Is there any documents or publication i can refer to?
Sure, you have quite a selection on that regard. For example, you have the following: Disability Benefits; What you need to know when you get social security disability benefits and lastly, How we decide if you still have a qualifying disability.
O.k, got it written down. Say, can you tell me about average earnings for those visually disabled?
Sure, in the most recent year, 2019, average earnings were of $1220 or more per month and $2,040 or more per month if you're blind.