With my vision issues I have a really hard time threading needles of any sort. What works best for me are the "bird" ones like the one shown in this video. There are some other makers but these are easily found at sewing shops or of course on Amazon.
https://www.youtube.com/watch?v=fiWm...nel=123Dreamit
They have a little hook much like on many machine needle threaders. I can easily feel my way into the needle and catch the thread on the hook. They also fit in my hands nicely and I can typically find them easily when I drop them!