A lack of specialist support for blind and partially sighted school children has lead to a new "attainment gap" opening up, charity campaigners claimed.
Royal Blind, the organisation which runs the Royal Blind School in Edinburgh, said the number of visually impaired students going on to university was a third less than for sighted youngsters.
It called on the Scottish Government to do more to help blind and partially sighted school pupils, after a significant rise in the number of such students in Scotland's classrooms
According to the charity, the number of children with some form of visual impairment in Scotland's schools increased from 2,005 in 2010 to 4,175 in 2016.
But there was a reduction in the number of specialist teachers for these youngsters over the same period, Royal Blind said - with chief executive Mark O'Donnell saying this meant that "too often these pupils are being let down".
A lack of specialist resources, and the current presumption for sending students to mainstream schools, is hindering the education of blind and partially sighted students, he argued.
Mr O'Donnell said: "Mainstreaming can work for many vision impaired children, but currently too often the right support isn't there for them."
He spoke out after 18-year-old Lewis Shaw, who is now studying at the Royal Blind School, told how he was "excluded" in a mainstream secondary.
The teenager, who is preparing to go to university, said he had a "horrible" time at his previous school and "felt very lonely".
He recalled: "It didn't help that some class teachers refused to change the way they taught. One teacher used PowerPoint presentations for most lessons and refused to adapt this saying, 'it's just the way I work'. All I could hear was the tap tap tap of her pen on the board."
Mr O'Donnell said: "We support blind and partially sighted pupils being educated in mainstream schools where that is right for them, but too often these pupils are being let down.
"We have learned of instances where pupils have not been able to participate in classes because they are told they are 'too visual' or cannot engage in subjects or activities because it is "not safe." This does not represent real inclusion for these pupils.
"Up to 80% of our learning is through our use of vision, therefore, it is vitally important that specialist support is provided for pupils with vision impairment who have a huge learning disadvantage in comparison to their fully sighted peers.
"More research is required into the numbers of vision impaired pupils in Scotland and their specific needs, but the trend is clear - we have an increasing number of pupils with vision impairment. That means more resources needed to support these children, but in fact in many ways there is less.
"Our highly specialist teachers in vision impairment do a great job, with no additional incentives provided for them to undertake their training. But our understanding is that there are fewer of them, being asked to do more and more."
A Scottish Government spokeswoman said: "We want all children and young people to receive the support they need to reach their full potential. Children and young people should learn in the environment which best suits their needs, whether that is in a mainstream or special school setting. There is a range of provision in place in Scotland to meet the wide range of children and young people's needs.
"We are currently working to implement the recommendations of the Education Committee on the attainment of pupils with sensory impairment and will provide an update later this year.
"The Scottish Government is currently consulting on guidance on the implementation of the presumption to mainstream education. We welcome feedback in response to our consultation and will consider all the responses received. The guidance will be finalised taking account of the research which we are currently undertaking into the experiences of pupils, families and those who provide support in schools."