Sensory inputs of hearing and vision during early childhood development support the achievement of language, speech and educational milestones. The early detection of sensory impairment is essential for facilitating early childhood development, socio-emotional well-being and academic success, in addition to obtaining sustainable educational development goals. The majority of children with sensory impairment live in low- and middle-income countries where services are often unavailable or inaccessible, because of the absence of systematic screening programmes for children, prohibitive equipment cost, a shortage of trained personnel and centralised service-delivery models. Therefore, research is needed to investigate whether a community-based mobile health (mHealth) supported service-delivery model for hearing and vision screening can increase access to hearing and vision services for children in resource-constrained settings. This study aimed to describe an implemented hearing and vision screening programme and evaluate its success in terms of acceptability (consent return numbers), coverage (number of eligible children screened), referral rates and quality indicators (duration of tests and number of hearing tests conducted under conditions of excessive noise levels). The study also explored the challenges faced during a community-based screening programme and the strategies developed to address these. Four non-professionals were appointed and trained as community health workers (CHWs) to conduct combined sensory screening using mHealth technology (hearScreen application, hearXGroup, South Africa and Peek Acuity application, Peek Vision, United Kingdom) on smartphones at preschools in low-income communities in Cape Town, South Africa. The consent form return rate was 82.0%, and the coverage rate was 94.4%. An average of 501 children were screened each month, at a cost of US$5.63 per child. The number of children who failed hearing and vision screening was 435 (5.4%) and 170 (2.1%), respectively. Failing of hearing tests was associated with longer test times (odds ratio [OR]: 1.022; 95% confidence interval [CI]: 1.021–1.024) and excessive background noise levels at 1 kHz (e.g. OR for left ear: 1.688; 95% CI: 1.198–2.377). Failing of visual screening tests was associated with longer test duration (OR: 1.003; 95% CI: 1.002–1.005) and younger age (OR: 0.629; 95% CI: 0.520–0.761). The study also aimed to describe and compare the performance of two screening protocols that were used in this preschool hearing screening programme to determine optimal referral criteria that is responsive to available resources. Secondary data analysis was done to compare a protocol using a single-frequency fail criterion (which 2,147 children were screened with between 1 October 2017 and 25 February 2018) with a screening protocol using a two-frequency fail criterion (which 5,782 children were screened with between 26 February 2018 and 30 November 2018). For both protocols, screening was done at a 25 dB hearing level (HL) at 1000, 2000 and 4000 Hz. Both protocols included an immediate rescreen at the frequencies that were failed. The referral rate was 8.7% (n = 186) for the one-frequency fail protocol and 4.3% (n = 250) for the two-frequency fail protocol. Compared to the one-frequency fail protocol, children screened with the two-frequency fail protocol were 52.9% less likely to fail (OR: 0.471; 95% CI: 0.385–0.575). Gender (OR: 0.807; 95% CI: 0.531–1.225) and age (OR: 0.996; 95% CI: 0.708–1.402) had no significant effect on screening outcomes. Maximum permissible ambient noise levels (MPANLs) were exceeded in 44.7% of cases in at least one ear at 1000 Hz across both protocols. There was no significant difference between the protocols for both true positive cases and false positive cases. Protocol (OR: 1.338; 95% CI: 0.854–2.098), gender (OR: 0.807; 95% CI: 0.531–1.225) and age (OR: 0.996; 95% CI: 0.708–1.402) demonstrated no significant effect on the odds of producing true positive results. Average time for conducting the screening was 72.8 s (78.66 SD) for the one-frequency fail protocol and 64.9 s (55.78 SD) for the two-frequency fail protocol. Estimating the prevalence and describing the characteristics of sensory loss in a preschool population in low-income communities are important steps to ensure adequate planning and successful implementation of community-based hearing and vision care in this context. The study therefore also investigated the prevalence and characteristics of hearing and vision loss among preschool children (4 to 7 years) in an underserved South African community after implementing mHealth-supported community-based hearing and vision services. Children who failed hearing and vision screening were seen for follow-up assessments at their preschools. Follow-up assessments were also performed with smartphones and hearing and vision testing applications (hearTest application, hearX Group, South Africa and PeekAcuity app, Peek Vision, United Kingdom). A total of 10,390 children were screened at 298 preschools over 22 months. Of the children screened, 5.6% and 4.4% of children failed hearing and vision screening, respectively. Community-based follow-up hearing tests were done at the preschools on 88.5% (514) of the children, of whom 240 children (54.2% female) presented with hearing loss. A preschool-based follow-up vision test was conducted on 400 children (88.1%). A total of 232 children (46.1% female) had a vision impairment, and a further 32 children passed the test but had obvious signs of ocular morbidity. Logistic regression analysis found that age was a significant predictor of vision loss (p < 0.001): with every 1-year increase in age, participants were 51.4% less likely to have vision loss (OR: 0.49, 95% CI: 0.39–0.60). Age was not a significant predictor for hearing loss (OR: 0.821; 95% CI: 0.667–1.011). Gender was not a significant predictor of hearing loss (OR: 0.850; 95% CI: 0.658–1.099) or vision loss (OR: 1.185; 95% CI: 0.912–1.540). The prevalence of hearing loss at a pure tone average (PTA) of 25 dB HL ranged between 2.3% (240 out of 10,390; assuming none of the non-attenders and children who were unable to be tested had hearing loss) and 3.1% (321 out of 10,390; assuming all the non-attenders and children who were unable to be tested presented with hearing loss). The prevalence of vision loss ranged between 2.2% (232 out of 10,390; assuming none of the non-attenders had vision loss) and 2.8% (286 out of 10,390; assuming all the non-attenders presented with vision loss). Findings of this research project indicate that mHealth-supported CHW-delivered hearing and vision screening in preschools provide a low-cost, efficient and accessible service that can improve the provision of affordable hearing and vision care. This service-delivery model is affordable and scalable, because the same staff, needing minimal training, and the same equipment are used to screen for both vision and hearing. Timely identification of sensory losses is essential to ensure optimal outcomes and can be facilitated through community-based hearing and vision services by trained CHWs using mHealth technology. Future studies should aim to report on outcomes and the uptake and impact of interventions on the children diagnosed with sensory impairments following identification through a decentralised screening programme. / Thesis (PhD (Audiology))--University of Pretoria, 2021. / Sonova AG / Hear the World Foundation / Speech-Language Pathology and Audiology / PhD (Audiology) / Unrestricted