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

Abstract

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.

Keywords: Refractive error; astigmatism; hyperopia; myopia.