As an undergraduate in the field of optics, I feel that it may be prudent to bring up some points:
- Regular eye checks (perhaps yearly for most people or half-yearly for the elderly) are advisable, regardless of whether you have astigmatism.
- Slight under-correction is sometimes done in lenses for short-sighted people (to slow the progression of the myopia), but never for long-sighted people as doing so would apply constant strain on the eyes.
- Yes, there will usually be a slight adaptation period to lenses. However, if you see double images or colored fringes around objects, get the prescription checked as it is probably wrong (these are prismatic effects).
- Progressive lenses can be tricky to dispense due to the precision needed; it is best to consult a qualified optician/optometrist for one rather than purchase one cheaply from any Tom, Dick, or Harry (the progressive lenses require precise centering of the lenses in front of the eyes - erroneous centration leads to side effects).
Generally, though, more people need to be aware that regular eye checks should be done (like dental checks). Even if you have perfect eyesight, conditions like glaucoma have insidious onsets - by the time symptoms manifest, there may already be permanent damage to the optic nerve (that causes irreversible tunnel vision).
I should probably also stress on the potential importance of consulting an eye care practitioner (ECP) that you are comfortable with, and who is competent as well as trustworthy. It is better to have follow-ups with such an ECP than to hop all over, since the ECP would have an easier time recognizing possible problems. Plus, he/she would be less inclined to con a regular customer XD