What is the most common cause of low vision and blindness worldwide?

The most common cause of low vision and blindness worldwide is untreated cataract. Cataracts lead to clouding of the lens in the eye, which causes significant visual impairment. They can develop due to various factors, including aging, but also as a result of trauma, certain medications, or diseases such as diabetes.

As cataracts progress, they can obscure vision to the point where it affects daily activities and quality of life. The condition is particularly prevalent in low-income countries where access to surgical treatment is limited. When untreated, cataracts remain the leading cause of reversible blindness globally.

The other conditions listed, such as diabetic retinopathy, aging-related macular degeneration, and glaucoma, also contribute to vision loss, but either they are less common in the overall population or have different prevalence rates based on geographic and demographic factors.