Xerophthalmia is considered a problem in a community if:-

Prevalence criteria for determining the Xerophthalmia problem in a community: Criteria Prevalence Night blindness >1.0% Bitot's spots >0.5% Corneal xerosis / corneal ulceration / keratomalacia >0.01% Corneal ulcer >0.05% Serum retinol >5.0%