If conditions deteriorate you may find you can use visual correction more.

If you have less than perfect vision you might get by if the lighting is good but start to suffer if you are forced to work with emergency lighting. With very good lighting I can read for hours without eye strain but my less than perfect vision betrays me if I'm trying to read with dimmer lighting typical in post-disaster or emergency situation. I can just about read well enough for a while if I use a very bright propane lantern but my eyes give out in a short time if I try to do the same thing with kerosene lamps. Ten minutes trying to read without corrective lenses and poor lighting and I go cross-eyed and develop a headache.

Stress, dehydration, exposure to dust or smoke, and fatigue can make marginally good vision deteriorate temporarily. Point being that if you are sliding by and avoiding getting corrective lenses you really need to break down and get them. Even if you don't routinely wear them they could be important if things go south.

Zenni, and other discount supplier, can make this a lot easier by dropping the cost of glasses. The most expensive part of the process may be the examination and prescription.

If you do get glasses for emergency use you might consider the various benefits of scratch resistant and anti-reflective coatings. I have found them to be so beneficial that they are just about essential and insist on them on any but the cheapest and most expendable glasses far down on the list.