Genesis 19:11

Blindness. God permitted Lot to make an attempt to change the wicked design of the Sodomites in order that he might be impressed with the degree of their depravity. When his extreme efforts proved unavailing the heavenly visitors stepped in to protect both him and themselves from harm. The Hebrew word here translated “blindness” is used but once elsewhere in the OT (see 2 Kings 6:18-20). In both instances it denotes a supernatural form of blindness. It may not have been total, and perhaps involved only a temporary loss of clear vision that bewildered the mind. That they “wearied themselves to find the door” implies mental as well as visual confusion. Had they been struck totally blind in the usual sense of the word it seems unlikely that they would have persisted in their evil purpose.