This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nasolacrimal Disorders, Subject name: Ophthalmology
[{'content': 'Not a cause of tear film deficiency:- \nSelect and explain. \nA. Infiltrative disease of lacrimal glands, B. Post corneal transplant, C. Systemic Vitamin C deficiency, D. congenital absence of meibomian gland', 'role': 'user'}, {'content': "Answer: C \nExplanation: 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", 'role': 'assistant'}]