Prevalence and causes of visual impairment and blindness in Lao People's Democratic Republic: the Vientiane Eye Study.

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.

Prevalence of Refractive Error in Vientiane Province, Lao People's Democratic Republic.

PURPOSE: To determine the prevalence of adult refractive error and associated risk factors in the Vientiane Province of the Lao People's Democratic Republic. METHODS: Population-based, cross-sectional ophthalmic survey of individuals ≥ 40 years of age in Vientiane Province. Suitable refractive data was available in 1058 individuals. Demographic data, which included age and gender, was obtained from all participants. Smoking status, presence of diabetes and hypertension was also recorded. The ophthalmic examination included autorefraction, grading of cataract, applanation tonometry and ultrasound pachymetry for ocular biometry, including axial length. RESULTS: Mean refractive error measured -0.36 diopters (D) (standard deviation [SD], 1.41) and mean cylindrical error measured -0.33 D (SD 0.95). Myopia ≤ -0.5 D and ≤ -5.0 D occurred in 53.2% (95% confidence interval [CI]: 43.7 to 62.6) and 2.0% (95% CI: 0.4 to 3.6) of participants, respectively. There was a correlation between myopia and both age and higher grading of nuclear cataract (p < .001). Hyperopia ≥ +0.5 D was present in 26.4% of participants and was associated with increasing age (p < .001). Astigmatism was present in 55.8% (95% CI: 51.5 to 60.2) of the population and was associated with increased nuclear cataract (p < .001). Urban participants had a reduced prevalence of myopia compared with rural participants. CONCLUSION: Myopia was associated with younger age and a higher grade of nuclear cataract. The prevalence of myopia in the adult population of Vientiane Province was higher than that reported in neighbouring Asian regions and contributed to low vision.

Prevalence and risk factors for cataracts in the Lao People's Democratic Republic: The Vientiane Eye Study.

Purpose: To determine the prevalence and risk factors for cataracts in the Vientiane Province. Methods: We conducted a population-based study of 1264 participants aged ≥40 years of age from urban and rural areas of Vientiane Province. Data collection included demographic information, smoking history, body mass index, blood pressure, history of trauma and dilated lens examination using the World Health Organization WHO Simplified Cataract Grading System. Aphakic and pseudophakic eyes were included as operated cataracts for statistical analysis. Results: The mean age of the 1264 participants was 57.6 years. The prevalence of any cataract including operated eyes was 46.8% (95% CI: 44.1 - 49.6%): 36.9% nuclear, 21.7% cortical and 10.1% posterior subcapsular cataracts. Conclusion: The prevalence of cataract in the Vientiane Eye Study is similar compared to the prevalence reported in other studies from Asian regions; however, the median age in this study was low, reflecting the age group of the population and the rapid urbanisation occurring in the Lao People's Democratic Republic. A significant association for any cataract was found with elevated blood pressure >148mmHg (OR2.48, 95%CI:1.55 - 3.97, P < 0.01), increasing age (OR1.19, 95%CI:1.17 - 1.22, P < 0.001) and rural inhabitants for cortical cataract (OR1.99, 95%CI:1.37 - 2.90, P < 0.001). An inverse relationship between rural inhabitants with any cataract and nuclear cataract was found (OR 0.63, 95%CI: 0.45 - 0.89, P < 0.01 and OR 0.42, 95%CI: 0.31 - 0.59, P < 0.001) respectively. Nevertheless, cataract remains a high prevalence disease in this population.

Prevalence of glaucoma in the Lao People's Democratic Republic: the Vientiane Eye Study.

AIMS: To determine the prevalence and subtypes of glaucoma in Vientiane Province. METHODS: We conducted a population-based study of 1264 participants aged ≥40 years of age from urban and rural areas of Vientiane Province. Data collection included Snellen visual acuity, slip lamp examination, tonometry, gonioscopy, dilated stereoscopic disc examination and perimetry. Glaucoma was categorised by clinical subtype. RESULTS: The mean age of the 1264 participants was 57.6 years; 91.9% of eyes had a gradable disc. The prevalence of glaucoma of any category in at least one eye was 1.54% (95% CI 0.66% to 3.59%). The overall prevalence of primary open-angle glaucoma, primary angle-closure glaucoma and secondary glaucoma was 0.62% (95% CI 0.19% to 1.98%), 0.55% (95% CI 0.12% to 2.54%) and 0.37% (95% CI 0.07% to 1.86%); 12 (66.7%) of participants with glaucoma were at least unilaterally blinded by WHO definition. CONCLUSIONS: The prevalence of glaucoma in the Vientiane Eye Study is relatively low compared with the prevalence reported in other studies from Asian regions; however, the median age in this study was low, reflecting the age group of the population and the rapid urbanisation occurring in the Lao People's Democratic Republic. Nevertheless, glaucoma remains a blinding disease in this population.