If I find myself doing enough welding, I might pursue to a MIG conversion via replacement parts, but for now I'll manage with my simple fixed voltage stick welder. Builds character(?!) I'll bet Glort's new inverter welder will be a dream boat to weld in comparison.
I wear my "arms length work" glasses for welding. I'm nearsighted with presbyopia. I have glasses for every working distance, as I found bifocals impossible and variable lenses a headache (literally). With some study and my own trial lens/frame set it was easy to get just the right lens RX. ZenniOptical is marvelously inexpensive.
I still have some range of focus for my eyes, and MS affects my ability to scan and focus rapidly but I have way less headaches when I can put my work in the middle of that focus range. Avoiding overcorrection strain is especially helpful, undercorrection is much less of a problem, I've found. "Soft focus" beats a headache by a mile.
There was a brilliant bit of research done by a Australian eye doctor. He found that if kids were given bifocals with plane glass for distance or close, depending on whether they are nearsighted or farsighted, their vision didn't deteriorate rapidly, requiring new lenses every year, stronger and stronger. He proved this in fairly large trials of school kids. So while good for their profits, the current practice of optometry is adversely affecting kids vision health, and costing parents a fortune. I've found that almost every field of medicine is like this- profitable procedures are supported and protected first and foremost, public health be damned.