What if I encounter scissor movement when doing retinoscpe?

[alchemist7]

i cannot find neutral point easily!!

help!

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[JMU07]

Sounds like there's some astigmatism present.

 

[Habitual Rx]

If you encounter scissor movement, you know that you are are pretty close to neutral at that point

 

[KHE]

i cannot find neutral point easily!!

help!

1) Use a corneal topographer or keratometer if available

2) When you have scissor, it's usually best to forego retinoscopy and uncover the cause of the scissor.

 

[WoodyJI]

You'll want to try and find the place where the scissors are the brightest/fastest, and the scissoring motion is most uniform. Take that as neutrality for the given meridian and move on. Note that this is probably a waste of time if you're just using your retinoscopy just to set up for refraction.

If you're not perscribing off of your retinoscopy (i.e., playing the "scope and hope" game), then I wouldn't worry about bracketing neutrality. Pick a reflex that you like to look at and add lenses slowly to bring it closer to neutrality. Once you lose the discernible reflex motion (maybe scissors start) you're close enough to neutrality, so switch to the other meridian and add lenses to make that reflex motion stop. If you start with against-motion in both meridians, then you'd be done at this point.

Assuming you're using a minus cyl phoropter, if you plus the patient up to get against motion in both meridians, the brightest reflex will be your sphere. Once you remove the against motion from that meridian slowly with (–) sphere lenses, you can eliminate the remaining against motion in the other meridian with (–) cylindrical lenses, and you've essentially done the same thing as pushing plus while refracting. This is because you're biasing your endpoint towards the least minus side of neutrality. We have to remember that neutrality is a zone for a lot of patients—not a single dioptric point.

 

[KHE]

You'll want to try and find the place where the scissors are the brightest/fastest, and the scissoring motion is most uniform. Take that as neutrality for the given meridian and move on. Note that this is probably a waste of time if you're just using your retinoscopy just to set up for refraction.

If you're not perscribing off of your retinoscopy (i.e., playing the "scope and hope" game), then I wouldn't worry about bracketing neutrality. Pick a reflex that you like to look at and add lenses slowly to bring it closer to neutrality. Once you lose the discernible reflex motion (maybe scissors start) you're close enough to neutrality, so switch to the other meridian and add lenses to make that reflex motion stop. If you start with against-motion in both meridians, then you'd be done at this point.

Assuming you're using a minus cyl phoropter, if you plus the patient up to get against motion in both meridians, the brightest reflex will be your sphere. Once you remove the against motion from that meridian slowly with (&#821 sphere lenses, you can eliminate the remaining against motion in the other meridian with (&#821 cylindrical lenses, and you've essentially done the same thing as pushing plus while refracting. This is because you're biasing your endpoint towards the least minus side of neutrality. We have to remember that neutrality is a zone for a lot of patients—not a single dioptric point.

What, in the name of Christ is that happy horseschitt? lol

Seriously....that method be fine for a 1st or 2nd year retinoscopy assessment but here's how it's done in the real world:

1) The first goal is to get the patient seeing as well as possible (usually)

2) The second is to determine the cause of the scissor.

3) Therefore, you start with a corneal topography since that's what the problem is 99.99% of the time. Then you perform a quick and dirty refraction.

4) Throw on an RGP which matches the flat K and perform spherical refraction one more time.

5) Tell the patient they need RGPs if they want any sort of meaningful vision.

6) If they decline, prescribe quick and dirty refraction and recommend that they fill it at the optical of some establishment you don't like because 90% of the time, they aren't satisfied with the glasses.

 

[JMU07]

KHE (and other OD's too) - how often do you actually do direct in your practice? Some docs love it, others hate it. Do you think it's useful even if you have an autorefractor to give you a starting place for your refraction?

 

[KHE]

KHE (and other OD's too) - how often do you actually do direct in your practice? Some docs love it, others hate it. Do you think it's useful even if you have an autorefractor to give you a starting place for your refraction?

If you mean ophthalmoscopy when you say "direct" then I would say I do it rarely because we dilate most patients. On those that are not dilated, I usually use a 90 at the slit lamp.

If you are referring to retinoscopy, I would say I do it on children under 14 and if there seems to be a large difference in the autorefractor reading and what the patients current prescription is. This rarely happens. Modern autorefractors are pretty accurate.

 

[JMU07]

If you mean ophthalmoscopy when you say "direct" then I would say I do it rarely because we dilate most patients. On those that are not dilated, I usually use a 90 at the slit lamp.

If you are referring to retinoscopy, I would say I do it on children under 14 and if there seems to be a large difference in the autorefractor reading and what the patients current prescription is. This rarely happens. Modern autorefractors are pretty accurate.

Oh sorry, I meant ret. Kind of had ophthalmoscopy on the brain lately! Thanks for the input.

 

[goosedander]

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[WoodyJI]

Seriously....that method be fine for a 1st or 2nd year retinoscopy assessment...

That's right, I'm talking about a quick and dirty ret here. Ideally, one would just start with an autorefractor rx.

The point that I think we can agree on is that things need to be done for that patient other than having them sit for a 20 minute retinoscopy session because they have scissors and it'd be really cool to nail them down.

 

[luvthemhogs]

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Scissor me timbers! Nice!

 

[Mixin Marc]

it'd be really cool to nail them down.

nail them down physically?

 

[eyepoker]

ahh...I think the title should be what are the chances that I won't encounter scissoring patients...and the answer is.....drum roll......5%, haha, just kidding....but it is true within our school population, lots of my Asian classmates have scissoring (well I'm one of them)....and the teacher says...that's life, just practice and you'll be great after 4-5 yrs......hm..so far when I have my assessment, I just pray really hard that I won't get one of the scissoring classmates.