Vertex Lens Calc converts your glasses prescription to the correct contact lens prescription using the clinical vertex distance formula. Most people don't realize the two prescriptions are different — the gap between a glasses lens and your eye changes the effective power, and for higher prescriptions that difference is significant. Enter your Rx, get the corrected values instantly. No account, no ads, free.

Built this because the prescription conversion question comes up constantly and there was no clean, modern tool to handle it. Most people switching from glasses to contacts have no idea their prescription numbers will look different — and when they do notice, they assume something went wrong. The vertex distance adjustment is something opticians do automatically but rarely explain. I wanted to make that math accessible to anyone who's curious about their own Rx. Would love feedback from anyone in eye care or anyone who's been through the glasses-to-contacts switch.

Built this because the prescription conversion question comes up constantly and there was no clean, modern tool to handle it. Most people switching from glasses to contacts have no idea their prescription numbers will look different — and when they do notice, they assume something went wrong. The vertex distance adjustment is something opticians do automatically but rarely explain. I wanted to make that math accessible to anyone who's curious about their own Rx. Would love feedback from anyone in eye care or anyone who's been through the glasses-to-contacts switch.
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