanes .

[@nurgulsantiago5958]

You are amazing! I will be a great optician just like you one day! Thank you!

[@jackchapman7910]

This is really helpful I'm just an apprentice optical assistant but watching your vids are very educational so yh please keep bringing stuff out I would really love a video about the different layers or the eyes and how they function with each other. 😊

[@LaramyKOptical]

Jack, You will need to look around for that one. Maybe under certified ophthalmic assistant or COA? OpticianWorks is all about moving away from the "opticians in healthcare" model and moving us towards the "opticians in business" model instead. If it weren't for anatomy being on so many optician exams I wouldn't even cover it at all. Knowing the layers of the eye and/or the retina gives us a warm fuzzy feeling but does absolutely nothing to elevate the profession of optician. Heck, I had to do a full, real, semester long, dissection biology class during my program. Why? I'll never, ever know! Don't get me wrong if that is of interest to you then go for it! But it isn't something I'll ever be covering. John

[@hooyomcnewankujclhay1019]

Thnks sir 🙏🙏🙏

[@mln180]

I missed this lecture in school but look now laramy k to the rescue……

[@haydermahdi131]

Keep going ❤

[@NoneMechanic101]

Nice. Thank you for the poem

[@LaramyKOptical]

You are welcome... I'm thinking about doing a book of them. John ;-)

[@NoneMechanic101]

You should

[@LearnQuran820]

You are doing an amazing job....please upload more of these basic kind of videos

[@LaramyKOptical]

Thanks and we will!

[@LearnQuran820]

sir can you do an introductory video on basic retinscopy and a short summary type video on lensmeter....as an ophthalmogist these are quite helpful

[@LaramyKOptical]

waleed, We do cover the lensmeter in a multi-part video series. You should find them on the Laramy-K KZbin channel. Sorry nothing on retina-scopes of any kind. That is outside the area of opticians here in the US. In other parts of the world, yes, here we stop where the cornea begins.

[@LaramyKOptical]

Here are the lensmeter videos: kzbin.info/aero/PLA9-eUzNO2Jg5CmXzSZrlCdH9n1TDDzph

[@Anon-ps5ch]

Awesome video John, very understandable. I start my opticianry program on Monday but I am pretty nervous, do you have any pointers for me? Thanks!

[@LaramyKOptical]

Matt, YES best pointer ever = OpticianWorks.com! John

[@d.perera7875]

Please keep these videos coming. Quick question; what is the difference between bending light and redirecting it?

[@LaramyKOptical]

Bending implies a curve and "rays" only travel in straight lines. It is just better language to use. John

[@rashifarsya]

That poetry is spot on Sir hhehhehe 👌🏽

[@lisawallner2136]

Why didn’t i know you until now, you would habe made my life way easier

[@rajneeshchathle7621]

Great

[@Meryem-gm3jm]

thank you for teaching us this!! can you please explain what first focal length and second focal length is and how do I calculate it?

[@LaramyKOptical]

Meryem, That section is being worked on right this minute. Look for an entire new section on the OpticianWorks website in early December (or maybe a little sooner). John

[@damienford3587]

Good God, John, you are a talented chap. Don't recall watchung this on before... Genius, or legend...?

[@ariel9785]

Hello, "redirecting" light is the same thing as "bending" light. From my understanding, many people use the terms "redirect" and "bend" interchangeably with "refract" when talking about the change in direction of light rays. The lens both inside the eyeball and on eyeglasses are transparent materials that refract, redirect, or bend light. Your diagrams did help me visualize this concept though...thanks.

[@LaramyKOptical]

Many people might - we don't because bending implies curvature and light doesn't curve it only travels in straight lines.

[@carlaaddison9868]

Going through your training program on optician works site confused why this video isn't included right at the beginning.... Working through more difficult videos and hadn't seen this one yet ... or the one about some of the terms. Did I somehow miss it? If not it should be included before one gets too far in!

[@LaramyKOptical]

Very first course, in the fourth section, in the lesson Examples of Lenses Correcting Refractive Errors.

