Frequency And Causes Of Distance Vision Impairment And Blindness In Adults Assisted In Primary Health Care Units In The City Of Barcelos, Brazilian Amazon

To determine the frequency of distance vision impairment and blindness and their causes in adults with limited access to eye care services, assisted in public primary care units in the city of Barcelos, Amazonas state, Brazil. 

This investigation was conducted in Barcelos, Amazonas, Brazil. Barcelos is characterized by limited ophthalmological services. The selection of Barcelos is warranted due to its high UV radiation levels, with a UV index of 13. At 40 meters elevation, Barcelos has a Human Development Index (HDI) of 0.50, compared to Manaus's HDI of 0.73. This context reveals stark health disparities in remote areas, emphasizing the need for improved ophthalmologic access and reduced visual impairments.

Participants aged 18 years and older who sought healthcare for various reasons in two public primary health care units in Barcelos were invited to undergo eye exams. Uncorrected (UCVA), presenting (PVA), and best-corrected (BCVA) distance visual acuity were measured from each eye using a logMAR chart positioned at 4 m. Anterior and posterior segment assessments and subjective refraction, were performed by ophthalmologists to determine the main cause of visual impairment (PVA less than 20/32) and blindness (PVA less than 20/400) in the better vision eye. Multiple logistic regressions were applied to determine associated factors with visual impairment and blindness. 

A total of 262 persons (59.9% females), aged 18-86 years (mean=52.5±14.0) were examined. The prevalence of presenting moderate to severe visual impairment (<20/63->20/400) in the better eye was 14.1% (95% CI: 10.4% - 18.9%), and 4.2% (95% CI: 2.3% - 7.4%) with best correction. The prevalence of bilateral blindness (<20/400 in both eyes) was 1.9% (95% CI: 0.8% - 4.5%) for both presenting and best-corrected visual acuity. Presenting vision impairment and blindness were associated with older age (p<0.05). Uncorrected refractive errors (56.3%), cataract (35.3%), pterygium (3.6%), corneal scar/opacities (2.4%) and retinal disorders (2.0%) were the most common causes of visual impairment and blindness (PVA<20/32) in this population.  

The current results indicate that visual impairment and blindness is a significant problem in adults from this remote area of the Brazilian Amazon. Initiatives to prevent blindness and provision of refractive services are needed to diminish this evident limited access to eye care services for this population.