The eye is our organ of sight. The eye includes cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous. Some common problems associated with eye vision are strain in eyes, red eyes, uveitis, anisocoria, blurry vision, night blindness, dry eyes, cataract, glaucoma, conjunctivitis, eyelid problems, corneal diseases, etc.
A tear film consists of outer lipid layer, intermediated aqueous layer and inner mucus layer. The outermost lipid layer contains low polarity lipid (wax, cholesterol esters) and high polarity lipid (triglycerides, phospholipids). It restricts overflow of tears and prevents evaporation. The middle layer constitutes the main portion of the tear film. This layer provides oxygen to corneal epithelium and washes the debris. The inner most mucus layer plays an essential role in stability of the tear film. It lubricates the ocular surface and protects against irritants. Dry eye syndrome is a condition when the quality of a normal tear film deteriorates by excessive tear evaporation which causes damage to the cornea.