What data does Contact Lens Calc collect?
The conversion, vertex, toric, multifocal, transposition, and over-refraction calculators run as client-side scripts. There is no calculator API in this codebase and no fetch of refraction values. Entered powers remain in the browser for that session.
This site does not run first-party analytics (no Google Analytics, no other tracker in src/). We do not operate an account system, and we do not store a contact-lens prescription.
Ordinary web-server logs on whatever host serves the static files may record IP address, user agent, and requested URL. Those logs are a property of the host, not of the calculator code.
How does Google AdSense use cookies on this site?
Contact Lens Calc is built to display Google AdSense units. When a publisher ID is configured, Google’s advertising services load on the page.
According to Google’s required-content policy for publishers (AdSense Help: Required content), a privacy policy must state the following, which applies here:
- Third party vendors, including Google, use cookies to serve ads based on a user’s prior visits to this website or other websites.
- Google’s use of advertising cookies enables it and its partners to serve ads to users based on their visit to this site and/or other sites on the Internet.
- Users may opt out of personalized advertising by visitingGoogle Ads Settings. Alternatively, you can opt out of some third-party vendors’ use of cookies for personalized advertising ataboutads.info/choicesand, in the EU, atyouronlinechoices.eu.
According to How Google uses information from sites or apps that use our services, when you visit a site that uses AdSense your browser sends the page URL and your IP address to Google. Google may set or read cookies. If ad personalization is on, that information can be used to make ads more useful; if it is off, ads may still appear based on the page topic or general location, but not on an ad profile built from your interests or browsing history.
Ads on this site are labeled “Advertisement”. Auto ads (interstitials, anchors, vignettes) are not enabled from this codebase. We do not encourage clicks on ads.
EEA, UK, and Switzerland: consent
According to Google’s EU user consent policy, sites that use Google advertising products must obtain legally valid consent from end users in the European Economic Area, the UK, and Switzerland for (1) cookies or other local storage where legally required, and (2) the collection, sharing, and use of personal data for personalization of ads. Consent records and a way to revoke consent are required.
This site does not currently show a consent banner or CMP. Until that is implemented, personalized ads should not be served to users in those regions. That is a remaining compliance gap, not a claim that consent is already collected.
California privacy rights
If you are a California resident, the California Consumer Privacy Act (as amended by the CPRA) may give you rights to know, delete, and opt out of the “sale” or “sharing” of personal information, including sharing for cross-context behavioral advertising.
Contact Lens Calc does not sell spectacle-prescription input — that input never leaves the browser. Google AdSense may use advertising cookies that some interpretations treat as “sharing” for behavioral advertising. UseGoogle Ads Settingsandaboutads.info/choicesto opt out of that advertising use. This site does not yet expose a “Do Not Sell or Share My Personal Information” control of its own.
Retention and children
We do not retain calculator input on a server. Google’s retention of advertising data is described inGoogle’s Privacy PolicyandGoogle’s advertising technologies page.
This site is written for eye-care practitioners and educated adult patients. It is not directed at children under 13.
Who answers privacy requests?
Send access, deletion, or disclosure questions tohello@contactlenscalc.comor through thecontact page. There is little to retrieve — calculator input never reaches a server — but the inbox is read, and requests about advertising cookies are answered with the opt-out routes above.
Changes
If collection practices change (for example adding analytics or a consent banner), this page will be updated and the effective date above will change.
Related: About · Contact · Medical disclaimer · How we calculate