I never found a technical explanation of why you shouldn't reuse dailies after overnight cleaning. I looked at papers, manufacturers' websites, and spoke to two ophthalmologists.
Though not a safety issue, my own experience is that dailies are more fragile than long-term lenses. (Could this be deliberate?) They fit less comfortably after a week of reuse. Also, they sometimes develop a very tiny nick at the periphery after many days; when that happens you feel it the moment you put it in.
My rule of thumb is that I reuse dailies for 5 days--disinfecting each day of course--and throw them out. The ophthalmologists, who are friends and can speak freely with me, agree that my regimen is fine.
Dailies are more comfortable because they are softer and more porous. That lets more oxygen through and reduces irritation. But it also makes them less resistant to scratches and tears. That's why the manufacturers say you shouldn't clean and reuse them.
Source: my sister manages an optometrist's office.
Dalies are great if you can have them but they don't fix all conditions.
Is it that you can't make use of "soft" contacts in general for this, or just (presumably) that making contacts to correct for this would be sufficiently costly for daily disposibles as to be infeasible?
Stuff is changing all the time
[ * ] Wearing lenses that correct for short-sightedness but not astigmatism is weird. I can see perfectly well, except that text is unreadable. Just text. I wonder if this is how dyslexics feel.
Additionally, I normally wear glasses, and whenever I put my lenses in my first thought is always 'wow, my feet are huge!'...
Literally impossible to correct with soft lenses.
It's hard lenses or a (risky) cornea transplant really (other options like intacs could help but not fix it)
I actually have Pellucid which is often mistaken for Kerataconus so I did the whole shebang of diagnosis!
Mine are fancy and have a soft "skirt" on the edges that make them larger but VERY comfortable.
When I tried to switch back to contacts, with a better prescription [1], I found out that I couldn't stand a full day of them anymore, they just weren't comfortable. Later I realized that I had switched to dailies; when I tried bi-weeklies or monthlies again, they were still as comfortable as I remembered.
[1] I'm short sighted, and although I'm technically not astigmatic, I have need a strong astigmatism correction as well. For the same reason I can't get LASIK either.