A spokeswoman confirmed that trustees will meet this month to review how money is being spent throughout the charity's operations and within its services in a bid to address an anticipated shortfall in legacy donations.
"We're expecting the value of legacies to be left to us to reduce in the coming year," said a spokeswoman for the RNIB, which uses the proceeds from donated company shares and properties to fund its services.
"If the stock market goes down, our assets bring in less money. Other charities have been affected by the stock market, not just us. We have to ensure that things like our pension fund are adequate."
The RNIB said reports suggesting that the charity was facing a £6.2 million shortfall were "not totally incorrect", but added that a cost-cutting plan of £4.2 million was being considered.
The spokeswoman said the review could involve reducing subsidies for services or increasing the charity's prices.