Bitot Spots — Vitamin A Deficiency

A 3-year-old malnourished child from rural India presents with progressive night blindness over 2 weeks, followed by a complaint of gritty eyes. On examination, foamy, triangular gray-white plaques are noted on the temporal bulbar conjunctiva bilaterally, as marked **A** in the diagram. The child's mother reports he has not received any vitamin A supplementation under the Universal Immunization Program. What is the pathological basis of the lesion marked **A**?