[@mudkittens]

How can you tell the difference between a compound hyperopic astig and a mixed astig from looking at the RX examples (if there weren't any diagrams shown)? The RX's look extremely similar to me. Thanks!

[@LaramyKOptical]

By looking at the total power for each principle meridian by doing flat transposition. If you have ++ or +- is your answer.

[@zainraza4655]

great

[@melissayouell8629]

Please present a video in how to explain where the thickness will be in a lenses with astigmatism and in all scenarios or prescription Thank you John

[@LaramyKOptical]

Here: kzbin.info/www/bejne/j4vConeIerajqck

[@sujugajurel6396]

Sir please upload video on refraction

[@nehamahadevan914]

Hey John, could you please explain what happens to the path of light when it passes through a lens of no power? Thank you so much.

[@LaramyKOptical]

That kind of depends on many things. Short answer is, "nothing." Long answer involves material, strike angles, curvature, plate, etc. But any combination of front and back that equals 0 the light passes through as if the lens "wasn't there" or "isn't there." (a window)

[@j-boogiebrown9961]

Hi. I've got a question for you. My 11-year-old nephew has just been told he needs to wear glasses for a year, to strengthen his eyes, after which he will apparently be able to stop wearing them for ever. How is this possible? If he walked around on crutches for a year, his legs would become weaker, not stronger, so how is it different when it comes to eyes and glasses?

[@LaramyKOptical]

That is outside the scope of an optician. An optometrist or ophthalmologist might suggest it but I'm not about to question the why behind it. Now if the glasses have prism then it can force the eye to hold a different position thus "strengthening" the correct alignment. As to glasses making eyes weaker or stronger --- the jury is still out on that one. John

[@RaquelHi]

Is there a video that explains monovision correction in glasses?

[@LaramyKOptical]

No because basically there is no such thing. Some people are born that way and it works for them. Mono-vision contact lenses can work, sometimes. Have some people been successful doing mono-vision glasses? Yeah a few, but it is not a commonly accepted practice.

[@timothylampron9175]

thanks

[@LaramyKOptical]

You are welcome. John

[@pradeeprawat3684]

How to do eye testing with trial lenses

[@brentdietiker]

Just a head scratcher here....How come the light doesn't bend toward the base on a 'minus lens'? Thanks for your videos, still trying to pass the ABO for Costco.

[@LaramyKOptical]

Sounds like you really need to work through the OpticianWorks.com optician training program!

[@brentdietiker]

@@LaramyKOptical I’ve been using the videos and other sources. I was just curious on the illustrations shown in this particular video. I’m still working at it though.

[@brentdietiker]

@@LaramyKOptical does the yearly subscription cover NCLE as well? I’ll need to pass both in order to work in the department(again).

[@LaramyKOptical]

@@brentdietiker We have some great CL content written by a board member of the NCLE. We don't have specific prep quizzes for it.

[@brentdietiker]

@@LaramyKOptical Ok thank you. I will probably plan to enroll with the ABO subscription

[@ikrammisbah4798]

just woooooooooooooooooooooow

[@user-kw7qo8cz4w]

I'm trying to understand how you determine the axis. i get all of your explanations but, I am lost when it comes to the axis

[@LaramyKOptical]

That is determined during the refraction process. I just chose one at random. We have plenty of other videos that cover that.

[@amp4117]

If the power +1.00 +1.25cyl × 180 then what it is called?

[@LaramyKOptical]

Flat transposition gives us +2.25 -1.25 X 90 you have + power in both principle meridians and you have 1.25 cylinder so compound hyperopic astigmatism. There is another video that covers the refractive conditions.

[@Yarely420]

How to pass the NCLE (National Contact Lens Examination)?

[@LaramyKOptical]

Yarely, Sorry, but, no. We cannot find anyone who can create the content we need. We have been trying for years now...

[@EppingForest304]

👍

[@qabashaitham6850]

❤❤

[@user-pv6oh5cn6l]

☺️☺️☺️☺️☺️

[@michaelashcraft8569]

Ok then, been fun watching ya John, but, why do opticians make so little money? Taking my degree in optics, getting back in my truck to get retirement cash, poverty wages just ain't my thing!

