Do cast affects index usage?

["Anibal David Acosta" <aa@xxxxxxxxxxxx>]

I have a table with a column of type timestamp with time zone, this column has an index

 

If I do a select like this

 

select * from mytable where cast(my_date as timestamp without time zone) > '2012-10-12 20:00:00'

 

this query will use the index over the my_date column?

 

Thanks