The three organisations said they wanted to cooperate more effectively in order to deliver the UK Vision Strategy, which was established in 2008 to improve eye health, eye care and sight loss services.
A joint statement from the three organisations said: "The aim would be to rationalise which charity does what and allow each to focus on their particular areas of specialisation in pursuit of the UK Vision Strategy."
The charities said there may also be "some potential to share resources for common functions", although they did not give any concrete examples.
A spokeswoman for the three organisations said she was unable to give further details at this stage.
In the statement, Lesley-Anne Alexander, chief executive of RNIB, said: "We share a joint commitment to improving services across the sight loss sector and have begun discussions on the potential opportunity to maximise the strengths of all three excellent organisations.
"We firmly believe that joining together in this way will provide improved services and a more unified voice for blind and partially sighted people."
Alexander said that she hoped other organisations might join in with the arrangement.
The three charities are working towards making the arrangement operational by 2012, she added.