I wonder why the AXS for astigmatism is so hard to pinpoint consistently for minor astigmatism, i.e. CYL = -0.25. Even if this astigmatism is the smallest, its correction manages to convey a final sharpness clarity that I very much long for. Have gone to several optometrists and even my ophthalmologist over the years, but I get different AXS numbers from all: 165º, 0º, 14º, 45º, and 88º. Have worn 165º for several years, but my vision in that eye with that correction has been slightly off for some years already. By flippling the lens I could clearly see better, which made me think my actual AXS should rather be around 15º. And by rotating one of my older glasses manually, my own best guess is that it's between 14º and 45º, favoring the 45º end. What puzzles me: how come different measurements done by different professionals just days/weeks apart do not end up relatively close to each other within a narrow range of angles?
@@arthurkorir7846 I worn some contacts years ago and stopped wearing them. They weren't as sharp as glasses, and also once a contact got pushed back under my eyelid, that was so uncomfortable and quite difficult to get back out. Since then never again. After more close and careful inspection, I realized after flipping the older lens, in fact the clarity got better when I turned it very slowly counter clockwise (from my own wearer´s point of view) as opposed to clockwise. So instead of near 45º, my axis I think is between 14º and 0º, favoring the 0º end of that range. Only one out of the last ~8 optometrists have told me my axis for that eye is 0º. One of of eight. Or out of nine really, since the ophtalmologist was also quite off.
Higher power means more convergence, but light bending is greater at the periphery than at the center because the incident angle is less perpendicular at the edges. According to Snell's law, more bending will occur. Therefore, the center portion remains normal, and as we move outward, the image becomes increasingly distorted, resulting in a pincushion effect. This is reversed in low power lenses.
Your explanations are awesome. Thanks mam.
I'm not even a doctor, but this video satisfied my curiosity
That's wonderful 😊
@@InsightOphthalmology thank you! I had bad smile surgery so now I collect as many information about eyes as I can
Thanks Dr
Great explanation, instant subscribe. 🙂
Thanks :)
Thank you alot 🎉 we need more vedio about optics of human eye
I wish I could give more like for the brilliant explanation.
Thank you ! Share the knowledge:)
Can a lense still be replaced if the capsule that holds the lense was removed by a doctor?
mam ,pls make a detailed video on pseduaphakia and IOL power calculation
I wonder why the AXS for astigmatism is so hard to pinpoint consistently for minor astigmatism, i.e. CYL = -0.25. Even if this astigmatism is the smallest, its correction manages to convey a final sharpness clarity that I very much long for. Have gone to several optometrists and even my ophthalmologist over the years, but I get different AXS numbers from all: 165º, 0º, 14º, 45º, and 88º. Have worn 165º for several years, but my vision in that eye with that correction has been slightly off for some years already. By flippling the lens I could clearly see better, which made me think my actual AXS should rather be around 15º. And by rotating one of my older glasses manually, my own best guess is that it's between 14º and 45º, favoring the 45º end. What puzzles me: how come different measurements done by different professionals just days/weeks apart do not end up relatively close to each other within a narrow range of angles?
You need contact lenses
@@arthurkorir7846 I worn some contacts years ago and stopped wearing them. They weren't as sharp as glasses, and also once a contact got pushed back under my eyelid, that was so uncomfortable and quite difficult to get back out. Since then never again.
After more close and careful inspection, I realized after flipping the older lens, in fact the clarity got better when I turned it very slowly counter clockwise (from my own wearer´s point of view) as opposed to clockwise. So instead of near 45º, my axis I think is between 14º and 0º, favoring the 0º end of that range. Only one out of the last ~8 optometrists have told me my axis for that eye is 0º. One of of eight. Or out of nine really, since the ophtalmologist was also quite off.
Why convex lenses causes pin cushion distortion... And concave barrel..what is the reason and underlined mechanism for these phenomena
Higher power means more convergence, but light bending is greater at the periphery than at the center because the incident angle is less perpendicular at the edges. According to Snell's law, more bending will occur. Therefore, the center portion remains normal, and as we move outward, the image becomes increasingly distorted, resulting in a pincushion effect. This is reversed in low power lenses.
How much visual angle increase in aphakic eye
Make video on subjective refraction and objective refraction mcqs geometrical optics mcqs.
Mam i request to make a video on" vergence relationship and Accomodation formula" a topic of visual Optics
Thank you ma'am
Most welcome 😊
Thank you mam❤
Most welcome 😊
mam i think you are taking paraxial rays wrong,paraxial rays are the rays close to the principle axis of the optical system.
Yes you are right...I meant marginal rays
Please keep little gape when you speak some words.