In the last few years, I have had more and more children on my caseload with significant vision issues. They have some unique challenges when learning to communicate, and the research that I was able to find was scarce. Here is some information on speech and language development from what I could find:
1. Imitation Skills: Much of how children learn language is through initiation. Sighted babies will look at their parents and start imitating facial features. Growing up, children will watch their parents and then re-enact it through play. Children who are blind or have significant vision loss, don't have the same opportunities. And while children who are blind may imitate sounds earlier than others, they take longer to attach meaning to the sounds and later words because they are unable to see what their words are referencing. As a result, many children who are blind become echolalic. They also require more direct teaching around vocabulary than their sighted peers.
2. Classification: Classification other than size, shape, and texture can be difficult to learn and often need to be explicitly taught.
3. Vocabulary: Children with visual impairments need to be taught that objects with different forms still are called one word. For example, a fried egg, an egg in its shell and an egg that is broken are all eggs.
4. Multiple Meaning Words: These can be very challenging to learn and to generalize.
5. Non-Verbal Communication and Social Language Skills: Not being able to see how a person's behaviour effects others makes it challenging to learn social cues. They will not have access or adequate access to see or read facial expressions, and body language. Incidental social learning does not happen as often as with children who do not have vision deficits. Skills such as how far away to be when talking, orienting your head and body towards a person you are talking with will need to be explicitly taught.
5. Articulation delays: Due to the lack or limited visual input, there is a higher probability that children with visual impairments will have articulation delays as compared to typically developing peers.
While this isn't a lot of information, it does and has provided a basis to start to provide therapy. If you have any useful information, articles, etc... on this topic, I would love to hear from you.
Brouwer, Kyle et al., (2013) SLP Services with Visual Impairments: A Qualitative Report of Practitioner Practices. Presented at ASHA Convention. Found on ASHA's website.
Brouwer, Kyle et al., (2015) Speech Sound–Production Deficits in Children With Visual Impairment: A Preliminary Investigation of the Nature and Prevalence of Coexisting Conditions. Contemporary Issues In CommunicatIon Science and Disorders, Volume 42 (33-46).