The short answer
SPH is how short- or long-sighted you are. CYL is how much astigmatism you have, and AXIS is where that astigmatism sits around the eye. PD is the distance between your pupils, and it decides where the lens centres sit in the frame.
Everything else on the slip describes how the lenses are made or what they are made of, not how well you see.
SPH — the main number
A minus sign means short-sighted, so things far away are blurred. A plus sign means long-sighted. The bigger the number, the stronger the correction, and this is usually the number people mean when they say their prescription is getting worse.
CYL and AXIS — astigmatism
CYL says how much astigmatism you have. AXIS says its orientation in degrees from 0 to 180. A high CYL with the right AXIS is what stops things looking stretched or ghosted — and AXIS on its own means nothing without CYL.
PD — pupil distance
The gap between your pupils in millimetres. Lens centres are aligned to it, and a wrong PD is a common reason a new pair feels subtly off. Ask for it to be measured rather than estimated.
ADD, prism and the rest
ADD is the extra power in the reading section of a multifocal. Prism and base are rarer corrections for eye alignment or double vision. If either appears on your slip, it needs discussing rather than guessing at.
What this means for what you buy
- Strong prescriptions benefit most from high-index lenses, which are thinner and lighter — and cost more.
- Anti-reflective coating earns its price at any prescription; it is the one upgrade nearly everyone should take.
- Photochromic lenses suit people moving between indoors and outdoors; that is a preference, not a necessity.
- Progressive lenses need an accurate PD and a practice willing to adjust the fit afterwards.
Before you order
Ask for your prescription in writing, with the PD on it. It is your record, most practices provide it without being asked twice, and having it means you can compare quotes instead of taking the first one.