There is, but you might find it easier to either change the case of what you are storing using an insert/update trigger, or you can create a function based index on either the upper() or lower() functions. You would then search with the upper() or lower() functions being applied to the search criteria. For me if the column was a username, email or code I would just use a trigger to force everything to be lower case. Then I would use lower() to make sure that the search criteria is lower case. If it is a name I might use initcap to force proper capitalization for names.
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