[@LaramyKOptical]

I hear ya! Why do opticians make so little? Lack of any national standard, no consistent demand for a specific defined skill set, no unions and well really hard to kill anyone with a pair of glasses. Just IMO! John

[@LaramyKOptical]

OR because opticians are entirely too focused on dispensing rather than being indispensable, on doing a job rather than providing and creating value. There is more money to be made on the eyewear side of the house than the medical side. There's a reason opticians aren't getting much of it. -Keith

[@michaelashcraft8569]

@@LaramyKOptical This is true, I made more money working as an Ophthalmic Assistant, but, I thought I would do well in optics, not so.

[@bpark10001]

Your diagrams are misleading and confusing. First, no significant light bending takes place, except at the cornea/eye lens, and at the corrective lens. Myopia diagram should show rays coming in PARALLEL from the left side object, to the cornea/eyelens where they are bent converged, then proceeding STRAIGHT to the retina where they meet at a point (for normal vision) or meet and cross in front of the retina (for myopia). For corrected myopia, the rays come from the left PARALLEL, pass through the corrective lens, where they are bent divergent then STRAIGHT to the cornea/lens where they are bent converged, going STRAIGHT to the retina, meeting at a point. On all but the most extreme cases, almost all of the bending takes place at the cornea. Here is link to correct diagram eduladder.com/viewquestions/6730/Describe-with-a-ray-diagram-how-a-person-with-myopia-can-be-helped-by--spectacles--2005-CBSE-Physic-class-10 (Hyperopia diagram at that site is also flawed). The rays are PARTIALLY converged by the corrective lens, then usually MOST of the convergence bending takes place at the cornea/lens. Elsewhere, the rays are STRAIGHT. It needs to be emphasized that these diagrams show the rays from only one point on the object. The image is made up of a huge number of these bundles, each arriving at a different angle to the eye, and landing on different parts of the retina. A most useful video would be to set up optical bench and lenses and model the eye in full scale. You can use pin-source and smoke to show light rays, and small screen for retina. Never have I seen such material available, so this would stand out.

[@LaramyKOptical]

Brian, I can't say how sad I am to see this from you. As I would reply to any other --- if you can do better then please do. Heck, make your own series of videos and if they are better than what I produce I'll gladly point people your way. I added Disclaimer 1 and then repeated it again for a reason. We just don't play this way here so maybe it is time to move on? I'm sure you can find a social media group worthy of you. John

[@bpark10001]

I mean no harm. Your site is a wonderful source of optical information, which is relied upon by many. What I am trying to prevent is the propagation of misleading information (I found plenty of it when searching for a good diagram how the light propagates). Everything you say is 100% correct, but the ray diagram misleads. (You even drew an arrow correctly, but then hastily removed it). Don't you want your site to be accurate? Or should I find a way to make these statements to you without creating a social scene? (as having knowledge of physics and optics, I feel this is important, to be able to visualize what is happening. What would Steve Machol say?) The reason I am commenting is I feel your site renders a useful service and is "worth it". Is there a more constructive way for me to do this, or should I give up and buzz off?

[@LaramyKOptical]

Brian, Listen to Disclaimer 1 and then listen to it again when I repeat it. It was repeated because I was 100% certain that someone (most likely you) would pop up and say they were wrong. Ask Keith, I insisted that he leave in the repeat! These are concepts presented at a level for beginner opticians. I never (ever) claim a understanding of physics or optics for that matter. If I was here preaching from a pedestal and acting like a know-it-all or pretending to be an engineer or physicist then have at me! From the very first video I have been as open and honest about my level, my math skills and saying straight up that this is, "how I understand this stuff." It seems to help others so I keep doing it. If you watch all the videos you will see several where I do complete red-faced mea-culpas. If I'm wrong, I'm wrong and I admit it in public. I know you don't believe me but if you can do better, please do so and I'll point people to your videos. Heck if you want some tips on getting started, equipment etc, drop me an email. You might try checking outThe Optical Society on Facebook it may be more like what you are looking for? Walking away now... John

[@emil.jansson]

Do not use glasses they will make the problem worse!

[@ebicandrew715]

Great