Which components compose the pre-corneal tear film?

• A. Only mucous
• B. Mucous, aqueous, and oily tears
• C. Only aqueous tears
• D. Only oily tears

Answer: (B)

The pre-corneal tear film is made of three layers: a mucous (glycoprotein) layer closest to the cornea, an aqueous (watery) layer in the middle, and an oily (lipid) layer on the outer surface. The mucous layer helps the tear film spread and adhere to the hydrophobic corneal surface; the aqueous layer provides most of the tear volume, nutrients, and antimicrobial components; the lipid layer from the Meibomian glands reduces evaporation and stabilizes the film. All three work together to create a smooth optical surface, nourish the cornea, and protect the eye. So the correct answer includes mucous, aqueous, and oily tears. Focusing on only one component misses essential parts of the tear film, making it insufficient.