Abstract: Individuals with cognitive and developmental disabilities have a high probability of visual impairment. This study revealed the effects of deficits in the appropriate diagnosis of vision and medical treatment, as well as the lack of necessary refraction correction and support, specifically for adults with intellectual and developmental disabilities.
There have no been studies of the prevalence or type and severity of visual impairments (both blindness and low vision) in adults with cognitive disabilities in the Federal Republic of Germany to date. A literature review of research in Denmark, the Netherlands, and Great Britain points to a prevalence of 5% to 50% for this population (Evenhuis, Theunissen, Denkers, Verschuure, & Kemme, 2001; Van Splunder, Stilma, Bernsen, Arentz, & Evenhuis, 2003; Warburg, 2001) and leads to the assumption that a similar proportion of adults with cognitive and developmental disabilities in Germany would also have visual impairments that are often not diagnosed. A literature review also showed that people with Trisomy 21 have a high risk of ocular disorders (Down's Syndrome Medical Interest Group, 2005) and that the prevalence of individuals with a visual acuity of less than 20/40 (0.5) is increasing with age (Deremeik et al., 2007).
Undiagnosed visual impairments, untreated eye diseases, and insufficient correction of refractive errors may have direct medical consequences. Furthermore, there can be additional difficulties in the lives of individuals in this population because behavioral patterns are not appropriately interpreted and interventions specifically for visual impairments are not implemented. There is a danger that the goal of participation in social life and particularly in the employment sector will be limited in individuals with cognitive disabilities and undiagnosed visual impairment.
Adults with cognitive and developmental disabilities in Germany work mainly in sheltered workshops for individuals with disabilities and live in small group homes or dormitories, with their families, or independently in the community. The study presented here evaluated the functional vision of 241 employees with cognitive disabilities in a sheltered workshop for individuals with cognitive and developmental disabilities in Glueckstadt, northern Germany. This workshop has two departments: the manufacturing and vocational training department for employees who need intermittent, limited, or extensive support (those with mild, moderate, or severe cognitive disabilities) and the day-support center, with services for individuals with extensive or pervasive needs (severe and pervasive cognitive disabilities). The 241 persons shared the characteristics of an almost complete sample in the two departments of the sheltered workshop; only those who worked outside the workshop in the community or who were ill for a long period of time were not included.
To estimate the degree of intellectual and developmental disability of the participants, we used the classification of the American Association on Intellectual Disabilities. This classification is based on the needs for support of the individual (Luckasson et al., 2002). For 53.5% of the employees, the cause of cognitive and developmental disabilities was unknown to the staff of the workshop. Early childhood brain damage was diagnosed for 14.5%; Trisomy 21 was the cause of intellectual disability for 12.9%; and other causes, such as "accident," "meningitis," or "brain tumor," were mentioned for 19.1%.
COURSE OF THE INVESTIGATION
The evaluation of functional vision was conducted in a room of the sheltered workshop by the first author (a low vision specialist and special education teacher of children who are visually impaired at the State Resource Center for the Visually Impaired in Schleswig) from September 2006 until April 2008. …