A 40 year old male patient complains of diminished vision during night and dryness of eyes. Patient gives history of recurrent bacterial infections. Ophthalmic examination reveals white triangular plaques on conjunctiva. This patient is suffering from deficiency of:

Night blindness (nyctalopia) is one of the earliest symptoms of vitamin A  deficiency. Severe deficiency of vitamin A leads to xerophthalmia. This is characterized by dryness in conjunctiva and cornea, and keratinization of epithelial cells. In certain areas of conjunctiva, white triangular plaques known as Bitot's spots are seen. Satyanarayana- Biochemistry, 3rd edition, pg-123