Social Determinants and Their Impact on Visual Impairment in Southern Mexico.

Purpose: Visual impairment in disadvantaged populations in Mexico has been scarcely reported. We compared the prevalence of visual impairment and its associated risk factors in populations in rural compared to urban areas of the Mexican southern state of Chiapas.

Methods: In a population-based study, the prevalence of visual impairment in rural and urban areas of Comitan, Chiapas, was estimated. All eligible individuals aged ≥20 years living in rural areas were invited to participate; persons from urban areas were chosen randomly. Individuals were considered of indigenous (IND) origin either by self-report or if they spoke an IND language. Visual acuity (VA) and pinhole VA were measured using a tumbling E chart. VA was defined as normal (better than or equal to 20/60), moderate impairment (worse than 20/60 but better than or equal to 20/200), severe impairment (worse than 20/200 but better than or equal to 20/400), or blindness (worse than 20/400).

Results: Data on VA were obtained from 969 persons (610 rural, 359 urban) whose mean age was 43.3 years (standard deviation 15.6 years). Prevalence of moderate visual impairment was higher in rural (10.2%, 95% confidence interval, CI, 7.2-14.2%) than urban (3.9%, 95% CI 1.9-7.9%) areas (p < 0.001). Persons with moderate visual impairment were older and less educated (both p < 0.001). Rural individuals aged 50 years and older had 4.4 times (95% CI 1.8-11.3, p = 0.002) the likelihood of having moderate visual impairment compared with urban persons.

Conclusion: Unfavorable socioeconomic conditions were associated with higher prevalence of moderate visual impairment in rural compared with urban populations in Mexico.