TABLE 1.

Summary of articles selected for review.

Title	Authors, year and country where study was conducted	Participant age range	Number of participants, including controls	Research method	Level of evidence (ASHA 2004)	Visual characteristics of participants
Development and characteristics of children with Usher syndrome and CHARGE syndrome	Dammeyer, 2012, Denmark	Usher syndrome: 3–17 years CHARGE syndrome: 0–15 years	Usher syndrome: 26 CHARGE syndrome: 19	Survey using medical case records and deafblind consultants	III	Congenital and progressive deafblindness
The dynamic landscape of exceptional language development	Peltzer-Karpf, 2012, Austria	Four studies: 6–10 years, 5–11 years, 18 months-8 years Main case: 18 months-3 years	72	Longitudinal study over 18 months with control groups	IIb	Congenital VI
Development of a vocabulary of object shapes in a child with a very-early-acquired visual agnosia: A unique case	Funnell & Wilding, 2011, England	Study conducted between 2 and 14 years	1	Longitudinal design over 8 years, single case study with retrospective data included	III	Acquired visual agnosia
Developing a schedule to identify social communication difficulties & autism spectrum disorder in young children with visual impairment	Absoud et al., 2011, England	1 year 9 months-6 years 11 months	23	Comparative design for observational tool development	IIb	Congenital VI
Social communication difficulties and autism spectrum disorder in young children with optic nerve hypoplasia and/or septo-optic dysplasia	Parr et al., 2010, England	10 months-6 years 10 months	83	Longitudinal study over 32 years, retrospective case notes review with between subject comparison	III	Congenital VI
Differentiating characteristics of deafblindness and autism in people with congenital deafblindness and profound intellectual disability	Hoevenaars-van den Boom et al., 2009, The Netherlands	7–28 years, developmental age of less than 24 months	10	Comparative design for observational tool development	IIb	Congenital deafblindness
Communication in the early stage of language development in children with pCHARGE syndrome	Peltokorpi & Huttunen, 2008, Finland	Three participants: 1.4, 3.9 and 8.4 years	3	Descriptive multiple single case study design with survey elements	III	Congenital deafblindness
Early communication in dyads with visual impairment	Rattray & Zeedyk, 2005, England	6–18 months	5 dyads (n10)	Longitudinal, comparative design over 1 year with static four-group design	IIb	Mother or child or both had VI
Emotional status and development in children who are visually impaired	Ashkenazy et al., 2005, Israel	0–5 years	74	Longitudinal, comparative design over 18 years	III	Congenital VI