I read this story a while ago, probably before 2015. It did not seem to be -very- old. Perhaps it was written some time between 1980 and 2015. I read it in an athology but I do not recall if it was a physical book or online.
The blind lady's husband is a highly skilled neurosurgeon. At first he is trying to develop a way to operate on her brain to restore her sight.
Her husband comes to the conclusion that there is no way to restore her sight. However, he thinks that if he can repurpose the huge part of the brain normally used for processing vision, he can greatly improve her intelligence.
He does not tell her about the change of plans. She goes into the operating theatre believing he is attempting to restore her sight.
When she comes around from the anaesthetic, she is extraordinarily intelligent. It takes her a very short time to work out what her husband has done and why. She forgives him for lying to her and hugs him.
Several other blind people have this operation and also become much more intelligent.
Then some sighted people decide to have the procedure, to increase their intelligence, even though they know they must give up their sight in return.
Eventually so many people are having the operation that it is impossible for anyone not operated on to compete with them and get almost any job.
There are exceptions, some jobs still require the person to be able to see, such as a trainer of guide dogs.
The surgeon feels pretty guilty that the operation he developed has caused so many people to voluntarily become blind in order to compete with those who have already had the operation.
