Fan and Block
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- Опубліковано 17 жов 2024
- Fan and Block used to be a common method for correcting astigmatism but has been superseded by the cross cyl technique. It is however still a useful method especially when dealing with larger cyls and sometime patients finds the fan and block method less confusing. Its certainly a useful backup especially in situations where hi tech equipment is not available.
I missed my lecture on this. This is a life saver, thanks.
It seems to me that in order to do the reversal test, a -0.25 cylinder at 100 deg (perpendicular to the original sharpest line) should be added, instead of a -0.25 sphere. Because the former would be an over-correction, causing the anterior focal line to go further back, becoming the new posterior focal line, thus causing a reversal, while the latter would just move the entire pencil closer to the retina, therefore shouldn't cause a reversal. Am I missing something?
Hi Ian,sorry it may sound silly,cant you put +0.50 with spare (to bring 2nd focal point infront of ret) before even turn on fan and bloack chart?
i just did nt got whay Alen started with +1.Is it because u have + ve prescription or is something that we have to do prior to fan and block. appreciate any help
+Ian Squire many thanx ur videos are hepling me a lot in my optometry education.
We use minus spheres to activate accommodation for Cross Cyl, can you/anyone explain why this is important in terms of the COLC and focal points?
Wish you were my lecturer in university Ian.
my left ear enjoyed this
Thank you for this informative video. It is extremely helpful for me
Hello sir kindly upload a video on fogging method. Thanks
Anyone pls tell me how he choose that 100degree axis and why he turn the arrow in clockwise direction...plss
i'm sorry sir, can i get explanation about how you determined the X is 100,
Thank you for your great video
From Sudan, thanks a lot.
I confused with adding minus power.
Very clear explanation. Thank you!
Thank you soooooooooo much Sir
sir plz also explain in new video madox rod and worth 4 dot test and glare test.
i donot understand the axis chosen
+Ian Squire thank you so much i think i got it now
principle:
Find BVS with a subjective or ret test. bring 2nd FL to ret with pos. bring 1st FL to ret with neg.
test: occlude one eye. use BVS fo estimate the cyl power, add half the pos cyl to get 2nd FL onto ret. adjust the axis. (at 90* to test chart axis). add 0.5 sph plus as a check for later. now onto blocks. need to add minus cyl until blocks are equally blurred. the check: remove the 0.5 sph and there should be a reversal of block clarity.
This summary got multiple points wrong.
Good explanation sir :)
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