Define WHO classification for assessment of vitamin A status?

In addition, to the above mentioned manifestations, thickening of the hair follicles (follicular hyperkeratosis) is a cutaneous manifestation of vitamin A deficiency. From the description above it must be clear that xerophthalmia represents the ocular consequences of vitamin A deficiency that includes various manifestations, about which we have learnt above and the same are classified by WHO as given in Table.

Table: WHO classification for assessment of vitamin A status

The classification presented above may be summarized as:

• Stage XN is the earliest stage, involving night blindness owing to impaired dark adaptation,
• Stage XI A is corneal xerosis caused by reduction of goblet cell mucus,
• The appearance of Bitot's spot, a foamy excrescence on the temporal surface of the conjunctiva, constitutes the advancing stages (XIB),
• X2 consists of simple drying of the cornea, a When the cornea undergoes the liguification process of keratomalacia, corneal ulceration, or both, it is classified as X3,
• The situation is classified as X3A if <1/3 of the corneal surface is involved,
• Past involvement leaves a corneal scar (XS), and
• A globe destroyed by advanced keratomalacia is xerophthalmic funclus (XF).

The discussion above focused on the signs and symptoms of vitamin A deficiency. Let us now learn how common the problem of vitamin A deficiency is i.e. the prevalence of vitamin A in our country.