The phrase "an offense to the eye" is often used to describe something that is visually unappealing or unpleasant. There are several synonyms that can be used instead of this phrase, such as eyesore, ugly, unattractive, repulsive, and unsightly. These words are often used to describe buildings, structures, or objects that are perceived to be out of place or visually unpleasant in their surroundings. Additionally, the phrase "an offense to the eye" can also be replaced with more colorful language, such as "a visual nightmare" or "a repugnant eyesore." Regardless of the word used, these phrases all convey a sense of displeasure with something's visual appearance.