According to WHO. blindness is defined as a visual acuity of the better eye, less than –
**Core Concept**
The World Health Organization (WHO) defines blindness in terms of visual acuity, which is a measure of the sharpness and clarity of vision. Visual acuity is typically measured using a Snellen chart, with higher scores indicating better vision.
**Why the Correct Answer is Right**
According to the WHO, blindness is defined as a visual acuity of the better eye of less than 3/60 (20/400 in metric notation). This means that individuals with a visual acuity of 3/60 or worse in their better eye are considered blind. This definition is used to track the prevalence of blindness and visual impairment worldwide, as well as to guide public health initiatives to prevent and treat vision loss.
**Why Each Wrong Option is Incorrect**
* **Option A:** This value is not recognized by the WHO as a threshold for blindness.
* **Option B:** This value is actually the threshold for low vision, not blindness.
* **Option D:** This value is not a valid measure of visual acuity.
**Clinical Pearl / High-Yield Fact**
The WHO's definition of blindness serves as a critical benchmark for global efforts to reduce the burden of vision loss and improve access to eye care services.
**Correct Answer:** C. 3/60