OT skills guide: Best vision sphere

This video was launched to OT members in 2017

This video demonstrates how to determine the best vision sphere for a myope during a subjective refraction routine. We explain the duochrome test and how to control accommodation. This is used before and after determining the astigmatic component of a subjective refraction.

[piotragoda]

It's an excellent introductory tutorial and I appreciate the way you explain everything in simple words. Experienced practitioners all understand that patients that can easily differentiate +/- 0.25 difference or designate red / green on duochrome test are not easy to be found. Problems occur when the answer we get for power change is "I don't know". I would love to see an expert-level video on communication skills. One on patients with impaired visual acuity (0.5-0.7 c.c. is quite common with +65yo patients) would be beneficial too.

[janjilek]

Hello and thanks for the nice video. I would perhaps ADD a little comment of my own.

Communication is "KEY" when asking the patient regarding the small +/- 0, 25-0, 50 D changes.

When putting in the +0, 50 D the question to ask is not if it "gets better", it is rather "Does it get worse or is it the same"? As you are "waiting" for blur to kick in, thanks to + overcorrection.

Worse = too much plus
Same = can get more plus (if you aim at full correction).

With slightly higher hyperopes the answer to +0, 50D in front of the eye can indeed be "it is not worse or the same, it is better", that is why I personally blur the patient with a "stronger than expected" sph EQV (sph. overcorrection). If I expect him to be +1, 00 I usually start with a +2, 00 in front of patients eyes, telling her/him, that "This should make the letters more blurry" + any extra accommodation for "hidden hyperopes" will have to relax (in most patients)...

After that it is basically treating the person as a myopic patient, using -0, 25 (-0, 50) lenses and again ask the proper question...

"Does it get better or does it stay the same? Also if the letters become more distant or smaller, please tell me".

Better = give more minus.
Same = keep the sph eqv. in the trial frame and continue with cyl examination.
Letters become smaller = too much minus (at this point).

The final binocular balance will often change the sph according to cyl. Lastly, never forget to check your R/L distance result on a "real world distance" ideally an object/letters 20+ meters away for the last bits of +/- 0, 25D, which will be super important when dispensing progressive lenses.

Cheers :)

[NIFFINCPHILIPOSE]

The chart used here for testing is LogMAR chart. The test distance used in LogMAR chart is different from Snellen's chart.Also the notation used in LogMAR chart is different from what is used with Snellen's. Eg: If we read with LogMAR chart, each letter read is assigned a value 0.02.

[zahraal-batul]

This video is amazing - thank you so much ❤️

[otiebrown]

It seems a very complex way to do Best Vision Sphere.
That is why I use my own test lenses, to measure my own refractive state.
Thank you!

[askanaunty]

Is it a routine to check left eye first?

[indirafranque]

What if with the -1.25sph the patient says they see clearer when you add +025 lens?