A team of international researchers recently found that there hasn’t been a significant reduction in the amount of preventable vision loss cases over the last decade. The study’s results, published in the Lancet Global Health, fell short of the World Health Assembly Global Action plan’s target of a 25% global reduction of avoidable visual impairment, defined as cataract and undercorrected refractive error.

The investigators conducted a systematic review and meta-analysis of population-based surveys of eye disease that were administered for over 35 years. They estimated the prevalence of moderate and severe visual impairment and blindness by cause, age, region and year in adults aged 50 and older.

The study reported avoidable visual impairment and blindness didn’t change between 2010 and 2019. Additionally, the age-standardized prevalence of avoidable blindness decreased by about 15.4%, while avoidable moderate and severe visual impairment showed no change.  However, the number of cases increased for both avoidable blindness (11%) and moderate and severe visual impairment (32%).

Cataracts were the leading global cause of blindness in 2020 at 15 million cases, followed by glaucoma (3.6 million cases), undercorrected refractive error (2.3 million cases), AMD (1.8 million cases) and diabetic retinopathy (one million cases). Leading causes of moderate and severe visual impairment were undercorrected refractive error (86 million cases) and cataract (79 million cases).

In 2020, blindness due to cataract and undercorrected refractive error comprised 50% of global blindness, and moderate and severe visual impairment due to cataract and undercorrected refractive error represented 75% of all global moderate and severe visual impairment cases, the researchers found.

The study results suggest eye care contributed to the observed reduction in avoidable blindness but not to a decrease in moderate and severe visual impairment.

Given that the vast majority of visual impairment and blindness caused by cataract, undercorrected refractive error, diabetic retinopathy and glaucoma can be avoided with early detection and timely intervention, the investigators highlighted the large potential for reducing morbidity in these areas.

GBD 2019 Blindness and Vision Impairment Collaborators; Vision Loss Expert Group of the Global Burden of Disease Study. Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study. Lancet Glob Health. December 1, 2020. [Epub ahead of print].