Part of Headlight Lens Cloudy on the Inside (Not Moisture)

[Bluesky 07]

My headlights look great with just an occasional polish with Plast-X except for this spot at the upper curve of the right one. It's crazed/cloudy on the inside of the lens and I can't figure out 1) how that happened or 2) what to do about it. The left one is fine. TIA for any thoughts or suggestions.

 

[Will_M]

I simply replace the yellowed headlight with a new one from RockAuto. They are only 80 bucks (SR5/Limited) there. Exact same construction, tabs, materials, and patterns. I have had my yellowed ones restored professionally before but they don't last/come out perfect. For 80 bucks, it's a no-brainer! Aside from the 10 mm bolt, you have to pull back the fender liner to get at, it's easy.

2008 TOYOTA 4RUNNER 4.7L V8 Headlamp Assembly | RockAuto

 

[Seymore Butts]

Looks like the airtight seal failed and it oxidized inside. You'll probably see water in there eventually.