Hi ya tween
Some eyesight improvement may occur from IHM simply because the release of muscular tension and sinus drainage. Also working the energy lines, acupressure points and 6th "brow" chakra may have benefits from a energetic point of view.
Personally I wouldn't state that IHM can help improve eyesight as that are many hundreds of reasons for poor eyesight, eventhough for some clients there may be improvement.
Best Wishes
IHM Pixie