Terms
Terms of use
Last updated: May 28, 2026
What these terms say, in plain English.
- VCS-Test is a free contrast-sensitivity screening tool. It is not a medical device, not a diagnosis, and not a replacement for clinical care.
- You can use it as much as you want, for personal use, free of charge.
- We do not promise the test is right for everyone. Your results are your own to interpret, ideally with a clinician.
- We can change these terms. We will note major changes here and on the homepage.
- If we launch a paid tier later, additional account terms will apply at that time.
- Don't scrape the site, spam the test endpoints, or use the tool to attack or defame anyone.
- We are not a HIPAA-covered entity. Nothing here creates a doctor-patient relationship.
The team behind the tool.
VCS-Test is built and maintained by the VCS-Test team. In this document, “we,” “us,” and “our” refer to that team. “You” means whoever is reading this and using the site.
Note: a formal legal entity (likely an LLC) is not yet in place. Once it is, this section will name it, and these terms will become a contract with that entity.
A free, browser-based screening tool.
VCS-Test is a free, browser-based contrast sensitivity test. It estimates how well you can see low-contrast patterns across a few spatial frequencies, and shows you the result as a curve plus a small set of numbers.
It is a screening signal, not a diagnostic device. It is not a substitute for a real eye exam, neurological exam, or any other clinical evaluation. We are not your doctor. Nothing on the site creates a doctor-patient relationship.
Educational, not clinical.
The test, the results page, the blog posts, the FAQs, and every other piece of content on this site are educational. They are not medical advice. Even when an article cites peer-reviewed research and discusses specific conditions, the article itself is general information — not a recommendation about your situation.
Always consult a qualified clinician (an optometrist, ophthalmologist, neuro-ophthalmologist, neurologist, or your primary-care doctor, depending on the issue) before making any medical decision. If you are experiencing a medical emergency, contact your local emergency services — do not rely on this site.
What you can — and can’t — do.
You can:
- Use the test as often as you want, for your own personal vision tracking.
- Share your results with a clinician (print them, save the share link, or — when available — email a PDF).
- Reference our methodology in research, journalism, or academic work, with attribution back to this site.
- Link to the site or to any individual blog post.
Please don’t:
- Resell or repackage the test as if it were a clinical instrument or a regulated medical device.
- Scrape the site at volume, spam the test endpoints, or run automated load that degrades the service for real users.
- Reverse-engineer the calibration step in order to circumvent it (the calibration step exists so results are comparable — bypassing it produces meaningless numbers and undermines the science).
- Use the tool, the results, or the content to defame, harass, or impersonate any person or organization.
- Attempt to gain unauthorized access to any account, server, or data.
Who owns what.
Site content (text, original diagrams, branding) is copyright the VCS-Test team. The underlying methodology draws on publicly described vision-science work (Campbell-Robson, Pelli-Robson, qCSF and related lines) and is publicly described on our methodology page — anyone may reference it. Commercial reuse of our specific implementation, our copy, or our diagrams requires written permission.
Code is currently closed source. We may open-source parts of it later; if and when we do, the open-sourced portions will carry an explicit license file.
Your test results are yours. They are computed in your browser, stored locally on your device, and not claimed as our property. If you share them with a clinician, with a research group, or with anyone else, that is your call.
For the future paid tier.
The core test is free and does not require an account. We may offer a paid tier later (history across devices, clinician-shareable reports, etc.). When that launches, additional terms specific to accounts and payments will apply, and you will be asked to accept them before creating an account.
Account authentication will be handled by Clerk; payments will be handled by Stripe. Their terms govern the parts of the service they provide (authentication and payment processing, respectively). We do not store passwords or card numbers ourselves.
In plain English.
The site and the test are provided “as is.” We do our honest best to make them accurate, calibrated, and useful, but we make no clinical claims about them. We may be wrong. Calibration may be imperfect on your specific device. The science of contrast sensitivity is evolving, and the curves we plot are estimates, not certainties.
Use the tool at your own discretion. We are not liable for medical decisions you make on the basis of this tool, including the decision to seek (or not seek) a clinical evaluation. If your result concerns you, the right next step is to talk to a clinician.
To the maximum extent allowed by law, our total liability for any claim arising out of your use of the site is limited to what you paid us — which, for the free tier, is zero. For the paid tier, it is limited to the amount you paid for the paid tier in the twelve months before the claim arose.
Don’t drag us into your medical decisions.
You agree to indemnify and hold the VCS-Test team harmless from claims, damages, and reasonable legal costs that arise out of (a) your use or misuse of the site, (b) medical decisions you make on the basis of the test or any content here, or (c) your violation of these terms. This does not waive any right you have under applicable consumer-protection law that cannot be waived.
Where disagreements get resolved.
These terms will be governed by the laws of the U.S. state where the operating entity is registered, without regard to its conflict-of-laws rules. Disputes that can’t be resolved by talking should first go to good-faith negotiation; if that fails, to non-binding mediation; and only after that to a court of competent jurisdiction in that same state, or to binding arbitration under the rules of a recognized U.S. alternative dispute resolution body — your choice.
Note: the operating entity and its home state are not yet finalized, so this section names a U.S.-state default rather than a specific jurisdiction. It does not waive any right you have to bring a claim in your local courts under your local consumer law. Once the entity is formed, the governing state will be named here.
When this updates.
We’ll note material updates on this page with the date in the “Last updated” line at the top. For substantive changes — anything that changes what you’re allowed to do, what we promise, or how disputes get resolved — we’ll also call them out in our newsletter (if you’re subscribed) and in a banner on the site for at least 30 days. Continued use of the site after a change becomes effective means you accept the updated terms.
Severability and the whole agreement.
If any part of these terms turns out to be unenforceable in your jurisdiction, that part will be read to the minimum extent necessary, and the rest of the terms will still apply.
These terms, together with our privacy policy, are the entire agreement between you and the VCS-Test team about your use of the site. They replace any earlier statements we’ve made about the same subject.