Can you clean inside the headlight lens glass ?

What is your question?

My headlights look a bit milky. I know some of it is on the outside but I can also see discoloration inside. Have had the lights off but can't get inside. My 1999 528i Touring wagon has 412,000 km on it. 257,000 miles. Still goes great but has a fault in the tailgate lock that seems to flatten the battery over 10 days or so. NO codes appear. just the left rear tail light warning light on.