J Values

[kcengage]

My dad will be getting his lens replaced (cataracts), and the doctor mentioned to him, which he then asked me, that realistically his vision will be at J3 to J4.  What does this actually mean?  I know it has something to do with the Snellen chart...?

[John C Hagan III, MD, FACS, FAAO]

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[kcengage]

Thank you

[John C Hagan III, MD, FACS, FAAO]

I'm looking at the near card we use here in our offices. Jaeger (J) 1 = 20/20  J2= 20/30 and J3 = 20/40.

So J1 or J2 would be required for very fine print, very small near work like sewing.

Best near vision of J3 is equal to a 15% loss of visual efficiency.

JCH MD

[peakhope]

I had a lot of trouble finding out what J1, J3 etc really meant.

I finally found an online PDF article from "INSIGHT The Journal of the American Society of Ophthalmic Registered Nurses, Inc.", October-December 2004, which  says (paraphrased) that: J1means you can read 4 point type, J2 is 5 point, J3 is 6 point, and J5 is 8 point.

You can search the web for "Rosenbaum pocket eye chart" and see one device that measures J values at a distance of 14 inches. Some of the vendors of that card show large enough images to confirm the point values mentioned above.

Keep in mind that different fonts of the same "point size" can be different sizes. So I'm not sure what the "official" font would be.

These seem like VERY small fonts to me. I would consider anything below 6 point to be very rare in the real world...which makes me wonder why J1 is considered to be important. Based on what I have seen so far, I would think that good J3 vision would be fine for everyday life.

[John C Hagan III, MD, FACS, FAAO]

Its a measure of near vision (Jaeger).  You can go to google images and type Jaeger Chart in and see what that size looks like. It would be roughly 20/30-20-40 vision. Its also important to know whether the surgeon was talking about with or without glasses.

JCH MD