<s>[INST] context: Causes of Dry Eye:- Aqueous Deficiency Aqueous deficiency dry eye also known as keratoconjunctivitis sicca (KCS). Its causes include:a. Sjogren's syndrome (Primary keratoconjunctivitis sicca).b. Non-Sjogren's keratoconjunctivitis sicca. Causes can be grouped as below:1. Primary age-related hyposecretion is the most common cause.2. Lacrimal gland deficiencies as seen in congenital alacrima, infiltrations of lacrimal gland, e.g., insarcoidosis, tumours, post-radiation fibrosis of lacrimal gland and surgical removal.3. Lacrimal gland duct obstruction as seen in old trachoma, chemical burns, cicatricial pemphigoidand Stevens-Johnson syndrome.4. Reflex hyposecretion (neurogenic causes) as seen in Familial dysautonomia (Riley-Day syndrome),Parkinson disease, reflex sensory block, reflex motor blade, 7th cranial nerve damage, reducedcorneal sensations after refractive surgery and corneal lens wear. Lipid Abnormality Absent meibomian Glands: ectodermal Dysplasia Blepharitis Meibomianitis Mucin Deficiency Goblet cell destruction: Chemical burns, cicatricial pemphigoid Vitamin A deficiency Drugs: practolol, Echothiophate Other causes of dry eye Lid problems Exposure keratitis Entropion Ectropion Symblepharon Large lid notches Lagophthalmos Keratinised lid margins [/INST] question: Not a cause of tear film deficiency:- | options: A: Infiltrative disease of lacrimal glands B: Post corneal transplant C: Systemic Vitamin C deficiency D: congenital absence of meibomian gland | answer: C </s>