According to WHO , blindness is defined as a visual acuity of the better eye, less than –
**Core Concept**
Blindness is a severe visual impairment that significantly affects an individual's quality of life. The World Health Organization (WHO) has established a standard definition for blindness based on visual acuity.
**Why the Correct Answer is Right**
The WHO defines blindness as a visual acuity of the better eye, which is less than 3/60 or 20/400. This definition is based on the Snellen visual acuity chart, where 6/60 or 20/200 is considered as a severe visual impairment. A visual acuity of 3/60 or 20/400 in the better eye indicates a profound loss of visual function, making it difficult to perform everyday activities without assistance.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the WHO definition of blindness is based on a visual acuity of less than 3/60 or 20/400, not less than 6/60 or 20/200.
**Option B:** This option is incorrect because it is too broad and does not accurately reflect the WHO definition of blindness.
**Option C:** This option is incorrect because it is too narrow and does not account for individuals with severe visual impairments who may still have some residual vision.
**Clinical Pearl / High-Yield Fact**
The WHO definition of blindness is critical for public health efforts to address visual impairment and blindness worldwide. Understanding this definition is essential for healthcare professionals to provide accurate diagnoses and interventions for patients with visual impairments.
**Correct Answer: D. 3/60 or 20/400**