Lacrimal Apparatus

Layers of the tear film:

• The superficial lipid layer is a monomolecular film at the air-tear interface derived from meibomian glands. It is thought to retard evaporation and form a watertight seal when the lids are closed.
• The middle aqueous layer is elaborated by the major and minor lacrimal glands and contains water-soluble substances (salts and proteins).
• The deep mucinous layer is composed of glycoprotein and overlies the corneal and conjunctival epithelial cells. It is elaborated by goblet cells of the conjunctiva and also by the crypts of Henle and glands of Manz.

A i.e. All of the above

C i.e. Aqueous layer is formed by filtration from blood capillaries

D i.e. Keratoconjunctivitis sicca 

Tear film consists of mucinous (mucus) layer (secreted by goblet cells, crypts of henle, & gland of Manz), antibacterial aqueous layer (by lacrimal gland)Q and oily lipid layer (by meibomian, moll & zeiss glands)Q. It keeps conjunctiva & cornea moist protecting them from drynessQ, & infection and facilitating movements of lid over the globe. It provides oxygen to cornea & washes noxious debris.

A i.e Keratoconjunctivitis sicca

Ans. Mucus layer

Ans. Aqueous layer

Ans. Aqueous tear deficiency dry eye

Ans. 15 to 30 seconds

Ans. Between the last blink and the appearance of first dry spot on the cornea

Ans. Keratoconjunctivitis sicca

Ans. D: 7.5

Human tear film/ precorneal film has three distinct layers, from the most outer surface:

I. Lipid layer secreted by meibomian glands (or tarsal glands) – coats the aqueous layer; provides a hydrophobic barrier that evaporates and prevents tears spilling onto the cheek.

These glands are found among the tarsal plates.

Thus, the tear fluid deposits between the eye proper and oil barriers of the lids

II. Aqueous layer- secreted by lacrimal gland – promotes spreading of the tear film; promotes the control of infectious agents; promotes osmotic regulation

III. Mucous layer- secreted by conjunctival goblet cells – coats the cornea;provides a hydrophilic layer;allows for even distribution of the tear film; covers the cornea

Ans. is ‘d’ i.e., Lacrimal puncta

The major function of lacrimal apparatus is to secrete and drain the tear. Tear film consists of 3 layers :‑

1. Mucous or mucin layer (innermost):- Secreted by conjunctival goblet cells, crypts of Henle, glands of Manz.
2. Aqueous layer (intermediate) :- This forms the bulk of the tear. It is secreted by main lacrimal and accessory lacrimal glands.
3. Lipid layer (outermost) :- Secreted by the Meibomion Zeis, and Moll glands.