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Reading your glasses and contact-lens prescription
Reading your glasses and contact-lens prescription: one rich page plus ~12 item pages: what SPH, CYL, AXIS, ADD, PRISM, BASE and PD mean, minus vs plus…
This guide is general education, not a diagnosis or an individual treatment plan. Urgent, severe or worsening symptoms belong with the local emergency service or a qualified clinician.
What this guide covers
One rich page plus ~12 item pages: what SPH, CYL, AXIS, ADD, PRISM, BASE and PD mean, minus vs plus cylinder and why two prescriptions can look different and be identical, what -2.75 actually means for how far you can see, the near-addition-by-age table for reading glasses, contact-lens parameters (BC, DIA) and why they are not the same numbers as glasses, varifocal vs bifocal vs separate readers, index and coatings without the sales pitch, children's prescriptions and the myopia-control options, and how often an eye exam is recommended at each age.
One focused section asks: "What -3.50 means in real distances".
How to use it
Start with the description that most closely matches your question about Reading your glasses and contact-lens prescription. Use the evidence section to understand what is known, then use the boundary section to decide when self-education should stop and clinical care should begin.
The page keeps the main question, its evidence base and its limits together in one canonical place. That makes it useful as a quick orientation and avoids splitting a broad subject into shallow pages before each narrower answer has enough verified material of its own.
Search vocabulary in four languages
Terminology changes across borders. These are example phrases people use for the same subject in Estonian, Finnish, Russian and English; they are included as a practical vocabulary aid, not as hidden keywords.
| Language | Example phrase |
|---|---|
| Estonian | mida tähendab sfäär ja silinder prilliretseptil |
| Estonian | prillide tugevus dioptrid |
| Finnish | silmälasimääräys sfääri sylinteri akseli |
| Russian | что означает sph cyl ax в рецепте на очки |
| English | what does -3.50 vision mean |
Evidence and provenance
The evidence map below records the primary, official or openly licensed material chosen for this guide. It is deliberately visible so a reader can tell the difference between a rule published by an authority, a measured dataset and an editorial explanation.
Source: own writing and computed conversions; ISO 13666 ophthalmic optics vocabulary (standard, cited not reproduced); WHO World report on vision for examination intervals. · checked 2026-09-09
Source names are preserved even where an authority changes its web address. No figure is added to this launch page unless it is already present in the cited source description or can be computed from a named dataset.
Scope and boundaries
/medterms decodes doctors' notes and lab reports generally; this decodes the one slip of paper almost every adult owns.
Connected TempoLife guides
The following paths are the intentional hand-offs named in the brief. They keep adjacent subjects separate while making the next useful reference easy to find.
Vision
Continue to the related TempoLife reference.
Medterms
Continue to the related TempoLife reference.
Why it belongs on TempoLife
/eyes, /vision, /medterms, /sizes.
Frequently asked questions
What does this guide cover?
One rich page plus ~12 item pages: what SPH, CYL, AXIS, ADD, PRISM, BASE and PD mean, minus vs plus cylinder and why two prescriptions can look different and be identical, what -2.75 actually means for how far you can see, the near-addition-by-age table for reading glasses, contact-lens parameters (BC, DIA) and why they are not the same numbers as glasses, varifocal vs bifocal vs separate readers, index and coatings without the sales pitch, children's prescriptions and the myopia-control options, and how often an…
What evidence does it use?
own writing and computed conversions; ISO 13666 ophthalmic optics vocabulary (standard, cited not reproduced); WHO World report on vision for examination intervals.
Where does this guide stop?
/medterms decodes doctors' notes and lab reports generally; this decodes the one slip of paper almost every adult owns.
Turn the reference into a routine
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