It was just "made up Lois and Clark science."
Ultra-violet light can indeed cause blindness (which is why many kinds of sun glasses are ultra-violet opaque)but there isn't anything mysterious about it. Ultra-violet light damages the lens of the eye and eventually, with sufficient exposure, causes cataracts. If infra-red light were the antidote, there would be a lot of ophthalmic surgeons with a lot less business. The only cure for cataracts is surgery, where the cloudy lens is removed and an artificial lens is inserted in its place.
Admittedly, modern science has produced replacement lenses that are very good. In the old days people had to wear those clunky "cataract glasses". Thank heavens that is no longer necessary, since modern artificial lenses are amazing (my mother had cataract surgery and all she reported was that she had to wear reading glasses, which she had worn for years anyway since she was in her seventies at the time, and the fact that she saw some colors a little differently.) I'm sure that the lenses have been vastly improved in the fifteen years since, as well.
The only thing I can suggest for Clark would be that his Kryptonian healing powers might allow him to repair the damage the same way he can heal from injuries in seconds, or maybe Dr. Klein could come up with some miracle cure, but it wouldn't be grounded anywhere in reality.
Nan
