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Accuracy was checked with Trial Lenses

sorry - I don't understand

Hi I notice this as well. I think that it might be because of various optical aberrations which our lenses can't correct - that is assuming that I have got the result correct !! My experience is that there aren't many real "scissors" reflexes - these are only seen in people with keratoconus and rarely lens impurities. It's more likely that my cylinder is off axis. Sometimes combined with the spheres and cylinders being wrong. So I look at the cylinder axis first. My method would be :- 1 Remove the cylinder. 2 Check that the sphere is correct. 3 Tighten the retinoscope collar ( pushing the collar towards the parallel light setting) to make it easier to see the axis of the cylinder. 4 Line up the reflex line in the eye with the line of the retinoscope streak on the outside of the eye. 5 Focus the retinoscope streak until it is a thin line to read on the trial frame what the axis is. 6 Put the cylinder back in at the axis that i think it is. 7 ROTATE the cylinder a few degrees on both sides of the axis I thought it was, whilst looking at the reflex. Sometimes this shows up what the real axis is, rather than the one I thought it was. Essentially, the reflex becomes more pure and less scissors. I would need to rotate smaller cylinders more than bigger ones. So -0.50DC I might rotate 30 degrees either side, whereas -2.00DC I might rotate only 5-10 degrees. Usually it's harder to get the axis of smaller cylinders. When I see that the reflex is the best I can get, I move inside my working distance and check that the WITH movement is the same in both meridians. Then adjust the spheres and cylinders until it is the same. Although it's very annoying if you have spent a long time to get to a "scissors" reflex, it's often best to start all over again with the cylinder. If its really important to get the result correct as it is with cycloplegic - I would take the frame off, let the patient have a rest, do a couple of other tests so that the patients don't lose the illusion that i know what I'm doing. Then have another go With experience I found that I was able to judge the cylinder axis much easier. Hope this helps - thanks for the comment - much appreciated.

me too. you have accurate observation.

Thank you. Glad you enjoyed it. prescribing for children can be tricky. There's lots of opinion about how much to give. This paper sums it up but is now 7 years old - so might be superseded by newer research. onlinelibrary.wiley.com/doi/full/10.1111/j.1444-0938.2011.00600.x I do use cycloplegic on a lot of children as it's hard to trust their subjective responses. Mostly i take off an extra +0.50 from my measurements. Then stick the guidelines in the paper - if I can remember them !

th-cam.com/video/C32gaAVfmZk/w-d-xo.html

Thank you that makes sense to try that, another thing is can we use binocular refraction for a patient who is a hyperope in their 60s instead of monocular refraction. To save balancing the vision afterwards. ? Also, some people do balancing in older patients is it actually needed? I'm a pre-registration trainee so I am looking for ways to speed up my routine.

I'm very grateful for your videos and help

Hi Dja M I always use binocular refraction. No matter what age. It saves balancing. Although there’s not a lot of balancing with people who can’t accommodate. Although I sometimes find that balancing does change things if I refract monocularly with somebody with cataract or a squint. Maybe it’s something to do with pupil size. Not sure. The only times I revert to monocular refraction is if there is a squint. Or uneven va. Or high dominance to the other eye. My big tip is to use +1.50 as the fogging lens. Not +0.75. Much more reliable. I sometimes come down to +1.25 if I’m confident that there is not much problem with dominance. But that’s less these days.

@@lenshuffler5261 Really good tips there! Thank you so much for your replies as well as new video!. I've been doing as you describe binocular on most px except the certain exclusions, and it's quicker! One thing sometimes patients say with the opaque occluder is that post removal of it they get double. I guess that is because it's like cover test. Is there any advantage to a frosted occuluder? I'm not sure of its use? Also one thing I get with Ret is sometimes much more cylinder than the patient will accept. Is that due to poor technique do you think or is this normal? E.g finding maybe -2.00DC when the px won't take more than -1.25DC? Thank you

Hi Sorry for delay in replying. I've never tried a frosted occluder - but i guess it would have the same effect as a solid one. No chance to fuse. I think the higher cylinder situation you describe could be caused by being off axis. Either being too high or being too low. Alternately off axis to the left or right will cause error. Have a look at Part 2 of the Masterclass video. That deals with alignment issues. Having said all that, sometimes i get the same as you and there is no obvious reason. The cornea is an unusual shape so off axis doesn't help. For that matter the lens is complex too.

Thank you Kostas - I enjoy making them. I'm working on getting more views and subscribers but it's hard work. I have a few other films to upload. I hope you enjoy them.