Isn't lense the British spelling for lens? It could be the old spelling of it and now it's standardized to lens but I swear I've seen it with an e at the end a few times.
I'm from the UK but I've been in Japan so long where they use American English I have forgotten! Sorry.
I wouldn't be surprised. M-W redirects "lense" to "lens", and a post dated 2002 cites the OED as using "lens" exclusively. I for one don't plan to lose any sleep over it, I'd rather see less apostrophe abuse.