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2. Kim BH, Han SH, Shin YG, et al. Aided distance visual acuity and refractive error changes by using smartphone. J Korean Ophthalmic Opt Soc. 2012;17(3):305-309.
3. The Korea Optical News. 10747 Opticians during the COVID-19 era in Korea, 2021. http://www.opticnews.co.kr/news/articleView.html?idxno=34555(30 August 2021).
4. KOSIS(Korean Statistical Information Service). Current Status of Clinics by Designated Subject by City, County, and District, 2022. https://kosis.kr/statHtml/statHtml.do?orgId=354&tblId=DT_HIRA4G(12 December 2022).
5. The Korea Optical News. The Number of Opticians has Increased by 2,127 in 10 years in Korea, 2017. http://www.opticnews.co.kr/news/articleView.html?idxno=28735(30 August 2021).