How does Chromatic Dispersion affect your choice of 1.67 v. 1.74 high index lenses?

My dad must decide whether to buy 1.67 v. 1.74 Nikon lenses for his eyeglasses. Can someone please explain like I’m 5 this purported optometrist’s comment on Reddit? This Webpage by Dr. Rüdiger Paschotta moots chromatic dispersion, Abbe number, but it’s too abstruse.

The higher the index, the more reflective ("shiny") the material. The "shine" can be annoying so it justifies an antireflective coating.

Also ask about chromatic dispersion; the refractive index predicts thickness and shine, but the Abbe number predicts the tendency to see rainbows at edges. Big values > 45 are better.

Also in high index lenses, barrel distortion is different with higher index and there’s more fishbowl-distortion and minification, for the wearer and for people looking at your eyes.

All this to say high-index isn’t a fix-all, even if it makes them thinner and lighter.

Nothing works well in a big or square frame. Choose a frame with small, round lenses and high-index materials may be unnecessary.