Have you installed the latest patch?

If that doesn't help, use iZakaroN's SaveEditor to remove the points you put in Elven Sight, load the game, put the skill points back into Elven Sight, save, and repeat if necessary to boost your sight back to normal.

An alternate method to work around this bug would be to use an idem editor to add a large sight bonus to a ring, etc.
please help with my blind hero
A more up-to-date editor than the one mentioned in the above topic;
DAD's item editor or the mirror site