How to Refract with a Phoropter, [WITH HELPS]

A quick overview on my technique of refraction for a coworker

Unedited video, without slides, here: http://www.youtube.com/watch?v=Vj5mhd12SWs

Recorded on my iPhone, using ReelDirector to edit.

Category:

Education

Tags:

• How
• To
• Refract
• Howto
• Photopter
• Sphere
• Plus
• minus
• Cylinder
• Axis
• Balance
• better
• One
• Or
• Two
• Ophthalmology
• Optometry
• subjective
• manifest
• Refraction
• refine
• glasses
• prescription
• eye
• exam
• vision
• sharp
• clear
• blur
• tutorial
• iphone
• reeldirector

[Commando303X]

Doing the left eye, shouldn't you have made adjustments to the sphere as you dialed in more cyl. power, to maintain the spherical equivalent? Also, for the same eye, when checking axis, isn't it important to reach neutrality, get reversal, then go back to neutrality?

Thanks.

[SilmaYevrah]

@Commando303X Yes, I should have; then I wouldn't have needed to adjust so much at the end. As for the axis, it depends on how much time you'd like to spend refracting. It's very different scenarios if your refracting a patient seeing an ophthalmologist for medical reasons who needs only the manifest and no prescription will be written, verses a 2.5+ cylinder patient being seen complaining about his glasses.

[greenroneye1]

Good to see the tutorial. The mistake in the left eye was made because you forgot the critical 2for1 rule of refracting. The sphere is changed by 0.25 in the opposite direction of the cylinder when changing the cylinder by 0.50. In this case you changed the LE cyl from +1.25 to +1.75 but failed to compensate in the sphere to keep the circle of least confusion on the retina. If you had added -0.25 to the sphere prior to the next power determination then the cyl would have come down.

[SilmaYevrah]

@greenroneye1 Very true, I had forgotten to do this. I've been trying that recently after reading your comments and found my accuracy improved on the first go around, thanks!

[otissumnerbrown]

I like the instructional value of this video. I do think that a motivated person should first read his Snellen with no phoropter. If you wish to teach the general concept to a person, simple hand-held spherical lenses (and a Snellen at 20 feet) would get the concept to the person in a manner that he could understand this process. Thanks!

[SilmaYevrah]

@otissumnerbrown True, that would be informative.  As this was originally a video made for a coworker with a solid vision background, I went straight to the refraction bit, assuming she knew the basics.

[IBMaccMartelli]

really cool

[otissumnerbrown]

@chechnya The auto-refractor is SUPPOSED to do this. The last time I had an auto-refractor measurement it was fro -9 diopters. (My visual acuity was in fact 20/40). You can not "digitize" or "automate" this process -- in my opinion. You need the "feedback" from the person as this video demonstrates.

[chechnya]

How is this not digital yet?

[CitrusLuifer]

some video like this one, in spanish? please =C

[SilmaYevrah]

@dstewart1117 I find duochrome useful for finding sphere power in the first steps of refraction, not for balancing at the end, i.e. s/p cornea transplant patients where you can't get an auto-refract. However, if you have a nice and bright projector with duochrome and like using it to confirm your manifest, go ahead. Refraction isn't an exact science, there's some art to it aided by many tools. Find the ones you like and use them.

[SilmaYevrah]

@dstewart1117 To refine cylinder power, you align the white and red dots of the Jackson-Cross cylinder with the axis arrows, so yes. Refracting in plus cylinder, you add cylinder power if the patient chooses the white dots on the axis, or reduce power if the white dots are perpendicular, (opposite in minus power.) You only "follow" the dots when refining axis, turning the axis knob towards the white dot in plus cyl., or red dot in minus.

[dstewart1117]

@SilmaYevrah Do you place the knobs according to the axis when searching for the cylinder power or make sure that the white and red dots are btw the white arrow. Need clarification? And is the tech following the white dot only for cylinder axis? And instead of adding an additional 75 diopters at the end, why didn't you use the duochrome to ensure that the sphere was correct? Thanks.