Purpose:
With continually improving medical screening and treatment techniques for infants and the projected changes in population demographics, it is expected that the number of children and older adults with dual sensory impairments (hearing & vision) will drastically increase. These trends require that eye care professionals and audiologists prepare for appropriate service provision, specifically where low vision and hearing rehabilitation are integrated into dual impairment programs. In order to facilitate effective resource allocation and professional training, the present study summarizes client characteristics from active files across the three rehabilitation agencies in Montreal for individuals with dual sensory impairment, across the lifespan.
Methods:
A total of 614 electronic and paper files of current clients were reviewed of which 50 were excluded based on their living distance from Montreal (> 75 km). The main variables of interest were demographics, diagnosis and severity of vision- and hearing-loss, based on the requirements for service delivery within the Ministère du santé du Québec guidelines (acuity < 20/60, visual field < 60 degrees in the better eye, respectively, pure-tone average hearing loss of more that 26 dB in the better ear).
Results:
Of the 355 female and 209 male individuals, 71.5% were over the age of 64, with 44.5% over the age of 84. Using the Montreal population census information from 2010, the resulting prevalence estimate for DSI is 15/100,000. Only 2.5% (n = 14) of all clients were affected with congenital vision- and prelinguistic hearing-impairment, while 19.7% (n = 110) had a diagnosis of Usher Syndrome. For individuals where both vision and hearing measurements were available, a surprising 39.7% (n = 194) demonstrated losses in both acuity and visual field. 282 individuals (50.6%) were affected with vision and hearing loss combinations that were adult-onset or age-related, such as age-related macular degeneration/presbycusis (n = 179, 32.1%) or glaucoma/presbycusis (n = 25, 4.5%). The results are displayed in dual-sensory-impairment space, whereby visual loss severity is plotted as a function of hearing loss, and layered according to demographic variables, diagnoses, and service delivery programs.
Conclusions:
This population is characterized by great variability across all measures. The display in dual impairment space facilitates visualization of the client distribution and potential gaps in program planning, service allocation and training needs for professionals involved with dually impaired clients. Specifically, eyecare professionals should be aware that great variability exists in both visual field and acuity impairments across all groups of clients with dual loss.
Keywords: low vision • aging • visual acuity