You are going to have to replace the entire Headlamp Assembly, very expensive.
remove cap of the back of your light to expose the bulb. then remove the bulb from the head light. leave for a couple of hours to let moisture evaporate. or do the above and use a bit of kitchen roll to dab up the moisture being care full not to damage/scrape the reflective surface of the light replace bulbs when condensation disappears hope this helps
Remove the head light cover plate, then remove head light braket, once you have done that pull the light out and un-plug it.
In the head liner right by the dome light and sun roof control
HOW DO I CHANGE LIGHT BULBS
The 2009 Lexus IS-350 has 36.7 in. of rear head room.
The 2014 Lexus IS-F has 36.7 in. of rear head room.
The 2012 Lexus IS-350 has 37.2 in. of front head room.
The 2009 Lexus IS-F has 37.2 in. of front head room.
The 2010 Lexus IS-350 has 36.7 in. of rear head room.
The 2013 Lexus IS-250 has 37.2 in. of front head room.
The 2013 Lexus IS-350 has 36.7 in. of rear head room.
The 2008 Lexus IS-350 has 36.7 in. of rear head room.