Most employers believe they perform equally to their sighted colleagues.
Three out of four employers believe visually impaired staff work just as well as sighted employees, according to research carried out by Action for Blind People.
The charity itself has 504 employees, 97 of whom (19 per cent) have visual impairments. Nevertheless, the charity has no positive discrimination policy in place.
"We look at getting the best people, so the recruitment process is the same for all employees," said Martin Sissons, head of information and support services at the charity.
"If at the end of that process we are lucky enough to find that a visually impaired person has emerged as the best candidate, then it's a benefit, because they will bring personal experience to the post.
"Although visually impaired people are individuals, they all have different needs and different things they must access to participate fully in society and the working environment. So although a visually impaired employee will have some insight, it will come from a very personal perspective."
Heather Billington, manager of the charity's hospital information project, is visually impaired and used to benefit from the charity's services.
"Because I have a sight problem, I can understand how clients feel," she said. "I can also understand issues from the point of view of sighted people because I used to have full use of my sight."
At the RNID, 20 per cent of the workforce is deaf, disabled or hard of hearing. Vicky Hemming, director of human resources, agreed that the charity benefits from employing service users - but, like Sissons, she believes people should be recruited solely on the basis of ability.
"People ought to know that if they work for the RNID it's because they are the best person for the job," she said.
Scope takes a more proactive approach. It has set a target to increase the proportion of disabled staff in its workforce to 20 per cent by 2007.
Two years ago, only 150 of its 4,000 staff, or 3.8 per cent, had a disability.
Today that proportion has risen to 17.9 per cent.
"It would be laughable for an organisation like ours not to employ a significant number of disabled people," said Alexandra Burden, Scope's head of communication.
But Burden insists the policy doesn't compromise the charity's ability to pick the best person for the job. "There's no difference in performance - no more than there is a difference between individual employees, disabled or otherwise," she said.