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To go back to the original question:
I have designed a few eyepieces over the years and found that the most difficult aberration to correct was field curvature - where ED glass would not have helped.
Eyepieces contain strong lens elements that call for high refractive index glasses, to minimize surface curvatures. Lanthanum glasses are high index and ED glasses are low index.
My guess is that it's not worth the trouble and expense including Fluorite or ED glass into an eyepiece design.
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