Students with visual impairments deserve equal access to educational materials and have a legal right to accessible materials. This study explored the critical role and proficiencies of teachers of students with visual impairments (TVIs) in acquiring digital accessible instructional materials (AIM). The Cultural-Historical Activity Theory, Technological Pedagogical, and Content Knowledge frameworks were combined to provide a holistic understanding of TVIs' technological experiences with digital AIM. A mixed-methods transdisciplinary approach surveyed 114 K-12 TVIs across the US to understand their technology use, self-reported proficiency, and experiences acquiring AIM. The study also assessed TVIs' skills in applying digital accessibility best practices through two inaccessible digital document simulations. The results showed that TVIs were the primary personnel responsible for all the major steps in acquiring digital AIM (including gathering, adapting, and teaching technology skills). Time constraints, difficulty obtaining materials from teachers, and technological difficulties were all common obstacles. In 41% of cases, students did not consistently receive accessible materials on time. Despite the rise of digital resources, there was a high need to adapt print materials. A mere 28% of participants were considered proficient in multiple aspects of technology knowledge. Participants primarily used mainstream technology to acquire digital AIM, spent eight hours a week, and commonly spent time outside working hours to meet their students' needs. The number of years of experience did not impact the time spent each week acquiring digital AIM. However, technological proficiency had a significant impact; TVIs who were proficient spent 3.24 hours more per week acquiring digital AIM than those who were not proficient. Participants with higher technology proficiency also spent significantly more time adapting simulations and tended to have greater simulation accuracy. A discussion on the implications of the quality of education for students who are blind or visually impaired led to practical recommendations for more frequent hands-on training using commonly available tools, simplified accessibility guidelines, and building awareness to streamline collaboration processes. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]