| Non-prescription | Prescription | |
|---|---|---|
| Corrects vision | No | Yes — the part with a clear mechanism behind screen fatigue |
| Requires an eye exam | No | Yes, plus your pupillary distance |
| Typical cost | Low | Higher, though online retailers have narrowed the gap considerably |
| Lead time | Immediate | Days to weeks |
| Suits | People with confirmed good vision who want to try the idea | Anyone who wears glasses, or who has not had an exam recently |
| Risk | Masking an uncorrected prescription with an accessory | Getting the prescription or PD wrong when ordering online |
The case where this matters most
A spectacle wearer who buys non-prescription filtering glasses for computer work has created an impossible choice: wear the filter and work uncorrected, or wear the correction and skip the filter. In practice they wear the correction, the new pair goes in a drawer, and the money is gone.
The alternative is straightforward: when you next order lenses, ask for the filter as an add-on. And while you are having that conversation, ask about two things that will do more for screen comfort — an anti-reflective coating, and, if you are presbyopic and work at a monitor all day, whether an occupational or intermediate-distance lens would suit you better than a standard progressive.
The case for non-prescription
If an eye exam has confirmed you do not need correction, a non-prescription pair is a cheap thing to try, particularly if what you want to test is the evening-light idea. Buy a strongly tinted pair for that purpose rather than a clear one, and spend little.
Buying prescription lenses online
- You need a current prescription. Retailers cannot issue one, and an expired one defeats the point.
- Ask for your pupillary distance at the exam. Self-measurement introduces error that shows up as eye strain.
- Simple single-vision prescriptions are where online ordering works best. Strong powers, significant astigmatism and progressives are where it disappoints.
- Check the returns policy for prescription orders specifically — it is usually stricter than for plain frames.
The longer version: prescription or not?