This is a cryptic definition - the entire clue describes the answer in a deliberately misleading way that makes literal sense once you know the answer.
Think about what kind of 'white dominance' could literally trouble or affect viewers' sight. The answer is a compound word (4,9) describing a condition caused by whiteness.
Answer: SNOW BLINDNESS | This is a cryptic definition where 'white dominance' refers to the overwhelming whiteness of snow, and 'troubling viewers' describes how this snow blindness affects people's sight.