The focuser on your telescope is used to make up for near or far sightedness. TeleVue Dioptrx compensates for your astigmatism. These units connect and lock onto the top of more than twenty long eye-relief Tele Vue eyepieces to attain the sharpest full-field observing achievable.
Dioptrx versions are offered in ¼ to 3½ diopter (¼ steps from ¼ to 2½ diopters, then ½ diopter steps to 3½-diopters), and are rotatable for adjusting to the ideal orientation.
There are a series of engraved letters on the barrel that enables you to keep tabs on orientation. You just select the Dioptrx model to suit your eyeglass prescription for astigmatism. Every one of the lenses are multi-coated glass in anodized aluminum housings with rubber eyeguards.
By using Dioptrx over eyeglasses you are more likely to see a sharper, higher contrast image, because the Dioptrx is always entirely aligned to the eyepiece optics, cutting out aberrations from a decentered mismatch of eyeglass power and astigmatic axis.
Dioptrx can be rotated to compensate for the astigmatic axis angle in real time, due to the fact that both head angle and age can vary your eyesight astigmatic angle.
In all likelihood it has superior multi-coatings to eyeglasses, and indeed is way better in transmission and reflection reduction than uncoated eyeglass.
It is probably going to be cleaner than eyeglasses, which could quite possibly have scrapes and streaks from continuous usage and you are just about guaranteed to see the full field in 100° TeleVue Ethos eyepieces since your eyeglasses tend to be more limiting in "effective eye-relief".
Long Eye-Relief Tele Vue Eyepieces that Accept Dioptrx