According to the WHO definition of blindness (2019 ICD-11 revision), bilateral blindness is defined as presenting visual acuity in the better eye of:
- A Less than 6/60 (20/200)
- B Less than 6/120 or visual field less than 20 degrees
- C Less than 3/60 (20/400) or visual field less than 10 degrees ✓
- D 6/60 or worse in the better eye
Correct answer: C. Less than 3/60 (20/400) or visual field less than 10 degrees
Explanation
The 2019 WHO/ICD-11 definition retained the earlier threshold: blindness = presenting visual acuity <3/60 (equivalent to <0.05, <20/400, or <1/20) in the better eye, or a visual field of less than 10 degrees in the better eye. Moderate visual impairment is <6/18, and severe visual impairment is <6/60. India uses the same WHO criteria for national blindness prevalence surveys (NPCB).
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
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Written and medically reviewed by the StethoPrep medical team.