You can pay for your contact lenses on contactlenses.co.uk (without prescription!) using #bitcoin, and they offer a 5% discount!

However, the UX on their website is poor. The integration with BitPay is terrible. The QR code shown in the screenshot doesn't lead to a Lightning invoice, but rather to a URL. To proceed with the payment, you have to open the page in your browser, select a wallet, and then you'll finally be presented with the Lightning invoice.

I plan to write to their support team to provide some constructive feedback.