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Prevalence and causes of visual impairment and blindness in Lao People’s Democratic Republic: the Vientiane Eye Study
  1. Yiran Tan1,2,
  2. Brad Guo1,
  3. Stephen Nygaard2,
  4. Cesar Carillo1,
  5. Huy-Dat Pham2,
  6. Kham Od Nouansavanh3,
  7. Kitar Souksamone3,
  8. Robert J Casson1,2
  1. 1Department of Ophthalmology, Royal Adelaide Hospital, Adelaide, South Australia, Australia
  2. 2Discipline of Ophthalmology and Visual Sciences, The University of Adelaide, Adelaide, South Australia, Australia
  3. 3Department of Ophthalmology, National Ophthalmology Centre, Vientiane, Lao People's Democratic Republic
  1. Correspondence to Professor Robert J Casson, Department of Ophthalmology, Royal Adelaide Hospital, Adelaide, South Australia, Australia; casson.robert{at}


Aims To determine the prevalence and causes of visual impairment and blindness in Vientiane Province, the Lao People’s Democratic Republic (Lao PDR).

Methods We conducted a population-based, cross-sectional study of 1264 participants aged 40 years and older from urban and rural areas of Vientiane Province. The ophthalmic examination included presenting and pinhole Snellen visual acuity (VA) with an illiterate E chart, slit-lamp examination of the anterior segment and dilated stereoscopic fundus examination. Visual impairment and blindness were defined by both presenting and pinhole VA based on the better eye according to WHO criteria: VA worse than 6/12 to 6/18 for mild impairment, VA worse than 6/18 to 6/60 for moderate impairment, VA worse than 6/60 to 3/60 for severe impairment and VA worse than 3/60 for blindness.

Results Comprehensive ophthalmic examinations were performed on 1264 participants (77.8% participation rate). Population-weighted prevalence of presenting bilateral blindness was 1.4% (95% CI 0.8 to 2.0) and bilateral visual impairment was 22.4% (95% CI 14.7 to 30.1). After pinhole correction, the corresponding prevalence of blindness was 1.3% (95% CI 0.8 to 2.0) and that of visual impairment was 12.6% (95% CI 8.2 to 16.9). Cataract was the leading cause of presenting bilateral blindness (52.9%), whereas uncorrected refractive error was the predominant cause of presenting visual impairment (40.3%).

Conclusions Visual impairment and blindness remain major public health problems in Lao PDR. There is an ongoing need to fund ophthalmic care resources and community education programmes to improve access to healthcare in this region.

  • epidemiology

Data availability statement

Data are available upon reasonable request.

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Data availability statement

Data are available upon reasonable request.

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  • Contributors In accordance with the International Committee of Medical Journal Editors (ICMJE) guidelines, all co-authors were involved in either drafting or revising the manuscript critically for important intellectual content. All authors gave final approval of the version to be published and agree to be accountable for all aspects of the manuscript. In addition, RJC made substantial contributions to the conception and design of the project. YT, SN, CC, KON and KS made substantial contributions to the acquisition of the data. YT, BG and H-DP made substantial contributions to the analysis and interpretation of data.

  • Funding The project was financially supported by the non-government organization Sight For All.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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