Sensory Impairment, Vision and Hearing

Types of Dual Sensory Loss and Prevalence

Individuals with combined vision loss and hearing impairment can be classified into three heterogeneous groups (Glass, 2000). The first group comprises persons who have experienced vision and hearing impairments since birth or early childhood. Many infants and children with congenital or perinatal sensory loss also have other physical or cognitive impairments (Zambone, Ciner, Appel, & Graboyes, 2000). In some cases, the etiology of the sensory loss is unknown or undetermined, but major causes for sensory loss in this population are premature birth/low birth weight, other childbirth complications, mental retardation, neurological impairments (e.g., cerebral palsy), trauma, or infectious disease (e.g., rubella). A number of specific congenital syndromes are characterized by the presentation, progression or development of concurrent losses of vision and hearing in this population, including Usher syndrome, Goldenhar syndrome, and Hurler syndrome (Zambone et al., 2000). Prevalence estimates of dual vision and hearing impairment among infants and children are imprecise, but it is estimated that approximately 11,000 children in the United States are deaf-blind, accounting for 12% of the roughly 100,000 visually impaired children (i.e., birth to 21 years) who receive special education services (Kirchner & Diament, 1999).

The second group consists of persons who experienced one sensory loss since birth/early childhood and have become dual impaired as a result of age-related disease, for example, a person born deaf who develops age-related macular degeneration. The third, and most numerous, group consists of those who have lived most of their lives with so-called normal vision and hearing and have developed age-related losses in both senses. Glass (2000) noted that these individuals have not had the life experience with sensory loss or relevant training to cope and adapt with these conditions. The numbers of older people experiencing concurrent age-related loss in vision and hearing can be expected to grow substantially with the aging of the population.

Given the well-documented relationship between single sensory impairments and advanced age, it is not surprising that the prevalence of dual sensory impairment also has a strong, positive relationship with age. For example, in adults 51 to 60 years of age, the prevalence of dual impairment among these preretirees is 4% (Su & Brennan, 2003). Among adults age 70 and older, the prevalence of dual sensory loss ranges from 10% to 21%, depending on the sample and how impairment is assessed. However, there is evidence that the prevalence of vision and hearing loss is decreasing in the older population in line with the decrease in the rates of other chronic conditions in later life (Brennan, 2003).

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